Genetic connection found between male courtship gifts and female behavior in decorated crickets
At first glance, studying the mating habits of crickets may not seem as important as developing life-saving medicines or as exciting as exploring the tropical rainforest. However, studying reproductive behavior in crickets allows scientists to learn how animal behavior evolves over time. Further, studying the genetics of behavior in crickets helps researchers understand how connections between genes help or interfere with the evolution of behaviors in all animals.
Ohio State Marion Assistant Professor, Dr. Susan Gershman recently co-authored a research article in the Journal of Evolutionary Biology entitled, Food fight: Sexual conflict over free amino acids in the nuptial gifts of male decorated crickets. This paper focuses on courtship gifts, food produced by males and given to females as a part of mating.
Previous research has demonstrated that male and female Gryllodes sigillatus decorated crickets appeared to be in sexual conflict: males produce courtship gifts that females cannot resist consuming. If a female consumes these courtship gifts, the male benefits because he can transfer more sperm to the female, and he can father more of her offspring. However, consuming the gift does not provide the female with any nutrition for herself or her offspring. Consuming the courtship gift also prevents the female from mating with other males, which denies her the opportunity to have fitter, more genetically diverse offspring. The big question is why female crickets have not evolved behaviors that allow them to reject these empty gifts from males.
In the study published by Gershman and co-authors, a complex breeding design was used to demonstrate that one reason that males and females may be locked in conflict with one another, is that the genes that allow males to have more irresistible gifts are linked to the genes that influence whether or not females can refuse gifts. Because of the genetic link between males and females, females are not able to evolve defenses to avoid being attracted to empty gifts. These results suggest a possible explanation for how conflicts between males and females can persist over long periods of evolutionary time.
Dr. Gershman’s video footage of courtship feeding in Gryllodes sigillatus, the decorated cricket was recently used in a television segment called “Ritual Gifting,” in the Discovery Channel Canada program Daily Planet.
In spring 2014, the paper was featured in dugdug.com, an online research publication (http://www.dugdug.com/dr-susan-gershman-discusses-nuptial-gifts). The article was also selected as editor’s choice by Journal of Evolutionary Biology.
Dr. Susan Gershman is an Assistant Professor at The Ohio State University, Marion, in the Department of Evolution, Ecology and Organismal Biology. She earned her PhD from the University of California, Riverside, studying sexual selection and sexual conflict in crickets. She currently studies the evolution of reproductive behavior in crickets, flies, bedbugs and other insects.