FEMALE RECEPTIVITY AND MALE MATE-GUARDING IN THE JEWEL SPIDER GASTERACANTHA-MINAX THORELL (ARANEIDAE)

In field populations, several male jewel spiders Gasteracantha minax T horell (Araneidae) may be found at the periphery of the orb web of a f emale, indicating that males may compete for fertilisation success. La boratory experiments revealed that virgin female G. minax readily rema te shortly after their first mating. However, they appear to enter a r efractory period between 1 and 24 h postmating and respond aggressivel y to courting males. Males that have mated with a female initially def end her from rival males but cease to do so after the onset of the ref ractory period. These data can be interpreted within the context of ma te-guarding and sperm competition. There is marked size dimorphism in this species, which may be the result of selection for protandry. In c ontrast with other orb-weaving spiders, this selection pressure does n ot seem to be counterbalanced by selection for larger male size throug h either sexual cannibalism or male-male competition.