Spatial phylogenomics of acrobat ants in Madagascar: mountains function as cradles for recent diversity and endemism.. Crematogaster ants

We delineate spatial patterns of diversity in Malagasy acrobat ants (genus Crematogaster) on a phylogenetic and taxonomic level to identify centers for diversity and endemism and investigate their evolutionary history. We estimated species distributions for 33 Crematogaster species and generated a phylogeny based on ultraconserved elements. We calculated species richness (SR), phylogenetic diversity (PD), weighted (WE) and phylogenetic endemism (PE), randomized phylogenetic diversity (PD_sig), and relative phylogenetic diversity (RPD) and endemism (RPE). Categorical analyses of neo- and paleo-endemism (CANAPE) and phylo-Jaccard were used to delineate centers of endemism. We correlated these measures with mean elevation to investigate whether mountains have played an important role in ant diversification. We found extensive phylogenetic clustering (significantly low PD_sig) and short branches (low RPD) at higher elevations in central and south-central to southern Madagascar. In contrast, phylogenetic overdispersion (significantly high PD_sig) and long branches (high RPD) predominate at lower elevations in eastern and northern dry deciduous forests. CANAPE and phylo-Jaccard estimated five centers of endemism, whereby neo- and mixed endemism were significantly correlated with higher elevations, and paleo-endemism with lower elevations. Mountainous areas have functioned as cradles of recent diversification for acrobat ants, whereas lower elevations may be museums for relict lineages. Species diversification among acrobat ants may have coincided with the arrival of a new biome in the central highlands of Madagascar. The current protected area network only partially includes the centers of endemism identified here and may require future expansion based on insect diversity data.