Significant Divergence and Conservatism in the Niche Evolution of the Eurasian Green Woodpecker Complex (Aves, Picidae)

Integrating ecological niche models (ENMs) into phylogeographic studies, enables identifying the evolutionary processes and can be used to confirm species delimitation, particularly in species complex. The current study examined the divergence of two lineages of Eurasian green woodpecker complex (Picus viridis and P. innominatus), which were recently genetically proposed to the species level, using ecological niche modeling (ENM).

The ENMs were built using 1346 occurrence points, and environmental layers including 19 bioclimatic variables as well as elevation and land cover for past and present timescales. Niche identity, background tests and principal component analyses (PCA) were then performed to compare their ecological niches and explain ecological differentiation.

Results of identity and background tests and PCA revealed the lineages occupy unique and distinctive niches, and supported recently proposed genetically distinct species. Regarding the environmental variables, PCA results revealed that precipitation has a more important role in the separation of P. viridis and P. innominatus.

This study, in addition to provide an ecological support for recent molecular classifications, revealed niche conservatism had a more important role in the evolution of the two lineages of Eurasian green woodpecker complex.