Vagabond males and sedentary females: spatial ecology and mating system of the speckled rattlesnake (Crotalus mitchellii)

• Published in: Biological journal of the Linnean Society Vol. 103; no. 3; pp. 681 - 695
• Main Authors: GLAUDAS, XAVIER, RODRÍGUEZ-ROBLES, JAVIER A
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.07.2011; Wiley-Blackwell
• Subjects: Amphibia. Reptilia; Biological and medical sciences; Biological evolution; body size; Crotalus; Crotalus mitchellii; females; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; hibernation; home range; males; mate-searching activities; mating systems; Mojave Desert; movement; sex role; sexual selection; snakes; spring; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Mojave Desert; North America; USA, California, Mojave Desert; Mojave Desert; mate-searching activities; Sex role; Biological evolution; Male; Ecology; Ophidia; Mating system; Vertebrata; Female; Reptilia; Sedentary; movement; Mate searching
• ISSN: 0024-4066; 1095-8312
• DOI: 10.1111/j.1095-8312.2011.01677.x

We used radiotelemetric data and behavioural observations to characterize seasonal (mating versus post-mating seasons) and sexual variation in movement patterns, as well as to examine some of the ecological factors contributing to the evolution of the mating system in a venomous predator from the Mojave Desert of North America, the speckled rattlesnake, Crotalus mitchellii. Mating occurs in spring from late April to early June, shortly after emergence from hibernation, when snakes are predictably aggregated around the dens. Males and females travelled further per unit time in the mating season compared to the post-mating season. Males also travelled longer distances per unit time than females in the mating and post-mating seasons, and males with larger home ranges during the mating season had more potential mating partners. The results obtained suggest that males actively locate females during the mating season, and that the drastic increase in distance travelled by males during the mating season may be caused by strong male-male competition for access to females, probably because of the limited availability of sexually receptive females. Furthermore, males fight for access to females, and males of larger size are more likely to acquire females. Therefore, sexual selection apparently acts on two different male phenotypic traits: investment in mate-searching activities and male body size. The present study demonstrates that combining quantitative spatial analyses and behavioural observations in an explicit temporal context can significantly advance our understanding of the ecology and evolution of organismal mating systems. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 681-695.