26! 27! Aim. The standard latitudinal diversity gradient (LDG), in which species richness 28! decreases from equator to pole, is a pervasive pattern observed in most groups of 29! organisms. Despite its commonness, an increasing number of non-conforming 30! lineages have been identified, presenting a challenge for general explanations of the 31! standard LDG. Although problematic, documenting and studying these contrarian 32! groups can help us to better understand LDGs generally. To that end we identify the 33! ant tribe Stenammini, a diverse lineage with over 400 species, as a contrarian clade, 34! and we attempt to explain the group's atypical diversity pattern using a historical 35! approach. We evaluate the following alternative hypotheses: time-for-36! speciation/center-of-origin (TFS/COO), niche conservatism, and differences in 37! diversification rate. 38! 39! Location. Global. 40!
41!Methods. We examine the shape of the LDG in Stenammini by plotting latitudinal 42! midpoints for all extant species. We then infer a robust phylogeny using a 43! phylogenomic approach that employs ultraconserved element loci and we use the 44! phylogeny to estimate divergence dates, biogeographic history, and ancestral habitats.
45!We also test for diversification rate heterogeneity across the tree and among lineages 46! within the tribe. 47! 48!