Cryptic Male Choice in a Cellar Spider: Evidence of Strategic Sperm Allocation

ABSTRACT Sexual selection theory traditionally emphasizes female mate choice, yet an expanding body of research highlights the prevalence and evolutionary importance of male mate selectivity. In species where ejaculate production is energetically costly, males may exhibit cryptic mate choice by modulating pericopulatory or postcopulatory investment in response to female quality. Here, we tested for cryptic male mate choice in the long‐bodied cellar spider Pholcus phalangioides , a species in which males and females mate multiply and males repeatedly induct their pedipalps with sperm throughout their adulthoods. We mated virgin males with either large or small virgin females, then remated the same males with medium‐sized virgin females after a recovery period. Offspring production from medium females served as a correlate for ejaculate investment. As predicted, males that first mated with large females had reduced reproductive success in subsequent matings than males whose initial mates were small, indicating a trade‐off in ejaculate allocation. However, offspring survival did not differ between groups, suggesting that sperm quantity rather than quality was affected. Although alternative explanations for our results cannot be dismissed and should be considered for future studies, our results are consistent with the hypothesis that P. phalangioides males strategically allocate reproductive resources in response to female phenotype and face sperm limitation under repeated mating. Our findings provide evidence of cryptic male choice in spiders and underscore the fitness consequences of strategic ejaculate allocation in systems lacking paternal investment.