The determinants of land snail diversity along a tropical elevational gradient: insularity, geometry and niches

Abstract

Aim We investigated the patterns of species richness in land snails and slugs along a tropical elevational gradient and whether these patterns correlate with area, elevation, geographic constraints, and productivity. We did so both at the scale at which land snail population processes take place and at the coarser scale of elevational zones. Location Mount Kinabalu (4096 m) and the adjacent Mount Tambuyukon (2588 m) in Kinabalu Park, Sabah, Malaysian Borneo. Methods We used an effort‐controlled sampling protocol to determine land snail and slug species richness in 142 plots of 0.04 ha at elevations ranging from 570 to 4096 m. Extents of elevational ranges were determined by interpolation, extended where appropriate at the lower end with data from lowlands outside the study area. We used regression analysis to study the relationships between species density and richness on the one hand and elevation and area on the other. This was done for point data as well as for data combined into 300‐m elevational intervals. Results Species density (based on the individual samples) showed a decline with elevation. Elevational range length profiles revealed that range lengths are reduced at greater elevations and that a Rapoport effect is absent. Diversity showed a mild mid‐domain effect on Kinabalu, but not on Tambuyukon. When the data were combined into 300‐m elevational intervals, richness correlated more strongly with elevation than with area. Ecomorphospace was seen to shrink with increasing elevation. Main conclusions The elevational species richness patterns show the combined effects of (1) reduced niche diversity at elevations with lower productivity and (2) historical events in which the upward migration of lowland species as well as the speciation of highland endemics took place.

Gastropod communities in alpine grasslands are characterized by high beta diversity

“…Similar elevation-related declines in snail diversity in different habitats were reported from Mount Kenya in Tanzania (Tattersfield et al 2001), on mountains in Malaysian Borneo (Liew et al 2010) and in south-eastern France (Aubry et al 2005). However, in contrast to these studies, our investigation was restricted to a single habitat type, namely grasslands.…”

Terrestrial gastropod diversity in an alpine region: disentangling effects of elevation, area, geometric constraints, habitat type and land‐use intensity

“…4). Th e mid-domain eff ect on species richness was evaluated by calculating the regression between interpolated local gastropod species richness and MDE-null model predictions following Liew et al (2010). We applied the RangeModel software with continuous domain analysis (Colwell 2006) to examine whether geometric constraints aff ect the empirical species richness.…”

A review of the Cholevinae from the island of Borneo (Coleoptera, Leiodidae)

“…Recent paleoclimatic modelling (Raes et al 2014) suggests that even during cooler periods of marine regression, evergreen wet forests dominated the area that now comprises Borneo. This, and the fact that the island, because of its mountainous character (with Gunung Kinabalu reaching almost 4,100 m) contains a great variety of habitats, has generated and maintained a rich biodiversity, not least in its soil and litter-dwelling invertebrate fauna (e.g., Hanski and Hammond 1986, Rahman et al 2002, Liew et al 2010). …”