Effect of topography on genetic divergence and phenotypic traits in tropical frogs


Effect of topography on genetic divergence and phenotypic traits in tropical frogs

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dc.contributor.advisor Cannatella, David C.
dc.creator Guarnizo, Carlos Enrique
dc.date.accessioned 2011-10-20T20:45:30Z
dc.date.available 2011-10-20T20:45:30Z
dc.date.created 2011-08
dc.date.issued 2011-10-20
dc.date.submitted August 2011
dc.identifier.uri http://hdl.handle.net/2152/ETD-UT-2011-08-3726
dc.description.abstract Complex interactions between topographic heterogeneity and steep gradients in climate and environmental conditions are commonly assumed to promote biotic diversification. Using tropical frogs as a model, I investigate the nature of these interactions that disrupt migration between populations, causing genetic divergence and speciation. I determine the role of several putative factors that affect gene flow (Euclidean distances, Least Cost Path (LCP) distances, topographic complexity, and elevation difference) and promote genetic structure (FST) between populations of three tropical Andean frog species. Moreover, I investigate, from an intraspecific perspective, whether montane frog species display on average larger genetic distances per kilometer relative to lowland species. Finally, I test if recent genetic divergence caused by topographic barriers to gene flow is paralleled by independent character systems such as acoustics and morphological traits in the high Andean frog Dendropsophus labialis. Even though the effect of geographic features on migration (and conversely, FST) was species-specific, LCP and Euclidean distances had the strongest effect on migration rate. Topographic complexity also reduced migration rate whereas elevation difference did not have an effect. I found that indeed highland species show larger genetic distances per kilometer between haplotypes than do lowland species. Also, genetic divergence is strongly associated with topographic heterogeneity, which is an intrinsic characteristic of montane regions. Finally, I found that acoustic variation in D. labialis diverges according to genealogical history, but external morphology does not follow this relationship. Stochastic processes due to genetic drift appear to be a better explanatory mechanism for the divergence in calls than adaptive variation. The strong and congruent divergence observed in acoustic and genetic characters indicates that these two groups correspond to morphologically cryptic parapatric species. Overall, the results of this study suggest some of the mechanisms that allow tropical mountains to promote intraspecific genetic divergence. The combined effect of ridges (promoting allopatric differentiation) and environmental gradients across elevation (promoting parapatric differentiation) are effective forces that are present mostly in highland biomes. Unfortunately, such biomes are critically threatened by habitat destruction and climate change, possibly more than any other biome on earth.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subject Biogeography
dc.subject Andean frogs
dc.subject Mountains
dc.subject Lowlands
dc.subject Genetic structure
dc.subject Tropics
dc.subject Elevation gradients
dc.subject Vicariance
dc.subject Isolation by distance
dc.title Effect of topography on genetic divergence and phenotypic traits in tropical frogs
dc.date.updated 2011-10-20T20:46:04Z
dc.identifier.slug 2152/ETD-UT-2011-08-3726
dc.contributor.committeeMember Bull, James J.
dc.contributor.committeeMember Juenger, Thomas
dc.contributor.committeeMember Wilke, Claus
dc.contributor.committeeMember Perez, Francisco
dc.description.department Ecology, Evolution and Behavior
dc.type.genre thesis
dc.type.material text
thesis.degree.department Ecology, Evolution and Behavior
thesis.degree.discipline Ecology Evolution, and Behavior
thesis.degree.grantor University of Texas at Austin
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy

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