Graduation Semester and Year
2021
Language
English
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Quantitative Biology
Department
Biology
First Advisor
Matthew K Fujita
Abstract
The effects of genetic introgression on species boundaries and how they affect species’ integrity and persistence over evolutionary time have received increased attention. The increasing availability of genomic data has revealed contrasting patterns of gene flow across genomic regions, which impose challenges to inferences of evolutionary relationships and of patterns of genetic admixture across lineages. By characterizing patterns of variation across thousands of genomic loci in a widespread complex of true toads (Rhinella), we assess the true extent of genetic introgression across species thought to hybridize to extreme degrees based on natural history observations and multi-locus analyses. Comprehensive geographic sampling of five large-ranged Neotropical taxa revealed multiple distinct evolutionary lineages that span large geographic areas and, at times, distinct biomes. The inferred major clades and genetic clusters largely correspond to currently recognized taxa within Rhinella; however, we also found evidence of cryptic diversity within taxa. Phylogenetic analyses revealed extensive mito-nuclear discordance, while genetic clustering analyses uncovered several admixed individuals within major genetic groups. Accordingly, historical demographic analyses supported that the evolutionary history of these toads involved cross-taxon gene flow both at ancient and recent times. Lastly, ABBA-BABA tests revealed widespread allele sharing across species boundaries, a pattern that can be confidently attributed to genetic introgression as opposed to incomplete lineage sorting. These results confirm previous assertions that the evolutionary history of Rhinella was characterized by various levels of hybridization even across environmentally heterogeneous regions, posing exciting questions about what factors prevent complete fusion of diverging yet highly interdependent evolutionary lineages.
Keywords
Phylogenomics, Phylogeography, Gene flow, Introgression, Demographic modeling
Disciplines
Biology | Life Sciences
License
This work is licensed under a Creative Commons Attribution-NonCommercial-Share Alike 4.0 International License.
Recommended Citation
Rivera, Danielle George, "GENOMIC STRUCTURE AND DIVERSITY IN NEOTROPICAL HERPETOFAUNA: THE ROLE OF DEMOGRAPHIC HISTORY AND GENE FLOW" (2021). Biology Dissertations. 190.
https://mavmatrix.uta.edu/biology_dissertations/190
Comments
Degree granted by The University of Texas at Arlington