Phylogeography and ecological niche modelling of Long‐tailed Tit Aegithalos caudatus in the Palaearctic region, emphasizing Iranian populations

This study offers significant insights into the phylogenetic relationships and ecological niche dynamics of the Long‐tailed Tit Aegithalos caudatus species complex, with a particular focus on the differentiation among Iranian populations. We reconstruct the phylogenetic tree for the entire genus Aegithalos based on two nuclear introns (transforming growth factor beta 2 and beta fibrinogen intron 7) and one mitochondrial gene (cytochrome‐ b gene). The Aegithalos caudatus species complex is divided into three well‐supported primary clades: (1) populations from Iran, in the Alborz Mountains ( A. c. alpinus ) and the Zagros Mountains (except the Marivan area in the west; A. c. passekii ); (2) Silver‐throated Bushtit A. glaucogularis ; and (3) the Marivan populations of A. c. passekii and A. c. caudatus , A. c. europaeus, A. c. taiti , A. c. irbii , A. c. trivirgatus and A. c. magnus , which include European and East Asian populations. The relationships among these three clades are effectively unresolved. Within the first of these clades, there is no well‐supported structure. Within the second primary clade, the Marivan A. c. passekii forms the sister clade, although with poor support relative to a clade comprising the other subspecies. There is no well‐supported structure within the latter group, indicating a close genetic relationship despite the considerable geographic distances between them. Although the support for the relationships among the three primary clades within the A. caudatus–A. glaucogularis clade is lacking, these three clades are similarly shallowly diverged and, based on this, we suggest that A. glaucogularis is more appropriately treated as a subspecies of A. caudatus . Ecological niche modelling found the greatest ecological convergence to be between A. c. alpinus and A. c. passekii from Iran and between these taxa and A. c. trivirgatus from Central Japan and the southern coast of South Korea.