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- Cooperation among unrelated individuals: the ant foundress case
Trends in Ecology & Evolution, Volume 14, Issue 12, 1 December 1999, Pages 477-482
Giorgina Bernasconi and Joan E. Strassmann
AbstractAnt foundress associations are an example of cooperation among non-kin. Across a dozen genera, queens able to found a colony alone often join unrelated queens, thereby enhancing worker production and colony survivorship. The benefits of joining other queens vary with group size and ecological conditions. However, after the first workers mature, the queens fight until only one survives. The presence of cofoundresses, and their relative fighting ability, also affects the extent of cooperative investment before worker emergence. This reveals previously overlooked early conflicts among queens, which reduce the mutualistic benefits of cooperation.
Abstract | Full Text | PDF (193 kb)
- Alternative reproductive strategies: a queen perspective in ants
Trends in Ecology & Evolution, Volume 15, Issue 12, 1 December 2000, Pages 508-512
Jürgen Heinze and Laurent Keller
AbstractAnt colonies are commonly thought to have a stable and simple family structure, with one or a few egg-laying queens and their worker daughters. However, recent genetic studies reveal that the identity of breeding queens can vary over time within colonies. In several species, some queens are apparently specialized to enter established colonies instead of initiating a new colony on their own. The previously overlooked occurrence of queen turnover within colonies has important consequences not only on the genetic structure and nature of kin conflict within colonies, but also on the evolution of social parasitism.
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- Sex Allocation Conflict in Ants: When the Queen Rules
Current Biology, Volume 16, Issue 3, 7 February 2006, Pages 328-331
Hervé Rosset and Michel Chapuisat
SummaryInsect societies are paramount examples of cooperation, yet they also harbor internal conflicts whose resolution depends on the power of the opponents [1,2,3,4]. The male-haploid, female-diploid sex-determining system of ants causes workers to be more related to sisters than to brothers, whereas queens are equally related to daughters and sons . Workers should thus allocate more resources to females than to males, while queens should favor an equal investment in each sex. Female-biased sex allocation and manipulation of the sex ratio during brood development suggest that workers prevail in many ant species [1,2,5]. Here, we show that queens of Formica selysi strongly influenced colony sex allocation by biasing the sex ratio of their eggs. Most colonies specialized in the production of a single sex. Queens in female-specialist colonies laid a high proportion of diploid eggs, whereas queens in male-specialist colonies laid almost exclusively haploid eggs, which constrains worker manipulation. However, the change in sex ratio between the egg and pupae stages suggests that workers eliminated some male brood, and the population sex-investment ratio was between the queens' and workers' equilibria. Altogether, these data provide evidence for an ongoing conflict between queens and workers, with a prominent influence of queens as a result of their control of egg sex ratio.
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Copyright © 2006 Elsevier Ltd All rights reserved.
Current Biology, Volume 16, Issue 24, 2424-2427, 19 December 2006
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Queen-Queen Competition by Precocious Male Production in Multiqueen Ant Colonies
1 Department of Biology, Faculty of Education, Gifu University, Gifu 501-1193, Japan
2 Institute of Biological Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
3 Biologie I, Universität Regensburg, 93040 Regensburg, Germany
- Arriving earlier in the breeding area than his rivals may be beneficial for a male when females mate only once or during a short time span. The timing of a male's entrance is usually determined by the male himself, e.g., through returning early from his winter quarters or through accelerated larval development [1,2,3]. Here, we document a surprisingly simple way of “first come, first served” in a species with local mate competition. In multiqueen colonies of a Cardiocondyla ant, mother queens make sure that their own sons are the first to monopolize mating with a large harem of female sexuals by producing extremely long-lived males early in colony life. Whereas queens in newly founded single-queen colonies started to produce male and female sexuals only several weeks after the eclosion of their first worker offspring, queens in multiqueen colonies precociously reared sons long before the first female sexuals and even before the emergence of their first workers. These early males killed all later emerging males in the nest and mated with all female sexuals subsequently produced. Our data document that the patterns of growth and productivity of insect colonies are surprisingly flexible and can be turned upside down under appropriate selection pressures.