2026-05-28 バーミンガム大学
A St Kilda Wren (photo credit: Craig Nisbet)
＜関連情報＞
- https://www.birmingham.ac.uk/news/2026/new-research-helps-scientists-unlock-evolution-of-gigantism-in-scottish-island-wrens
- https://academic.oup.com/evolinnean/article/5/1/kzag008/8696167
島嶼症候群の並行進化は、スズメ目の鳥類における限られた並行遺伝的分化と一致する Parallel evolution of island syndromes coincides with limited parallel genetic differentiation in a passerine bird
Michał T Jezierski,Jenny C Dunn,Carolina R F Chagas,William J Smith
Evolutionary Journal of the Linnean Society Published:28 May 2026
DOI:https://doi.org/10.1093/evolinnean/kzag008
Abstract
Islands host elevated levels of species endemism, as geographic isolation and unique ‘insular’ environments promote in situ evolution. As these conditions are broadly repeated across islands globally, similar ecological pressures act on geographically separate island populations leading to phenotypic convergence among island endemics. These so-called ‘island syndromes’ have received considerable interest with respect to phenotypic comparisons within and between species. However, the patterns of genetic change underpinning the evolution of island syndromes have received less attention. An outstanding question, which is also of interest to the broader study of convergent evolution, is whether phenotypic convergence among island populations is associated with evolution across shared genomic regions. Here, we examine putative parallel island syndrome evolution of the Eurasian wren Troglodytes troglodytes, a passerine bird. In the British Isles, four island populations in Scotland are recognized as distinct subspecies, different to the subspecies found across ‘mainland’ Great Britain. We examine the evolution of island syndromes in these four subspecies, finding trait-based idiosyncrasies, but also identifying that the St Kilda and Shetland subspecies are both within the 25% most extreme cases of avian island gigantism worldwide. Our population genomic and phylogenetic analyses reveal these subspecies to be monophyletic and distinct from the ‘mainland’ subspecies of Great Britain. Among the four Scottish island subspecies, patterns of evolution across the genome are mostly population specific. However, 3.6% of the top 1% of genomic windows which are most differentiated from mainland wrens are shared between the subspecies endemic to Shetland and St Kilda. Our results suggest that the parallel insular phenotypes of wrens in the British Isles co-occur with largely distinct patterns of genetic evolution, likely driven by reductions in genetic diversity and drift, although partial genetic parallelism cannot be excluded. Furthermore, very low gene flow and potential phenotypic reproductive boundaries, such as distinct songs, may reflect ongoing speciation.
