Putting Beta-Diversity on the Map: Broad-Scale Congruence and Coincidence in the Extremes

Imperial College London, United Kingdom
PLoS Biology (Impact Factor: 11.77). 11/2007; 5(10):e272. DOI: 10.1371/journal.pbio.0050272
Source: PubMed

ABSTRACT Beta-diversity, the change in species composition between places, is a critical but poorly understood component of biological diversity. Patterns of beta-diversity provide information central to many ecological and evolutionary questions, as well as to conservation planning. Yet beta-diversity is rarely studied across large extents, and the degree of similarity of patterns among taxa at such scales remains untested. To our knowledge, this is the first broad-scale analysis of cross-taxon congruence in beta-diversity, and introduces a new method to map beta-diversity continuously across regions. Congruence between amphibian, bird, and mammal beta-diversity in the Western Hemisphere varies with both geographic location and spatial extent. We demonstrate that areas of high beta-diversity for the three taxa largely coincide, but areas of low beta-diversity exhibit little overlap. These findings suggest that similar processes lead to high levels of differentiation in amphibian, bird, and mammal assemblages, while the ecological and biogeographic factors influencing homogeneity in vertebrate assemblages vary. Knowledge of beta-diversity congruence can help formulate hypotheses about the mechanisms governing regional diversity patterns and should inform conservation, especially as threat from global climate change increases.

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Available from: Robert Mcdonald, May 27, 2014
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    • "The similar scaling pattern in the b-diversity of macroinvertebrates and fish contrasts with the low congruence in a-diversity previously shown for the same system (Larsen et al. 2012). However, this result is in line with other studies demonstrating higher cross-taxon concordance in b, rather than a-diversity (McKnight et al. 2007; Kessler et al. 2009; but see Cabra-Garcia et al. 2012). This is partly explainable by the fact that a-diversity does not take into account information on taxonomic composition, in opposite to bdiversity . "
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    ABSTRACT: Although the important contribution of β-diversity to regional (γ) diversity is increasingly recognised, our understanding of how the spatial scaling of β-diversity differs among taxonomic groups is still limited, especially in dynamic lotic ecosystems. In this study, we assessed the difference in the partitioning of diversity at nested spatial scales, from reach to catchment, among riparian birds, fish and benthic macroinvertebrates in Mediterranean river systems. Fish and macroinvertebrates showed similar scaling patterns, with β-diversity always larger than expected by a random distribution of individuals at all spatial scales (among reaches, rivers and catchments), and local (α) diversity always lower than expected. Conversely, β-diversity of riparian birds appeared larger than expected only at the largest scale (among catchments), while local diversity did not differ from random expectation. For birds, however, results partly depended on the weighting of abundant and rare species. Although the relative contribution of β to γ-diversity did not differ substantially among groups (with multiplicative β representing five to six distinct communities), its deviation from random expectations showed marked differences indicating that functionally different groups exhibit distinct spatial patterns. This study is among the first to investigate scaling patterns in β-diversity across taxonomic groups with different ecological requirements and dispersal ability, and provides a holistic picture of riverine biodiversity. From a conservation perspective, the results suggest that, in these river systems, flexible conservation strategies are required in order to protect multiple taxonomic groups.
    Aquatic Sciences 12/2014; DOI:10.1007/s00027-014-0390-3 · 2.71 Impact Factor
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    • ", ␤-diversity has played a major role to provide insights both for ecological-theory related research (e.g., which processes create and maintain biodiversity) and for conservation-oriented questions (e.g., how different communities are in a given area) (Jost et al. 2010; McKnight et al. 2007; Myers et al. 2013). In the conservation context, the concept of ␤-diversity has helped to identify sites with high compositional uniqueness or regions of rapid species turnover (Legendre & De Cáceres 2013; McKnight et al. 2007). "
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    ABSTRACT: We investigated how cactus diversity at the regional level (γ-diversity) is distributed into within-unit diversity (α-diversity) and among-unit diversity (β-diversity), and analysed the contribution of dissimilarity due to species replacement (turnover) and dissimilarity due to species loss (nestedness) to β-diversity patterns of cacti. We quantified the diversity of endangered small cacti using data from 34 1° × 1° cells spanning most of the South Brazilian grasslands (ca. 75%). We used the contribution diversity approach (richness-based) derived from additive partitioning and unit distinctiveness and additive partitioning of β-diversity into turnover and nestedness components. Most of the γ-diversity was partitioned among units, showing that β-diversity played a fundamental role in determining the contribution of units to the region. The relative diversity contribution for 12 grid cells was higher than the average of all units, indicating a high distinctiveness and a high conservation value for these units, most of them (N = 10), inserted into the Pampa biome. Species turnover was responsible for most of the total β-diversity, suggesting an important role for spatial and/or historical constraints (e.g., dispersal limitation) in determining changes in cactus species composition in the study region. We suggest that cacti conservation strategies in the South Brazilian grasslands should preferentially include the Pampa grasslands along to borders with Argentina and Uruguay and that this will lead to an intensification of nature conservation efforts in general in the region.
    Journal for Nature Conservation 08/2014; 24. DOI:10.1016/j.jnc.2014.07.005 · 1.83 Impact Factor
    • "Davis, 2005). This could arise due to increased habitat specialization of the groups examined, or due to environmental changes such as increased environmental heterogeneity or the formation of dispersal barriers (e.g. the rise of new mountain ranges; McKnight et al., 2007). "
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    ABSTRACT: AimThe Palaeocene–late Eocene transition in North America marks a critical interval in the evolution and diversification of land mammals, including adaptive radiation in the Palaeocene, and repeated waves of immigration over habitat bridges at the Palaeocene–Eocene boundary. We investigate the fossil record of ungulate mammals over this period to understand the effects of immigration and faunal exchange on local (alpha), regional (gamma) and between-site (beta) diversity. LocationNorth America. Methods We use Palaeocene and Eocene records of North American ungulate mammals taken from the Paleobiology Database (PBDB), and calculate beta diversity among families and genera within the seven stages of the Cenozoic. We reconstruct geographic ranges sizes for studied taxa, and test trends in these ranges against null models used to control for sampling biases. Finally, we use Mantel tests to quantify the relationship between geographic distance and faunal dissimilarity within each time slice, in order to visualize changes in the spatial complexity of mammal communities. ResultsGamma diversity increases over the studied interval, with varying contributions from alpha and beta diversity. Beta diversity increases from the Palaeocene to Eocene, reflected in decreasing range size and increased correlation between reconstructed distance and faunal similarity. Increase in beta diversity over the Palaeocene–Eocene transition is driven by smaller geographic ranges among putatively invasive ‘immigrant’ and secondarily endemic taxa; range contraction among these groups in the middle–late Eocene leads to a Bartonian peak in beta diversity. Main conclusionsHigh gamma diversity in the Eocene was driven by high beta diversity rather than alpha diversity, indicating that range contraction in both immigrant and secondarily endemic taxa restructured the spatial organization of mammal communities. These parallel trends suggest that factors such as tectonic uplift or climate change were responsible, as opposed to ecological differences. Increase in beta diversity over the Palaeocene–Eocene boundary suggests that over longer time-scales, mass immigration events can lead to greater overall richness and greater heterogeneity, rather than homogeneity, within regional assemblages.
    04/2014; 23(7). DOI:10.1111/geb.12156
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