An experimental test for ecologically dependent reproductive isolation across an avian migratory divide

Divergent adaptation can promote ecological speciation if hybrids have reduced fitness because they are poorly adapted to either parental niche. We tested for ecologically dependent, postzygotic isolation between two subspecies of Swainson’s thrushes, which form a migratory divide and hybrid zone in western North America. To do this, we translocated backcrossed and admixed birds from the hybrid zone into the range of each subspecies at the beginning of fall migration. We estimated a proxy for their survival on migration and migratory behaviour using automated radio tracking. Apparent survival of birds in the two environments did not depend on their genomic ancestry, suggesting that Swainson’s thrushes’ divergent adaptation to different fall migration routes does not fit the classic model of ecological speciation. We propose an alternate scenario where ecological selection on migration may interact with intrinsic maladaptation in hybrids to produce reduced hybrid survival on migration. B..., , # An experimental test for ecologically dependent reproductive isolation across an avian migratory divide

#### motusTranslocatedBirds.csv

* data for birds that were caught in the hybrid zone and translocated to Squamish (coastal) or Lillooet (inland)

Column descriptions:

* reference: Individual ID from banding sheets
* name_in_vcf: Individual ID from vcf file
* hiest_heterozygosity: Autosomal interspecific heterozygosity, based on AIMs
* hiest_ancestry: Autosomal genomic ancestry, based on AIMs
* release_site: Name of release site
* capture_site: Name of capture site
* release_year: Year tagged and released
* sex_binary: Sex based on read counts from sex chromosomes
* age_release: Age bird was tagged and released; HY = Hatch year
* release_gps.n: GPS coordinate of release latitude
* release_gps.w: GPS coordinate of release longitude
* capture_gps.n: GPS coordinate of capture latitude
* capture_gps.w: GPS coordinate of capture longitude
* translocated: Translocation status; yes or no...,