Unravelling population genetic structure of black oystercatcher (Haematopus bachmani) in North America

Abstract

This study analyzed the genetic structure of the black oystercatcher (Haematopus bachmani) across its range using an improved version of genotype by sequencing (GBS) to understand the genetic variation, gene flow, and population differentiation. I used Bayesian clustering and principal coordinate analysis (PCoA) to identify the population genetic structure of the black oystercatcher. Population-level analyses with PCoA and pairwise FST showed moderate to high connectivity and gene flow among most sampled populations, with some subtle north-south structuring. I also employed connectivity modeling approaches, such as isolation by distance and the least-cost corridor model, to understand the pattern of gene flow. The moderate isolation by distance implied that gene flow decreases with increasing geographical distance. The least-cost corridor analyses provided additional spatial context by showing pathways as dispersal corridors and highlighting potential isolation between distant populations. Additionally, I conducted a redundancy analysis, examining the relationship between environmental and spatial factors and genetic variation, which revealed a weak association between environment and genetics, but also supported the isolation by distance model to some extent. My thesis demonstrates how a species' genetic structure is shaped by geographic distance and how behaviors, such as breeding site fidelity, play a significant role.