Abstract
Understanding the processes through which ecological communities are assembled remains a major challenge, particularly in hotspots of biodiversity such as tropical mountains. Here, we apply continuous-time Markov models to elevational, geographical and phylogenetic data for 166 avian sister pairs to infer the relative frequency of different historical pathways involved in the build-up of species on Neotropical mountains, the Earth’s most biodiverse terrestrial region. We show that sister species arising in geographic isolation but now sympatric (i.e. living on the same mountain slope), have assembled through a mix of different routes. Ecological sorting whereby species diverge to different elevations in allopatry occurs with a similar frequency to ecological displacement where divergence in elevation occurs upon secondary contact. However, both these routes are far less common than ecological niche conservatism, whereby species transition to sympatry without diverging in their elevation range. Our results suggest the predominance of this more direct and thus faster route to sympatry may help explain the exceptional species richness of tropical mountains.
Competing Interest Statement
The authors have declared no competing interest.