Evolution in Isolation: Genetic Insights to Conserve Madagascar's Biodiversity

Abstract We taught a conservation genetics workshop at the University of Antananarivo, Madagascar, in May 2026 to 40 university students. Plant and animal taxa on Madagascar are extraordinarily speciose. Virtually all plant, amphibian, reptile, and mammal species are endemic. Here we present four examples of the primary topics from the workshop. The future of the indri (Indri indri), the largest extant lemur, is bleak because of ongoing loss of habitat. We predict that inbreeding depression will accelerate its extinction once population sizes become small enough to be affected by inbreeding. Genetic analysis has greatly increased the estimates of the number of Malagasy frog species. There were an estimated 100 described species in 1940. Recent genetic results suggest there actually over 400 actual species. Mouse lemurs (Microcebus) also have undergone a rapid increase in the number of described species. The number of recognized species of mouse lemurs increased from two in the 1990s to 25 today. However, recent genomic results suggest that species diversity has been overestimated due to the interpretation of geographic divergence between populations as interspecific variation. Seven of the nine baobab species (Adansonia) are endemic to Madagascar. Individual trees in all species have a high proportion of their genome identical by descent based on runs of homozygosity because of inbreeding. We recommend that conservation management of baobabs should not be based on the current species taxonomy because of the amount of historical admixture and gene flow among species detected by genetic analysis.