Conservation Biogeography of the Dwarf Lemurs (Cheirogaleus) of Madagascar, Investigated via Ecological Niche Modelling

Ecological niches are the environmental conditions under which an organism can maintain viable populations. A detailed understanding of an organisms’ ecological niche can provide information on its taxonomy and biogeography, and ecological niche modelling allows researchers to investigate how closely-related species are able to coexist. Ecological niche models also enable conservationists to determine species’ habitat requirements, map distributions, and assess threats. We used this approach to investigate the conservation biogeography of the dwarf lemurs (genus Cheirogaleus), a group of cryptic, nocturnal primates endemic to Madagascar. Using climatic and vegetation-related variables, we constructed ecological niche models for three species to investigate niche overlap among taxa. We also constructed maps of the availability of forest habitat, and we assessed anthropogenic risk and protection. Our ecological niche models and background tests indicated that each of the three analysed Cheirogaleus species occupies distinct environmental space. The area of suitable habitat (realized niche) varied interspecifically (28,889–41,934 km²). This also was mirrored by variation in the percentage of each species’ realized niche within protected areas (20,065–25,266 km²) and near anthropogenic features (5,744–16,999 km²). Our results support the 2020 taxonomy of the dwarf lemurs recognised by the IUCN Red List and provides information on their biogeography. Furthermore, our ecological niche models have highlighted that the habitat of some dwarf lemur species, such as C. crossleyi, are more threatened than other species, such as C. medius and C. major, and these species require urgent conservation attention.