| Summary: | Thesis (M.S.) University of Alaska Fairbanks, 2021 Alaska is a prime location to study avian speciation, divergence, and gene flow. The area of Beringia, the region extending from the Russian Far East across the Bering Sea though Alaska, has historically experienced periodic cycles of glaciation. These cyclic fluctuations in climate have had genetic consequences on the organisms that reside in this region. In this thesis, I examine the genetic relationships between Old World and New World lineages of Holarctic avian taxa. Specifically, I examine how intercontinental movements (i.e., gene flow) have shaped divergence, speciation, and phylogenetic relationships in several key lineages of Holarctic waterbirds. Using ultraconserved elements (UCEs) as a molecular marker, I implemented population genomic analyses to better understand divergence, speciation, and levels of gene flow among several Beringian waterbird lineages. In the first of the two studies, I examine mitogenomic and nuclear DNA in a small clade of ducks with historically uncertain relationships and species limits: the Eurasian common teal (Anas crecca crecca), the North American green-winged teal (Anas crecca carolinensis), both seasonal migrants, and the sedentary Aleutian green-winged teal (Anas crecca nimia). In addition to the three subspecies of green-winged teal, I included the South American yellow-billed teal (Anas flavirostris), a close relative of Anas crecca, to fully resolve this teal complex. Phylogenetic relationships using nuclear DNA showed the three subspecies of Holarctic greenwinged teal (Anas crecca spp.) to form a polytomous clade with A. flavirostris being sister to this clade. However, mitogenomic data show a different phylogeny, with A. c. carolinensis being sister to A. flavirostris, while A. c. crecca was sister to A. c. nimia. Evidence for divergence with gene flow was present in all three pairwise contrasts of our demographic analyses. Given prior work, gene flow was expected among the Holarctic taxa, but gene flow between ...
|
|---|