Genetic differences between willow warbler migratory phenotypes are few and cluster in large haplotype blocks

Area of Science:

• Evolutionary genetics
• Animal behavior
• Genomics

Background:

• Genetic basis for migratory behavior in songbirds is established, but underlying genes are largely unknown.
• Willow warblers (Phylloscopus trochilus) exhibit distinct migratory phenotypes with different wintering grounds.

Purpose of the Study:

• To identify candidate genes responsible for migratory behavior differences in willow warblers.
• To associate genomic variation with migratory phenotypes using whole-genome sequencing and SNP arrays.

Main Methods:

• De novo genome assembly of the willow warbler (Phylloscopus trochilus).
• Whole-genome resequencing and SNP array analysis of over 1100 individuals.
• Multidimensional scaling-based clustering to analyze SNP genotypes and haplotype clusters.

Main Results:

• Identified three highly differentiated genomic regions on chromosomes 1, 3, and 5 between migratory phenotypes.
• Distinct haplotype clusters associated with each migratory phenotype, suggesting limited recombination possibly due to inversions.
• Genes within differentiated regions, particularly those involved in fatty acid synthesis, correlate with migratory strategies and geographical distribution.

Conclusions:

• Genomic regions on chromosomes 1, 3, and 5 harbor genetic variation crucial for willow warbler migration.
• Genes related to fatty acid metabolism may represent key physiological adaptations for different migratory routes.
• These findings provide a foundation for future research into the genetic architecture of avian migration.