Caullerya mesnili, a common microparasite of the cladoceran Daphnia . At three sites, we also studied parasite genetic variation over time (three to four sampling points) and tested for associations between parasite genotypes and host species.Detailed knowledge of spatial and temporal variation in the genetic population structure of hosts and parasites is required for understanding of host − parasite coevolution. As hot-spots of contemporary coevolution in natural systems are difficult to detect and long-term studies are restricted to few systems, additional population genetic data from various host − parasite systems may provide important insights into the topic. This is particularly true for parasites, as these players have been under-investigated so far due to the lower availability of suitable molecular markers. Here, we traced genetic variation  among seven geographically isolated populations of the ichthyosporean Caullerya. However, the distribution of parasite genotypes was similar across different host species, which might in turn have important consequences for parasite epidemiology.Parasite (and host) populations were significantly structured across space, indicating limited dispersal. Moreover, the frequency of parasite genotypes varied significantly over time, suggesting rapid evolutionary change in The approach proposed here can be applied to track spatial and temporal changes in the population structure of other microparasite species for which sequence variation in the ITS or other highly variable genome regions has been documented but other types of polymorphic markers are lacking. Screening of parasite sequence variants allows for reliable detection of cross-species infections and, using advanced sequencing techniques in the near future, for detailed studies of parasite evolution in natural host − parasite systems.The online version of this article (doi:10.1186/s12862-014-0247-3) contains supplementary material, which is available to authorized users. Daphnia–microparasites . Howe. Howe3])es e.g. -8), chyt, chytDapes , and, andDaphes e.g. ,14). In . In Daphes . For. For20])Daphnia (Crustacea: Cladocera), key components of zooplankton in many lakes and ponds across the globe, and their microparasites . In . In Daphly e.g. ,28). For. ForDaphulations ,16. We dulations ,30), haval phase ,32.Daphnia species from the D. longispina hybrid complex. In Europe this complex includes, among other taxa, the widespread and ecologically important species D. cucullata, D. galeata and D. longispina, as well as their interspecific hybrids [Daphnia are frequently infected by a variety of parasites  of ribosomal DNA can be used [Caullerya populations collected from three geographically isolated lakes were distinct from each other [In the present study, we analysed infections of  hybrids ,34. Theses (e.g. ). Among phonida, ) is part Daphnia . This paduction, ,37). Indn levels ,37. For  be used ,38. SpecCaullerya populations in more detail. We studied parasite genetic variation over space . We expected to observe substantial spatial isolation among parasite populations, as Caullerya appears to have no transmission vector other than its passively dispersing Daphnia hosts [Caullerya populations should change genetically, to remain infective to their ever-changing host. For Caullerya populations from three of the studied sites, we simultaneously collected genetic data from their individual Daphnia hosts. At this point, we aimed to compare the distribution of parasite genotypes across different coexisting host Daphnia species and their hybrids. We expected that host species would exhibit differing spectra of parasite genotypes, as previous experimental studies showed a varying likelihood of infection when these species were exposed to Caullerya [Here, we applied the same ITS marker to study genetic changes in ia hosts . We thenaullerya .Caullerya genotyping. All 16 samples had been genotyped after pooling of 20 infected hosts, per sample. Additionally, three of those samples were genotyped on the individual level: ten infected hosts per sample [Caullerya ITS sequence variants were identified among 795 obtained ITS sequences. These ITS variants were further assigned by statistical parsimony network analysis to ten different representative sequence variants, TCS-types . The spatial  variance component was significant in all three cases analysed , explaining up to ~22% of the parasite genetic diversity  or after a shift in time (Římov 2004 and Vír 2005). The extent of the spatial and temporal separation of Daphnia hosts selected from Římov, Vír and Želivka, sampled in 2004. These individual Daphnia  were analysed at 15 microsatellite loci. The position of Daphnia individuals relative to reference genotypes in the FCA plot  was more similar across different host species originating from the same lake than within host species from different lakes , the only host species present in all three lakes was D. galeata . AMOVA tests revealed that a significant amount of genetic variation in the D. galeata dataset was explained by the among-lakes component . The latter finding is consistent with previous studies on the D. longispina complex; Daphnia populations from different lakes are often genetically differentiated even within a single region at relatively small spatial scales  could survive the passage through the bird’s gut because of a thick and robust spore wall [Daphnia host on the body surface of waterfowl. However, even if parasite spores are spread by birds in this way, such dispersal pathways would need to provide infective doses high enough for successful transmission . The. TheDaphphippium ,45. Immiphippium ,46,47. Iinfected . Insteadore wall , and theon (e.g. ).Caullerya populations observed here might also be influenced by processes other than limited gene flow. In particular, temporal changes within Caullerya populations, as were observed in the studied reservoirs, may cause rapid genetic divergence. Moreover, environmental differences among the studied lakes such as the trophic level  might piewed in ). Finalliewed in ,50 mightCaullerya. In lakes Římov and Vír, for example, the genetic composition of Caullerya populations varied substantially during the five-year study period. Again, it cannot be excluded that the observed temporal changes are not only a result of adaptation of the parasite to its changing host, but fluctuating environmental conditions might play a role too. Indeed, genotype-by-environment interactions have been previously observed in the Daphnia − Caullerya system [Daphnia − Caullerya system appears to be an attractive model for studying host − parasite coevolution in the wild, because of its accessibility . Thus, lations, ,37), theDaphnia host species were all infected by the same genotypic array of the parasite Caullerya. This is surprising at first sight, because a prerequisite for parasite-driven, negative frequency-dependent selection is a strong genetic specificity for infection, resulting in genetically different hosts being infected by genetically different parasite strains [D. longispina system studied here, where different Daphnia species coexist despite some differences in their ecological preferences [Caullerya genotypes between different Daphnia species is host hybridization. Specifically, Daphnia hybrids might serve as ‘stepping stones’ that allow parasites to switch among host species . Despit strains , but ide strains . Such ho strains . This miferences ,58. Anot’ model, ). Regard’ model, ,61, a pr’ model, .Daphnia host species and even genotypes differ in their likelihood of becoming infected with Caullerya . Sti. StiDaphon (e.g. ). If a ssts (see ).Daphnia (microsatellites) and for Caullerya (ITS region). Although these markers would still be linked to loci under selection in our (mainly) clonal host − parasite system, the outcome of coevolution actually depends on the loci coding for resistance in hosts and infectivity in parasites see . In thee e.g., ,65,66). ,66. Daphnologies -69.Caullerya mesnili infecting the cladoceran Daphnia host. Our results suggest that Caullerya can evolve rapidly and is thus likely to adapt to its hosts, as we detected significant genetic variation in parasite populations across space and time. When upcoming molecular and bioinformatic tools allow changes in genotype frequencies of parasites and hosts to be tracked together on a large scale and over the long term, the Daphnia − Caullerya system might become a useful model for host − parasite coevolution in the wild. Moreover, the methods proposed here allow access to molecular studies of other microparasite species, for which sequence variation in the ITS or other highly variable genome regions has been documented but other types of polymorphic markers are lacking.In summary, by analysing ITS sequences, we successfully addressed spatial and temporal variation in the genetic structure of the ichthyosporean microparasite Daphnia communities from eleven drinking water reservoirs in the Czech Republic were screened for parasite prevalence in summer and autumn of 2004 and 2005, across three stations along each reservoir’s horizontal axis: upstream, middle and downstream [Daphnia hosts in these lakes are represented almost exclusively by members of the D. longispina complex [Caullerya mesnili was abundant in seven of these lakes , mainly in autumn and at the upstream sites, infecting up to 40% of the entire Daphnia community [Daphnia populations already collected for other purposes. Collections were taken at all seven lakes in autumn of 2004 and 2005 [In a previous work, wnstream . The Dap complex ,34. The ommunity . The posommunity . For theand 2005 , as wellCaullerya-infected Daphnia, for analyzing parasite genetic variation. This resulted in 16 zooplankton samples across seven locations, 1 to 4 per lake  from Římov, Vír and Želivka, sampled in autumn 2004, and determined host genotypes from the respective DNA samples .We randomly selected ~50 additional Both ITS data sets  was genotyped at 15 microsatellite loci. These hosts originated from Římov, Vír, and Želivka, sampled in 2004  in GENETIX 4.05 [D. cucullata, D. galeata and D. longispina), as well as their interspecific hybrids. Thus, we obtained joint information on the taxonomic classification of 30 host individuals (microsatellite data) and the genotypes of parasites (ITS data) infecting each of these Daphnia hosts. Second, to study the extent of among-population genetic differentiation in hosts, we genotyped approximately 50 randomly selected Daphnia individuals from each of the three aforementioned lakes, sampled in 2004, at 10 of the above used 15 microsatellite loci  were uses as in ). This res as in , using tes as in .Daphnia, and 3 of these population samples in which infected Daphnia were also genotyped individually, see Table Caullerya representative ITS-sequence variants (TCS-types) in each sample. Then, to test for statistical differentiation, we applied hierarchical analyses of molecular variance, AMOVA  among lakes, and 2) within lake. AMOVA was applied separately per year, focusing on years with more than two spatially isolated population samples with sufficient Caullerya prevalence  on the entire parasite sequence dataset , on subHere, we used ITS parasite data combined with microsatellite data from hosts, obtained from 30 host individuals sampled in 2004 from Římov, Vír, and Želivka  was performed for this species only.Based on the microsatellite screening of ~50 randomly selected The ITS data set supporting the results of this article has been published elsewhere  and is a


Platanus mexicana is a dominant arboreal species of riparian ecosystems. These ecosystems are associated with altitudinal gradients that can generate genetic differences in the species, especially in the extremes of the distribution. However, studies on the altitudinal effect on genetic variation to riparian species are scarce. In Mexico, the population of P. mexicana along the Colipa River (Veracruz State) grows below its reported minimum altitude range, possibly the lowest where this tree grows. This suggests that altitude might be an important factor in population genetics differentiation. We examined the genetic variation and population structuring at four sites with different altitudes  using ten inter-simple sequence repeats (ISSR) markers. The highest value for Shannon index and Nei’s gene diversity was obtained at 1700 m a.s.l.  and polymorphism reached the top value at the middle altitude (% p = 88.57). Analysis of molecular variance (AMOVA) and STRUCTURE analysis indicated intrapopulation genetic differentiation. The arithmetic average (UPGMA) dendrogram identified 70 m a.s.l. as the most genetically distant site. The genetic structuring resulted from limited gene flow and genetic drift. This is the first report of genetic variation in populations of P. mexicana in Mexico. This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems. Platanus mexicana, is an arboreal species distributed on the slopes of the Gulf of Mexico, the Gulf of Tehuantepec and Guatemala. It is mainly found naturally near streams and river banks, where it is a dominant species. It is also found in cities, planted as an ornamental tree, because of its quick growth and resistance to air pollution [The sycamore, ollution . Ripariaollution . Ripariaollution . NeverthP. mexicana related to altitudinal gradients. The altitudinal genetic variation of riparian vegetation is affected by several factors, including ecological ones such as landscape characteristics , landscape fragmentation, sexual reproduction, and flowering phenology [There are no studies of genetic variation in henology ,5. Moreohenology . As suchhenology .Fraxinus mandshurica [Euptelea pleiospermum [Myricaria laxiflora whose seed movement by hydrochory increased heterozygosity in the lower part of the gradient [Gene flow through pollen and seed dispersion is the most important factor in genetic exchange between populations . In ripadshurica  and Euptospermum . The unigradient . The evogradient .Pinus hartwegii population, in which the effect of selection was inferred from the number of low frequency alleles present in the subpopulations of the altitudinal gradient’s end [The reduction in population size can cause random alterations in allele frequencies (genetic drift). The allele frequency can undergo large fluctuations in different generations in an unpredictable pattern and can result either in fixation or loss of alleles . Howevernt’s end ,11.P. mexicana, their populations are in a normal distribution range between 600 and 1800 m a.s.l., however, populations growing at altitudes of 160 to 2400 m a.s.l. have been reported [P. mexicana along the Colipa River grows at altitudes as low as 70 m a.s.l. For this reason, the aim of this study is to analyze the genetic variation of P. mexicana and understand its ability to respond to different environmental conditions along an altitudinal gradient, especially in unusual conditions for the species. Since there are no records of this species growing at such a low altitude, the study also aims to understand the ecological and evolutionary factors that promote genetic differentiation. Inter-simple sequence repeats (ISSR) molecular markers were used because of their high variability [P. mexicana genomic sequences. This is the first study that reports the effect of riparian altitudinal gradients on the variation and genetic differentiation of P. mexicana.The edges of distribution of a species may affect genetic variation in populations because in these places environmental conditions are often adverse or unusual for individual establishment . In the reported . In the iability  and the Ten selected ISSR primers generated a total of 105 bands. The size range of polymerase chain reaction (PCR) fragments was 180–1700 bp. The number of bands and the percentage of polymorphisms varied with each primer. Primer 857 produced the highest number of bands (15), of which 14 were polymorphic .P. mexicana with respect to its distribution on the altitudinal gradient. At 1700 m a.s.l. Nei’s gene diversity (He), effective number of allele per locus (Ne) and Shannon index (I) exhibited the highest values compared to the other sites . There was a gradual decrease of these parameters as the altitude of the sampled populations decreased. Comparison between He, Ne and I among sites, revealed that both ends of the gradient display significantly different values ; the main variation component (80%) was attributable within sites. Paired AMOVA showed the existing differentiation between sites mainly between 70 m a.s.l. and the others elevations (K) in STRUCTURE was determined using the ΔK method. We assumed K = 8 as the best model that explains the genetic structure of P. mexicana population in the Colipa river  and so the hypothesis of isolation due to distance was discarded.The AMOVA analysis corroborated the genetic structure, the value of Φevations . A UPGMAevations  based onpa river  (See Suppa river  where wep < 0.05) confirmed the effect of genetic drift at the lowest site, given that it had a significantly higher number of rare-fixed alleles relative to the sites at 200 m a.s.l. (p = 0.02) and 1700 m a.s.l.  and the fact that its altitude ranges from sea level to 1700 m a.s.l., four sites were chosen along this gradient: at 1700 m a.s.l., in “Barranca del Maíz”, Chiconquiaco Municipality  with a mean annual temperature of 20 °C; at 600 m a.s.l. in “Dos Caminos”, Yecuatla Municipality  with a mean annual temperature of 22 °C; at 200 m a.s.l. on “Rancho La Esmeralda”, Yecuatla Municipality  with a mean annual temperature of 24 °C; and the site at 70 m a.s.l. on “Rancho San Jerónimo” in the Colipa Municipality  with a mean annual temperature of 26 °C .2 squares of leaf tissue were cut per tree and stored in small plastic bags with an air-tight seal and silica gel inside to keep them dry until their analysis [At each site, 30 trees were randomly selected and healthy mature leaves with no signs of physical damage were collected from them. The leaves were washed in the field in a soapy solution with 5% bleach for five minutes, after which they were rinsed with distilled water and cleaned with cotton batting dampened with 70% alcohol, rinsed again in distilled water and dried with paper towels. One hundred 1 cmanalysis .2 and dNTPs and eliminating the use of formamide. Only the samples showing successful amplification for the ten primers were used for further analysis. The ISSR primers used were divided according to annealing temperature in group 1:818, 824, 827 and 829; and group 2:835, 841, 845, 848, 850 and 857. PCR reactions were performed using a total volume of 20 μL, using 10 ng DNA, 1× PCR buffer (NH4)SO4, 3 mM of MgCl2, 0.375 mM of dNTPs, 1 µM of each primer, 1 unit of Taq-DNA polymerase  and double distilled water. The amplification parameters were: initial denaturation for 4 min at 94 °C; 35 cycles of 30 s at 94 °C, 45 s at the annealing temperature , 90 s at 72 °C; followed by a final extension of 8 min at 72 °C. Amplification products were separated on a 1.5% agarose gel on 1× TBE buffer, stained with ethidium bromide and followed by photo documentation using Kodak ID 3.5.DNA extraction was done using the CTAB method ,28, modip and q were inferred using the Lynch and Milligan adjustment for dominant markers, were recessive allele is determined by p), number of alleles per locus (A), effective number of alleles per locus (Ne), Nei’s gene diversity (He) and Shannon index (I) were calculated using the TFPGA v1.3 software [All the amplified bands were treated as dominant genetic markers. ISSR bands were scored as 1 (present) or 0 (absent) and this binary data was used to assemble a rectangular matrix. Allele frequencies by p=1−q . The persoftware . To detesoftware .ST. In addition, paired AMOVAs were computed between sites to pairwise differentiation indices. To test the results of this analysis, genetic distances were inferred with the method of Nei and Lee [To estimate the genetic differences among sites along the altitudinal gradient, an analysis of molecular variance (AMOVA) was run in GenAlEx, v. 6.41 software , this an and Lee , and sim and Lee .K ranging from 2 to 10, a burn-in length of 50,000 followed by 10 runs at each value of K. Estimates were obtained under the admixture model using the correlated allele frequencies and the LocPrior algorithm, which incorporates sampling location information and is appropriate for detecting weak population structure [K) was determined using the ΔK method, as well as by examining the plateau of the Ln Pr(X/K) [A further classification was made using STRUCTURE v. 2.3 software . The RECtructure . The mos Pr(X/K) .STversus geographic distances were tested for correlation using Mantel’s test [To test whether the genetic structure is a result of isolation because of distance, pairwise Φl’s test  run in Tl’s test .P. mexicana along the altitudinal gradient of the Colipa River. It is necessary to restore the ecological importance of P. mexicana to riparian ecosystems; these ecosystems are in steady decline and sycamore is one of the most dominant species among them. In addition, there are problems of colonization and establishment of individuals especially in the lower part of the river. Individuals present in these areas must be resistant to adverse abiotic factors as previously mentioned, and adapted to support this type of environment. Thus the possibility of formation of new populations from a low number of trees in which genetic differentiation is low, favoring the presence of rare alleles and the scarcity of other common alleles as compared to the allelic frequency of the original population cannot be discarded. The results of this research highlight the importance of P. mexicana as a dominant species and its ecological and evolutionary implications as a key species of riparian ecosystems. The results presented in this report represent a basic knowledge of the genetic variability of this species in the Colipa River region.Genetic differences were observed in


This article examines the role that vernacular notions of racialized-regional difference play in the constitution and stabilization of DNA populations in Colombian forensic science, in what we frame as a process of public science. In public science, the imaginations of the scientific world and common-sense public knowledge are integral to the production and circulation of science itself. We explore the origins and circulation of a scientific object – ‘La Tabla’, published in Paredes et al. and used in genetic forensic identification procedures – among genetic research institutes, forensic genetics laboratories and courtrooms in Bogotá. We unveil the double life of this central object of forensic genetics. On the one hand, La Tabla enjoys an indisputable public place in the processing of forensic genetic evidence in Colombia . On the other hand, the relations it establishes between ‘race’, geography and genetics are questioned among population geneticists in Colombia. Although forensic technicians are aware of the disputes among population geneticists, they use and endorse the relations established between genetics, ‘race’ and geography because these fit with common-sense notions of visible bodily difference and the regionalization of race in the Colombian nation. Technologies that use DNA to identify human remains or link a suspect and a crime work by drawing mathematical associations between an individual person, a DNA sample, and the DNA profile of a relatively fixed ‘reference population’. DNA ‘fingerprints’, known as ‘profiles’ in Colombia, intertwine an individual with a population; that is, a DNA fingerprint needs a population to gain its meaning . As one La Tabla (The Table), is widely used for forensic purposes. It fulfils a normative role in forensic science by providing the genetic reference populations with which DNA matching is carried out. La Tabla establishes certain relations between populations, regions, race and genetics, yet the populations it constructs are far from being comfortably settled among population geneticists; indeed, they are questioned and criticized. Expert criticisms of La Tabla are not directed towards its usefulness – it has been a standard tool for forensic genetics in Colombia for over ten  years. Rather, they question the scientific validity of the argument that La Tabla presents populations.This article explores how the unwieldy and unruly construction of ‘population’ fits common-sense notions of race, nation and region in Colombia. In Colombia, a table describing allelic frequencies for four populations defined as distinctive , commonl1 – are analysed to determine the probability that they occur in another random individual in the population to which the individual is deemed to belong o belong : 261–263o belong  and entaperitos (experts) routinely use La Tabla’s reference populations to calculate match probabilities after having found a preliminary match between suspect and reference sample. The peritos are aware of the debates about La Tabla, but use it nonetheless. It works for pragmatic purposes, and the links it establishes between race, region and population appear, at one level, obvious, commonsensical and unproblematic. However, La Tabla’s explicit use of race can be uncomfortable for the peritos, a discomfort they partly resolve by emphasizing what they describe as the ‘bioethical’ nature of the DNA markers used to make matches. Compared to technologies such as fingerprints, which were actively divested of the racialized narratives built around them throughout the 19th and 20th centuries , criminal investigators and the relatives of victims, La Tabla’s DNA racialized reference populations tend to disappear almost entirely, leaving only the probabilities that are said to match an individual with a sample and make a genetic profile into a ‘unique barcode’ and thus the ‘gold standard’ in forensic identification.In forensic practice – for example, in Colombia’s National Institute of Legal Medicine and Forensic Science ) – technicians known as enturies : 101–103public science, in the sense of scientific knowledge in which we may identify such implicit human–public dimensions as part of the science itself. (p. 68)[i]maginations of the public world, however that is construed, can be taken as integral to scientific knowledge-generation, not simply as afterthoughts. Thus I talk of We explore the multiple lives of this scientific object – La Tabla – as it moves through the worlds of the population geneticists, the peritos and the courtrooms. Despite what some population geneticists see as scientific flaws, La Tabla has become a national standard in forensic genetic practice. To explain the successful standardization of a disputed scientific object, we explore how common-sense notions of national and racial difference are accommodated into scientific knowledge and become integral to its successful circulation. We argue that this can be best understood as a case of what Based on ethnographic work in the Colombian forensic system, we show how the coexistence of multiple and potentially conflicting constructions of difference is facilitated by sometimes separating and sometimes conflating the visible  and the invisible (the DNA). Depending on the context in which forensic genetics is working, different scientific objects (facts) and narratives (fictions) about race and nation are mobilized, making genetic populations appear, disappear and sometimes become problematized.The imaginaries and practices of sameness/difference pertaining to race, nation and region enter into the production of science through the making and circulation of forensic DNA populations. This dovetails with mestizaje  that supposedly make such differences inapplicable in the first place. Indeed, the tensions between notions of genetics, mestizaje, race and regional difference are found throughout the forensic identification process, including post-mortem forms that ask for the race (raza) of the deceased and the framing of DNA profiles as based on ‘bioethical markers’ that avoid links with physical appearance. Forensic specialists have developed many strategies to deal with the tensions arising from the conflicting mobilization of racial, ethnic and national categories in the process of forensic identification. Racial difference both appears and disappears in Colombian forensic practice, as it does in Colombian public life . Our ethnography included observations in courtrooms, five focus groups with police officers preparing to become criminal investigators and three group interviews and many personal interviews with the forensic peritos  of the INMLyCF and the Fiscalía Nacional or Public Prosecutor’s Office . We also did 25 semi-structured interviews with population geneticists in various research organizations in Bogotá and with users of forensic science, mostly public prosecutors and relatives of victims of forced disappearance.The INMLyCF and the other laboratories of the National System of Legal Medicine should have proofs based on the application of scientific knowledge to our national reality, which is why it is of vital importance – for forensic genetics – to know the genetic composition of our country’s population, so we can generate a correct interpretation of results, this in turn will allow the judicial apparatus to make an approximation to truth, and in this way contribute with the correct application of justice. At the end of the 1960s, the first paternity cases were solved by Emilio Yunis, who is now recognized as a pioneer of human genetics in Colombia, at the Colombian Institute of Family Welfare . The standardization of blood groups to solve paternity cases began in 1968 as a result of Law 75, designed to protect minors and guarantee their right to know their biological origins. In those days, paternity cases were solved by an ‘anthropological–hereditary–biological’ examination, based on the analysis of blood groups, as well as ‘pathological, morphological, physiological and intellectual characters transmissible between generations’ ,2 in combination with facial reconstruction, continued to be used. Genetic identification technologies at the time consisted of a ‘curious combination of blood groups and DNA markers, which did not yield a very high likelihood ratio or random match probability’ .The move from the anthropological–hereditary–biological examination to the widespread use of genetic technologies as a ‘gold standard’ took several decades. Before the move, the reliability and impartiality of forensic science, including genetics, were often publicly questioned, especially when related to high-profile events of violence. This period of Colombia’s history was especially violent, and impunity and corruption reigned. In the 1980s and beginning of the 1990s, when the war against drug dealers and armed insurgents was at its height, forensic genetics was increasingly being used in the identification of human remains . At the Iconic events in which forensic science failed to provide robust evidence became milestones of change, challenging impunity and lack of due forensic process . A famouThe Lalinde case was a public blow to the existing forensic system and its identification practices. In response to such challenges to forensic credibility, in 1993 a genetic forensics laboratory was created at the INMLyCF, which, around 2000, established Colombia’s first DNA database following Combined DNA Index System (CODIS) protocols. CODIS is a DNA database and software platform established by the Federal Bureau of Investigation (FBI), in which genetic profiles from individuals convicted of felonies or looking for their relatives are stored; it is based on thirteen STRs  that are standardized for purposes of comparability. Similar CODIS-like databases and collection protocols exist worldwide . In Colo3 As a consequence, La Tabla and the populations it contains have become an obligatory point of passage In relation to the first criticism, even one of the authors of the article containing La Tabla voiced scepticism about the significance of the genetic differences among the populations described in this article:For this co-author, La Tabla was supposed to constitute a first phase of forensic research on Colombian genetic diversity, followed by a more rigorous exercise – but this second phase never happened. As we will see below, this criticism is also implicit in the experience of the peritos who use La Tabla and find that it makes little difference which of the four tables they use when generating a probability ratio for a match.st (fixation index) values – measures of genetic distance – which are often used in this kind of analysis  between 1985 and 2009, establishing links between genetic populations and geographic demarcations is, in the eyes of many population geneticists in Colombia, a complex and even impossible task.Although Paredes has stated  that La Tabla shows only minute differences between populations, he maintains that the differences are due to the fact that people tend to stay in the same region for various generations; the article states that 80 percent of the sampled individuals were born in the ‘locality’ where they were sampled and approximately 63 percent lived in the same ‘geographic region’ as his or her parents, although neither ‘locality’ nor ‘region’ is defined : 67. In I think that using STRs to differentiate populations at the local level [is wrong] – this is a global technology, using it to describe local populations means that you do not understand the first thing about existing forensic technologies! With thirteen STRs you need something like 700 billion individuals to find the same genetic profile, and with twenty markers even more; so using these markers to state what we already know does not make a lot of sense. Jaime Bernal and Emilio Yunis, senior geneticists in Colombia, share the first criticism that the divisions this article makes are not supported by its data and that forensic practice can do as well with or without the four different populations, as the data presented do not establish significant genetic differences between them. The fact that the genetic populations in La Tabla more or less coincide with common-sense notions of Colombia’s regions and populations suggests the imposition of pre-existing frames on the data. But Bernal and Yunis add a second critique, which is that the thirteen CODIS-based STRs are not an adequate tool to distinguish between regions or populations. This second criticism of La Tabla derives from geneticists’ claims that its methods are not fit for the purpose of describing genetic populations. For example, STR markers are highly polymorphic (i.e. highly variable), which allows them to overcome the kind of genetic differences commonly attributed to ethno-racial and bio-geographical groupings on the basis of other kinds of markers (e.g. AIMs or ‘ancestry informative markers’). This does not mean that Bernal and Yunis reject the idea of a regionalized nation. For Yunis, Colombia is an ‘ethnic mosaic’, in part because of ‘cultural mestizaje’ , but also because it is a country of regions in which both race and genes are regionalized, resulting in a ‘black Colombia’, represented mainly by the coastal regions, a ‘Mestizo Colombia’, with a strong ‘Caucasoid’ component, strongest in the Andean interior, and with indigenous components most evident in the far southwest . In Bernal’s view, marked by the anti-reductionist and humanist tradition of the Institute of Human Genetics at the Pontificia Javeriana University, which he directs see , it is m5 His own studies reveal a rather less neat relation between common-sense national imaginaries and their genetic representations.6 For Diogenes, it is not only that the four populations of La Tabla are redundant – they state without appropriate data what ‘everybody knows’ about Colombia – but also that using existing racialized categories to capture human diversity in Colombia might not be adequate in the first place. He argues that population categories and their relation to geography should be based on a detailed study of each locality’s history, demography and genealogical knowledge:7For me it is more adequate to use local categories based on interviews, self-ascription to a group or a community, demography, matting patterns and the number of generations that the families have lived in the area. That, I think, is far better than to say that they are Afro-Colombians, Caribbeans, Mestizos or Caucasoid-Mestizos … I think these categories are too broad and too ambiguous, and they are not really appropriate because these categories don’t recover much of the history of the populations. These categories can, and should be adjusted. This is done when you go there and find out for yourself the history of the population. Diogenes (pseudonym) is a population geneticist who has deeply and publicly questioned the making of such geographical-genetic clusters.La Tabla was compiled through ‘the numerous paternity cases at hand, which provided good biological material with existing informed consent and came from all the corners of the Colombian territory’ . For Diogenes, the technical need to fill a table with allelic frequencies, characteristic of many forensic geneticists’ practice, is exactly the opposite of the proper practice of population genetics research:Diogenes:Of course it is not the same to take one hundred random samples from the freezer – using your paternity cases – type them and then move on to say that you represent the genetic population of this or that place: like Antioquia [a Central Andean sub-region], the Caribbean or whatever. Here in Colombia almost anyone can claim to be doing population genetics, and I say no […] The characterization of Colombia that I am now doing will take like eight or ten years. Just so you can imagine, for four departments I have 1100 samples with genealogies and everything.E.S.M.:So do you think a map done at a population level with demography and all the rest, against this one, let’s say done with the forensic samples at hand, will really change?Diogenes:Yes of course! Definitely. Radically! … Radically! For example, we right now … in the work we did for El Tolima and Huila [departments of Colombia], we have not found a geographical relationship with anything, but we have had populations, for example the [indigenous] Wayúu, which are linked to the geographical zone in which they live. Of course both populations have a very different history … so the genetic-geographic relation is not necessarily true.Geneticists claimed that the INMLyCF was obstructing the development of the field of forensic genetics with its stubbornness in asking for a reference population to provide results, and then again just amongst geneticists, the idea that there were four subpopulations was questioned, something that I don’t think is the case anymore … however yes, they questioned these different populations. But then again, they use the tables based on our large databanks to do their work, because despite all these criticisms they [the tables] are rigorous and well done, and we have not had any complaints about their efficacy. This is a critique not only of Paredes but more generally of the common-sense grammars of difference that Colombian population geneticists have used for so long , and whiFor Paredes, as for many other forensic geneticists dealing with the everyday workload of an overwhelmed forensic system, the question of the artificiality of the population categories is solved by the fact that La Tabla works and that his critics themselves constantly work with it.The critics prefer an approach that envisages new and different categories for population genetics, and they point to the lack of robust evidence for distinguishing four different populations or criticize the use of STR markers. However, common-sense ideas of the Colombian nation and its regions infuse the DNA populations of La Tabla and are taken for granted by many of its critics, who also reproduce the idea of a basic correlation between region, race and genetics.What better than an article that – for better or worse – everybody talks about … and time goes by and it survives … in that sense the paper [Paredes et al.] has excelled in a test that goes way beyond my criticisms. In the end they say: ‘criticize all you want, we use it just the same all over the country … and everybody knows it, and we have used it for over a decade’ […] Historically he [Paredes] has no data to sustain those classifications and we have still used it for ten years, nonetheless!! The exigencies of standardization – especially its needs for stability, fixedness and reproducibility – make it difficult for peritos to engage in a systematic way with the debates going on among population geneticists about the artificiality or appropriateness of existing categories to classify human diversity. They are certainly aware of these debates – after all, almost all of them had studied (or were still studying) in a genetics research institute in Bogotá or had attended conferences in which population geneticists challenged each other – but their everyday world is one of processing DNA samples according to established protocols. Thus, when peritos tried to explain why La Tabla had four populations, without really knowing the logic behind their creation, they usually pointed to Paredes’ office, if we were at the INMLyCF, or referenced the debate between Paredes and Diogenes, which is a shorthand way to synthesize what they considered to be population geneticists’ theoretical disputes. In that sense, while being producers of ‘truth’ (about DNA identification), they are consumers of the ‘truths’ produced by population geneticists.If you do paternity tests with any genetic region, regardless of where the person comes from, you will see that the paternity index does not change you will still have 99.999%, and the LRs are also very similar … so it shows that we don’t have great genetic diversity here in Colombia. For the peritos, La Tabla had an ambiguous status and they showed contradictory tendencies in relation to it. They tended to downplay genetic and especially racial difference. We saw this manifest in two ways. First, in the peritos’ everyday experience, no matter which of the four reference populations was used, a similar LR (or random match probability) and/or paternity index was obtained:This clearly undermines the premise that Colombia can be easily divided up into different regions with particular racial-genetic characteristics through La Tabla’s thirteen STRs. However, as discussed below, the claims of population geneticists, such as Yunis, that genetic regions can be differentiated using other markers such as single nucleotide polymorphisms (SNPs) resonates with many peritos.mestizaje in the already very mixed landscape of Colombia:mare magnum of genetic composition. And then of course, there is no structure that you can call ‘pure’, more or less ‘pure’, simply because there is none … people move from one place to another and then, of course, they mix.The two great migrations: the first one between 1948 and 1950, called the time of violence, marked by the fight between the Liberals and the Conservatives for political power, well, that made many people move from their original places; on top of the cultural, ancestral admixture, add this layer of displacement. Then, add the forced displacement that derived in the second huge migration, a product of the conflict of the 80s and 90s: this makes Colombia the Second, our focus groups and interviews found that ‘race’ was an uncomfortable word for peritos and forensic experts in the INMLyCF and in the Fiscalía. Occasionally explicit mentions of race – or race-like differences – arose when talking about the logics of making populations or evaluating distinctions. For example, during one of the focus groups a forensic specialist said, ‘you see, you made me say race … it is just that this word has been used as a justification for terrible things in the past … we know there are no pure races’ . We found in these contexts that talking about race was understood as talking about purity; therefore, the discussion is not about whether race is a valid biological category, nor if ‘populations’ are intertwined with racial categories; instead the argument is that racial admixture has been so thorough in Colombia that no claims of race (i.e. purity) can be made.  were submerged into ideas about a generalized mixture was reinforced by the peritos’ constant reiteration that forensic genetic identifications are based on genetic markers that they understand as ‘bioethical’. The markers are seen to avoid possible ethical problems related to racial, and potentially racist, identifications because the STRs used for the forensic work are located in non-codifying regions of the genome and are thus seen to be unrelated to race or physical appearance.It is clear that other tendencies were also at work among the peritos, contradicting the denial of regional and racial diversity and instead reinforcing the basic premise of Colombia as regionally and racially differentiated. Importantly, these processes did not generally involve direct references to race, but instead used the language of region, with racial difference figuring as a subtext. The imaginaries of race, region and the composition of the Colombian nation are built into the forensic process from the very start, beginning with the way a case is filed and opened. As soon as a case receives a criminal file or number, it is assigned to a department in the Colombian territory and then to one of the four different populations defined in La Tabla. Material evidence will be checked to see if there are useful biological traces, and if found, it will then be sent to the genetics laboratory to be processed. Once it is determined that there is enough forensic evidence (DNA) to run a polymerase chain reaction (PCR) and an identification kit, genetic analysis will start. In the final report produced by a perito for a judicial case, the populations are reiterated. Such a report might say, ‘The Andean Region of Colombia was the reference population, and its frequencies have been previously analysed and reported by the laboratory of genetics at Instituto Nacional de Medicina Legal y Ciencias Forenses’ , and they met in Bogotá, and they filed the dispute here in the city, consequently we will be using the Andean population as the referent … despite the fact they are not Bogotanos. But I still need a reference population to calculate the LRs. When we asked how reference populations were assigned to bodies, suspects or potential parents, the responses we got from peritos at the INMLyCF were always the same: It was an assumption based solely on the location of the crime scene, mass grave or parental dispute. No other criteria could be used by the peritos since they only dealt with the biological samples and had no access to any other case information, such as pictures or case narratives . Therefore, no criteria based on appearance or self-declared ancestry could be used to assign a reference population to a case. We found these bio-geographical assumptions troubling, given that close to 5 million people have been internally displaced in Colombia. When we asked the peritos about internal displacement and migration, they agreed that such assumptions could be misleading, but still necessary:The regionalization of our country is born of the natural regions; at least that is what I think, right? One thing is the environment in the high mountains … natural regions delimited by the height of the mountains basically, or the coasts, which makes contrast with the sea, the interior of the country, the mountain, you know … so I think that a person who lives at sea level behaves in a very different way. I would not reduce it to only that, but I think it has a lot to do with it.The public imaginary of Colombia as regionally and racially differentiated was part of the common sense of the peritos as members of the Colombian nation. In a focus group at the INMLyCF (18 February 2012), many peritos and forensic specialists recognized that Colombia is a very mixed nation, but other members of the focus group insisted that, despite this mixture, clear distinctions between different regions in Colombia and the people living in them could be made:paisas (the people of the Antioquia region), reputed to be relatively White in Colombian terms. When talking with the peritos at the Fiscalía, they resorted to a similar regional–racial repertoire to explain difference in Colombia. Although they agreed on the idea that in Colombia ‘somos muy mezclados’ (we are very mixed), the notion that it made sense to divide the country into regions was strongly articulated as well: ‘That is what they teach us from our early days at school’.In this account, words such as ethnicity and/or race are avoided, and the weight of regionalization is given to geography and climate. But these ‘natural regions’ also were immediately articulated by other members of the group in terms of people living within them, citing the idea that ‘the south of Colombia is visibly more indigenous’ or that certain highland areas are more European, being home to groups like the 9The following excerpt of a conversation with J.E., a molecular biologist who trained at the INMLyCF and introduced us to the field of forensic genetics there, shows the deeply rooted image of Colombia as regionally and racially differentiated and demonstrates the way in which common sense and the ‘visible’ differences among Colombians work in the stabilization of scientific knowledge:J.E.:mescolanza (a mixture) – of an almost weird kind – because a bit of everything came to the country: black slaves, our indigenous people, lots of Europeans and here everyone mixed with everyone.I think Colombia is one of the most mixed countries there is … here we are a E.S.M.:That is precisely why I am so interested in why you divide the country in regions, when there is no significant genetic distance.J.E.:cabildos [indigenous councils] still exist, their indigenous reservations still exist … they still keep a lot of that, there is also certain degree of endogamy, it is effectively a closed population. Not a lot of people enter or leave the community, that is the reason for saying that they are pure indigenous, right? … Then, in the Caribbean region many Jewish people arrived afterwards, many Muslims, many Arab people, which might have been the reason to treat it as an isolated region. […] For instance if we were looking at the paisas, if we were to look into a deeper level in Antioquia, we might find these [genetic] differences and the same thing could happen in other regions, because of endogamy. The same happens in the Atlantic Coast, in Palenque de San Basilio [previously a maroon community], where the slaves who were able to escape made their own town and stayed there; those who live there now are the great-great-grandsons of the original slaves. Then I would say that there is a substructure, especially one that tends to be African, they are descendants of real slaves, who were brought from Africa against their will … So again I think it all depends if your magnifying glass allows you to see what is very, very small. For me the way we are looking at it does not allow us to see that …Maybe the Afrodescendants. Why? Because that is a region where most of the people are black, and of course there is a great difference at least phenotypically, of course there is. [… And] in the south of the country nowadays are the people who most conserve their indigenous structure, their social ways; the In their scientific and practical context, peritos mobilize common-sense ideas about the diversity of the Colombian nation including the demographic history taught in school and obvious phenotypic differences such as skin colour to reinforce the idea that Colombia is made up of populations-regions, despite the challenges to such a concept presented by the facts of the mestizaje, violence-related displacements and the lack of genetic diversity. J.E. believes that the degree of resolution limits the scientific gaze, while not considering other explanations, such as the possibility that the regionalized cartography of Colombia does not have a genetic counterpart. During the focus group at the Fiscalía, a similar repertoire of explanations – which links the phenotypically ‘obvious’ to the molecular – was given to us when explaining the fact that genetic distances do not justify the categories made by E.S.M.:So why divide the country in regions, if there aren’t significant differences?Perito 1:Well, that is a good question [generalized laughter].Perito 2:[…] Definitely you do need to do a kind of division, at least demographically, of the Colombian population … we are definitely not the same, I mean if you travel to the Pacific coast of Colombia you will find a totally different race, from what you find here in the centre of the country, and the same will happen if you go to the eastern side of our country, you will find lots of indigenous population, the same in the southwest, and they are not the same … we are not the same …In sum, despite their objections to the idea of race and their commitment to using what they see as ‘bioethical markers’ and despite their recognition that the regional–racial populations of La Tabla made no statistical difference in producing LRs, La Tabla and its categories continued to work smoothly in the context of the peritos’ laboratories and work protocols. This is because regions were a common-sense reality for these practitioners and because La Tabla could still be used to produce valid results for legal purposes.This is an example of public science, as we use the term in this article, in two senses: (a) insofar as public imaginations of Colombia as a country with distinctive racialized regions facilitated the routine use and normalization of La Tabla and (b) insofar as the peritos’ concern with being seen to endorse ideas of race (as purity) and to potentially be involved in distinctions that smacked of racism – both morally inimical to the peritos’ imagination of the Colombian public sphere – pushed them to avoid explicit mention of race and accept the fact that, in practice, La Tabla’s four populations produced very similar LRs.In the next section, we argue that, in a different context – that of the courtroom – the regional–racial populations produced by La Tabla are once more erased or at least back-grounded and overshadowed by the apparent power of forensics to make secure identifications, irrespective of region or race.10From the previous calculation it can be said that the genetic profile we analysed is found in one of 21,265 trillion persons in the reference population used for this case. This result means that it is 21,265 trillion times more probable that the evidence analysed comes from  than from another random individual in the reference population. Normally, before public hearings dealing with genetic data take place, a report is produced by peritos to communicate the LRs of DNA profiles or paternity indexes to their legal audiences. It is through this document that peritos provide their expert evidence. It is designed to be circulated to public prosecutors or other actors in the public sphere and its contents detail the laboratory processes and scientific standards that led to the forensic statement. In Colombian forensic practice, LRs can be as high as 21,265 trillion:explíquenoslo en cristiano’ (explain it to us in Christian language). Public prosecutors and attorneys have told us that, although in Colombia there is no official hierarchy of evidence, ‘DNA is what the judges and victims are looking for, and we feel confident with our cases when we have it … defenders know this, and they do whatever they can to avoid their clients’ getting a genetic test’. Public prosecutors told us that as part of their professional routine and legal practice when dealing with genetic profiles, they like to ask the genetic specialists the following question when presenting their case in a public audience or hearing:The courtrooms are places in which the forensic genetics and the astronomical LRs it yields are taken to be responsible for ‘80 or 90 percent’ of the weight of evidence . Throughout the public trials that we witnessed during our fieldwork, deference towards genetics was the norm and it was common practice to ask genetic specialists to translate their knowledge into everyday language: ‘Prosecutor:Please tell us how many human beings living today on planet earth we would need to find the same genetic profile by sheer chance?Perito:According to our reference population, we would need approximately 3 times the population of planet earth to find the same genetic profile by sheer chance.LRs linked to DNA profiles are so high that what is commonly known as ‘genetic proof’ among legal specialists becomes certainty in everyday juridical practice cf. . Despite11 We found that, when preparing for a trial, prosecutors and defence lawyers had never considered the possibility of contesting DNA evidence in terms of the adequacy of the reference population being used by the peritos. As one prosecutor told us, hesitantly,Yeah, yeah, I know the probabilities are based on the different regions in Colombia, but in my experience I have never questioned the use of the different regions in a genetic test. Nor has the defence attorney […] I mean, what I see is not if the results consider the Andean region, but rather the general Colombian population […] so it is not determined by regions […] The peritos give me the probabilities in terms of trillions, so I just ask: ‘This number equals how many times the human population on earth?’ And they tell me: seven or eight. And then, that’s it. In the expert reports produced by peritos and circulated to defenders and public prosecutors, the idea that Colombia is composed of genetic regions is routinely reproduced. As we saw above, such reports name the reference population used to calculate the LR – for example, ‘The Andean Region of Colombia was the reference population’. However, interestingly, most of the prosecutors and government attorneys we interviewed did not know about the use of reference populations to produce genetic profiles. During our focus groups, genetic profiles and fingerprints were described as the two main identification techniques. The two attorneys and police investigators who were aware that populations were used to produce genetic profiles assured us (after consulting with each other) that the DNA of individuals was compared against a global referent: the regionalized genetic populations of La Tabla were obscured, despite being written in every forensic report as a part of the standardized protocol.The public properties of forensic DNA as a ‘silent witness’ , capableNarratives that emphasize the power of DNA commonly construe it as the ultimate individualized proof of identity in the public sphere. In Colombian courts, this dominant ‘silent witness’ narrative overwhelms the regional–racial populations that are used by the peritos to produce the LR or random match probabilities that prosecutors deploy and judges consume. The public enactment of genetic fingerprinting or profiling makes it possible to establish a strong statistical link between individuals and biological material while at the same time sidestepping potentially troubling racialized narratives. Indeed the conceptual and practical separation made between race, as a visible character of bodies, and DNA, as an invisible yet essential property of the same bodies, makes forensic genetics a powerful tool for individual identification that transcends racial or ethnic difference not only for forensic experts but also in the public courtrooms and in the media reports of courtroom forensic DNA identifications, which generally background racial difference and present the matching process as neutral and heroic .By approaching forensic genetics in Colombia as a form of public science, we can understand the successful stabilization of DNA populations and the re-articulation of race and region in forensic genetic practice. In the courtroom and among the criminal investigators, public prosecutors, and relatives of the disappeared, the regionalized-racialized populations of Colombian forensic genetics tend not to be seen, leaving instead only the typical astronomical probabilities of DNA profiling. Genetic profiling assumes proof of identity that transcends race and appearance; it travels as a set of ‘bioethical markers’ unrelated to the physical appearance of a suspect or victim. Thus, genetic profiling does not lie, does not forget and, even better, because it is apparently blind with respect to racial difference, it is incapable of discriminating. The dominance of the ‘silent witness’ narrative helps to obscure the racialized dimensions intertwined with forensic genetic practice and constructs forensic genetics as an individualized and unique barcoding technique legitimated by its powerful statistical apparatus.The disappearance of racial difference in the courtroom is also due to the way forensics figures as pivotal to national efforts to find justice and reparation in the context of widespread civil violence. Ironically, the emergence of La Tabla was linked, as we showed above, to efforts to improve public confidence in the reliability of state forensics. But the regional populations La Tabla created to enhance the accuracy of identification become unimportant in the context of a search for justice which is seen as, ideally, surpassing and over-riding divisions of region and race in a search for national unity.Following La Tabla from the world of population geneticists to the everyday practice of peritos allowed us to bring forth the workings of common sense, in terms of how La Tabla operates in the standardization of science and as it fuels disputes about the categories it underwrites. For population geneticists, La Tabla’s forensic genetic reiteration of the common-sense notion that Colombia is a country of regions, inhabited by different populations, often described in racial terms, is both redundant (it merely states the obvious) and problematic in genetic terms (the specific techniques used in forensic genetics are not adequate for a proper population genetics). However, many population geneticists also reproduce the standard images of Colombia differentiated by racialized regions, and it is precisely because of the same common-sense constructs that peritos do not mind glossing over the lack of genetic distances between regional populations in La Tabla.Drawing on common-sense historical and demographical knowledge of the Colombian nation, as well as phenotype differences of ‘others’ deemed to be Black in the coastal regions, indigenous in the south and more European in the highlands, peritos link the visible and apparent to the molecular. Here, common sense predates and supports the categories created by scientific knowledge; science will eventually confirm what everyone already knows about the nation and its ethno-racially endogamous or mixed landscapes. Questions about the proper place of racial categories and their relation to nature and ‘reality’ do not bother forensic specialists in the same way as they bother those devoted to population genetics. The way in which racial categories matter or do not is one of the boundaries constructed by population geneticists to differentiate themselves from their practice-oriented forensic counterparts, the peritos.Strategies that draw on both history and appearance are a common tactic in lay engagement with genetic science in Colombia see . With reIn their everyday practice, peritos are selectively crafting many knowledge registers at the same time: what is seen by population geneticists as inconsistency and the imposition of pre-conceived frames in La Tabla are, for the peritos, questions of scale of resolution and representative sampling. In addition, race and its relation to genetics is less problematic for the peritos who tend to deploy differences of physical appearance to make sense of the genetic and regional composition of the Colombian nation. At the same time, making connections between racial appearance and genetics is seen as potentially discriminatory, a problem that can be circumvented by referring to the bioethical status of forensic genetic markers that are disconnected from phenotype.In sum, the relations between race and nation in forensic science need to be constantly managed, and despite all the statistical and mathematical tools devised to produce certainty, common sense and dominant imaginaries of difference are still fundamental to the way population geneticists and peritos conceptualize and dwell in their life-worlds, shaping the assumptions that delimit genetic populations and the symbolic frames they use to engage and produce further knowledge with them. What is striking about the Colombian material explored here is the power of the racial–regional imaginary to inflect, in varied ways, the world of forensic genetics – its researchers and technicians – and population genetics more widely. In Mexico, as noted above, a sense of regional difference has not shaped forensic genetic practice in the same way. This Colombian imaginary is long standing and has been co-produced in the interactions of scientists of various kinds, administrators, politicians, educators and lay people over a long period. Genomics is one more domain where we can detect its presence, as well as attempts, by such as Diogenes, to challenge some of its contours.Genetics enacts tension as it produces representations of racialized regions, which can easily reinforce and naturalize a sense of difference, while simultaneously highlighting the processes of movement, migration and mixture, which are also said to constitute the nation and characterize major cities such as Bogotá. In La Tabla itself, these latter processes remain hidden, as they tend to in most representations of racialized regions, but the peritos clearly emphasized them in their discourse, while in the courtroom regional difference was erased more radically still by individualized identifications assumed to take place in relation to a global population. In that sense, genetics provides a specific language for talking about perennial issues of sameness and difference, without providing a means to resolve the tension between them.


Tabebuia aurea (Bignoniaceae). Exploring different algorithms and paleoclimatic simulations, we used ecological niche modelling to generate alternative hypotheses of potential demographic changes through the last glacial cycle and estimated genetic parameters using coalescent modelling.Glaciations were recurrent throughout the Quaternary and potentially shaped species genetic structure worldwide by affecting population dynamics. Here, we implemented a multi-model inference approach to recover the distribution dynamics and demographic history of a Neotropical savanna tree, Comparing predictions from demographic hypotheses with genetic parameters of modern populations, our findings revealed a likely scenario of population decline, with spatial displacement towards Northeast Brazil from the last glacial maximum to the mid-Holocene. Subsequently, populations expanded in response to the return of the climatically suitable conditions in Central-West Brazil. Nevertheless, a wide historical refugium across Central Brazil likely maintained large populations connected throughout time. The expected genetic signatures from such predicted distribution dynamics are also corroborated by spatial genetic structure observed in modern populations.Tabebuia aurea population dynamic in response to the Quaternary climate changes.By exploring uncertainties inherent in multiple working hypotheses, we have shown that multi-model inference is a fruitful and efficient approach to recover the nature, timing and geographical context of the The online version of this article (doi:10.1186/s12862-014-0213-0) contains supplementary material, which is available to authorized users. Glaciations were frequent throughout the Quaternary, with potential consequences for population genetic structure by affecting distribution and demographic dynamics of species through time . RecoverCoalescent modelling, for instance, has provided significant advances in hypothesis testing by estimating genetic parameters following predefined demographic histories  . The hypAt the same time, ecological niche modelling  has allTo overcome such problems, the full range of modelling uncertainties should be accounted for as part of the process of exploring the dynamic of species distribution through time. In this case, by exploring different assumptions about the dynamics of species ecological niche (i.e. modelling uncertainty), ENMs can actually generate multiple and independent hypotheses of species' distributional history that reflect, at the same time, ecological and biogeographical realism ,12,15. S14C yr BP, until reaching the current pattern around 4,000 14C yr BP ), http://cmip-pcmdi.llnl.gov/cmip5/) and PMIP3 databases (https://pmip3.lsce.ipsl.fr/). Climatic layers were obtained for pre-industrial (representing current climate conditions), mid-Holocene (6 ka) and Last Glacial Maximum  to characterize climate oscillations, hence the palaeodistribution dynamics through the last glacial cycle.To explore uncertainties across the ecological niche modelling and generate alternative demographic hypotheses, we considered palaeoclimatic simulations from four coupled atmosphere–ocean general circulation models . Precipitation and temperature are the basic components of climatic axis of species niche and are frequently used as surrogates of water and energy availability, which are considered the main drivers of species distributions at macroscales   .FST and geographical distances  among pairs of sampled populations were correlated using a Mantel test. Statistical significance was established from 10,000 random permutations using the software Arlequin 3.11 [We used spatially explicit analysis to detect gradients in observed genetic diversity or sectors of low genetic diversity in response to late Quaternary climate oscillations. To test for spatial structures, the linearized uin 3.11 .He) and allelic richness (Ar*) using quantile regression [He and Ar*) against these spatial distances.We also analysed the relationship of climatic suitability and stability through time with genetic diversity (gression . For thiAdditional accessibility data is provided as Additional file.