The effects of predation risk on mating system expression in a freshwater snail.
Environmental effects on mating system expression are central to understanding mating system evolution in nature. Here, I report the results from a quantitative-genetic experiment aimed at understanding the role of predation risk in the expression and evolution of life-history and mating-system traits in a hermaphroditic freshwater snail (Physa acuta). I reared 30 full-sib families in four environments that factorially contrast predation risk and mate availability and measured age/size at first reproduction, growth rate, a morphological defense, and the early survival of outcrossed/selfed eggs that were laid under predator/no-predator conditions. I evaluated the genetic basis of trade-offs among traits and the stability of the G matrix across environments. Mating reduced growth while predation risk increased growth, but the effects of mating were weaker for predator-induced snails and the effects of predation risk were weaker for snails without mates. Predation risk reduced the amount of time that individuals waited before self-fertilizing and reduced inbreeding depression in the offspring. There was a positive among-family relationship between the amount of time that individuals delayed selfing under predation risk and the magnitude of inbreeding depression. These results highlight several potential roles of enemies in mating-system expression and evolution.
Auld
Josh R
JR
Department of Biological Sciences, University of Pittsburgh, 4249 5th Ave., Pittsburgh, Pennsylvania 15260, USA. josh.auld@nescent.org
D000818:Animals; D003400:Astacoidea / Q000502:physiology; D020387:Food Chain; D014644:Genetic Variation; D057850:Hermaphroditic Organisms; D007178:Inbreeding; D010414:Pennsylvania; D010641:Phenotype; D012641:Selection, Genetic; D012726:Sexual Behavior, Animal; D012908:Snails / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*