Evolutionary consequences of avian migration and dispersal /

Saved in:
Bibliographic Details
Author / Creator:Winger, Benjamin M. A., author.
Ann Arbor : ProQuest Dissertations & Theses, 2015
Description:1 electronic resource (189 pages)
Format: E-Resource Dissertations
Local Note:School code: 0330
URL for this record:http://pi.lib.uchicago.edu/1001/cat/bib/10773302
Hidden Bibliographic Details
Other authors / contributors:University of Chicago. degree granting institution.
Notes:Advisors: John M. Bates Committee members: Shannon Hackett; Marcus Kronforst; Trevor Price; Richard Ree.
Dissertation Abstracts International, Volume: 77-02(E), Section: B.
Summary:From local adaptation to macroevolutionary patterns of diversity, the course of evolution is profoundly influenced by how organisms disperse through the landscape (Bohonak 1999). For example, dispersal across barriers is an important precursor to speciation because it can result in the concomitant expansion of species' ranges and isolation of populations (Mayr 1963). Yet, ongoing dispersal between geographically separated populations can prevent them from diverging, and these competing influences of dispersal on the speciation process creates a dynamic tension that is poorly understood (Rasanen and Hendry 2008; Kisel and Barraclough 2010; Claramunt et al. 2012; Weeks and Claramunt 2014). Variation in dispersal ecology is especially consequential for lineage diversification in birds, whose movement capacity ranges from species that cover the entire globe in a single migratory event to flightless taxa with highly restricted dispersal (Belliure and Sorci 2000; Winkler 2005). On a global scale, the movements of birds are thought to have promoted ecologically and taxonomically diverse radiations (Rolland et al. 2014; Smith et al. 2014; Marki et al. 2015; Pigot and Tobias 2015). However, a consequence of high dispersal in birds are fluidly evolving geographic ranges that, like waves over sand, erase the signature of past speciation events and challenge our ability to infer species' geographic histories. In this thesis, I employ a diversity of phylogenetic, phylogeographic, and population genomic approaches to infer past geographic events in avian evolutionary history and thereby explore the evolutionary influences of avian movements, from macroevolutionary patterns of biogeography and diversification to localized patterns of range expansion and population differentiation.
In Chapter 1, I address the enigmatic evolutionary dynamics of one extreme of avian movement -- the long distance seasonal migrations of birds between breeding and nonbreeding areas. The seasonal migrations of birds and other animals have long captured human imagination, but our understanding of how these extraordinary journeys have evolved remains poor (Zink 2011). Consider the Blackpoll Warbler, a songbird renowned for its trans-oceanic migratory journey between breeding grounds in the spruce-fir forests of Canada and wintering grounds in the Amazon (Deluca et al. 2015). If a migratory species like the Blackpoll Warbler has the adaptive capacity to exist in habitats as diverse as subarctic forest and Amazonian jungle, why is its actual distribution throughout the year restricted to such highly specific, yet highly disparate regions? The complexity of these types of distributions present a considerable challenge for evolutionary inference, and consequently, most research on the evolution of geographic range has focused on species that do not migrate. Here, I address this challenge by developing a novel phylogenetic approach for reconstructing the biogeographic history of seasonal migration. The approach I present employs Bayesian phylogenetic methods and network theory to enable the simultaneous modeling of the evolution of breeding and winter ranges. The results of this chapter challenge the dominant paradigm of the evolution of migration, which contends that migration evolves when species shift their breeding ranges out of the tropics and into the temperate zone (Rappole 1995). In contrast, my results suggest that in a major radiation of New World songbirds, migration evolved more frequently via shifts of winter ranges from the temperate zone into the tropics. The results of this chapter further suggest that the evolution of migration bolstered colonization of the tropics by lineages that originated in the temperate zone, whereas tropical birds rarely invaded temperate regions. This pattern is relevant to one of the most fundamental biogeographic questions in ecology and evolution (Wiens and Donoghue 2004): Why are there more species in the tropics than in temperate regions?
Whereas my research on migratory birds highlights the dynamic and complex evolutionary histories of highly mobile lineages, in Chapter 2 and 3 I shift focus to tropical montane birds to explore the factors that regulate speciation in sedentary taxa with more restricted dispersal. In Chapter 2, I take a comparative phylogeographic approach to investigate the relationship between neutral genetic differentiation and plumage divergence in cloud forest Andean birds. This research addresses a fundamental question in speciation and biogeography (Mayr 1942; Endler 1977): why do some taxa have show geographic variation in phenotype, whereas others are uniform throughout their ranges? By comparing levels of genetic and phenotypic differentiation among sister pairs of cloud forest birds isolated across a major biogeographic barrier to dispersal, the Maranon Valley of Peru, I show that sister taxa that are similar in plumage on either side of the Maranon have been isolated from one another by this barrier for less time than pairs that show substantial plumage differences. This result suggests that patterns of geographic variation in phenotype in tropical montane birds are partly explained by their history of dispersal across barriers. However, it remains unclear whether taxa with low plumage differentiation on either side of the Maranon have had greater ongoing dispersal throughout their history (serving to maintain uniformity in phenotypes), or whether these species are undifferentiated simply because they have more recently colonized one side of the barrier.
Disentangling these two aspects of dispersal---the ongoing exchange of individuals between populations versus recent colonization---represents a major challenge for research in speciation and biogeography, and will require inference of the timing of lineage dispersal and subsequent divergence across barriers. Therefore, in Chapter 3, I take a phylogenomic approach to infer the geographic and temporal history of lineage dispersal and vicariance in one of the study genera of Andean passerine birds in Chapter 2, the bay-backed antpitta species complex (Grallaria hypoleuca s.l.). The bay-backed antpitta complex is an ideal lineage for testing hypotheses on the geographic history of speciation, because it is composed of a series of geographically adjacent, phenotypically distinct taxa that have diverged across arid valleys or other dispersal barriers. Using phylogenies built from thousands of short-read loci that I gathered using a restriction site associated (RAD) sequencing approach, I show that the bay-backed anpittas originated in the northern Andes and dispersed southward. However, rather than dispersing across existing barriers in a stepping-stone manner, the phylogenetic results of Chapter 3 suggest that the ancestor of the species complex was widespread in the Andes before its range was sundered by the formation of arid valleys. Although dispersal across existing barriers is profoundly important for speciation in tropical birds (Zink et al. 2000; Barber and Klicka 2010; Smith et al. 2014), vicariant events driven by geologic and climatic change have also likely contributed to the evolution of tropical diversity (Ribas et al. 2011), and the results of Chapter 3 further suggest that species with relatively low dispersal abilities, such as the Grallaria antpittas, may be prime candidates for taxa that have experienced this type of static vicariant speciation.