Niche-separation and conservation biogeography of Madagascar’s fork-marked lemurs (Cheirogaleidae: Phaner): Evidence of a new cryptic species?

Abstract

Ecological niche modeling can provide insights into a species’ demography, ecology and biogeography, and the environmental factors that determine them. Exploration of ecological niche models and niche-divergence among closely-related and cryptic organisms can also be useful for species delineation and discrimination, and such information can inform and facilitate conservation of their populations. In this study, I used an ecological niche modeling approach to investigate the conservation biogeography of the fork-marked lemurs (genus Phaner), a group of cryptic, nocturnal primates that are endemic to Madagascar. I constructed all ecological niche models in MaxEnt, using a range of climatic and habitat-related variables. I examined interspecific niche-separation within the Phaner genus, and among two sub-populations of P. electromontis, a species which has previously been hypothesized to represent two distinct, cryptic taxa. All ecological niche models performed well and with high accuracy, and whilst the percentage contribution of each environmental variable differed between species, the results suggested that climate may be the primary determinant of Phaner distribution. Further, all four Phaner species occupied distinct ecological niches, a result that was also mirrored in the two P. electromontis sub-populations. This suggests that one of the two sub-populations may indeed be a distinct, as-yet undescribed species, but further genetic and ecological research is needed to substantiate this result. Finally, the ecological niche models revealed that only 23.0% of the suitable land area for Phaner occurrence within Madagascar is forested, limiting the geographic distribution of these lemurs. Whilst much of this suitable habitat is thankfully protected, deforestation continues throughout Madagascar, and this under-studied group of lemurs requires further research attention and continued conservation efforts.