Repeatability of reproductive traits in a stream-associated population of Northern Cottonmouths (Agkistrodon piscivorus)

Greene, Brian D.         

BrianGreene@missouristate.edu

Department of Biology                                                                                                                                

Missouri State University                                                                                                                            

Springfield, Missouri USA 

The expression of traits in wildlife species is a consequence of both genetic and environmental influences.  Measuring the consistency of expression of within-individual reproductive life history traits in species that experience multiple reproductive events can provide insight into the relative amount of trait variation related to heritability rather than environmental effects. During a 20+ year mark-recapture study of Northern Cottonmouths (Agkistrodon piscivorus) in southwest Missouri, I measured female SVL, litter size, relative clutch mass, total litter mass, and mean offspring SVL and mass for 45 females that produced 2-4 litters. No female was ever observed to produce a litter in successive years. Despite this temporal gap in litter production that would presumably allow body mass recovery between litters, I observed low, non-significant repeatability values (all < 0.4) in litter characteristics except for litter size between first and second litters. My results suggest that environmental variation in prey availability may exert a significant influence on the individual expression of reproductive life history traits in this population.