Genetic Confirmations of Dwarf Lemurs Across Madagascar Highlights Complex Biogeographic Patterns

Abstract

Conservation action, vital in biodiversity hotspots, depends on reliable data on endangered taxa. This is especially important for species that are morphologically cryptic and difficult to distinguish in the field. The dwarf lemurs of Madagascar (Cheirogaleus spp.) exemplify these challenges: They are widespread but endangered, nocturnal, small-sized, and cryptic. The genus is diverse, with nine described species and as many candidate species, falling into four distinct lineages (“medius,” “sibreei,” “crossleyi,” and “major”). Many protected areas in Madagascar harbor dwarf lemur populations that await genetic species confirmation. Here, we collated tissue samples from 30 individual dwarf lemurs in 10 forest sites collected by a network of collaborators over a decade. We sequenced the simple but diagnostic cytochrome-b marker gene and placed samples into a curated database of > 200 published sequences. Except for an individual from the “sibreei” lineage in Marojejy that separated from close relatives farther south, our samples fell into described or candidate species, supporting geographic clustering within lineages. We identified two sites in the northeast that harbor different assemblages of species from three distinct lineages in sympatry. We confirmed the presence of C. crossleyi at sites across Madagascar's central highlands, considerably extending its known range, and posit that this is the dominant dwarf lemur of the highlands north of the Mangoky river. Although our results are limited in resolution and call for in-depth genomics, we advocate for foundational field work, natural history exploration, and survey/sampling expeditions to generate the very data on which sophisticated genomics and computational methods rely.