Web wars: Males of the golden orb-web spider invest more in fights for mated and aggregated females

In addition to resource value, the cost of finding mates may affect how much males invest in fights for females. The cost of finding females may be imposed through natural factors extrinsic to males, such as female spatial distribution and predation pressure, which can be challenging to simulate in laboratory conditions. Therefore, studies under natural conditions may be suitable for understanding how the costs of finding mating partners affect male investment in fights. We used the spider Trichonephila clavipes to evaluate the hypotheses that males in field conditions invest more in contests for access to (1) unmated and (2) more fecund females, and (3) when access to females is harder. To test these hypotheses, we recorded the occurrence, duration and escalation of induced contests between males located in webs of females that differed in reproductive status (estimated by female life stage), fecundity (estimated by female abdominal area) and spatial distribution (i.e. isolated or aggr...