In search of the perfect web? Males of the golden silk orb-web spider trichonephila clavipes do not aggregate in webs of high-quality females

In many species, the location of females may affect the spatial distribution of males. If females vary in their reproductive quality, and males have to fight for access to the females, then weaker males should aggregate around high-quality females while avoiding areas occupied by males of high fighting capacity. However, this aggregation pattern should only occur if males have low dispersing costs. Otherwise, males should preferentially stay near the first female they encounter. In this study, we used the golden silk orb-web spider, Trichonephila clavipes, to evaluate the following hypotheses: When costs of moving between female webs are low, weaker males should aggregate at the periphery of (a) webs of females that have higher reproductive quality and (b) webs of females occupied by central males (i.e., stronger males that are guarding females in the central web position) with lower fighting capacity. To evaluate these hypotheses, we counted the number of males at the periphery of female webs that were aggregated with other female webs (i.e., areas with lower dispersal costs among webs) or isolated from other female webs (areas with higher dispersal costs among webs). We used the ontogenetic status of the females (mature or immature) as a surrogate of female reproductive quality and the length of the first pair of male legs as a surrogate of male fighting capacity. We found that, independently of the spatial disposition of female webs, the number of males per web was unrelated to female reproductive quality or the fighting capacity of the central males. We conclude that this pattern provides an intriguing system in which the intensity of intra-sexual competition for males presumably varies in unpredictable ways between different female webs.

Automated summary

This study evaluated the tendency of males to aggregate around females using the golden silk orb-web spider. Results showed that the number of males around females was unrelated to female quality and central male fighting capacity across different female webs.