book reviews frontiers of biogeography 8.3, e32702, 2016 The mammals of Luzon island The Mammals of Luzon Island: Biogeography and Natural History of a Philippine Fauna by Law- rence R. Heaney, Danilo S. Balete and Eric A. Rickart, 2016, John Hopkins University Press, 304 pp. $75.00 (Hardback) ISBN: 978-1-4214-1837-7; https://jhupbooks.press.jhu.edu With the publication of this book, the mammals of Luzon Island deserve to take their place among the classic case studies in the biogeographical canon. The depth of information presented is im- pressive, condensing the contents of numerous papers, alongside natural history observations accumulated over the course of decades of gruel- ling and dedicated fieldwork. As an exemplar of how to construct a cohesive, integrated, bio- geographical research program I cannot think of its equal. In my own undergraduate lectures I have spent many years teaching students about New Zealand and Madagascar; this time they will learn about Luzon instead. Luzon has long been recognised as an ex- ceptional region. I began with an ignorance shared by Wallace, who believed the Philippines to con- tain few endemic mammals. This casual assump- tion was overturned by Whitehead, who reached the summit of the appositely-named Mount Data on a collection trip in 1895, and stumbled upon a rich mammal assemblage. He discovered that their species richness increases with altitude, a pattern replicated elsewhere on the archipelago. That the giant cloud rats had remained undiscov- ered by Western science was at least in part be- cause no-one had imagined that such creatures might dwell in the mountains. In total the island contains 47 native species of murid rodent, 96% of which are endemic. Even among tropical mountain regions, can there be another region with as many endemic mammals in such a small area, and with as many centres of endemism? The key to the generation and mainte- nance of such richness has been the isolated mountain chains, which are themselves highly variable in their edaphics. Hence the discovery that 79% of the species are locally endemic to re- stricted areas. Luzon originated 26–30 million years ago (Mya) as a merging of small islands, with its cur- rent form developing in the last million years. De- spite being separated by only 15 km from greater Mindanao, sea levels at the last glacial maximum have maintained a striking faunal barrier across the San Bernardino Strait. Luzon’s formation in- cluded both volcanism and continental uplift, gen- erating an ever-increasing degree of topographic complexity as the island grew in size. The wet and foggy conditions in the high mountains preserve unique communities, at altitudes which receive occasional frost, with climatic barriers revealed daily by patterns of cloud cover. The endemic small mammals form two dis- tinct groups. One set arises from two ancient ra- diations, whose species are diverse and special- ised. Cloud rats arrived 14 Mya and now comprise 12 species on Luzon (with six elsewhere on the archipelago). Earthworm mice were present from 7 Mya and now make up at least 36 species, in addition to 16 on neighbouring islands. These reach remarkable degrees of alpha richness, with up to 6 cloud rat and 7 earthworm mice living in the same habitat patches, all at medium to high elevations in mature montane and mossy forest. More recent endemics (less than 4 Mya) are typi- cally habitat generalists and related to Greater Mindanao species with limited differentiation. Based on painstaking accumulation of evi- dence, a picture emerges of how the assemblage of mammals was formed. Among small mammals, local speciation accounts for seven times as many species as colonisation. This clearly contravenes traditional island biogeographical theory, though here MacArthur and Wilson were prescient; Lu- zon’s mammals are recognised in their original text as a potential exception to the general model (1967:173–175). Unsurprisingly the converse is true of bats, with colonisation overwhelmingly exceeding speciation in generating the assem- blage, although there may be cryptic endemism. The island does not, however, present a clear fit frontiers of biogeography, ISSN 1948-6596 — © 2016 the authors; journal compilation © 2016 The International Biogeography Society