Genetics of bird migration : Study on East Siberian willow warblers (Phylloscopus trochilus)

Seasonal long-distance bird migration between wintering and breeding grounds is oneof the most remarkable phenomena in the history of life on earth. Migration strategies androutes vary greatly. Some birds migrate in social groups whilst others migrate alone at night,some cross few hundreds of km whilst others cover thousands of km. Avian migration has beenstudied extensively nevertheless numerous important questions remain unanswered. This studyaims to contribute to the understanding of the genetic basis of the innate migratory program ofa common songbird.From results of classical crossbreeding and orientation experiments with captiveblackcaps (Sylvia atricapilla) we can be sure that songbird migration directions as well asdurations are traits that are being inherited genetically and most likely have a multi-locusgenetic architecture. The chosen model species for my project is the willow warbler(Phylloscopus trochilus), one of the most common leaf warblers in the Palearctic. The willowwarbler has a continuous breeding distribution from the coast of the Atlantic to the coast ofPacific. They overwinter in sub-Saharan Africa. Three subspecies have been recognized: P. t.trochilus (breeding in central/western Europe and migrating SSW to western Africa), P. t.acredula (breeding in northern and eastern Europe, migrating SSE to east and south Africa)and P. t. yakutensis (breeding east of Ural Mountains, presumably migrating to SouthernAfrica). Morphological differences across the willow warbler subspecies are subtle and it has been previously shown that genome wide FST is close to zero. The low level of neutral back-ground divergence offers a good system for studying the genetics of passerine migration. This report contributes with novel data on phenotypes and genotypes of the subspecies yakutensisstudied at Chaun river delta, at the very eastern range limit of the species. As a proxy for thewintering location of yakutensis I used C and N stable isotope signatures from winter grownfeathers and inferred wintering range to be in Southern Africa. I genotyped 36 yakutensis fromChaun on four nuclear markers, of which three are located on the only divergent regions thatdiffers between the migratory phenotypes in Europe + CLOCK gene (a candidate for timing ofmigration). Analyzes revealed that yakutensis, despite strong differences in migration direction,distance, timing and wintering ground location cannot be separated from acredula genetically