Does microhabitat use affect population differentiation? A test with southwestern Palaearctic forest birds

Abstract

We tested whether microhabitat use affects dispersal and population differentiation in forest birds of the southwestern Palaearctic, a link previously suggested in Neotropical birds. To approach this, the number of subspecies within 32 species was used as a metric of population differentiation and was related to their feeding substrata and seasonal changes in abundance (a surrogate of dispersal) in a mountain range (Guadarrama Mountains, Central Spain). Multivariate analyses in which the effect of range size (a main correlate of within-species diversification) and phylogeny relatedness were considered, showed that those birds adapted to exploit the tree canopy had lower seasonal changes in abundance and more subspecies than ground-dweller birds. Our results support a cause-effect link between the use of stable resources in the canopy, seasonal movements and population differentiation of birds from temperate forests of the southwestern Palaearctic.