| Genetic mating systems are generally understood to be an important component of wild animal population assessments, as they can influence the amount of genetic diversity within a population, as well as the ability of that population to recover from depletion. For the first chapter of this dissertation I employed polymorphic microsatellite markers to provide the first information on genetic parentage in a beach-spawning marine fish, the California grunion, Leuresthes tenuis. I document (a) no instances of multiple maternity for progeny within a nest; (b) a high frequency of nests (88%) with multiple paternity; and (c) an appreciable fraction of nests (18%) in which the estimated number of genetic sires (as many as nine) proved to be greater than the observed number of male attendants, thus implicating occasional extra-group fertilization events.;For the second chapter of my dissertation I use microsatellite as well as mitochondrial DNA markers to test for molecular genetic differentiation between spatially and temporally diverse populations of Leuresthes tenuis. I also use these same markers to examine the separate species status of the Gulf grunion, Leuresthes sardina. I report no significant differences between temporal samples, but small significant differences between spatial samples of L. tenuis. We conclude that the data likely elucidate a relatively recent range expansion from south of Point Conception, California to northern California waters. In addition we present unequivocal molecular evidence in support of the separate species status of Leuresthes sardina.;For the third and final chapter, I employed microsatellite markers to analyze genetic paternity in litters of the brown smoothhound shark, Mustelus henlei, and I review the existing literature on genetic mating systems in sharks. I show the first evidence of multiple paternity for this species, as well as the highest prevalence of multiple paternity seen to date in any species of shark. We note that multiple paternity seems ubiquitous in sharks, and that their reproductive behavior has likely evolved in response to conflicting selection pressures between the sexes. |
