Competitive males have higher quality sperm in a monogamous social bee

BMC Evolutionary Biology

Research Article

Hiara Marques Meneses¹  Sheina Koffler²  Astrid de Matos Peixoto Kleinert²  Rodolfo Jaffé³ 

[1] Department of Animal Sciences, University of Ceará, Center of Agrary Sciences, Fortaleza, CE, Brazil;Department of Ecology, University of São Paulo, Institute of Biosciences, Rua do Matão, travessa 14, 321 (05508-090), São Paulo, SP, Brazil;Department of Ecology, University of São Paulo, Institute of Biosciences, Rua do Matão, travessa 14, 321 (05508-090), São Paulo, SP, Brazil;Vale Institute of Technology, Sustainable Development, Belém, PA, Brazil;

关键词: Aggregation;    Male competition;    Sexual selection;    Sperm;    Social insects;   

DOI  :  10.1186/s12862-016-0765-2

 received in 2016-07-20, accepted in 2016-09-13,  发布年份 2016

来源: Springer

【 摘 要 】

BackgroundReproductive success is determined by the interplay between mating and fertilization success. In social insect species with male-biased sex ratios and queen monogamy, males face particularly strong pre-copulatory sexual selection since they must compete with thousands of other males for a unique mating opportunity. Ejaculate quality is also expected to be under selection, because queens are long-lived and store sperm for life, so males with higher quality ejaculates are expected to provide queens with larger and longer-lived colonies, which in turn may produce more daughter queens (the only direct fitness gains of haplodiploid males). Considering the action of pre and post-copulatory sexual selection on male traits, three scenarios might thus be expected: positive, negative or no association between male mating ability and fertilization success. Here we explored these scenarios in the stingless bee Scaptotrigona aff. depilis, where males gather in large aggregations and queens mate with a single male. Male mating ability was assessed through the capacity of a male to reach an aggregation and persist on it; while sperm viability, sperm number, and sperm morphology were used as proxies for sperm quality.ResultsSperm viability was associated with persistence time in the aggregation, and males that persisted longer presented shorter spermatozoa and higher variation in sperm length than recently arrived males. However, sperm traits of males that reached aggregations did not differ from those of males collected inside their colonies. In addition, males that persisted longer in aggregations were smaller than other males. Male size and sperm viability were not correlated, suggesting that the observed patterns were not due to trade-offs in male resource allocation.ConclusionsPersistence in male aggregations thus seems to select more competitive males with higher quality sperm. Our work is the first one to reveal an association between male competitive ability and fertilization success in a monogamous social insect. This finding sheds important light on the evolution of male traits in social insects and the general mechanisms of sexual selection.

【 授权许可】

CC BY   
© The Author(s). 2016