Multiple bursts of speciation in Madagascar’s endangered lemurs

Abstract

Abstract Lemurs are often cited as an example of adaptive radiation, as more than 100 extant species have evolved and filled ecological niches on Madagascar. However, recent work suggests that lemurs lack a hallmark of other adaptive radiations: explosive speciation rates that decline over time. Thus, characterizing the tempo and mode of evolution in lemurs can reveal alternative ways that hyperdiverse clades arise over time, which might differ from traditional models. We explore lemur evolution using a phylogenomic dataset with broad taxonomic sampling that includes the lorisiforms of Asia and continental Africa. Our analyses reveal multiple bursts of diversification (without subsequent declines) that explain much of today’s lemur diversity. We also find higher rates of speciation in Madagascar’s lemurs compared to lorisiforms, and we demonstrate that the lemur clades with high diversification rates also have high rates of genomic introgression. This suggests that hybridization in these primates is not an evolutionary dead-end, but potential fuel for diversification. Considering the conservation crisis affecting strepsirrhine primates, with approximately 95% of species threatened with extinction, this study offers a perspective for explaining Madagascar’s primate diversity and reveals patterns of speciation, extinction, and gene flow that will help inform future conservation decisions.