Dataset Information

Elevational Distribution of Flightless Ground Beetles in the Tropical Rainforests of North-Eastern Australia.

ABSTRACT: Understanding how the environment influences patterns of diversity is vital for effective conservation management, especially in a changing global climate. While assemblage structure and species richness patterns are often correlated with current environmental factors, historical influences may also be considerable, especially for taxa with poor dispersal abilities. Mountain-top regions throughout tropical rainforests can act as important refugia for taxa characterised by low dispersal capacities such as flightless ground beetles (Carabidae), an ecologically significant predatory group. We surveyed flightless ground beetles along elevational gradients in five different subregions within the Australian Wet Tropics World Heritage Area to investigate (1) whether the diversity and composition of flightless ground beetles are elevationally stratified, and, if so, (2) what environmental factors (other than elevation per se) are associated with these patterns. Generalised linear models and model averaging techniques were used to relate patterns of diversity to environmental factors. Unlike most taxonomic groups, flightless ground beetles increased in species richness and abundance with elevation. Additionally, each subregion consisted of relatively distinct assemblages containing a high level of regional endemic species. Species richness was most strongly and positively associated with historical and current climatic stabilities and negatively associated with severity of recent disturbance (treefalls). Assemblage composition was associated with latitude and historical and current climatic conditions. Although the results need to be interpreted carefully due to inter-correlation between historical and current climatic variables, our study is in agreement with the hypothesis that upland refugia provided stable climatic conditions since the last glacial maximum, and supported a diverse fauna of flightless beetle species. These findings are important for conservation management as upland habitats become increasingly threatened by climate change.

SUBMITTER: Staunton KM

PROVIDER: S-EPMC4871570 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Publications

Elevational Distribution of Flightless Ground Beetles in the Tropical Rainforests of North-Eastern Australia.

Staunton Kyran M KM Nakamura Akihiro A Burwell Chris J CJ Robson Simon K A SK Williams Stephen E SE

PloS one 20160518 5

Understanding how the environment influences patterns of diversity is vital for effective conservation management, especially in a changing global climate. While assemblage structure and species richness patterns are often correlated with current environmental factors, historical influences may also be considerable, especially for taxa with poor dispersal abilities. Mountain-top regions throughout tropical rainforests can act as important refugia for taxa characterised by low dispersal capacitie ...[more]

PMID: 27192085

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Project description:Background and aimsPlant cyanogenesis is the release of toxic cyanide from endogenous cyanide-containing compounds, typically cyanogenic glycosides. Despite a large body of phytochemical, taxonomic and ecological work on cyanogenic species, little is known of their frequency in natural plant communities. This study aimed to investigate the frequency of cyanogenesis in Australian tropical rainforests. Secondary aims were to quantify the cyanogenic glycoside content of tissues, to investigate intra-plant and intra-population variation in cyanogenic glycoside concentration and to appraise the potential chemotaxonomic significance of any findings in relation to the distribution of cyanogenesis in related taxa.MethodsAll species in six 200 m(2) plots at each of five sites across lowland, upland and highland tropical rainforest were screened for cyanogenesis using Feigl-Anger indicator papers. The concentrations of cyanogenic glycosides were accurately determined for all cyanogenic individuals.Key resultsOver 400 species from 87 plant families were screened. Overall, 18 species (4.5 %) were cyanogenic, accounting for 7.3 % of total stem basal area. Cyanogenesis has not previously been reported for 17 of the 18 species, 13 of which are endemic to Australia. Several species belong to plant families or orders in which cyanogenesis has been little reported, if at all (e.g. Elaeocarpaceae, Myrsinaceae, Araliaceae and Lamiaceae). A number of species contained concentrations of cyanogenic glycosides among the highest ever reported for mature leaves-up to 5.2 mg CN g(-1) d. wt, for example, in leaves of Elaeocarpus sericopetalus. There was significant variation in cyanogenic glycoside concentration within individuals; young leaves and reproductive tissues typically had higher cyanogen content. In addition, there was substantial variation in cyanogenic glycoside content within populations of single species.ConclusionsThis study expands the limited knowledge of the frequency of cyanogenesis in natural plant communities, includes novel reports of cyanogenesis among a range of taxa and characterizes patterns in intra-plant and intra-population variation of cyanogensis.

Project description:With the impending threat of climate change, greater understanding of patterns of species distributions and richness and the environmental factors driving them are required for effective conservation efforts. Species distribution models enable us to not only estimate geographic extents of species and subsequent patterns of species richness, but also generate hypotheses regarding environmental factors determining these spatial patterns. Projected changes in climate can then be used to predict future patterns of species distributions and richness. We created distribution models for most of the flightless ground beetles (Carabidae) within the Wet Tropics World Heritage Area of Australia, a major component of regionally endemic invertebrates. Forty-three species were modelled and the environmental correlates of these distributions and resultant patterns of species richness were examined. Flightless ground beetles generally inhabit upland areas characterised by stable, cool and wet environmental conditions. These distribution and richness patterns are best explained using the time-stability hypothesis as this group's primary habitat, upland rainforest, is considered to be the most stable regional habitat. Projected changes in distributions indicate that as upward shifts in distributions occur, species currently confined to lower and drier mountain ranges will be more vulnerable to climate change impacts than those restricted to the highest and wettest mountains. Distribution models under projected future climate change suggest that there will be reductions in range size, population size and species richness under all emission scenarios. Eighty-eight per cent of species modelled are predicted to decline in population size by over 80%, for the most severe emission scenario by the year 2080. These results suggest that flightless ground beetles are among the most vulnerable taxa to climate change impacts so far investigated in the Wet Tropics World Heritage Area. These findings have dramatic implications for all other flightless insect taxa and the future biodiversity of this region.

Project description:Insect macroecology and conservation biogeography studies are disproportionately scarce, especially in the Neotropics. Dung beetles are an ideal focal taxon for biodiversity research and conservation. Using distribution and body size data on the ecologically important Phanaeini, the best-known Neotropical dung beetle tribe, we determined elevational patterns of species richness, endemism, body size, and elevational range in Bolivia, specifically testing Bergmann's and Rapoport's rule. Richness of all 39 species and of 15 ecoregional endemics showed a hump-shaped pattern peaking at 400 m, but overall declined strongly with elevation up to 4000 m. The relationship between endemic and total species richness appeared to be curvilinear, providing only partial support for the null hypothesis that species-rich areas are more likely to be centers of endemism by chance alone. An elevational increase in the proportion of ecoregional endemics suggests that deterministic factors also appear to influence endemism in the Andes. When controlling for the effect of area using different species-area relationships, the statistically significant richness peak became more pronounced and shifted upslope to 750 m. Larger species did not have higher elevational mid-points, and mean body size decreased significantly with elevation, contradicting Bergmann's rule. Rapoport's rule was supported: species with higher elevational mid-points had broader elevational ranges, and mean elevational range increased significantly with elevation. The elevational decrease of phanaeine richness is in accordance with studies that demonstrated the combined influence of temperature and water availability on species diversity, but also is consistent with niche conservatism. For invertebrates, confirmation of Rapoport's and refutation of Bergmann's rule appear to be scale-invariant general patterns. Analyses of biogeographic patterns across elevational gradients can provide important insights for identifying conservation priorities. Phanaeines with narrow elevational ranges on isolated low-elevation mountains in eastern Bolivia are at greatest climate-change related extinction risk from range-shift gaps and mountaintop extinctions.

Dataset Information

Elevational Distribution of Flightless Ground Beetles in the Tropical Rainforests of North-Eastern Australia.

Publications

Elevational Distribution of Flightless Ground Beetles in the Tropical Rainforests of North-Eastern Australia.

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