Female receptivity and male mate-guarding in the jewel spiderGasteracantha minax thorell (Araneidae)

In field populations, several male jewel spidersGasteracantha minax Thorell (Araneidae) may be found at the periphery of the orb web of a female, indicating that males may compete for fertilisation success. Laboratory experiments revealed that virgin femaleG. minax readily remate shortly after their first mating. However, they appear to enter a refractory period between 1 and 24 h postmating and respond aggressively to courting males. Males that have mated with a female initially defend her from rival males but cease to do so after the onset of the refractory period. These data can be interpreted within the context of mate-guarding and sperm competition. There is marked size dimorphism in this species, which may be the result of selection for protandry. In contrast with other orb-weaving spiders, this selection pressure does not seem to be counterbalanced by selection for larger male size through either sexual cannibalism or male-male competition.