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Population genetics and population dynamics of Moapa dace

Hereford, Danielle M

Titre : Population genetics and population dynamics of Moapa dace

Auteur : Hereford, Danielle M

Université de soutenance : UNIVERSITY OF NEVADA, RENO

Grade : Master of Science (M.S.) 2014

Résumé partiel
The Mojave Desert is an arid environment where precipitation ranges from 3.4 to 31.0 cm of rain per year. Species adapted to live in the Mojave Desert tend to be drought resistant and typically utilize little water. Geothermal springs are scare but provide consistent dependable water resources from large carbonaceous aquifers. Springs in the Mojave Desert were manipulated by human populations for agriculture, recreation, or municipalities. As a result, aquatic ecosystems and aquatic species were disrupted on many levels. For example, habitat fragmentation limited movement and dispersal of organisms ; population isolation constrained meta-population dynamics and gene flow, and non-native species disrupted food webs, trophic interactions, and displaced native species. As water demands continue to increase in Southern Nevada, aquatic ecosystems are at greater risk and need to be carefully managed. Endangered species risk losing genetic variation and evolutionary potential when habitat is fragmented, limited, or both. Restricted habitat can also limit survival of individuals, recruitment within a population, and the size of a population. This study quantifies genetic variation, population structure, and population dynamics of Moapa dace Moapa coriacea in its restricted and fragmented habitat. Moapa dace Moapa coriacea is a thermophillic cyprinid endemic to the Muddy River and its tributaries in Clark County, NV. Historically, Moapa dace occurred in the upper 16 kilometers of the Warm Springs area- the Muddy River and its tributaries. Moapa dace are drift feeders that have unique physiology and biology adapted to live in warm water with low levels of dissolved oxygen. Populations of Moapa dace haveexperienced substantial population declines since they were first described by Hubbs and Miller in 1948. Humans manipulated dace habitat by diverting spring outflows for regional municipalities, agriculture, or recreation. After substantial population declines, Moapa dace were listed as endangered in 1967 and United States Fish and Wildlife Service began purchasing property at spring sources to create the Moapa Valley National Wildlife Refuge to protect Moapa dace habitat. Moapa dace populations increased, but later declined when a downstream diversion dam was removed and introduced the nonnative piscivore blue tilapia. A gabion barrier was installed in 1997 at the confluence of the Apcar tributary and the Muddy River to protect 2.8 kilometers of stream habitat from further tilapia invasion. Moapa dace have been restricted to the Apcar, Pederson, and Plummer tributaries since 1997.The Moapa dace population was around1000 individuals from 1999 to 2007, then substantially declined to less than 500 in 2008. From October 2009 to September 2012 I conducted a bimonthly mark recapture study and estimated Moapa dace abundance, survival, recruitment, and rate of population growth. DNA was extracted from fin clips and ten polymorphic microsatellite loci were used as tags to identify individuals. I also used genetic samples to quantify genetic diversity and population structure among stream tributaries over the three year period.

Mots clés : Population genetics, Genetics, Wildlife Conservation, Zoology, Moapa coriacea, Endangered species , Conservation, Fish, Species survival, Biological sciences

Présentation (GradWorks)

Page publiée le 4 février 2015, mise à jour le 27 décembre 2017