Biology subjects

Battey, C. J.

Publications and source records attributed to Battey, C. J..

3 recordsLinked to original sources

bioRxiv2018

Time Lags and Niche Shifts in a Biological Invasion of Hummingbirds

Shifts in a species realized niche can lead to rapid population growth by increasing the carrying capacity of local habitats and allowing colonization of new areas. This process is well known in \"invasive\" species introduced to novel ranges by humans, but can also occur when native species expand their range. In these cases expansions may be driven either by a shift in the available environment or by a shift in the species use of existing niche space, but identifying the specific environmental or behavioral changes involved is often hindered by time lags in the process of colonization. Here I document a century of range shifts in the Annas Hummingbird (Calypte anna) and show that recent abundance in the Pacific Northwest is the product of a series of range and niche expansions that started in the early 20th century following the spread of garden cultivation and introduced plant species in California. Demographic trends in the northwest have tracked simple models of exponential growth since populations became established in the 1960s and 70s, and nest records suggest that the species has delayed the beginning of the breeding season by at least 18 days in the north. Niche models trained on historic climate and occurrence data fail to predict the modern range, suggesting that climate change is not the primary cause of the expansion. Range expansions in the Annas Hummingbird thus closely track the dynamics of an invasive species spreading across a novel range, and were made possible by a mix of introduced plants, phenological acclimation, and an expansion of the realized climatic niche.

ecology↗

bioRxiv2017

Minor allele frequency thresholds strongly affect population structure inference with genomic datasets

One common method of minimizing errors in large DNA sequence datasets is to drop variable sites with a minor allele frequency below some specified threshold. Though widespread, this procedure has the potential to alter downstream population genetic inferences and has received relatively little rigorous analysis. Here we use simulations and an empirical SNP dataset to demonstrate the impacts of minor allele frequency (MAF) thresholds on inference of population structure. We find that model-based inference of population structure is confounded when singletons are included in the alignment, and that both model-based and multivariate analyses infer less distinct clusters when more stringent MAF cutoffs are applied. We propose that this behavior is caused by the combination of a drop in the total size of the data matrix and by correlations between allele frequencies and mutational age. We recommend a set of best practices for applying MAF filters in studies seeking to describe population structure with genomic data.

genomics↗

bioRxiv2017

A Migratory Divide In The Painted Bunting (Passerina ciris)

Divergence in migratory behavior is a potential mechanism of lineage divergence in sympatric populations and a key life history trait used in the identification of demographically independent units for conservation purposes. In the Painted Bunting (Passerina ciris), a North American songbird, populations on the Atlantic coast and interior southern United States are known to be allopatric during the breeding season, but efforts to map connectivity with wintering ranges in Mexico, Florida, and the Caribbean have been largely inconclusive. Using genomic and morphological data from natural history specimens and banded birds, we found evidence of three genetically differentiated populations with distinct wintering ranges and molt-migration phenologies. In addition to confirming that the Atlantic coast population remains allopatric throughout the annual cycle, we identified an unexpected migratory divide within the interior breeding range. Populations breeding in the Lower Mississippi River Valley winter on the Yucatan Peninsula, and are parapatric with other interior populations that winter in mainland Mexico and Central America. Across the interior breeding range, genetic ancestry is also associated with variation in wing length; suggesting that selective pressures may be promoting morphological divergence in populations with different migration strategies.

zoology↗