Document Type



Doctor of Philosophy


Integrative Biology

First Adviser

Itzkowitz, Murray

Other advisers/committee members

Burger, Michael; Rice, Amber; Kodric-Brown, Astrid


The overarching objective of this thesis was to: (I) synthesize and review the conservation history of an endangered species of pupfish (Cyprinodon bovinus), (II) test for genetic and phenotypic divergence between a captive and wild population, (III) examine the wild population for signs of introgression with its congener, C. variegatus, (IV) evaluate evidence for the exhibition of maladaptive behaviors following the release of captive animals into the wild, and (V) examine how the presence of a putative egg predator (Gambusia nobilis) may affect density-dependent behavior and the future persistence of C. bovinus in the wild. The first chapter illustrated that while there has been a contemporary increase in the number of territorial C. bovinus, there may be unintended consequences of habitat restoration projects on reproductive success. In the second chapter, landmark-based geometric morphometrics revealed considerable morphological divergence in body shape and examination of both neutral and adaptive variation revealed significant levels of genomic divergence as well as evidence for local adaptation, possibly relating to differences in salinity between environments. While the captive population showed higher levels of genetic diversity, the wild population has maintained substantial genetic variation despite its small estimated effective population size. The third chapter revealed that the wild population failed to show substantial evidence of introgression or contemporary hybridization with the congener, C. variegatus, which was demonstrated by a lack of morphological overlap with C. variegatus, distinct genotypic clustering, and high levels of genetic divergence with the conger. The fourth chapter illustrated that following the release of captive C. bovinus into their ancestral habitat, the behavior of the reintroduced population was both quantitatively and qualitatively similar to that of the wild population; the reintroduced captive and wild populations exhibited comparable levels of reproduction, foraging and agnostic behavior. The fifth chapter demonstrated that G. nobilis failed to exert a negative density-dependent effect on C. bovinus reproductive behavior or fecundity.