Year: 2017
Type: dissertation
Abstract: Hybridization not only combines the genomes of parental populations but also plays a role in the generation of genetic diversity and the formation of new species. Most knowledge on hybridization in nature owes to studies at temperate latitudes, especially in birds, that use few genetic markers. My research is one of the first studies to focus on hybridization in Amazonian birds that uses a next generation sequencing approach sampling broadly across the genome. I provide the first report of a bird species of hybrid origin in the tropics, the manakin L. vilasboasi. The genetic composition of L. vilasboasi consists of contributions from L. iris and L. nattereri. Currently, L. vilasboasi is not interbreeding with either parental species. Some components of the crown feather nanostructure in L. vilasboasi are intermediate between the parental species and may be partially responsible for its distinctive yellow crown, a trait likely to drive prezygotic reproductive isolation. I provide one of the first genomic assessments of the phylogeography and patterns of admixture for an avian species complex ocurring in Amazonian flooded forests. My data support four genetically divergent lineages, each showing phenotypic differentiation in plumage colouration. These four lineages hybridize extensively, resulting in clinally structured hybrid zones between several lineages , while large parts of western Amazonia is comprised of a non-clinal hybrid swarm between three of the four lineages. Given the prevalence of genetic admixture, it is uncertain if all four lineages will remain genetically distinctive. I performed analyses of geographic clines which suggest that hybridization is eroding the genetic differentiation between two of these lineages. It is likely that the final outcome will be the eventual extinction of one the parental species. In sum my thesis shows the evolutionary significance of hybridization by creating new species, shaping phylogeographical patterns or driving the collapse of incipient species. The outcome of hybridization is dependent on the strength of reproductive isolation and how the combined parental genotypes interact, and these are influenced by stochastic and deterministic factors.
Source: TSpace (University of Toronto)
Author: Alfredo O. Barrera‐Guzmán
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2922350421