CHAN, L. M.; Cornell University: Intra- and inter-annual variation in the genetic diversity of a desert breeding anuran.

In the deserts of the southwestern United States many anurans breed explosively at ephemeral ponds with the onset of monsoon rains in dense aggregations lasting only one to four nights. Mating system characteristics, life history traits, and unpredictable aquatic conditions (e.g. length of pond persistence, community structure) provide the opportunity for genetic diversity to be lost between parent and offspring groups such that census sizes of breeding aggregations may be much greater than the effective size. I use microsatellite markers to examine changes in genetic composition for the Great Plains toad (Bufo cognatus) across different age classes (adults, tadpoles, metamorphs) both within and across breeding seasons. Adult to tadpole and adult to metamorph comparisons are used to determine the relative importance of reproductive success and tadpole survivorship, respectively, on the maintenance of genetic diversity. This is discussed in the context of inter-annual variation in spatial genetic structure.