Evolution of endemism on a young tropical mountain

Abstract

Tropical mountains are hot spots of biodiversity and endemism, but the evolutionary origins of their unique biotas are poorly understood. In varying degrees, local and regional extinction, long-distance colonization, and local recruitment may all contribute to the exceptional character of these communities. Also, it is debated whether mountain endemics mostly originate from local lowland taxa, or from lineages that reach the mountain by long-range dispersal from cool localities elsewhere. Here we investigate the evolutionary routes to endemism by sampling an entire tropical mountain biota on the 4,095-metre-high Mount Kinabalu in Sabah, East Malaysia. We discover that most of its unique biodiversity is younger than the mountain itself (6 million years), and comprises a mix of immigrant pre-adapted lineages and descendants from local lowland ancestors, although substantial shifts from lower to higher vegetation zones in this latter group were rare. These insights could improve forecasts of the likelihood of extinction and 'evolutionary rescue' in montane biodiversity hot spots under climate change scenarios.

Soil Biology Research across Latitude, Elevation and Disturbance Gradients: A Review of Forest Studies from Puerto Rico during the Past 25 Years

“…High turnover in microbial species assemblages along an elevation gradient in eastern Puerto Rico [5] resembles patterns found on mountains in Malaysia, Mexico and Peru where high turnover of plant and fungal assemblages along elevation gradients are also found [52][53][54][55]. The study of phylogenetic origins of endemic species of plants, animals and fungi on a young mountain in Malaysia by Merckx et al [52] showed strong niche conservatism that results in high species turnover along the elevation gradient [55,56]. A subsequent analysis by Geml et al [57] from the same mountain showed that the peak in species richness of ectomycorrhizal fungi at lower-middle elevation was primarily tied to narrow environmental niches and not the result of broad-range species overlapping in the middle of the gradient (known as the mid-domain effect).…”

Small mammal diversity along two neighboring Bornean mountains

“…Hylomys suillus and Sundamys infdaluteus; Camacho Sánchez 2017). The observed high levels of endemism on the higher slopes is partially attributed to speciation from lowland taxa, a pattern which has been identified in other groups in Kinabalu (Merckx et al 2015). The structure of this diversity along the elevational gradients could be maintained by the lower extinction rates for mammals in the tropics compared to temperate regions (Rolland et al 2014).…”

Frequent colonization and little in situ speciation in Senecio in the tropical alpine‐like islands of eastern Africa

“…Kinabalu in East Malaysia. Th eir data does not contain a single case of in situ speciation in the alpine-like region among all angiosperms studied ( Merckx et al, 2015 ). Th e size of tropical alpine-like areas is highest in the Andes, followed by EA and Mt.…”

“…Even when considering EA Senecio at both montane and alpine-like altitudes, in situ speciation is rare. A recent study by Merckx et al (2015) investigated the evolution of endemism of another alpine-like region, the isolated Mt. Kinabalu in East Malaysia.…”