Ramifications of short-term meteorological variability on elevational range size
Spatial distributions of fauna are sensitive to climate variabilities. Classic ecological hypotheses have all suggested that greater seasonal climatic fluctuations will result in a wider species geographic distribution. These were proposed about a half century ago and have been heavily tested through the years. However, animals experience not only seasonal climatic but diurnal meteorological dynamics, and the latter one has rarely been addressed and investigated. A collaborative study led by Wei-Ping Chan and Sheng-Feng Shen of Academia Sinica, I-Ching Chen of National Cheng Kung University with Cho-ying Huang at National Taiwan University analyzed a global dataset of species distribution using new technologies to assess the influences of short-term physical environmental drivers to the elevational range sizes. Surprisingly, they found that, in general, species elevational range size is negatively correlated to diurnal temperature range, which is opposite to the effect of the seasonal one. The research was published in Science on March 25, 2016. The climatic variability hypothesis states that organisms distribute with wider geographic ranges are associated with greater climatic variability. Hence, tropical mountain species are recognized to be more susceptible to climate change than ones in the temperate regions since tropical species are inhabitants of a stable climate regime with narrower elevational range sizes. To examine the comprehensiveness of this hypothesis, the research team applied structural equation modeling to investigate the relationships among climatic factors from high-resolution climatic spatial datasets and more than 16,000 species elevational range sizes on 180 montane gradients. Results reveal a novel macroecological rule: species elevational range sizes are influenced by diurnal and seasonal climatic variability in opposite ways. Assessments (e.g., IPCC Working Group 2 Assessment Report) of impacts of climate change on species movements have mainly focused on the long-term climatic trends (mainly elevated temperature); this study provides a new insight to the research. This study was supported by National Taiwan University, Academia Sinica and Ministry of Science and Technology. | |
Reference: Chan W, Chen I, Colwell R, Liu W, Huang C, Shen S (2016) Seasonal and daily climate variation have opposite effects on species elevational range size. Science 351:1437–1439.：http://science.sciencemag.org/content/351/6280/1437
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| Unique geographical and biophysical settings of the mountainous regions of tropics and subtropics harbor a wide variety of endemic species. They are the global hotspots of biodiversity. Global climate change, specifically elevated temperatures, extreme meteorological events and lifted cloud bands, may have direct and collateral damages on the natural environments (the photograph was taken in Xueshan Range by Shiaohui Chan in February 2014). | |
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| Long-term averages of global seasonal temperature range (STR, the red channel [R]), diurnal temperature range (DTR, the green channel [G]) and mean annual precipitation (MAP, the blue channel [B]). Using the RGB display, three distinct bioclimatic patterns can be observed. High latitudes in the Northern Hemisphere are dominated by STR, and high humidity of tropics and near tropics acts as an intermediary to moderate the effects of DTR and STR. The rest of the land surface is mainly governed by DTR including arid lands, mountains and most of the terrestrial Southern Hemisphere. | |