Open Collections

Carbeck, Katherine

University of British Columbia

Species inhabiting heterogeneous environments often exhibit geographic variation in fitness-related traits shaped by natural selection, crucial for local adaptation. However, empirical studies linking genotype and phenotype to population growth and capacity for adaptation are scarce, hindering the reliability of predictions about population persistence. My dissertation investigates the effects of environmental heterogeneity on the eco-evolutionary dynamics of song sparrows (Melospiza melodia) across western North America by combining species distribution models, genomic analyses, and phenotypic and demographic data. In Chapter 2, I use a novel integration of nearly half a century of population-level demographic data from British Columbia alongside 1.2 million continental-scale citizen science observations to examine climate's influence on demography, range shifts, and seasonal migration in song sparrows. I demonstrate that local climate drives spatial variation in seasonal migration by limiting the fitness of year-round residents and that climate warming since the early 1900s has facilitated range expansion and upslope shifts of residents. Chapter 3 tests the genetic basis of Bergmann’s Rule, which posits that correlations between body size and temperature reflect local adaptation. By analyzing 79 whole genomes from nine subspecies, I identify genes associated with ~300% variation in body mass, providing evidence for a genetic foundation of Bergmann’s Rule. Such co-variation in environment, body mass, and genotype reflects the influence of natural selection on local adaptation, implying a capacity for contemporary evolution. In Chapter 4, I test how genetic variation, climate change, and migratory phenotype influence population growth of song sparrows across the range. Using 316 whole genomes from 21 subspecies, I validated 'genomic offset' predictions (i.e., local climate-genomic state mismatch) by confirming correlations with population trends, finding migratory populations tended to increase whereas residents declined. These results suggest migration may buffer populations against fitness declines associated with genomic mismatches. Overall, my dissertation employs novel and integrative approaches to illuminate the complex interplay among environmental, genetic, and phenotypic variation driving adaptive responses and range shifts in song sparrows. This research enhances our understanding of the eco-evolutionary dynamics driving species persistence and provides insight into potential conservation strategies that consider the adaptive capacities of populations facing rapid environmental change.

Text

2024-08-27

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89055

Forestry

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/