Search

Five alternative mating strategies among side-blotched lizards (Uta stansburiana) are examined, including the heritability of each strategy, morph fitness, and strategy links between the sexes.

Aggregate or explosive breeding is widespread among vertebrates and likely increases the probability of multiple paternity. We assessed paternity in seven field collected clutches of the explosive breeding spotted salamander (Ambystoma maculatum) using ten microsatellite loci to determine the frequency of multiple paternity, the number of contributing males, and the degree of reproductive skew among contributing males to a female's clutch. Using the Minimum Method of allele counts, multiple paternity was evident in 70% of these egg masses. We also analyzed genotype distributions using computer simulations that estimate the most likely number of contributing fathers given population allele frequencies when parental genotypes are unknown. We simulated levels of equal male contributions and two estimates of reproductive skew and determined that genotype data for a minimum of twenty to thirty offspring per clutch are needed to determine multiple parental contributions in this system. For those clutches meeting this minimum requirement we determined that between two and eight males contribute normally to A. maculatum clutches in naturally breeding populations. Estimates of reproductive skew have a significant influence on assays of the number of male contributors. These results suggest that multiple paternity is a common strategy in this species and that females may benefit from producing offspring sired by more than one male.

Metapopulation theory provides a framework for predicting population persistence and other population dynamic behavior when populations in a given landscape are connected by dispersal. Although many species of amphibians, especially those breeding in ephemeral ponds, are presumed to exist as metapopulations, there are precious few data demonstrating metapopulation structure of any amphibian. Nevertheless, there is much current interest in understanding landscape-level processes in terms of their impacts on the population biology of amphibian species. Most amphibians are cryptic in their terrestrial home ranges; therefore, indirect methods of measuring rates of individual dispersal provide an opportunity to construct realistic metapopulation models for many species. At the very least, metapopulation processes can only be reliably modeled once we have information about rates of movement of individuals among populations. We are interested in the role that metapopulation processes and landscape-level habitat variation contribute to the population dynamics of spotted salamanders (Ambystoma maculatum) in northeastern Ohio. We utilized 8 microsatellite loci to determine the genetic structure of spotted salamanders breeding at 17 ponds located within a landscape fragmented by roads, agricultural and urban areas, and the Cuyahoga River. Dispersal of individuals among populations influences gene flow and thus contributes to genetic differentiation among ponds. Using a variety of analyses (e.g., [F.sub.ST] BAPS, AMOVA) we uncovered interesting patterns of genetic structure that are not predicted by geographic interpond distances or landscape features believed to inhibit dispersal.