DOI: 10.5061/dryad.vdncjsxrx
title: Agriculture creates subtle genetic structure among migratory and non-migratory populations of burrowing owls throughout North America

description: Population structure across a species distribution primarily reflects
 historical, ecological and evolutionary processes. However, large-scale
 contemporaneous changes in land use have the potential to create changes
 in habitat quality and thereby cause changes in gene flow, population
 structure, and distributions. As such, land-use changes in one portion of
 a species range may explain declines in other portions of their range. For
 example, many burrowing owl populations have declined or become extirpated
 near the northern edge of the species’ breeding distribution during the
 second half of the 20th century. In the same period, large extensions of
 thornscrub were converted to irrigated agriculture in northwestern Mexico.
 These irrigated areas may now support the highest densities of burrowing
 owls in North America. We tested the hypothesis that burrowing owls that
 colonized this recently created owl habitat in northwestern Mexico
 originated from declining migratory populations from the northern portion
 of the species’ range (migration-driven breeding dispersal whereby
 long-distance migrants from Canada and the U.S. became year-round
 residents in the newly created irrigated agriculture areas in Mexico). We
 used 10 novel microsatellite markers to genotype 1,560 owls from 36 study
 locations in Canada, Mexico, and the United States. We found that
 burrowing owl populations are practically panmictic throughout the entire
 North American breeding range. However, an analysis of molecular variance
 provided some evidence that burrowing owl populations in northwestern
 Mexico and Canada together are more genetically differentiated from the
 rest of the populations in the breeding range, lending some support to our
 migration-driven breeding dispersal hypothesis. We found evidence of
 subtle genetic differentiation associated with irrigated agricultural
 areas in southern Sonora and Sinaloa in northwestern Mexico. Our results
 suggest that land-use can produce location-specific population dynamics
 leading to subtle genetic structure even in the absence of dispersal
 barriers.
description: We obtained DNA samples from 1,560 breeding burrowing owls from
 36 locations in Canada, Mexico, and the United States. We trapped
 burrowing owls during the summers of 2004-2009. None of the 1,560 birds
 that we included in our analysis were closely related (i.e., a parent and
 its offspring, or &gt;1 juvenile from the same nest burrow). Our
 primary source of genomic DNA was blood. We obtained ~50 μL of blood
 through a venipuncture of the brachial vein. We also used flight and/or
 body feathers occasionally as a source of genomic DNA when we could not
 withdraw a blood sample. We used 10 microsatellite markers developed
 specifically for this study (Macías-Duarte, Conway, Vega-Munguía,
 & Culver, 2010) to obtain genotypic data from our 36 study
 locations. We analyzed PCR products on an Applied Biosystems 3730 Genetic
 Analyzer and used an Applied Biosystems Genotyper 3.7 to score alleles. We
 used program Tandem (Matschiner & Salzburger, 2009) to assign
 integers to DNA fragment sizes.
description: This dataset contains the phenotypes of each of 1,560 burrowing
 owl. Missing data is coded as 0.