Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Welch, Mark E.
Committee Member
Wallace, Lisa
Committee Member
Ervin, Gary N.
Committee Member
Knapp, Charles R.
Committee Member
Counterman, Brian A.
Other Advisors or Committee Members
Gerber, Glenn P.
Date of Degree
12-9-2016
Document Type
Dissertation - Open Access
Major
Biological Sciences
Degree Name
Doctor of Philosophy
College
College of Arts and Sciences
Department
Department of Biological Sciences
Abstract
Understanding whether groups of individuals represent a single panmictic gene pool, or multiple genetically structured populations across a species range should aid in predicting whether specific conservation strategies would be more or less effective for species preservation. Further, contrasting the population structures of multiple coexisting taxa could foster an even deeper understanding of evolutionary divergence among demes and potentially even suggest local adaptation in the form of tight coevolutionary relationships. Finally, the analysis of population dynamics within small and isolated populations could improve our understanding of the relative importance that different evolutionary mechanisms have in predicting population persistence in the wild. Using microsatellite markers I characterized the population genetic structure in the critically endangered Cyclura cychlura cychlura iguanas on Andros Island. I found significant differences between inferred and realized rates of gene flow. This finding demonstrates that evolutionarily independent populations can occur even with high rates of dispersal. In the second and third study I contrasted patterns of genetic variability in Cyclura cychlura cychlura iguanas, ticks in the genus Amblyomma parasitizing these iguanas, and Rickettsia spp., potential pathogens transmitted by these ticks. I determined that genetic differences among Rickettsia samples and Amblyomma samples are highly concordant with genetic divergence among iguana populations. This finding suggests largely vertical dispersal of ticks and their super-parasite, a high specificity of this reptile-tick interaction, and historically low rates of dispersal in iguanas. This finding also indicates that island populations of iguanas may be locally adapted due to tight coevolutionary relationships. Finally, I investigated the mechanisms that eliminate harmful mutations in small isolated and natural populations of the critically endangered Cyclura cychlura cychlura iguanas. Using molecular tools I found indirect evidence suggesting that small natural populations can maintain significant levels of genetic variation in spite of strong selection acting against harmful mutations. Under regimes of random mating, the buildup of harmful mutations in small populations may result in a large number of inviable young. However, harmful mutations may also be eliminated when exposed to natural selection through increased competition, as population density increases. However, quantification of the relative role of competition was not feasible in this study.
URI
https://hdl.handle.net/11668/18934
Recommended Citation
Colosimo, Giuliano, "Natural Population Dynamics of Rock Iguanas in the Bahama Archipelago" (2016). Theses and Dissertations. 3268.
https://scholarsjunction.msstate.edu/td/3268
Comments
microsatellites||population structure||population dynamics||conservation genetics