Analyzing Adaptation and Extirpation in Response to Climate Change and Agriculturization in the Horned Lark (Eremophila alpestris)

EPA Grant Number: F13F21201
Title: Analyzing Adaptation and Extirpation in Response to Climate Change and Agriculturization in the Horned Lark (Eremophila alpestris)
Investigators: Mason, Nicholas Albert
Institution: Cornell University
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2014 through August 1, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Terrestrial Systems Ecology

Objective:

When faced with alterations to their habitat, species must adapt, migrate, or go extinct. Understanding how populations persist through changes in abiotic conditions and modifications of their native habitat is a central, urgent imperative for sustaining biodiversity. This research studies how organisms (specifically, the horned lark, Eremophila alpestris) respond to land use (specifically, agriculture). The project examines how the horned lark has responded to a century of desert farming in the Imperial Valley of the southwestern United States. Within the Imperial Valley, the population of horned larks has become darker as the desert substrate has become irrigated and arable. This research seeks to determine the relative contributions of selection acting on existing genetic variation and the introgression of favorable alleles from other populations in the adaptive evolution of cryptic coloration.

Approach:

This project will take an interdisciplinary approach to study how the horned lark has adapted to land use in the Imperial Valley. It will use novel high-throughput sequencing methods to analyze genetic variation among specimens collected before the All-American Canal was constructed in 1939. These “ancient DNA” samples will be compared to individuals form the extant population, samples that have been collected since 1990. Change in dorsal coloration will be assessed using a combination of digital photography and spectrophotometry. Finally, to evaluate whether the darkening of Horned Larks represents adaptive cryptic coloration, the coloration profiles of birds from both historic and current populations will be compared to reflectance profiles of the desert substrate before and after the agricultural era. This multifaceted approach will allow a comprehensive study of the evolutionary history and ecology of horned larks in the Imperial Valley.

Expected Results:

If natural selection has acted on an already-existing genetic variation in the horned lark population in the Imperial Valley, historic and extant individuals will be from a single population. In contrast, if introgression of favorable genetic variants from populations outside of the Imperial Valley have contributed to the phenotypic change observed, then horned larks in the Imperial Valley will show signatures of admixture. In terms of phenotypic variation, if horned larks have gained darker plumage as an adaptation to a darker substrate in the Imperial Valley, then a correlation can be expected between the coloration profiles and substrate reflectance profiles between historic and extant populations.

Potential to Further Environmental/Human Health Protection

The project described here integrates ecology, evolutionary biology, conservation, genetics, remote sensing and digital photography to comprehensively study how a tractable avian species has adapted to agriculturization, aridification and increases in ambient temperature. The interdisciplinary nature of this research will promote novel collaborations among faculty and students from traditionally disparate disciplines including Civil Engineering, Bioinformatics, Ecology and Evolutionary Biology. Using the horned lark as a model system, the results from this research will inform management units as to how best to protect grassland and desert birds amidst increased agricultural land use. Agriculture will continue to play an important role in efforts to feed a growing world. Thus, understanding how organisms respond to agricultural practices is important from a conservation perspective and will help promote environmental health and conservation.

Supplemental Keywords:

adaptation, climate change, land use

Progress and Final Reports:

  • 2015
  • Final