Meeting Abstract

33.3  Jan. 5  Fitness consequences of polyandrous mating for female marbled salamanders CROSHAW, Dean A.; Savannah River Ecology Laboratory croshaw@srel.edu

Female polyandry occurs to some extent in a very high proportion of species. Because mating likely involves considerable fitness costs to individual females, theory predicts that polyandrous females gain fitness benefits that outweigh the costs, allowing the behavior to be maintained in extant populations. Potential benefits are non-genetic (or material) and genetic, with only the latter likely to occur in species where males provide females with sperm only, as in most salamanders. Genetic benefits could involve increased genetic compatibility between parents, genetic variation among offspring, quality of paternal genes, and quality or attractiveness of sperm. In the first study of the evolutionary consequences of polyandry in an ambystomatid salamander, we compared fitness correlates of monandrous and polyandrous marbled salamander clutches from semi-natural breeding arenas at the egg, hatchling, and metamorph stages. Larvae from polyandrous and monandrous clutches, determined by genetic paternity assignment, developed together in competition within high density field enclosures until metamorphosis. Survival to metamorphosis was significantly greater for polyandrous clutches than monandrous clutches. Our study provides the first evidence of increased survival of larvae produced by multi-male mating in an amphibian. I discuss these potential genetic benefits in terms of competing hypotheses to explain the evolution of polyandry.