A trade-off between pre- and post-copulatory sexual selection in a bean beetle

Abstract

It is now generally recognized that it is necessary to examine how sexual selection operates across the lifespan of a male, in order to understand the total sexual selection in action. However, less attention has been paid to the fact that selection pressures can change in response to varying environmental conditions. Here, we examine male allocation to trait subject to pre-and post-copulatory sexual selection in Callosobruchus chinensis. We find evidence of a trade-off between dispersal ability and testes size and sperm transfer, across geographical strains. In addition, male mating success of strains with larger testes and better dispersal ability, respectively, changed in response to environmental conditions. Males with better dispersal ability had greater success in securing mates, compared to males with larger testes, under conditions where it was harder to find females. There was no difference in male ability to secure mates when it was easy for them to find females. However, we suggest that males with larger testes are likely to have an advantage in sperm competition under conditions where it is easier to find females, and when females are thus likely to mate multiply. Our results indicate that environmental fluctuations and trade-offs can work in conjunction to maintain alternative male behavioral reproductive strategies.

Investment in adult reproductive tissues is affected by larval growth conditions but not by evolution under poor larval growth conditions in Drosophila melanogaster

“…Trade-offs between pre- and post-copulatory traits have been reported several times across various insect systems ( Katsuki and Lewis, 2015 ; Simmons and Emlen, 2006 ; Yamane et al., 2010 ). It is argued that since both types of traits require intensive resources, it is beneficial for an organism to invest in either pre- or post-copulatory traits, depending on the mating dynamics.…”

Experimental immune challenges reduce the quality of male antennae and female pheromone output

“…Conventional theory predicts trade-offs between precopulatory traits (ornaments and armaments) and between post-copulatory traits (testes and ejaculates) 62 , although empirical investigations have focused primarily on male ornaments and armaments 63 . Early sperm competition models noted trade-offs between ejaculates and mate searching investment 64 , and while negative relationships between testes size and mate searching ability have been reported 65 , 66 , the potential for trade-offs between testes and organs of sense has rarely been explored, despite their primary function in mate searching and mating success. One study failed to find a trade-off between antennal investment and testes size in the monandrous painted apple moth, Teia anartoides 67 , but the present experiments revealed a clear trade-off between male mate searching investment (antennal length) and testes size in the similarly monandrous U. lugens , regardless of experimental treatment.…”