Linking global turnover of species and environments

Abstract

Patterns of species turnover are central to the geography of biodiversity and resulting challenges for conservation, but at broad scales remain relatively little understood. Here, we take a first spatially-explicitly and global perspective to link the spatial turnover of species and environments. We compare how major groups of vertebrate ectotherms (amphibians) and endotherms (birds) respond to spatial environmental gradients. We find that high levels of species turnover occur regardless of environmental turnover rates, but environmental turnover provides a lower bound for species turnover. This lower bound increases more steeply with environmental turnover in tropical realms. While bird and amphibian turnover rates are correlated, the rate of amphibian turnover is four times steeper than bird rates. This is the same factor by which average geographic ranges of birds are larger than those of amphibians. Narrow-ranged birds exhibit rapid rates of species turnover similar to those for amphibians, while wide-ranged birds largely drive the aggregate patterns of avian turnover. We confirm a strong influence of the environment on species turnover that is mediated by range sizes and regional history. In contrast to geographic patterns of species richness, we find that the turnover in one group (amphibians) is a much better predictor for the turnover in another (birds) than is environment. This result confirms the role of amphibian sensitivity to environmental conditions for patterns of turnover and supports their value as a surrogate group. This spatially-explicit analysis of environmental turnover provides understanding for conservation planning in changing environments.beta diversity ͉ biodiversity ͉ distance decay ͉ environmental gradients ͉ spatial turnover U nderstanding patterns of species turnover is central to both applied issues of conservation planning (1, 2) and to long-standing conceptual questions on the origin and distribution of biodiversity (3, 4). Linking these species turnover patterns to changes in environmental conditions is crucial to addressing how the edges of species' ranges are delineated (5). Both environmental dissimilarity and geographic distance are central causes of species turnover (6). Along local environmental gradients, species distributions often represent the outcome of competitive sorting (7,8). At broader scales, evolutionary histories of speciation and extinction, along with environmental conditions, constrain the richness and distribution of species (9-11). We examine how both the environment and species composition change over geographic space to disentangle the influence of environmental conditions and space on species turnover. This extends Whittaker's studies (8) of species turnover along environmental gradients to global scales.We term our examination of changes in species composition along spatial and environmental gradients species turnover (8,12). While beta diversity is often used synonymously with species turnover (13), beta diversity can also refer to mathematical part...

Taxonomic groups with lower movement capacity may present higher beta diversity

“…The same was observed for reptiles, an equally ectothermic and little vagile group (see Qian, 2009b;Qian & Ricklefs, 2012). Amphibians may even show turnover values four times higher than birds (Buckley & Jetz, 2008). The opposite happens to the median size of the geographic distributions of these two groups.…”

“…Besides, amphibians are usually considered as animals with low dispersal ability (Qian, 2009b;Dobrovolski et al, 2011;Qian & Ricklefs, 2012). When compared to mammals and birds, amphibians always show higher beta diversity (see Buckley & Jetz, 2008;Qian, 2009b;Dobrovolski et al, 2011;Qian & Ricklefs, 2012). The same was observed for reptiles, an equally ectothermic and little vagile group (see Qian, 2009b;Qian & Ricklefs, 2012).…”

“…The high beta diversity of the group can be explained by two factors. First we have amphibians strict environmental requirements (Duellman & Trueb, 1994;Werner et al, 2007;Buckley & Jetz, 2008), especially their need for both water (for reproduction), and higher temperatures, due to ectothermy (Buckley & Jetz, 2008;Qian, 2009b). Since the studied fragments vary in terms of water availability and altitude (thus temperature), the environmental requirements for amphibians vary accordingly.…”

“…Specifically, our aims were: 1-to evaluate the relative contributions of alpha and beta diversities to the gamma diversity; 2-to test if there is higher similarity between closer localities than between farther ones due to spatial autocorrelation (Legendre, 1993;Jiménez-Valverde et al, 2010), especially regarding groups with relatively higher dispersal ability (birds and primates) (Buckley & Jetz, 2008;Qian & Ricklefs, 2012); and 3-to test whether beta diversity is higher in groups with lower dispersal capacity. A better understanding of these issues will allow taking more scientifically sound decisions for the management and conservation of these fragments, especially in a biome as threatened as the Atlantic Rainforest (Pinto et al, 2006).…”

Combinando informações ambientais e estrutura da paisagem para explicar padrões de biodiversidade: busca por alternativas eficientes para planejamento ambiental

“…A relação de padrões ambientais com a composição e distribuição de espécies é debate estabelecido para ecologia e suas disciplinas (Buckley;Jetz, 2008). O estudo dessa relação para os trópicos possui importância acentuada tendo em vista a relevância dessa região para a conservação da biodiversidade global e a ausência de padrões gerais que sejam bem estabelecidos e estáveis Graves, 2001).…”