The strategies of male fighting against female's sexual cannibalism in spiders
by Shichang Zhang | Hubei University, Wuhan, China
Abstract ID: 158
Event: The 3rd AsiaEvo Conference
Topic: Behavioral evolution in vertebrates: diversity, genomics and mechanisms
Presenter Name: Shichang Zhang

Female sexual cannibalism refers to the phenomenon that females attack, kill or even consume males during mating process. It is an extreme manifestation of sexual conflict, which is common in spiders, such as black widow spider. To circumvent the attack of female spiders, males have evolved a variety of behavioural adaptations. Here I summarized related discoveries of my lab recently. For example, I found in Nephila pilipes that male would perform a mating binding behaviour to calm down the female when she is trying to capture the male. Both tactile and chemicalare crucial for mate binding to succeed in rendering females less aggressive, but that tactile cues are more important. In many spider species, male mate with a female when she is disturbed or when she is feeding or undertaking moulting, called opportunistic mating. I found that the occurrence of male opportunistic mating was positively, though not statistically significantly, correlated with the intensity of female sexual cannibalism after investigating three species of web-building spiders with different intensities of female sexual cannibalism: Nephila pilipes, Nephilengys malabarensis, and Parasteatoda tepidariorum. In addition, After testing five typical species of web-building spiders, I found that males would choose the palp that contains more sperm to perform his first insertion, supporting the“better charged palp” hypothesis and “fast sperm transfer” hypothesis. Besides, I found in wolf spider Pardosa pseudoannulata that male conducted traumatic mating, in which male damages the inner walls of the female genital tracts with the sharp part of its intromittent organ. The traumatic mating caused hemolymph hemorrhage, which mixed with seminal fluid and gradually formed an impermeable amorphous mating plug after about 15 days, completely blocking the female copulatory opening, leading to a strict monandry of the female. Finally, I found in a communal orb weaving spider Philoponella prominens that males undertake a split-second catapult action immediately after mating, thereby fleeing their partner. I demonstrate that males achieve their superfast action (up to 88.2 cm/s) by extending the tibia–metatarsus joint of their first leg pair via hydraulic pressure in a joint that is known to lack extensor muscles in spiders. This rapid expansion greatly reduces the likelihood of the male being sexually cannibalized. These findings strengthened our current understanding of sexual selection and sexual conflict theory. We assumed that sexual selection has driven the evolution of these strategies in spiders as the degree of sexual cannibalism is more likely to occur in species which sexual dimorphism is obvious and female is choosy.