Does sexual experience affect the strength of male mate choice for high‐quality females in Drosophila melanogaster ?

Males are expected to mate with as many females as possible, but can maximize their reproductive success through strategic mating decisions. For instance, males can increase their own fitness by mating with high quality females that produce more offspring. Additionally, males can adjust mating effort based on the relative distribution of females and male competitors. To test factors that influence male mate choice, we assessed male mating decisions in the golden-web spider, Trichonephila clavipes (Nephilidae), a species in which females are polyandrous and males guard females before and after copulation occurs. We tested the hypothesis that males spend more time guarding high quality females that are spatially isolated, and when the risk of sperm competition is higher. We assessed solitary and aggregated female webs in the field and quantified female quality (i.e. female body condition), the risk of sperm competition (i.e. number of males in each female web), and mate-guarding duration (i.e. number of days each male spent in each web). We found that mate-guarding behaviour is influenced by the presence of male competitors. In addition, the type of web seems to moderately influence male mating decisions, with males spending more time guarding a female when on solitary webs. Finally, female body condition seems to play a small role in mate-guarding behaviour. As mate-guarding duration considerably increased per each additional male competitor in the web, and guarding behaviour prevents males from seeking additional mates, it seems that males do benefit from guarding females. We conclude that failing to guard a sexual partner promotes high costs derived from sperm competition, and a male cannot recover his relative loss in fertilization success by seeking and fertilizing more females. In addition, the search for more sexual partners can be constrained by possible high costs imposed by predators and fights against other males, which may explain why the type of web only moderately influenced male mate choice. Following the same rationale, if high-quality females are not easy to find and/or mating with a high-quality female demands much effort, males may search females and guard them regardless of female quality. In conclusion, the factor that most influences male mate-guarding behaviour among T. clavipes in the field is the risk of sperm competition.

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Be prudent if it fits you well: male mate choice depends on male size in a golden orb-weaver spider

10.32942/osf.io/g3s4n ◽

2019 ◽

Cited By ~ 1

Author(s):

Pietro Pollo ◽

Danilo Germano Muniz ◽

Eduardo S. A. Santos

Keyword(s):

Mate Choice ◽

Field Experiments ◽

Reproductive Potential ◽

Female Size ◽

Male Mate Choice ◽

Male Size ◽

High Quality ◽

Male Preference ◽

Female Quality ◽

Male Mate

Male preference for high-quality females is expected to evolve when male reproductive potential is restricted. However, when there is competition among males, some models predict the evolution of assortative male mate choice, in which good competitors choose high quality females while poor competitors choose lower quality females to avoid competition. In Trichonephila clavipes spiders, males have limited sperm supply and fight for access to females. We tested whether female quality and male size (a proxy of fighting ability) influence male decisions in T. clavipes. We used field experiments in which males could choose among two available females in a scenario free of competition. We found that males choose their mates based on both female size and female recent pairing status (whether the female was accompanied by a male before the experiment). Importantly, male mate choice exhibited plasticity, and varied with male size, as large males preferred larger females that were recently unpaired, medium-sized males showed no preference, and small males preferred smaller, recently paired females. Because all females appear to attract males, we predict that variation on male mate choice attenuates sexual selection on females. Our findings confirm the prediction of variable male mate choice when there is male-male competition and male reproductive potential is restricted, a pattern that may be common, but hard to detect.

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