We propose to investigate genetic and demographic effects of human- induced population subdivision on the wood frog (Rana sylvatica), an aquatic-breeding, terrestrial-dwelling amphibian of mesic woodlands. Our study will examine patterns of genetic variation within and divergence among 25 subpopulations of wood frogs in a heavily urbanized area of southern Connecticut, U.S.A., where subpopulations vary widely in size (10-1,000 individuals), length of isolation (O, 10, 100, and 10,000 years), and degree of habitat connectivity. Features of the landscape intervening subpopulations will be correlated with estimates of genetic similarity between subpopulations to examine which geographic features act as barriers versus paths to gene flow. A novel experimental procedure, involving placement of artificial breeding pools in selected landscape configurations, will be used to assess the "porosity" of human-created barriers to disperse froglets. An examination of how habitat and population fragmentation has proceeded in the study area during the last century (by inspection of maps and aerial photographs) will aid in understanding how both zoogeographic factors and historical demography shaped population-level phylogenies of wood frogs. Such information is of particular interest to conservation biologists. who are increasingly concerned with long-term maintenance of genetic diversity in artificially fragmented populations.
