Reduced hybrid survival in a migratory divide between songbirds

• DOI: 10.1111/ele.14420
• Publication Date: 2024-04-05T12:10:36Z
• Authors: Stephanie A. Blain; Hannah C. Justen; Wendy Easton; Kira E. Delmore
• Keywords: Genetic algorithm; Proxy (statistics); Hybrid zone

Abstract Migratory divides, hybrid zones between populations that use different seasonal migration routes, are hypothesised to contribute speciation. Specifically, relative parental species, hybrids at divides predicted exhibit (1) intermediate migratory behaviour and (2) reduced fitness as a result. We provide the first direct test of second prediction here with one largest existing avian tracking datasets, leveraging divide Swainson's thrushes where is supported. Using detection rates proxy for survival, our results supported hypothesis lower survival than forms. This finding was juvenile‐specific (vs. adults), suggesting selection against stronger earlier in life. Reduced not explained by phenotypes or negative interactions among phenotypes. Additional work connecting specific features needed, but these patterns strong support an ecological driver