Centres of endemism in Borneo and their environmental correlates revealed by endemic plant genera

Abstract

Identifying areas of high value for biodiversity and understanding their potential environmental correlates is a critical task useful for prioritising conservation attention as natural habitats continue to be threatened. The distributions of species of 65 plant genera endemic to Borneo were mapped and modelled to examine where they are concentrated in centres of endemism, taking into consideration the historical unevenness in general botanical collecting. Overlapping distributions indicate that the areas richest in species of endemic genera are found especially in the lowland forests of northwest Borneo. In comparison, endemic species from selected non-endemic genera are concentrated in upland areas such as the central mountain chain and Mount Kinabalu. Spatial regression models show that species richness of the endemic genera is negatively correlated with historical climate instability and present-day precipitation seasonality but positively correlated with present-day annual precipitation, temperature seasonality, number of rivers and number of geological types. Centres of plant endemism revealed by the endemic genera, a distinctive subset of Borneo's endemic species, reaffirm the critical importance of lowland forest habitats in Borneo for plant diversity and endemism.