The hyperdiverse shrew genus Crocidura is one of few small mammal genera distributed across Sundaland and all of its boundaries. This represents a rare opportunity to study the geological history of this region through the evolutionary history of these shrews. We generate a phylogeny of all recognized species of Sundaland Crocidura and show that most speciation events took place during the Pleistocene, prior to the inundation of the Sunda Shelf around 400 000 years ago. We find east–west differentiation within two separate lineages on Borneo, and that the current taxonomy of its two endemic species does not reflect evolutionary history, but ecophenotypic variation of plastic traits related to elevation. Sulawesi shrews are monophyletic, with a single notable exception: the black-footed shrew (C. nigripes). We show that the black-footed shrew diverged from its relatives on Borneo recently, suggesting a human-assisted breach of Wallace’s line. Overall, the number of Crocidura species, especially on Borneo, probably remains an underestimate.

Biodiversity across elevational gradients generally follows patterns, the evolutionary origins of which are debated. We trapped small non-volant mammals across an elevational gradient on Mount (Mt.) Kinabalu (4,101 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We also included visual records and camera trap data from Mt. Tambuyukon. On Mt. Tambuyukon we trapped a total of 299 individuals from 23 species in 6,187 trap nights (4.8% success rate). For Mt. Kinabalu we trapped a total 213 animals from 19 species, in 2,044 trap nights, a 10.4% success rate. We documented the highest diversity in the low elevations for both mountains, unlike previous less complete surveys which supported a mid-elevation diversity bulge on Mt. Kinabalu.Species richness decreased gradually towards the highlands to a more even community with different species (high turnover), less rich but with the highest levels of endemism.These patterns suggest that an interplay of topography and climatic history of the region were drivers of the diversity gradient, in addition to standing climatic and spatial hypothesis. AbstractBiodiversity across elevational gradients generally follows patterns, the evolutionary origins of which are debated. We trapped small non-volant mammals across an elevational gradient on Mount (Mt.) Kinabalu (4,101 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We also included visual records and camera trap data from Mt. Tambuyukon.On Mt. Tambuyukon we trapped a total of 299 individuals from 23 species in 6,187 trap nights (4.8% success rate). For Mt. Kinabalu we trapped a total 213 animals from 19 species, in 2,044 trap nights, a 10.4% success rate. We documented the highest diversity in the low elevations for both mountains, unlike previous less complete surveys which supported a mid-elevation diversity bulge on Mt. Kinabalu. Species richness decreased gradually towards the highlands to a more even community with different species (high turnover), less rich but with the highest levels of endemism. These patterns suggest that an interplay of topography and climatic history of the region were drivers of the diversity gradient, in addition to standing climatic and spatial hypothesis.

Biodiversity across elevational gradients generally follows patterns, the evolutionary origins of which are debated. We trapped small non-volant mammals across an elevational gradient on Mount (Mt.) Kinabalu (4,101 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We also included visual records and camera trap data from Mt. Tambuyukon. On Mt. Tambuyukon we trapped a total of 299 individuals from 23 species in 6,187 trap nights (4.8% success rate). For Mt. Kinabalu we trapped a total 213 animals from 19 species, in 2,044 trap nights, a 10.4% success rate. We documented the highest diversity in the low elevations for both mountains, unlike previous less complete surveys which supported a mid-elevation diversity bulge on Mt. Kinabalu.Species richness decreased gradually towards the highlands to a more even community with different species (high turnover), less rich but with the highest levels of endemism.These patterns suggest that an interplay of topography and climatic history of the region were drivers of the diversity gradient, in addition to standing climatic and spatial hypothesis. AbstractBiodiversity across elevational gradients generally follows patterns, the evolutionary origins of which are debated. We trapped small non-volant mammals across an elevational gradient on Mount (Mt.) Kinabalu (4,101 m) and Mt. Tambuyukon (2,579 m), two neighboring mountains in Borneo, Malaysia. We also included visual records and camera trap data from Mt. Tambuyukon.On Mt. Tambuyukon we trapped a total of 299 individuals from 23 species in 6,187 trap nights (4.8% success rate). For Mt. Kinabalu we trapped a total 213 animals from 19 species, in 2,044 trap nights, a 10.4% success rate. We documented the highest diversity in the low elevations for both mountains, unlike previous less complete surveys which supported a mid-elevation diversity bulge on Mt. Kinabalu. Species richness decreased gradually towards the highlands to a more even community with different species (high turnover), less rich but with the highest levels of endemism. These patterns suggest that an interplay of topography and climatic history of the region were drivers of the diversity gradient, in addition to standing climatic and spatial hypothesis.