2026-09-19T06:30:21.752592800Zhttps://opus.uleth.ca/server/oai/request

oai:opus.uleth.ca:10133/72132025-11-05T06:04:25Zcom_10133_3346com_10133_1com_10133_296col_10133_3347col_10133_298

Burg, Theresa M. Castro García, Sara University of Lethbridge. Faculty of Arts and Science 2025-11-04T18:44:27Z 2025-11-04T18:44:27Z 2025 https://hdl.handle.net/10133/7213 Over the last six decades, avian aerial insectivores in North America have experienced an overall decline of ~60% in their population across their breeding ranges. Understanding their population genetic structure and spatial connections across the annual cycle is critical to determining potential factors driving these trends; however, this information is limited for many species. This study uses RADseq data to examine population structure and connectivity in least flycatchers (Empidonax minimus) across North America. Supported by field and museum sampling, blood, feather, and/or tissue samples were collected from 14 sites throughout the breeding range as well as during migration in Canada and the USA, and on the non-breeding grounds in Mexico. The results from principal components analysis (PCA), pairwise FST, STRUCTURE, and least-cost corridor analyses indicate high levels of gene flow among breeding populations, with weak genetic structure observed between two groups that exhibit an east-west split, which is enhanced using outlier loci. A genetic stock identification analysis was conducted to determine the breeding origin of the non-breeding samples, utilizing outlier loci. Twelve out of 29 non-breeding samples were successfully assigned to a breeding population. In two of the three non-breeding locations, individuals of mixed origin were observed, indicating weak migratory connectivity. The results indicate that the weak migratory connectivity and young age of the species might contribute to the low levels of population structure observed. This study allowed to increase the comprehension of the genetic structure and migratory connectivity of the least flycatcher. en Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences Arts and Science Department of Biological Sciences Thesis (University of Lethbridge. Faculty of Arts and Science) least flycatcher genetic population structure migratory connectivity gene flow breeding populations Dissertations, Academic Population genetics Flycatchers--Research--North America Flycatchers--North America--Geographical distribution Flycatchers--Migration--North America Flycatchers--Ecology--North America Flycatchers--Breeding--Research--North America Bird populations--Research--North America Bird declines Migratory birds--Research--North America Empidonax--North America Genetic population structure of the least flycatcher (Empidonax minimus): implications for evaluating migratory connectivity Thesis Masters No open.access