Finding Sperm in the English Countryside—The 14th Biology of Spermatozoa Meeting
Most people wouldn't look to the rolling green hills of central England as the place to get a crash course on the latest in sperm biology. Yet, for the past quarter of a century, sperm biologists from around the world have congregated in the picturesque Peak District (near Sheffield) for Biology of Spermatozoa (BoS) Meetings - the most recent of which representing the 14th such gathering. BoS meetings are relatively small, typically consisting of 60-80 delegates, and attract a cadre of sperm enthusiasts who return year after year. As with previous meetings (e.g. Wolfner and Montgomerie 2016), the size and atmosphere of the event gives BoS meetings a special feel - part 'family' reunion, part meeting new colleagues, part solidifying and developing collaborations, and all cutting-edge science.
Spermatozoa in the Peak District
Conferences can be amixed bag. On the one hand, they are often invaluable for networking; for getting to, or staying at, the cutting edge; for getting helpful input from colleagues; for seeing friends and collaborators, old and new; and (occasionally) for getting to visit a new and exciting part of the world. Sometimes, unfortunately, scientific conferences are just too big; too expensive; too boring; too lonely, exhausting, and time consuming. Too often, delegates present old work that you already knew about, venues are hot and stuffy, and the chance of meeting old friends and making new ones is slim indeed. In September 2015, we attended a conference that epitomized all the positives (with none of the negatives) the biennialBiologyofSpermatozoa (BoS)meeting (http://www. bos.group.shef.ac.uk) in thegorgeousPeakDistrictofnorthern England. This small scientific meeting, run for the past 25 years by Tim Birkhead and Harry Moore, both at the University of Sheffield, focuses on the evolutionary biology ofspermatozoa,and reproduction ingeneral.Fourprinciples have guided the organizers from the start: (i) to keep the meeting small with no concurrent sessions; (ii) to require presenters to focus on unpublished research in progress or nearly finished; (iii) to invite 2-3 speakers from outside the core group of evolutionary biologists as a way of injecting new ideas and perspectives from other disciplines, such as physiology, imaging, proteomics/genomics; and (iv) to stay flexible, trying new approaches, replacing or modifying whateverdidnotworksowell in thepast.More thananything, this conference encourages and maximizes interaction and discussion whichmakesattending itsoproductiveand fun. To that end (and because there is only one presentation at a time) post-presentation questions and discussions are allowed to continue as long as they are interesting. Consequently, there isno rigidscheduleeachday except to finish in time for a drink before the sumptuous dinner served in an elegant dining room at the conference venue.
Gamete competition, gamete limitation, and the evolution of the two sexes.
Males and females are a fundamental aspect of human reproduction, yet procreation is perfectly possible without this division into two sexes. Biologically, males are defined as the sex that produces the smaller gametes (e.g. sperm), implying that the male and female sexes only exist in species with gamete dimorphism (anisogamy). Our ancestors were isogamous, meaning that only one gamete size was produced. The question of the evolutionary origin of males and females is then synonymous to asking what evolutionary pressures caused gamete sizes to diverge. Studying the ancestral evolutionary divergence of males and females relies largely on mathematical modelling. Here, we review two classes of models explaining the evolutionary origin of males and females: gamete competition and gamete limitation. These seemingly alternative explanations are not mutually exclusive, but two aspects of a single evolutionary process. Once evolved, anisogamy and the two sexes are evolutionarily very stable. This explains the maintenance of anisogamy in organisms with internal fertilization, which can cause large decreases in both gamete competition and gamete limitation. The ancestral divergence and maintenance of gamete sizes subsequently led to many other differences we now observe between the two sexes, sowing the seeds for what we have become.