New paper published
Scientists at The Copperhead Institute, and their collaborators at the University of Arkansas, the Chiricahua Desert Museum, the Georgia State University, and the Illinois Natural History Survey are pleased to announce that their latest paper has just been published in the scientific journal Biological Journal of the Linnean Society. The paper is available in an online early view version here.
The authors would like to thank S. Mussmann who spent numerous hours teaching molecular techniques and analyses to B. A. Levine, and also A. Reynolds and J. Reynolds for laboratory assistance. The Illinois Natural History Survey (Prairie Research Institute, University of Illinois/Urbana-Champaign) is acknowledged for providing a Summer Research Fellowship to B. Levine that yielded the data for the present study. The authors also appreciate the assistance of the W. M. Keck Center for Comparative and Functional Genomics (University of Illinois/Urbana-Champaign) for their quick translation of molecular amplifications into quantitative fragment data, as well as three anonymous reviewers for their comments that helped to improve the manuscript. Additional acknowledgements with regard to individuals, agencies, and NGOs, including sampling and IACUC permits, are provided in Smith et al. (2009).
ABSTRACT Assessment of sexual selection in organisms with cryptic life histories is challenging, although accurate parentage assignments using genotypic markers, combined with behavioural observations and a method to account for open population bias, allow for robust estimation of metrics. In the present study, we employed 22 tetranucleotide microsatellite DNA loci to interpret mating and reproductive success in a population of Copperhead (Viperidae, Agkistrodon contortrix) in Connecticut, USA. We sampled DNA from 114 adults (56 males, 58 females) and 137 neonates from known mothers to quantify Bateman gradients (βss), as well as sex-specific opportunities for selection (I) and sexual selection (Is). We also estimated selection on male size [snout-to-vent length (SVL)], a trait important for successful combat and subsequent copulations. Estimates of male I and Is differed significantly from those of females when estimated with four different methods and only males had a significant Bateman gradient. As predicted, male reproductive success was positively correlated with increasing SVL. These results contrast with those derived in another study investigating the same population but based solely on observational data and without correction for open population bias. We thus argue that molecular approaches to quantifying reproductive success and strength of sexual selection provide more accurate results than do behavioural observations alone.
Coauthor Brenna Levine (left)