Queen's University - Utility Bar

QSpace at Queen's University >
Graduate Theses, Dissertations and Projects >
Queen's Graduate Theses and Dissertations >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1974/7164


Files in This Item:

File Description SizeFormat
Morris-Pocock_James_A_201204_PhD.pdf2.12 MBAdobe PDFView/Open
Keywords: Speciation
Population Differentiation
Secondary Contact
Molecular Ecology
Habitat Preference
Issue Date: 30-Apr-2012
Series/Report no.: Canadian theses
Abstract: Speciation is an important process that is responsible for the generation of biodiversity on Earth. The importance of gene flow during speciation is hotly debated; however, it can be investigated by studying the process of intraspecific population differentiation. Here, I investigate the mechanisms that influence population differentiation and gene flow in brown (Sula leucogaster) and red-footed boobies (S. sula). These species are congeneric, broadly sympatric, and ecologically similar; however, they differ in their marine habitat preference (inshore vs. pelagic). I hypothesized that: (i) gene flow is restricted by major physical barriers in both species, and (ii) gene flow in the absence of physical barriers is more prevalent in red-footed boobies due to their pelagic marine habitat preference. First, I characterized the structure and function of the booby mitochondrial genome. Using extensive DNA sequencing and phylogenetic methods, I found that boobies have tandemly duplicated mitochondrial control regions that evolve in concert. I suggest that concerted evolution of duplicated control region may be common in seabirds. To quantify matrilineal population genetic structure and gene flow, I sequenced one control region in 513 brown and red-footed boobies. Both species exhibited strong population genetic structure that was attributable to continental barriers to gene flow such as the Isthmus of Panama. In the absence of physical barriers, gene flow was more prevalent in red-footed boobies. I also used microsatellite and nuclear intron loci to perform multilocus phylogeographic analyses of brown and red-footed boobies. Individuals of both species could be grouped into four genetic populations that corresponded to oceanographic regions. In red-footed boobies, gene flow following secondary contact of previously isolated lineages was common, perhaps due to a pelagic habitat preference. In brown boobies, major genetic populations apparently diverged in the absence of gene flow. Despite this, Isla San Benedicto in the Eastern Pacific is a site of secondary contact between brown booby lineages that diverged approximately one million years ago, and hybrids are apparently fertile. These findings suggest that gene flow following secondary contact may be an important, but overlooked, component of speciation.
Description: Thesis (Ph.D, Biology) -- Queen's University, 2012-04-28 17:28:53.302
URI: http://hdl.handle.net/1974/7164
Appears in Collections:Queen's Graduate Theses and Dissertations
Department of Biology Graduate Theses

Items in QSpace are protected by copyright, with all rights reserved, unless otherwise indicated.


  DSpace Software Copyright © 2002-2008  The DSpace Foundation - TOP