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Historical legacies in world amphibian diversity revealed by the turnover and nestedness components of Beta diversity.

Baselga A, Gómez-Rodríguez C, Lobo JM - PLoS ONE (2012)

Bottom Line: We partitioned intra-regional beta diversity into its turnover (differences in composition caused by species replacements) and nestedness-resultant (differences in species composition caused by species losses) components.When this threshold effect of historic climatic change is partialled out, current energy-water variables become more relevant to the nestedness-resultant dissimilarity patterns, while mountainous areas are associated with higher spatial turnover.This result suggests that nested patterns are caused by species losses that are determined by physiological constraints, whereas turnover is associated with speciation and/or Pleistocene refugia.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Zoología, Facultad de Biología, Universidad de Santiago de Compostela, Santiago de Compostela, Spain. andres.baselga@usc.es

ABSTRACT
Historic processes are expected to influence present diversity patterns in combination with contemporary environmental factors. We hypothesise that the joint use of beta diversity partitioning methods and a threshold-based approach may help reveal the effect of large-scale historic processes on present biodiversity. We partitioned intra-regional beta diversity into its turnover (differences in composition caused by species replacements) and nestedness-resultant (differences in species composition caused by species losses) components. We used piecewise regressions to show that, for amphibian beta diversity, two different world regions can be distinguished. Below parallel 37, beta diversity is dominated by turnover, while above parallel 37, beta diversity is dominated by nestedness. Notably, these regions are revealed when the piecewise regression method is applied to the relationship between latitude and the difference between the Last Glacial Maximum (LGM) and the present temperature but not when present energy-water factors are analysed. When this threshold effect of historic climatic change is partialled out, current energy-water variables become more relevant to the nestedness-resultant dissimilarity patterns, while mountainous areas are associated with higher spatial turnover. This result suggests that nested patterns are caused by species losses that are determined by physiological constraints, whereas turnover is associated with speciation and/or Pleistocene refugia. Thus, the new threshold-based view may help reveal the role of historic factors in shaping present amphibian beta diversity patterns.

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Graphical illustration of the method used to compute the multiple-site dissimilarity within regional cells of 250,000 km2.The original data was the presence/absence of species in 1°×1° cells (the upper map represents species richness in the 1°×1° cells, i.e. alpha diversity). A grid of regional cells of 250,000 km2 was superimposed on the original compositional table, and multiple-site dissimilarity was computed among all 1°×1° cells belonging to each regional cell (central row). A multiple-site dissimilarity value (βSOR, βSIM or βNES) was thus assigned to each regional cell (lower map). Regional cells with a low number of 1°×1° cells (n<15) or species (gamma diversity<5) were discarded in subsequent analyses.
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pone-0032341-g001: Graphical illustration of the method used to compute the multiple-site dissimilarity within regional cells of 250,000 km2.The original data was the presence/absence of species in 1°×1° cells (the upper map represents species richness in the 1°×1° cells, i.e. alpha diversity). A grid of regional cells of 250,000 km2 was superimposed on the original compositional table, and multiple-site dissimilarity was computed among all 1°×1° cells belonging to each regional cell (central row). A multiple-site dissimilarity value (βSOR, βSIM or βNES) was thus assigned to each regional cell (lower map). Regional cells with a low number of 1°×1° cells (n<15) or species (gamma diversity<5) were discarded in subsequent analyses.

Mentions: Global, digital amphibian range maps were obtained from expert-drawn range maps that reflect the ranges of 6157 species [38]; see data limitations in www.iucnredlist.org/. Polygonal range shapes were rasterised at a 1°×1° cell resolution. The basic units of this study are regional cells of 250,000 km2, which allow the measurement of beta diversity within regional cells by computing multiple-site dissimilarities among a relevant number of 1°×1° cells (Fig. 1). To define regional cells, we used the UTM grid of squares with the same area (250,000 km2) provided by the EDIT Geoplatform [39]. These large regional cells were superimposed on the original 1°×1° grid, and only regional cells that included more than 15 1°×1° cells and at least 5 species (regional or gamma diversity) were considered in subsequent analyses (n = 321).


Historical legacies in world amphibian diversity revealed by the turnover and nestedness components of Beta diversity.

Baselga A, Gómez-Rodríguez C, Lobo JM - PLoS ONE (2012)

Graphical illustration of the method used to compute the multiple-site dissimilarity within regional cells of 250,000 km2.The original data was the presence/absence of species in 1°×1° cells (the upper map represents species richness in the 1°×1° cells, i.e. alpha diversity). A grid of regional cells of 250,000 km2 was superimposed on the original compositional table, and multiple-site dissimilarity was computed among all 1°×1° cells belonging to each regional cell (central row). A multiple-site dissimilarity value (βSOR, βSIM or βNES) was thus assigned to each regional cell (lower map). Regional cells with a low number of 1°×1° cells (n<15) or species (gamma diversity<5) were discarded in subsequent analyses.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285684&req=5

pone-0032341-g001: Graphical illustration of the method used to compute the multiple-site dissimilarity within regional cells of 250,000 km2.The original data was the presence/absence of species in 1°×1° cells (the upper map represents species richness in the 1°×1° cells, i.e. alpha diversity). A grid of regional cells of 250,000 km2 was superimposed on the original compositional table, and multiple-site dissimilarity was computed among all 1°×1° cells belonging to each regional cell (central row). A multiple-site dissimilarity value (βSOR, βSIM or βNES) was thus assigned to each regional cell (lower map). Regional cells with a low number of 1°×1° cells (n<15) or species (gamma diversity<5) were discarded in subsequent analyses.
Mentions: Global, digital amphibian range maps were obtained from expert-drawn range maps that reflect the ranges of 6157 species [38]; see data limitations in www.iucnredlist.org/. Polygonal range shapes were rasterised at a 1°×1° cell resolution. The basic units of this study are regional cells of 250,000 km2, which allow the measurement of beta diversity within regional cells by computing multiple-site dissimilarities among a relevant number of 1°×1° cells (Fig. 1). To define regional cells, we used the UTM grid of squares with the same area (250,000 km2) provided by the EDIT Geoplatform [39]. These large regional cells were superimposed on the original 1°×1° grid, and only regional cells that included more than 15 1°×1° cells and at least 5 species (regional or gamma diversity) were considered in subsequent analyses (n = 321).

Bottom Line: We partitioned intra-regional beta diversity into its turnover (differences in composition caused by species replacements) and nestedness-resultant (differences in species composition caused by species losses) components.When this threshold effect of historic climatic change is partialled out, current energy-water variables become more relevant to the nestedness-resultant dissimilarity patterns, while mountainous areas are associated with higher spatial turnover.This result suggests that nested patterns are caused by species losses that are determined by physiological constraints, whereas turnover is associated with speciation and/or Pleistocene refugia.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Zoología, Facultad de Biología, Universidad de Santiago de Compostela, Santiago de Compostela, Spain. andres.baselga@usc.es

ABSTRACT
Historic processes are expected to influence present diversity patterns in combination with contemporary environmental factors. We hypothesise that the joint use of beta diversity partitioning methods and a threshold-based approach may help reveal the effect of large-scale historic processes on present biodiversity. We partitioned intra-regional beta diversity into its turnover (differences in composition caused by species replacements) and nestedness-resultant (differences in species composition caused by species losses) components. We used piecewise regressions to show that, for amphibian beta diversity, two different world regions can be distinguished. Below parallel 37, beta diversity is dominated by turnover, while above parallel 37, beta diversity is dominated by nestedness. Notably, these regions are revealed when the piecewise regression method is applied to the relationship between latitude and the difference between the Last Glacial Maximum (LGM) and the present temperature but not when present energy-water factors are analysed. When this threshold effect of historic climatic change is partialled out, current energy-water variables become more relevant to the nestedness-resultant dissimilarity patterns, while mountainous areas are associated with higher spatial turnover. This result suggests that nested patterns are caused by species losses that are determined by physiological constraints, whereas turnover is associated with speciation and/or Pleistocene refugia. Thus, the new threshold-based view may help reveal the role of historic factors in shaping present amphibian beta diversity patterns.

Show MeSH
Related in: MedlinePlus