# The Genetic and Morphological Basis of Local Adaptation to Elevational Extremes in an Alpine Finch

## TL;DR

This study explores how alpine birds adapt to extreme elevations by analyzing their physical traits and genetic makeup.

## Contribution

The paper provides one of the first in-depth genetic analyses of local adaptation in an alpine songbird.

## Key findings

- Morphological traits like wing length and bill size vary between populations with different environmental conditions.
- Genome-wide association studies identified loci linked to thermoregulation and cold tolerance.
- Multiple selective pressures, including temperature and food availability, shape adaptation in alpine birds.

## Abstract

Understanding patterns and mechanisms underlying local adaptation is becoming increasingly important for species conservation amid anthropogenically driven environmental change. Alpine systems are experiencing particularly intense pressure from environmental change resulting from increased rates of warming and corresponding loss of snow and ice. We integrate morphological and genetic analyses to identify traits important for local adaptation in one of the highest elevation breeding birds in North America, the Sierra Nevada Gray‐crowned Rosy‐Finch. We performed an in‐depth analysis of how traits with known links to thermoregulation in birds such as wing length, bill size, and feather microstructure vary between two populations at sites with contrasting climate and environmental conditions. We identified loci underlying these traits using a genome‐wide association study and further examined regions of the genome related to altitude adaptation and cold tolerance using FST outlier tests. Together, these results indicate that temperature, food availability, and alpine landscape features may impose multifaceted and potentially conflicting selective pressures on morphological traits important to adaptation in alpine birds. Overall, this work represents one of the first in‐depth analyses of the genetic basis of adaptation in an alpine specialist songbird.

We investigated morphological and genetic variation in the Sierra Nevada Gray‐crowned Rosy Finch to identify traits important for local adaptation in alpine environments. By combining trait measurements with genome‐wide analyses, we uncovered loci linked to thermoregulation, altitude adaptation, and cold tolerance. Our results highlight how multiple selective pressures shape adaptation in one of North America's highest‐elevation breeding birds.