Male burrow investment drives differential sperm transfer in a South American spider

 

Male burrow investment drives differential sperm transfer in a South American spider

Abstract

In species with male multiple matings, males may transfer sperm differentially according to several factors such as their reproductive status and body condition, and those of their sexual partners. Spiders provide exceptional models for studying sexual selection due to their unique reproductive system, sperm storage capabilities, and diverse mating strategies. However, the factors influencing male sperm transfer in this group remain underexplored. We examined the sperm transfer patterns in the Neotropical wolf spider Allocosa senex, males of which construct and donate burrows as reproductive and paternal investment. We investigated whether male and female traits such as age and body condition (i.e. the residuals of a linear regression between prosome width and weight), and male investment in burrow construction (burrow length) influence sperm transfer. Finally, we tested the relationship between sperm transfer, the number of ejaculations, and mating duration. Our results show that sperm transfer increased with burrow length, which serves both as an advertisement to attract mates and as paternal effort in this species, suggesting this trait probably serves as an honest signal of overall male quality. Interestingly, longer mating duration showed lower sperm transfer, indicating that mating serves multiple functions beyond sperm transfer, while the positive relation among sperm transfer and the number of ejaculations support using ejaculation count as a measure of sperm transfer in this species. These findings offer new insights into the diverse factors shaping ejaculate transfer in A. senex, contributing to the understanding of factors driving the evolution of reproductive strategies in spiders and other arthropods.

Bollatti, F., Aisenberg, A., & Peretti, A. V. (2026). Male burrow investment drives differential sperm transfer in a South American spider. Biological Journal of the Linnean Society, 147(1). https://doi.org/10.1093/biolinnean/blaf142