Biology Students Talk about Spider Sex Roles at State Capitol

By Purnell T. Cropper | March 30, 2010

Biology students Alyssa McDermott and Ashley Ziegler presented the combined findings of their respective theses projects at Undergraduate Research at the Capitol in Harrisburg on Tuesday, March 23, before Pennsylvania Speaker of the House Keith R. McCall, along with students from 24 other institutions.

The title of their poster was, “Adaptively flexible courtship and mating behaviors in a cellar spider.”

“They received many positive comments about the work and their presentation skills and enjoyed the experience,” says Dr. Chad Hoefler, Assistant Professor of Biology. See more information on the event in the Times News.

“Classic sex role stereotypes include sexually passive and choosy females that invest heavily in offspring, and promiscuous and indiscriminant males who contribute only inexpensive sperm to their progeny,” said McDermott and Ziegler in their abstract.

“These stereotypes underpin textbook explanations for a wide variety of sex differences in morphology and behavior. However, organisms often live in variable environments; thus, sex roles should be a product of adaptively flexible individuals responding to an array of ecological variables.

“We were interested in characterizing the sex roles of the cellar spider, Pholcus phalangioides, to reveal the degree to which these behaviors are fixed or respond to environmental variability. Specifically, we examined the effects of adult sex ratio, food quality and quantity on mating interactions between males and females.

“We discovered that adult sex ratio and food quantity influenced both male and female mating behaviors, which showed high degrees of adaptive plasticity. We also discovered sex differences in the amount of time necessary for individuals to be able to re-mate, and this difference was modulated by diet. The findings of our research link individual behavior to the characterization of sex roles, and this integration may contribute to a transformation of the classical approach to understanding the evolution of mating systems,” they concluded.