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Divergence in the ecology of two species of Gambusia in secondary contact


Please use this identifier to cite or link to this item: http://hdl.handle.net/1928/12845

Divergence in the ecology of two species of Gambusia in secondary contact

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dc.contributor.author Swenton, Daniella M.
dc.date.accessioned 2011-07-02T16:09:00Z
dc.date.available 2011-07-02T16:09:00Z
dc.date.issued 2011-07-02
dc.date.submitted May 2011
dc.identifier.uri http://hdl.handle.net/1928/12845
dc.description.abstract Gambusia nobilis, a federally endangered species, and G. affinis (Poeciliidae) are small, livebearing fishes found in the southwestern U.S. The invasive G. affinis has been introduced globally to control mosquito populations. It is found in some populations of G. nobilis on Bitter Lake National Wildlife Refuge (BLNWR), the field site for this study. It is unclear to what extent the two species have diverged in behavior and ecology and how extensively they have hybridized on BLNWR, thereby threatening the endangered G. nobilis via genetic introgression. In this study I examined divergence in behavior and ecology between two species with four main objectives: (1) To determine if there is assortative mating between the two species; (2) To determine if there is divergence in life history characteristics between the two species; (3) To assess habitat and dietary differences between extant populations of the two species; and (4) To determine the degree to which the two species have genetically introgressed on BLNWR. I found these two fishes are markedly different in behavior and ecology. Males and females of both species show assortative preference in visual/olfactory tests. This assortative preference pattern was held during copulation, probably as a function of female choice. Data from field caught and lab breeding individuals show differences in key life history traits that reflect the trade-offs in their current environments. To assess ecological divergence I characterized the habitats of the two species. G. affinis persists in ephemeral environments and G. nobilis is restricted to spring-fed, stenohaline and stenothermal habitats. The two species also show differences in ecological niche as G. nobilis appears to feed at a higher trophic level. Finally, I characterized genetic patterns of hybridization. I found low genetic diversity for G. nobilis, probably a result of range contraction. Gene flow and rates of hybridization are low providing further evidence for divergence and reproductive isolation between these two species. The results presented here include characterization of the habitat requirements, heterospecific interactions, and population genetics of these two species on BLNWR and may be helpful to management of a sensitive species such as G. nobilis. en_US
dc.description.sponsorship National Science Foundation, New Mexico Department of Fish and Game Share with Wildlife Program, University of New Mexico Department of Biology, University of New Mexico Graduate and Professional Student Association en_US
dc.language.iso en_US en_US
dc.subject Gambusia, reproductive isolation, population genetics, hybridization, mate choice, stable isotopes, life history en_US
dc.subject.lcsh Gambusia--New Mexico--Bitter Lake National Wildlife Refuge.
dc.subject.lcsh Divergence (Biology)
dc.subject.lcsh Gambusia--Hybridization.
dc.subject.lcsh Gambusia--Ecology.
dc.title Divergence in the ecology of two species of Gambusia in secondary contact en_US
dc.type Dissertation en_US
dc.description.degree Biology en_US
dc.description.level Doctoral en_US
dc.description.department University of New Mexico. Biology Dept. en_US
dc.description.advisor Kodric-Brown, Astrid
dc.description.committee-member Turner, Thomas F.
dc.description.committee-member Wolf, Blair O.
dc.description.committee-member Trexler, Joel C.

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