Article Review: The More the Merrier

What's good my fellow herp buddies, I'm back this week bringing with me everyone's favorite college topic, sex. I found this article published in the Animal Behaviour journal from January of 2019. The article, Sexual selection on female collared lizards favours offspring production with multiple males, delves into the what benefits, if any, arise from the eastern collared lizards, Crotaphytus collaris, choosing multiple male mates over one single male. These males are known as sires and it is typical for males to be polygynous, many female mates, to ensure reproductive success; however, it is unclear what benefits females would receive from being polyandrous, many male mates. The studied species were observed in a spillway off of the Arcadia Dam where they build their nests, where they live year-round. The males are highly territorial and preside over multiple females within their home range. Non-territorial males are cautious and avoid encounters with territorial males and females within these home ranges will try to avoid non-territorial males. This is interesting because females were found to mate almost evenly between both territorial and non-territorial, provoking the question, if there are benefits to polyandry, why choose the non-territorial males as mates? This led to questions of was sperm stored or removed as decided by female or other post-copulation mechanisms being applied to increase fitness. The researchers admit in their discussion that there were many variables they could not account for such as; # of actual mates, post-copulation decisions, or how many sexual encounters involved insemination. However, taking all of this into consideration, the researchers were able to conclude that females chose multiple males to increase their genetic fitness because as the number of sires increased so did hatching success. This study found that one benefit of multiple mates is greater chance of offspring hatching and survivorship; however, there was no difference found in the actual mortality rates of females with one mate vs multiple mates. This implies that females use multiple mates to increase total sperm count and then most likely make fitness decisions when time for fertilization based on observations of both the territorial and non-territorial males and their fitness. This could be a simple matter of the more sperm the female receives the greater the chance for reproductive success, or it could delve deeper into mate choices based on observations of dominance (defense) and foraging skills. The implications of this article are that little is understood when it comes to mate choice within most squamates, specifically post-copulation decisions in females for both reproductive and offspring success. It would seem that mating behavior is a particular area that requires both free range and lab based studies to fully comprehend the complexity of reptilian reproduction. 

Sexual selection on female collared lizards favours offspring production with multiple males 

Joshua R. York , Troy A. Baird

https://www.sciencedirect.com/science/article/abs/pii/S000334721830321X?via%3Dihub