Parallel Divergence by Allochrony and Cryptic Speciation in two Highly Pelagic Seabird Species Complexes (Hydrobates spp.)
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Authors
Taylor, Rebecca
Date
Type
thesis
Language
eng
Keyword
Speciation , Cryptic Species , Allochronic Speciation , Storm-Petrel
Alternative Title
Abstract
Sympatric speciation, the evolution of reproductive isolation between populations without physical barriers to dispersal, is less likely than allopatric speciation due to the need to overcome potentially homogenizing gene flow. Cryptic species - two or more species mistakenly classified as one usually due to morphological similarity - can form in allopatry or sympatry. One potential mechanism of cryptic speciation in sympatry is allochronic speciation, i.e. divergence driven by differences in breeding time. In this thesis, I first collated examples where allochrony caused divergence between populations to glean new insights into drivers of shifts in breeding time across taxonomic groups and the genetic underpinnings involved, and to create a framework for future investigations. Using both genetic and genome-wide sequencing techniques, I then investigated drivers of cryptic divergence and the evolution of allochronic populations across the global breeding ranges of two cryptic seabird species complexes, Leach’s and band-rumped storm-petrels (Hydrobates spp.). In Leach’s storm-petrels, I found non-physical barriers to be stronger drivers of divergence than physical ones, with some genetic differentiation between ocean basins but higher differentiation among colonies in the Pacific Ocean. Phylogenetic reconstruction revealed that Guadalupe seasonal populations likely speciated allochronically. In band-rumped storm-petrels, colonies in different ocean basins were genetically differentiated, however phylogenomic reconstruction placed South Atlantic colonies as sister to Pacific colonies, and revealed strong genetic structuring within ocean basins, again suggesting non-physical barriers as drivers of divergence. Band-rumped storm-petrels consist of seven reciprocally monophyletic groups, and thus likely represent up to seven different species. I then investigated whether allochronic populations of band-rumped storm-petrel formed due to a mutation shifting breeding time in a founder event, standing genetic variation at the population level, or plasticity in breeding time. My findings indicate breeding season changes are unlikely to have involved a mutation and founder event, however further work is needed to tease apart the potential roles of standing variation and plasticity. Altogether, this thesis reveals the importance of non-physical barriers to gene flow in Leach’s and band-rumped storm-petrels, uncovers cryptic species needing taxonomic and conservation consideration, and furthers our knowledge of allochronic divergence, an underappreciated mechanism of cryptic diversification.
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.