Island history affects faunal composition: the treeshrews ( M ammalia: S candentia: T upaiidae) from the M entawai and B atu I slands, I ndonesia

The M entawai and B atu I sland groups off the west coast of S umatra have a complicated geological and biogeographical history. The B atu I slands have shared a connection with the S umatran ‘mainland’ during periods of lowered sea level, whereas the M entawai Islands, despite being a similar distance from S umatra, have remained isolated from S umatra, and probably from the B atu Islands as well. These contrasting historical relationships to S umatra have influenced the compositions of the respective mammalian faunas of these island groups. Treeshrews ( S candentia, T upaiidae) from these islands have, at various times in their history, been recognized as geographically circumscribed populations of a broadly distributed T upaia glis , subspecies, or distinct species. We used multivariate analyses of measurements from the skull and hands to compare the island populations from S iberut ( M entawai I slands) and T anahbala ( B atu I slands) with the geographically adjacent species from the southern M entawai Islands ( T . chrysogaster ) and S umatra ( T . ferruginea ). Results from both the skull and manus of the S iberut population show that it is most similar to T . chrysogaster , whereas the T anahbala population is more similar to T . ferruginea , confirming predictions based on island history. These results are further corroborated by mammae counts. Based on these lines of evidence, we include the S iberut population in T . chrysogaster and the T anahbala population in T . ferruginea . Our conclusions expand the known distributions of both the M entawai and S umatran species. The larger geographical range of the endangered T . chrysogaster has conservation implications for this M entawai endemic, so populations and habitat should be re‐evaluated on each of the islands it inhabits. However, until such a re‐evaluation is conducted, we recommend that the IUCN R ed L ist status of this species be changed from ‘ E ndangered’ to ‘ D ata D eficient’. Published 2013. This article is a U.S. Government work and is in the public domain in the USA, B iological J ournal of the L innean S ociety , 2014, 111 , 290–304.