Abstract
Competition between organisms influences the processes governing the colonization of new habitats. As aconsequence, species or populations arriving first at a suitable location may prevent secondary colonization. Althoughadaptation to environmental variables (e.g., temperature, altitude, etc.) is essential, the presence or absence of certainspecies at a particular location often depends on whether or not competing species co-occur. For example, competition isthought to play an important role in structuring mammalian communities assembly. It can also explain spatial patternsof low genetic diversity following rapid colonization events or the “progression rule” displayed by phylogenies of speciesfound on archipelagos. Despite the potential of competition to maintain populations in isolation, past quantitative analyseshave largely ignored it because of the difficulty in designing adequate methods for assessing its impact. We present herea new model that integrates competition and dispersal into a Bayesian phylogeographic framework. Extensive simulationsand analysis of real data show that our approach clearly outperforms the traditional Mantel test for detecting correlationbetween genetic and geographic distances. But most importantly, we demonstrate that competition can be detected withhigh sensitivity and specificity from the phylogenetic analysis of genetic variation in space.