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Towards a biogeographic regionalization of the European biota

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Abstract

How species are distributed in time and space has been a major research theme since the mid-19th century, when biogeographers began dividing the world into floral kingdoms and faunal regions using only their own knowledge of species distributions (Wallace, 1876; Engler, 1879-1882). More recently, the development of quantitative methods together with improved data availability has stimulated analytically derived biogeographic regionalizations at all levels of scaling (Birks, 1976; Myklestad & Birks, 1993; Williams et al., 1999; Proche , 2005; Moline & Linder, 2006; Heikinheimo et al., 2007; Patten & Smith-Patten, 2008). Delineation of biogeo-graphic regions is now frequently the initial step for ABSTRACT Aim To determine if it is possible to generate analytically derived regionalizations for multiple groups of European plants and animals and to explore potential influences on the regions for each taxonomic group.

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... As computers have become more powerful, and knowledge of species distributions has increased and become accessible in digital databases, biogeographical regionalizations are now being performed and/or revised for animal and plant groups in different regions of the world (e.g. Kreft & Jetz 2010; Rueda et al. 2010). The Neotropics, particularly South America, have been less studied in many biological fields, including macroecology and biogeography, when compared to the northern temperate zone. ...
... Specifically, we determine the number and positions of these regions within South America using a quantitative clustering method (k-means clustering with v-fold cross validation). Further, following Rueda et al. (2010), we use general linear modeling and variation partitioning to examine abiotic and biotic predictors of the distribution of the faunal regions identified by our clustering method. ...
... The process is repeated (we used 50 iterations) so that the clusters and cluster centres change in each replicate, converging to a locally optimal position in the data space. To obtain the optimal number of clusters based on species composition without regard to the spatial proximity of grids, k-means clustering was combined with v-fold cross-validation (see Rueda et al. 2010). In this approach, the range of potential k groups is established in advance (we considered from two to 25 clusters), but the algorithm determines the 'best' number of clusters within this range. ...
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We devise a regionalization system based on the geographical distribution of 2,265 amphibian species in South America. We used range maps of amphibians to obtain a presence/absence data grid resolved to 9310 km(2). Biogeographical regions were generated by submitting the dataset to k-means clustering combined with v-fold cross-validation. The boundaries of the three clusters generated by multiple runs of the analysis are congruent with broadly defined biome structure in South America: 1) the Andes, the Atacama desert, Patagonia, and subtropics including grassland in southern Brazil, Argentina and Uruguay; 2) Amazon forest; 3) Atlantic forest and the Cerrado-Caatinga-Chaco complex. A few runs further distinguished Atlantic forest and Caatinga biome from other drier, more open biomes. The variable most strongly associated with the distribution of clusters was species richness, but climate also had moderately strong explanatory power. The regionalization scheme based on clustering is less finely resolved than previous schemes generated by expert opinion and rates of endemism but provides a general overview of the biogeographic signal contained in the current distribution patterns of amphibian species.
... This number is substantially lower than the optimal k value of 12 obtained for the analysis of vascular plant distributions using exactly the same statistical procedure [6]. Such differences in the number of regions retained within an explicit statistical framework using the same optimality criterion for the numbers of clusters to be retained have been interpreted in terms of differences in dispersal capacities [5]. The differences observed between the optimal number of regions retained from the analyses of bryophyte and vascular plant distributions hence support our second hypothesis that analyses of bryophyte species distributions would result in lower regions than analyses of vascular plants. ...
... Similar geographic regions were resolved from the analyses of plant and mammal taxa, suggesting that the distributions of these groups are controlled by the same environmental variables and that environmental forcing is sufficient to erode the signature of taxon-specific differences in life-history traits [6]. The main differences observed among groups were the number of regions identified, which was associated to species mean range size and dispersal ability [5]. ...
... First, a hierarchical classification was unnecessary and would result in a dendrogram of similarity that would be extremely difficult to interpret with >1000 observations. Second, this technique was most recently employed for other organisms in the same area [5], [6], which allows easy comparisons across taxa. ...
Article
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The definition of biogeographic regions provides a fundamental framework for a range of basic and applied questions in biogeography, evolutionary biology, systematics and conservation. Previous research suggested that environmental forcing results in highly congruent regionalization patterns across taxa, but that the size and number of regions depends on the dispersal ability of the taxa considered. We produced a biogeographic regionalization of European bryophytes and hypothesized that (1) regions defined for bryophytes would differ from those defined for other taxa due to the highly specific eco-physiology of the group and (2) their high dispersal ability would result in the resolution of few, large regions. Species distributions were recorded using 10,000 km(2) MGRS pixels. Because of the lack of data across large portions of the area, species distribution models employing macroclimatic variables as predictors were used to determine the potential composition of empty pixels. K-means clustering analyses of the pixels based on their potential species composition were employed to define biogeographic regions. The optimal number of regions was determined by v-fold cross-validation and Moran's I statistic. The spatial congruence of the regions identified from their potential bryophyte assemblages with large-scale vegetation patterns is at odds with our primary hypothesis. This reinforces the notion that post-glacial migration patterns might have been much more similar in bryophytes and vascular plants than previously thought. The substantially lower optimal number of clusters and the absence of nested patterns within the main biogeographic regions, as compared to identical analyses in vascular plants, support our second hypothesis. The modelling approach implemented here is, however, based on many assumptions that are discussed but can only be tested when additional data on species distributions become available, highlighting the substantial importance of developing integrated mapping projects for all taxa in key biogeographically areas of Europe, and the Mediterranean peninsulas in particular.
... The model selection approach was based on the lowest Akaike Information Criterion (AIC; [38]). We considered the best model to be the one based on the lowest AIC required to partition the deviance of each response variable into independent effects of a particular predictor and co-varying effects of two or more predictors that cannot be disentangled [6], [39]. ...
... Therefore, it is reasonable that climatic gradients determined by the latitudinal variation in the AF are important forces in determining the present clusters (Table 2). Furthermore, as reported previously in Europe [6], the underlying vegetation structure of the AF is also considerably important for predicting the present cluster patterns, in which some of the clusters represent specific AF eco-regions (e.g., the Araucaria forest and the ARAUC cluster), while others represent a combination of eco-regions (e.g., SOUTHEAST). Indeed, it is well known that the water-energy balance is a strong correlate of plant distribution [6], [19], so it is not surprising that the shared effect of climate and AF vegetation distribution on the anuran biogeographic patterns was relatively high in the present study. ...
... In summary, we propose that the anuran fauna of the AF can be split into four biogeographic regions characterized by: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests, where the weather is hot and seasonally dry (SEMID); b) northern small-ranged species that presumably evolved/survived to extinction within the Pleistocene forest refugia, where the climate nowadays is hot (NORTH); c) highly diverse and small-ranged species from the southeastern ombrophilous and its adjacent semidecidous forest, where the climate is cooler (except when compared to ARAUC) and the topography is rough (SOUTHEAST); and d) southern species from the Araucaria forest, where the weather is cooler and the rains are well distributed throughout the year (ARAUC). The high congruence among the cluster patterns and previous eco-regions identified for the AF (Figure 1A and 1B) corroborates the habitat templet concept [20], [21], and suggests that preserving the underlying habitat structure (i.e., natural forest formations) helps to preserve the historical and ecological signals that underlie the geographic distribution of species [6], including the AF anurans. Nonetheless, it is important to emphasize that our regionalization scheme did not consider the human-induced deforestation that reduced the AF extension to ∼7% of its original distribution [10]. ...
Article
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Anurans are a highly diverse group in the Atlantic Forest hotspot (AF), yet distribution patterns and species richness gradients are not randomly distributed throughout the biome. Thus, we explore how anuran species are distributed in this complex and biodiverse hotspot, and hypothesize that this group can be distinguished by different cohesive regions. We used range maps of 497 species to obtain a presence/absence data grid, resolved to 50650 km grain size, which was submitted to k-means clustering with v-fold cross-validation to determine the biogeographic regions. We also explored the extent to which current environmental variables, topography, and floristic structure of the AF are expected to identify the cluster patterns recognized by the k-means clustering. The biogeographic patterns found for amphibians are broadly congruent with ecoregions identified in the AF, but their edges, and sometimes the whole extent of some clusters, present much less resolved pattern compared to previous classification. We also identified that climate, topography, and vegetation structure of the AF explained a high percentage of variance of the cluster patterns identified, but the magnitude of the regression coefficients shifted regarding their importance in explaining the variance for each cluster. Specifically, we propose that the anuran fauna of the AF can be split into four biogeographic regions: a) less diverse and widely-ranged species that predominantly occur in the inland semideciduous forests; b) northern small-ranged species that presumably evolved within the Pleistocene forest refugia; c) highly diverse and small-ranged species from the southeastern Brazilian mountain chain and its adjacent semideciduous forest; and d) southern species from the Araucaria forest. Finally, the high congruence among the cluster patterns and previous eco-regions identified for the AF suggests that preserving the underlying habitat structure helps to preserve the historical and ecological signals that underlie the geographic distribution of AF anurans
... Hence, those breakpoints should also be examined using large-scale biotic, climatic and land cover data. Such examinations are also valuable owing to the fact that they provide important information about biogeographic regionalisation for environmental assessment and biodiversity conservation (Bailey 2010; Rueda, Rodriguez & Hawkins 2010). We examined geographical variation and breakpoints in the regional faunal composition of four beetle groups (Coleoptera: Carabidae, Dytiscidae, Hydrophiloidea, Cerambycidae), showing a wide variety of habitats (both aquatic and terrestrial groups) and trophic modes (ranging from predators through omnivores to herbivores). ...
... While a large number of studies have examined variation in species richness across large spatial grains and extents (see review by Field et al. 2009 ), fewer studies have examined species compositional variation at such broad scales (V€ ais€ anen, Heli€ ovaara & Immonen 1992; Baselga 2008; Rueda, Rodriguez & Hawkins 2010). We found that approximately half of variation in the provincial species composition of the four beetle groups was accounted for by the four groups of explanatory variables. ...
... Such abrupt changes may result from the fact that large-scale studies cross multiple species pools that are formed by either historical forces or climatic constraints or, more likely, their joint effects on species ranges. Such abrupt changes in faunal composition are even more likely at broader spatial scales than that of our study, and the very foundations of biogeographical regionalisation indeed rest on the assumption of clearly definable geographical areas harbouring species typical to each region in various taxonomic groups (Brown & Lomolino 1998; Heikinheimo et al. 2007; Rueda, Rodriguez & Hawkins 2010). Geographical patterns in faunal composition were very similar among ecologically disparate beetle taxa, as evidenced by RDA, spatial correlograms and multivariate regression trees. ...
Article
1. Regional faunas are structured by historical, spatial and environmental factors. We studied large-scale variation in four ecologically different beetle groups (Coleoptera: Dytiscidae, Carabidae, Hydrophiloidea, Cerambycidae) along climate, land cover and geographical gradients, examined faunal breakpoints in relation to environmental variables, and investigated the best fit pattern of assemblage variation (i.e. randomness, checkerboards, nestedness, evenly-spaced, Gleasonian, Clementsian). We applied statistical methods typically used in the analysis of local ecological communities to provide novel insights into faunal compositional patterns at large spatial grain and geographical extent.2. We found that spatially-structured variation in climate and land cover accounted for most variation in each beetle group in partial redundancy analyses, whereas the individual effect of each explanatory variable group was generally much less important in accounting for variation in provincial species composition.3. We also found that climate variables were most strongly associated with faunal breakpoints, with temperature-related variables alone accounting for about 20% of variation at the first node of multivariate regression tree for each beetle group. The existence of faunal breakpoints was also shown by the “elements of faunal structure” analyses, which suggested Clementsian gradients across the provinces, i.e., that there were two or more clear groups of species responding similarly to the underlying ecological gradients.4. The four beetle groups showed highly similar biogeographical patterns across our study area. The fact that temperature was related to faunal breakpoints in the species composition of each beetle group suggests that climate sets a strong filter to the distributions of species at this combination of spatial grain and spatial extent. This finding held true despite the ecological differences among the four beetle groups, ranging from fully aquatic to fully terrestrial, and from herbivorous to predaceous species.5. The existence of Clementsian gradients may be a common phenomenon at large scales, and it is likely to be caused by crossing multiple species pools determined by climatic and historical factors on the distributions of species.This article is protected by copyright. All rights reserved.
... Traditionally, main attention has been paid to broad spatial scales, where criteria of taxonomical distinctiveness at the level of genera (or above) were originally emphasized for the division of Earth's surface into geographical units of approximately continental extent (Wallace, 1876, 1894). However, biogeographical regionalizations have become of special importance also at fine spatial scales, where assemblage distinctiveness at the level of species has been commonly used for the delineation of subregions, districts, zones etc. within global biogeographical regions (Crowe & Crowe, 1982; De Klerk et al., 2002; Linder et al., 2012), continents (Heikinheimo et al., 2007; Rueda et al., 2010) or even smaller areas (Pasinelli et al., 2001; Moreno Saiz & Lobo, 2007; Filipe et al., 2009). This inevitably consists of the decrease of both total spatial extent of the study and the grain (size of the basic sampling unit), because large grid cells may not be appropriate for the division of smaller areas. ...
... Moreno Saiz et al., 1998 or Morrone & Escalante, 2002). Some findings about spatial properties of biogeographical regions in Europe were published by Heikinheimo et al. (2007) and Rueda et al. (2010) who classified the European continent based on the distribution of different animal taxa. Both studies used the same spatial framework represented by UTM grid cells spanning 50 9 50 km which are commonly used for mapping of the European biota (e.g. ...
... Heikinheimo et al. (2007) thus argued that Europe can be divided into cohesive regions despite a long history of human presence and habitat modification. Generally, spatial coherence seems to be a common feature of biogeographical delimitations at broader scales of approximately continental extent (Heikinheimo et al., 2007Heikinheimo et al., , 2012 Rueda et al., 2010; Linder et al., 2012). On the other hand, at finer spatial scales, biogeographical units resulting from the classification analysis often tend to disintegrate into spatially discontinuous patches (Pasinelli et al., 2001; Bunce et al., 2002; Eronen et al., 2011; Div ı sek et al., 2014). ...
Article
One of the fundamental tools in biogeography is the classification of the Earth surface into spatially coherent units based on assemblage distinctiveness. However, spatial coherence of biogeographical regions may be scale-dependent, that is, it may change with changing the size of spatial units used. We ask (1) how the clusters resulting from the classification of animal assemblages at different spatial scales differ in their spatial coherence, (2) whether there are geographical trends in the patterns of spatial coherence, and (3) what factors drive these patterns at different scales and in different areas of Europe.
... BRs are areas generally defined by similarity of biotic composition, and diverse classifications have been prepared at global [2,3,5,16], continental [4,8,[17][18][19][20][21][22][23][24][25], as well as regional scales [9,[26][27][28]. These are spatially "complete" in that all operational geographic units (OGUs) sensu Crovello [29] or cells sensu Crisp et al. [8] are assigned to a BR. ...
... Recently, partitioning techniques which avoid the use of subjective phenon-lines [50] have been employed in biogeographic analysis. An example of such methods is K-means analysis [21,54,55], but this method requires an a priori specification of the number of K clusters to be found by the algorithm [22]. Although the number of K clusters can be determined using the L-method [2,51], or a related method [53,56,57], it is not always readily apparent which is the most optimal method or optimal number of clusters. ...
... Our Witteberg BR (BR 3 in Fig 9a & 9b), comprising the Witteberg CoE (17) and the Laingsburg CoE (21), might be transitional between the NWBR and KMBR, which may account for the discrepancies in phytogeographic boundaries between Manning and Goldblatt [27] and Weimarck [26] in this area (Fig 10). ...
Article
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We used a very large dataset (>40% of all species) from the endemic-rich Cape Floristic Region (CFR) to explore the impact of different weighting techniques, coefficients to calculate similarity among the cells, and clustering approaches on biogeographical regionalisa-tion. The results were used to revise the biogeographical subdivision of the CFR. We show that weighted data (down-weighting widespread species), similarity calculated using Kulc-zinsky's second measure, and clustering using UPGMA resulted in the optimal classification. This maximized the number of endemic species, the number of centres recognized, and operational geographic units assigned to centres of endemism (CoEs). We developed a dendrogram branch order cutoff (BOC) method to locate the optimal cutoff points on the dendrogram to define candidate clusters. Kulczinsky's second measure dendrograms were combined using consensus, identifying areas of conflict which could be due to biotic element overlap or transitional areas. Post-clustering GIS manipulation substantially enhanced the endemic composition and geographic size of candidate CoEs. Although there was broad spatial congruence with previous phytogeographic studies, our techniques allowed for the recovery of additional phytogeographic detail not previously described for the CFR.
... As a greedy clustering approach it includes outliers in their nearest groups, rather than emphasizing them. The non-hierarchical or partitioning algorithm, k-means, has been used recently for clustering grid cells into biogeographical zones (Heikinheimo et al., 2007; Rueda et al., 2010), but the a priori specification of the number of groups to be found by the algorithm and the inability to determine the inter-group relationships limits its usefulness. We tested the distortion in translating the multidimensional similarity matrix into a phenogram with a co-phenetic analysis. ...
... Udvardy (1975) found that, at a global scale, there was agreement amongst zones developed by zoologists, except for areas of a transitional nature, but that the botanical zones were more different. At a continental scale, Rueda et al. (2010) observed substantial incongruence in the regionalization of trees, butterflies, reptiles, amphibians, birds and mammals in Europe. Consequently, it is unclear whether the congruence demonstrated in Africa is unusual, or whether this a global pattern, at least in tropical regions. ...
... The nature of the underlying data might affect the results, but a biological explanation seems more likely. Congruence could be the consequence of the vertebrate distributions being influenced by the vegetation and flora (predicted by Rueda et al., 2010), by common responses to the same climatic parameters or by a common underlying history. Interpreting the common response as being driven by the vegetation is consistent with the idea that the vegetation functions as a giant ecosystem engineer that creates the habitat for animals (Linder et al., in press), e.g. ...
Article
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Aim To test whether it is possible to establish a common biogeographical regionalization for plants and vertebrates in sub-Saharan Africa (the Afrotropical Region), using objective multivariate methods. Location Sub-Saharan Africa (Afrotropical Region). Methods We used 1° grid cell resolution databases for birds, mammals, amphibians and snakes (4142 vertebrate species) and c. 13% of the plants (5881 species) from the Afrotropical Region. These databases were analysed using cluster analysis techniques to define biogeographical regions. A β(sim) dissimilarity matrix was subjected to a hierarchical classification using the unweighted pair-group method with arithmetic averages (UPGMA). The five group-specific biogeographical regionalizations were compared against a regionalization developed from a combined database, and a regionalization that is maximally congruent with the five group-specific datasets was determined using a consensus classification. The regionalizations were interpreted against measures of spatial turnover in richness and composition for the five datasets as well as the combined dataset. Results We demonstrate the existence of seven well-defined and consistent biogeographical regions in sub-Saharan Africa. These regionalizations are statistically defined and robust between groups, with minor taxon-specific biogeographical variation. The proposed biogeographical regions are: Congolian, Zambezian, Southern African, Sudanian, Somalian, Ethiopian and Saharan. East Africa, the West African coast, and the transitions between the Congolian, Sudanian and Zambezian regions are unassigned. The Cape area in South Africa, Afromontane areas and the coastal region of East Africa do not emerge as distinct regions but are characterized by high neighbourhood heterogeneity, rapid turnover of species and high levels of narrow endemism. Main conclusions Species distribution data and modern cluster analysis techniques can be used to define biogeographical regions in Africa that reflect the patterns found in both vertebrates and plants. The consensus of the regionalizations between different taxonomic groups is high. These regions are broadly similar to those proposed using expert opinion approaches. Some previously proposed transitional zones are not recognized in this classification.
... The geographic grouping of various species using quantitative analysis avoids subjective errors and produces consistent results 14,105 . The European biogeographic regionalization research shows there were similarities in some cluster borders for the various groups, none of the clustering patterns was identical 106 . Amphibians and reptiles are ectothermic and susceptible to solar, temperature and moisture for survival. ...
... comprehension of the total distribution traits of the other animals in a same area that suffers the insufficient investigation. Meanwhile, they clearly are narrowly distributed comparing with the high vagility of birds, butterflies and mammals 106 . These physiological, morphological, and life-history traits 80 probably lead to narrower ranges and stronger regionalized distribution of fauna. ...
... The widespread species are not clearly distinguished on account of the computing process in cluster analysis, but this problem appeared in the study of distributions of other organisms as well, such as mammals, birds and insects 80,106 . The distribution of widespread species might be decided by other factors (vagility and physiology rather than climate and geography). ...
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The analysis of the biogeographic distribution of species is the basis for establishing a strategy for land management and responding to climatic change, but research on the distribution of amphibians and reptiles in the arid land in the middle of Asia is extremely limited. After classifying the chorotypes of amphibians and reptiles in the arid land of Central Asia using a clustering analysis, we delineated their distribution characteristics and discovered the ecological determinants for the chorotypes in terms of feature selection and the Akaike information criterion (AIC). We identified 6 chorotypes at the higher level and 16 sub-chorotypes at the lower level. Compared to small-scale or subjective research, which produces unstable results, research characterized by both large scale and clustering methods yields more consistent and stable results. Our results show that the Mean Altitude (MA), Mean Annual Temperature (MAT), and Mean Temperature in the Wettest Quarter (MTWE) are the critical variables determining the higher-level chorotypes. Furthermore, geographical factors appear to have a stronger influence on chorotypes than climatic factors. Several climatic variables and MA were identified as the best fit in the AIC model at the lower level, while the sub-chorotypes are determined more by multiple climatic factors with complex relationships. The research on amphibian and reptilian distribution patterns will shed light on the overall distribution of other species in the same understudied area. Widespread species in the study area are not clearly distinguished due to the cluster analysis computing process. This problem however, appears in studies of the distribution of other organisms thus warrants further research. Our methodology based on the selection of multiple models is effective to explore how the environment determines the distributions of different animal groups.
... 3b). mammals (Grabí nska 1992; Heikinheimo et al. 2007), and butterflies and trees (Rueda et al. 2010). The transitional role of southern France is reflected by the fact that, for several taxa, this area has been linked to either Iberia (Grabí nska 1994; Heikinheimo et al. 2007; Rueda et al. 2010), to Italy (Covas and Blondel 1998) and to both areas (Grabí nska 1993; Myklestad and Birks 1993; Olivero et al. 1998; Vargas et al. 2003; Heikinheimo et al. 2007; Rueda et al. 2010 ), probably because it contains northern extra- Mediterranean biotic elements (Grabí nska 1990). ...
... mammals (Grabí nska 1992; Heikinheimo et al. 2007), and butterflies and trees (Rueda et al. 2010). The transitional role of southern France is reflected by the fact that, for several taxa, this area has been linked to either Iberia (Grabí nska 1994; Heikinheimo et al. 2007; Rueda et al. 2010), to Italy (Covas and Blondel 1998) and to both areas (Grabí nska 1993; Myklestad and Birks 1993; Olivero et al. 1998; Vargas et al. 2003; Heikinheimo et al. 2007; Rueda et al. 2010 ), probably because it contains northern extra- Mediterranean biotic elements (Grabí nska 1990). On the other hand, Anatolia and the Italian–Balkan regions have been considered biogeographically different from each other also for both scrubland and steppe birds (Covas and Blondel 1998), but similar for other taxa (Grabí nska 1992Grabí nska , 1994 Covas and Blondel 1998), which is consistent with the existence of a wide and highly fuzzy transition zone between the Anatolian and the Balkan peninsulas. ...
... mammals (Grabí nska 1992; Heikinheimo et al. 2007), and butterflies and trees (Rueda et al. 2010). The transitional role of southern France is reflected by the fact that, for several taxa, this area has been linked to either Iberia (Grabí nska 1994; Heikinheimo et al. 2007; Rueda et al. 2010), to Italy (Covas and Blondel 1998) and to both areas (Grabí nska 1993; Myklestad and Birks 1993; Olivero et al. 1998; Vargas et al. 2003; Heikinheimo et al. 2007; Rueda et al. 2010 ), probably because it contains northern extra- Mediterranean biotic elements (Grabí nska 1990). On the other hand, Anatolia and the Italian–Balkan regions have been considered biogeographically different from each other also for both scrubland and steppe birds (Covas and Blondel 1998), but similar for other taxa (Grabí nska 1992Grabí nska , 1994 Covas and Blondel 1998), which is consistent with the existence of a wide and highly fuzzy transition zone between the Anatolian and the Balkan peninsulas. ...
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This study uses the amphibian species of the Mediterranean basin to develop a consistent procedure based on fuzzy sets with which biogeographic regions and biotic transition zones can be objectively detected and reliably mapped. Biogeographical regionalizations are abstractions of the geographical organization of life on Earth that provide frameworks for cataloguing species and ecosystems, for answering basic questions in biogeography, evolutionary biology, and systematics, and for assessing priorities for conservation. On the other hand, limits between regions may form sharply defined boundaries along some parts of their borders, whereas elsewhere they may consist of broad transition zones. The fuzzy set approach provides a heuristic way to analyse the complexity of the biota within an area; significantly different regions are detected whose mutual limits are sometimes fuzzy, sometimes clearly crisp. Most of the regionalizations described in the literature for the Mediterranean biogeographical area present a certain degree of convergence when they are compared within the context of fuzzy interpretation, as many of the differences found between regionalizations are located in transition zones, according to our case study. Compared with other classification procedures based on fuzzy sets, the novelty of our method is that both fuzzy logic and statistics are used together in a synergy in order to avoid arbitrary decisions in the definition of biogeographic regions and transition zones.
... Biogeographical units like ecoregions may be the closest we can get to map metacommunities because they reflect sharp boundaries in species turnover (Marcilio-Silva et al. 2017, Smith et al. 2018) and predictable species associations based on similar ecological requirements and non-neutral interactions Legendre 2012, Smith et al. 2018). Plant ecoregions are also habitat templates for animal species distribution and life-history evolution (Rueda et al. 2010). Importantly, ecoregion delimitation greatly improves conservation planning and management (Olson et al. 2001, Dinerstein et al. 2017) since it allows the conservation of unique biotas (Whittaker et al. 2005). ...
... Our bioregionalization approach followed previous work (Rueda et al. 2010, Moura et al. 2017 and was based on the unconstrained community-level modelling of the compositional distance (Ferrier and Guisan 2006). We produced a spatially contiguous estimation of floristic dissimilarity and then performed a regionalization based on this contiguous surface. ...
Article
Our aims were to quantify and map the plant ecoregions of the Atlantic Forest, a biodiversity hotspot that covers ca 150 million ha in eastern South America. We used a data set on the distribution of 4378 shrub and tree species across 711 localities. Plant ecoregions were identified using analyses of species turnover for both species occurrences and relative abundances. We interpolated NMDS axes of compositional variation over the entire the Atlantic Forest extent, and then classified the compositional dissimilarity according to the number of biogeographical ecoregions previously identified through k‐means analyses. We assessed the ability of environmental, historical vegetation stability, and the current human footprint to explain the occurrence of the identified ecoregions through multinomial logistic regression models. We identified 21 spatially cohesive occurrence and 14 abundance ecoregions. Aridity, soil, and historical biome stability were retained in the best model explaining both occurrence and abundance ecoregions. Broad compositional zones were identified through UPGMA cluster analysis of ecoregions, and formed north and south compositional blocks. Our work confirms the existence of a broad north‐south divide within the Atlantic Forest, previously suggested based on climatic and amphibious data. Differences between the occurrence and abundance maps suggest the location of transition zones to neighbouring domains and endemism centres. Due to the aggregate nature of our analyses, site‐level disturbance degree was not considered, implying that human impacts could be broader then we could detect. There was limited overlap between our results and previous Atlantic Forest regionalization efforts, indicating that multi‐taxa, physiognomic, and environmental regionalization schemes based on expert opinion or vegetation maps are poor proxies for compositional ecoregions. This article is protected by copyright. All rights reserved.
... ntified in the western part of the Rif, and these comprise Mediterranean species and others endemic to the Maghreb (the region that spans most of North-western Africa, excluding the Sahara ectotherms. They use GAM and find that amphibians and reptiles are more influenced by precipitation and temperature than birds and mammals (Aragón et al., 2010). Rueda et al. (2010) generate analytically derived regionalizations for multiple groups of European plants and animals and explore potential influences on the regions for each taxonomic group. They use GLM for modeling the obtained coherent clusters and identify a discernable biogeographic structure in the European biota, mainly influenced by climate (Rueda ...
... Rueda et al. (2010) generate analytically derived regionalizations for multiple groups of European plants and animals and explore potential influences on the regions for each taxonomic group. They use GLM for modeling the obtained coherent clusters and identify a discernable biogeographic structure in the European biota, mainly influenced by climate (Rueda et al., 2010). ...
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We present a review of the concepts and methods associated to ecological niche modeling illustrated with the published works on amphibians and reptiles of the Mediterranean Basin, one of the world's biodiversity hotspots for conservation priorities. We start by introducing ecological niche models, analyzing the various concepts of niche and the modeling methods associated to each of them. We list some conceptual and practical steps that should be followed when modeling, and highlight the pitfalls that should be avoided. We then outline the history of ecological modeling of Mediterranean amphibians and reptiles, including a variety of aspects: identification of the ecological niche; detection of common distribution areas (chorotypes) and other biogeographical patterns; analysis and prediction of species richness patterns; analysis of the expansion of native and invasive species; integration of molecular data with spatial modeling; identification of contact zones between related taxa; assessment of species' conservation status; and prediction of future conservation problems, including the effects of global change. We conclude this review with a discussion of the research that still needs to be developed in this area.
... The Wet Tropics is an area of high species richness and endemism for all these lineages. Bioregionalizations have been conducted on continental (Rueda et al., 2010; Linder et al., 2012) and global scales (Kreft & Jetz, 2010; Holt et al., 2012). These works provide an alternative approach as they consider a subset of the diversity of groups such as plants, insects and vertebrates within large geographical areas whereas our study focuses on a single fully sampled lineage at a continental scale. ...
... It is possible that the differing evolutionary histories of individual lineages, when combined in a single analysis, would produce the less defined patterns that were seen by Linder et al. (2012) in sub- Saharan Africa. More studies are needed to better understand whether bioregionalizations of plants and animal groups are congruent (Linder et al., 2012) or incongruent (Udvardy, 1975; Rueda et al., 2010) and what drives the patterns. Our finding that climate and dissimilarity of plant distributions correlate with species turnover confirms previous global studies (Buckley & Jetz, 2008). ...
Article
AimTo map spatial patterns of species richness, species endemism and species turnover of the eucalypts; to propose a biogeographical regionalization of eucalypts based on species turnover; and to identify the environmental correlates of these patterns. LocationAustralia and Malesia. Methods We analysed 798 eucalypt species (Angophora, Corymbia and Eucalyptus) with distributions across Australia and Malesia using square cells with a resolution of 100 × 100 km. Species richness, endemism and species turnover were calculated. Phytogeographical regions were identified using an agglomerative cluster analysis derived from a matrix of pairwise Simpson's beta (βsim) dissimilarity values. Eleven environmental variables were used to analyse the environmental correlates of species turnover. Non-metric multidimensional scaling (NMDS) of the βsim, Getis-Ord Gi* hotspot spatial statistics and an ordination of the βsim -NMDS were used to investigate the environmental drivers at the continental level and for each of the phytogeographical regions. ResultsWe identified three centres of species richness and fourteen of endemism, of which several are newly identified. The main centres of species richness agree with previous studies. Six major eucalypt phytogeographical regions are proposed based on the species turnover: monsoon, tropical/subtropical, south-east, south-west, Eremaean north and Eremaean south. These findings are supported by significant environmental differences of the NMDS vectors and the Gi* statistics. The environmental drivers of species turnover are broadly consistent with the continental patterns of summer and winter rainfall below and above the Tropic of Capricorn. Main conclusionsThe proposed phytogeographical regions are similar to the Australian biomes. Climate is the main driver of the phytogeographical regions, varying from region to region. Comprehensive bioregionalization frameworks and phytogeography updates, as proposed here, are fundamental for enhancing our understanding of the spatial distribution of biodiversity and therefore benefit global biogeography and help planners to identify regions of high conservation relevance.
... Traditionally, regionalization is a special form of classification in which spatial units are grouped together based not only on a set of defined criteria but also a set of contiguity constraints (Haining, 2003). A number of recent biogeographic and ecological 'regionalizations', however , have opted not to spatially constrain the classification process (e.g., Coops et al., 2009; Procheş, 2005; Rueda et al., 2010 ). To demonstrate the influence of imposing spatial contiguity on a regionalization, we classified our data using two additional non-spatial methods. ...
... In fine-scale environmental domain classifications (e.g., those at the landscape scale), spatial contiguity of ecological land types is rarely expected, so spatial contiguity of units belonging to the same class is unlikely to be a constraint. Even at broader spatial scales, a number of researchers have chosen not to enforce spatial constraints during clustering to avoid forcing cohesion of clusters that may not be justified by the environmental or ecological data (e.g., Rueda et al., 2010 ). Such studies emphasize within-region homogeneity over spatial contiguity and may, as our results show, result in comparatively complicated solutions comprised of regions with many disjunct units. ...
Article
Technological advances have created new opportunities for defining and mapping ecological and biogeographical regions on the basis of quantitative criteria while generating a need for studies that evaluate the sensitivity of ecoregionalizations to clustering methods and approaches. In this study, we used a novel regionalization algorithm, regionalization with dynamically constrained agglomerative clustering and partitioning (REDCAP), to identify hierarchical regions based on measures of forest extent, connectivity, and change for 2109 watersheds in the continental U.S. Unlike regionalizations developed using non-spatial clustering techniques, REDCAP directly incorporates a spatial contiguity constraint into a traditional hierarchical clustering method, resulting in contiguous regions that optimize a homogeneity measure. Results of our analyses identified nine- and eighteen-class Forest Pattern Regions that reflected the influence of natural and anthropogenic factors structuring forest extent and fragmentation. Because these regions are defined by the forest pattern metrics themselves, rather than pre-defined political or ecological units, they provide a valuable means for visualizing forest pattern information and quantifying forest patterns across a large, diverse geographic area. In contrast, regionalizations of the same data using two non-spatial methods (k-means clustering and non-spatial average linkage clustering) resulted in more homogeneous classes composed of many discontiguous units. While it should not be viewed as a replacement for non-spatial clustering techniques, REDCAP provides an alternative approach to developing ecological regionalizations by placing greater emphasis on maintaining the spatial contiguity of units, a property that may be desirable in many broad-scale regionalizations because it reduces data complexity and facilitates the visualization and interpretation of ecological or biogeographic data.
... Second, two of the procedures we followed here involved a certain degree of subjectivity: One was the selection of the cutoff point (the number of genera) beyond which an ecoregion was included in the relevant analysis, and the second was the selection of cross-taxon matching clusters in each dendrogram. Multitaxon biogeographical analyses in which such procedures are avoided (e.g., Rueda et al. 2010) do show great similarity across taxa, albeit not quite to the extent illustrated here. But true biogeographical commonalities may simply be more complex than what current computational algorithms can handle. ...
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The world's zoogeographical regions were historically defined on an intuitive basis, with no or a limited amount of analytical testing. Here, we aimed (a) to compare analytically defined global zoogeographical clusters for the herpetofauna, birds, mammals, and all these groups taken together (tetrapod vertebrates); (b) to use commonalities among these groups to propose an updated global zoogeographical regionalization; and (c) to describe the resulting regions in terms of vertebrate diversity and characteristic taxa. The clusters were remarkably uniform across taxa and similar to previous intuitively defined regions. Eleven vertebrate-rich (Nearctic, Caribbean, Neotropical, Andean, Palearctic, Afrotropical, Madagascan, Indo-Malaysian, Wallacean, New Guinean, Australian) and three vertebrate-poor (Arctic, Antarctic, Polynesian) zoogeographical regions were derived; the Neotropical,- Afrotropical, and Australian had the highest numbers of characteristic tetrapod genera. This updated regionalization provides analytically accurate divisions of the world, relevant to conservation, biogeographical research, and geography education.
... For instance, a biogeographical region like the Afrotropics contains many sub-regions that are assembled from different species pools with different evolutionary histories. Indeed, many finer- scaled, hierarchical biogeographic classifications are avail- able in the literature for many regions and taxonomic groups (de Klerk et al. 2002, Kreft and Jetz 2010, Rueda et al. 2010) that may provide useful geographic templates to inves- tigate regional effects. We suggest that these data should be utilized more and that the approach be expanded to fit the extent and resolution of macroecological analyses (i.e. ...
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Over the last two decades, macroecology – the analysis of large-scale, multi-species ecological patterns and processes – has established itself as a major line of biological research. Analyses of statistical links between environmental variables and biotic responses have long and successfully been employed as a main approach, but new developments are due to be utilized. Scanning the horizon of macroecology, we identifi ed four challenges that will probably play a major role in the future. We support our claims by examples and bibliographic analyses. 1) Integrating the past into macroecological analyses, e.g. by using paleontological or phylogenetic information or by applying methods from historical biogeography, will sharpen our understanding of the underlying reasons for contemporary patterns. 2) Explicit consideration of the local processes that lead to the observed larger-scale patterns is necessary to understand the fine-grain variability found in nature, and will enable better prediction of future patterns (e.g. under environmental change conditions). 3) Macroecology is dependent on large-scale, high quality data from a broad spectrum of taxa and regions. More available data sources need to be tapped and new, small-grain large-extent data need to be collected. 4) Although macroecology already lead to mainstreaming cuttingedge statistical analysis techniques, we fi nd that more sophisticated methods are needed to account for the biases inherent to sampling at large scale. Bayesian methods may be particularly suitable to address these challenges. To continue the vigorous development of the macroecological research agenda, it is time to address these challenges and to avoid becoming too complacent with current achievements.
... However, we also identified a similar latitudinal trend for regional species assemblages. This could be due to the higher beta diversity of Mediterranean fauna and flora (Underwood et al., 2009; Rueda et al., 2010), which is strengthened by the peninsular effect (Fraissinet & Fulgione, 2008 ). On the other hand, cities in southern Europe harbour a lower proportion of the regional bird community relative to more northern European cities, so this biogeographical setting may not be the sole effect generating the higher beta diversity in southern cities. ...
Article
Aim To compare macroecological patterns between bird communities of European cities and regional species assemblages in the surrounding landscape, and to reveal geographical trends in the urbanization of native avifauna. Location Forty-one towns and cities in continental Europe. Methods We compiled data on the species richness and community composition of urban avifauna from 41 European city breeding bird atlases, and of species assemblages comprising nine grid cells (each about 50 km × 50 km) from the EBCC Atlas of European Breeding Birds (hereafter regional assemblages). Species–area relationships (SARs), latitudinal trends in diversity and the distance decay of community similarity were compared using regression models (generalized linear models). Observed urban communities were compared with randomly assembled ones to reveal systematic effects of the urban environment on native bird communities across Europe. We employed variance partitioning to quantify the relative effect of environmental parameters and the spatial position of cities on species richness. Results The species–area relationships did not differ significantly between cities and regional assemblages. Species richness of both types of communities increased towards higher latitudes, although the relationship was unimodal for regional assemblages, in contrast to cities. The increase in beta diversity with distance was on average less pronounced in cities than in regional assemblages, and was lower between individual cities than between communities of the same size randomly drawn from regional species assemblages. Moreover, average beta diversity was lower in northern cities, which are characterized by a relatively higher proportion of species from regional species pools. Main conclusions The species–area relationship and latitudinal trends are largely congruent between cities and the regional assemblages. However, city avifaunas tend to be relatively more uniform across space, revealing biotic homogenization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities.
... Although several faunal, floral and phytocoenological studies do suggest such a division (i.e. Rivas-Martínez et al., 1990 Carrascal & Lobo, 2003; Galicia et al., 2010; Rueda et al., 2010), its primacy has not been supported by other studies, including our own (Moreno Saiz et al., 1998; García Barros et al., 2002 ). Floristic studies of both endemic and non-endemic plants show that this Eurosiberian–Mediterranean boundary has not been impermeable; many taxa at different times have crossed it in both directions for reasons related to ecology and history (Hewitt, 1999; Vargas, 2003; Gó mez & Lunt, 2007). ...
Article
We analysed the distributional pattern of the vascular flora of the Iberian Peninsula and Balearic archipelago using cluster and parsimony methods to delineate a biogeographical scheme for south-western Europe and to compare the results with previous regionalizations. Additionally, we aim to identify areas of endemism. South-western Europe (Iberian Peninsula and the Balearic Islands). Pattern analysis of a chorological dataset, consisting of the occurrences of 3041 vascular plant species in each of the 50 km × 50 km UTM cells of a grid covering Iberia and the Balearic Islands, was based on cluster analysis (unweighted pair-group method using arithmetic averages; UPGMA) and parsimony analysis of endemicity (PAE). The Jaccard similarity index was used in the UPGMA, and the set of most parsimonious trees from the PAE were summarized in a 75% majority consensus tree. The UPGMA dendrogram delineated two main branches in the study region: (1) an eastern area of six sectors including the Balearic Islands plus those regions of Iberia with basic substrates, and (2) a western area with three sectors comprising the regions with acidic soils. The majority rule consensus tree of 53 most parsimonious trees from PAE showed eight main clades similarly separating eastern Iberia plus the Balearic Islands with their basic substrates, from western Iberia with its acidic and basic substrates; in addition the PAE tree showed some previously undetected chorological patterns. The use of large and inclusive datasets allows for the recognition of different spatial patterns from those obtained using a limited number of endemic or indicator species. The analyses support some floristic regions previously recognized for Iberia, but not the classic Eurosiberian–Mediterranean division, and some transition territories. Our recognition of 19 areas of endemism consisting of two or more cells and 60 consisting of one cell in south-western Europe is new.
... We test for the existence of environmental barriers in Europe around 45 N latitude during the early Pleistocene using the distribution of mammal species. The distribution of recent mammal species in Europe is known to be related to environmental conditions (Heikinheimo et al., 2007; Rueda et al., 2010). Mammal fossils are abundant and widely distributed in the early Pleistocene continental record. ...
Article
The first human settlement of Europe occurred around 1.6 Ma, although human populations were unable to cross parallel 45°N until 1.2 Ma We analyse the distribution of mammalian species during the early Pleistocene to evaluate the possible existence of a climatic or ecological barrier that prevented the northern expansion of those early colonisers. Differences in the composition of the Mediterranean and northern species pools existed during the early Pleistocene, but the differences attained were maximal during the 1.6–1.2 Ma time period. The two regional pools were more similar in species composition during the Galerian (1.2–0.8 Ma), coinciding with the expansion of early Homo northward. The two regional pools also differed in ecological structures during the early Pleistocene, although the northern pool became more similar to the southern pool during the Galerian.
... The European landscape has a long history of human modifications and exploitation. Even so, the European fauna has retained a distinct biogeographical distribution of species indicating that climate is still one of the main controlling factors (Heikinheimo et al., 2007; Rueda et al., 2010). Direct or indirect effects of future climatic warming are expected to alter the distribution of wild ungulates, increasing the range of temperate species and limiting the distribution of northern species (Mysterud and Saether, 2011). ...
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It is predicted that future climate change will have a significant impact on the distribution of large ungulates on a continental scale. At the same time, changes in human land use on a more local scale may affect their distribution and dispersal abilities, possibly confounding the effects of climate. We analyze changes in the Holocene distribution and relative abundance of Alces alces (moose) and Cervus elaphus (red deer) skeletal remains along an overlapping range boundary of these species in western Norway. As moose and red deer are adapted to different climatic conditions we would expect the distribution of finds to reflect large-scale changes in climate. In accordance with this prediction our results indicate that red deer became the predominant ungulate in this area during the mid-Holocene warm period, c. 8000–4000 cal. BP. Contrary to this, remains of moose became even less abundant in the subsequent colder period to the present. This decrease seems tied to the spread of agriculture and deforestation, indicating the importance of considering changes in land use when predicting future changes in ungulate distribution.
... Non-hierarchical clustering approaches require an a priori choice of cluster number. Evaluation methods, such as the v folds technique, are used to explore a range of potential cluster sizes to find the optimum number (Rueda et al. 2010, Vasconcelos et al. 2011). Such techniques are also appropriate for hierarchical methods. ...
Article
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The species pool concept has played a central role in the development of ecological theory for at least 60 yr. Surprisingly, there is little consensus as to how one should define the species pool, and consequently, no systematic approach exists. Because the definition of the species pool is essential to infer the processes that shape ecological communities, there is a strong incentive to develop an ecologically realistic definition of the species pool based on repeatable and transparent analytical approaches. Recently, several methodological tools have become available to summarize repeated patterns in the geographic distribution of species, phylogenetic clades and taxonomically broad lineages. Here, we present three analytical approaches that can be used to define what we term 'the biogeographic species pool': distance-based clustering analysis, network modularity analysis, and assemblage dispersion fields. The biogeographic species pool defines the pool of potential community members in a broad sense and represents a first step towards a standardized definition of the species pool for the purpose of comparative ecological, evolutionary and biogeographic studies.
... However, we also identified a similar latitudinal trend for regional species assemblages. This could be due to the higher beta diversity of Mediterranean fauna and flora (Underwood et al., 2009;Rueda et al., 2010), which is strengthened by the peninsular effect (Fraissinet & Fulgione, 2008). On the other hand, cities in southern Europe harbour a lower proportion of the regional bird community relative to more northern European cities, so this biogeographical setting may not be the sole effect generating the higher beta diversity in southern cities. ...
Article
Full-text available
AimTo compare macroecological patterns between bird communities of European cities and regional species assemblages in the surrounding landscape, and to reveal geographical trends in the urbanization of native avifauna. LocationForty-one towns and cities in continental Europe. Methods We compiled data on the species richness and community composition of urban avifauna from 41 European city breeding bird atlases, and of species assemblages comprising nine grid cells (each about 50 km × 50 km) from the EBCC Atlas of European Breeding Birds (hereafter regional assemblages). Species–area relationships (SARs), latitudinal trends in diversity and the distance decay of community similarity were compared using regression models (generalized linear models). Observed urban communities were compared with randomly assembled ones to reveal systematic effects of the urban environment on native bird communities across Europe. We employed variance partitioning to quantify the relative effect of environmental parameters and the spatial position of cities on species richness. ResultsThe species–area relationships did not differ significantly between cities and regional assemblages. Species richness of both types of communities increased towards higher latitudes, although the relationship was unimodal for regional assemblages, in contrast to cities. The increase in beta diversity with distance was on average less pronounced in cities than in regional assemblages, and was lower between individual cities than between communities of the same size randomly drawn from regional species assemblages. Moreover, average beta diversity was lower in northern cities, which are characterized by a relatively higher proportion of species from regional species pools. Main conclusionsThe species–area relationship and latitudinal trends are largely congruent between cities and the regional assemblages. However, city avifaunas tend to be relatively more uniform across space, revealing biotic homogenization. Urban communities in northern cities are more uniform as a higher proportion of bird species breeds in cities.
... The limits of biogeographical regions are based on overall differences between species compositions (Cox et al., 2001; Kreft & Jetz, 2010; Rueda et al., 2010). This means that each of these regions tends to present, for a particular group of organisms, a typical regional species pool. ...
Article
Full-text available
AimTo investigate global patterns of phylogenetic beta diversity (phylobetadiversity, PBD) components in bats (Chiroptera), testing whether the strong dispersal barriers among realms led to lineage differentiation between them and whether the flight capability of the study group created distance-decay patterns in PBD, with lower turnover rates between the closest biogeographical regions. LocationGlobal, delimited by biogeographical regions. Methods Using the global distribution of bats and a supertree available for most species, we calculated PBD using the complement of the PhyloSor index. In addition, to distinguish the relative roles of local (e.g. lineage filtering) and regional processes (e.g. speciation) in shaping broad-scale patterns of PBD, we partitioned PBD into two components: the turnover component (PBDTurn) and the phylogenetic diversity (PD) component (PBDPD). We used a null model to test whether assemblages were more or less phylogenetically dissimilar than expected by chance. We also performed a Mantel analysis to analyse the distance-decay patterns of PBD and its two components. ResultsThe most striking difference in PBD was found between the Old World and the New World. In general, the PBD pattern was determined by PBDTurn. For some adjacent regions we noticed the PBDPD component was more important, indicating that the dissimilarity was mostly due to differences in phylogenetic diversity. On the other hand, for other adjacent regions, the observed PBDTurn was higher than expected by chance and the PBDPD was lower. This demonstrates that, although these regions are relatively close in space, there are other factors driving phylogenetic differences between them (i.e. ecological factors). Main conclusionsOur results suggest that at broad scales, the PBD of bats is determined by PBDTurn. We postulate that the flight ability of bats led to low turnover rates between adjacent regions in the absence of other factors that can drive differences between them (e.g. strong environmental barriers).
... Overstorey species richness has been found to be one of the main determinants of understorey species richness in some vegetation types (Burrascano et al. 2011). At a European scale, by analysing range maps, it was demonstrated that tree pattern was a strong predictor of animal (birds, butterflies, mammals) patterns (Rueda et al. 2010). Woody units' richness may therefore be considered a good surrogate for total vascular plant richness across the Italian administrative regions. ...
Article
A key problem in quantifying biodiversity is whether it is possible to infer overall diversity using suitable data subsets. The aim of this paper, based on updated data on the native woody flora of Italy, is to evaluate the reliability of such data as a predictor of vascular plant richness at a medium scale represented by the 20 administrative regions. Woody taxa were divided in trees, shrubs and lianas. We used stepwise multiple regression and principal component analysis to analyse the correlation between environmental heterogeneity, vascular plant units (species and subspecies) richness and woody units richness. Woody flora of Italy consists of 61 families, 133 genera, 469 species, 509 units. Shrubs constitute 74% of the woody flora, trees and lianas 23 and 3% respectively. Both stepwise multiple regression analysis and two principal component analyses strongly suggest that woody units, and trees in particular, are correlated with total vascular plant richness, at all hierarchical taxonomical levels. The environmental heterogeneity has been demonstrated to be much more important than the area for the Italian regions biodiversity. Woody flora, as a surrogate of total flora, is extremely useful for rapid assessments of overall vascular plant diversity that may be exploited for monitoring purposes.
... As argued by Wallace (1876), results at the species rank, with variable numbers of regions and boundaries, indicate that regions derived from species distributions are to some extent dependent on smaller-scale and shorter-term environmental factors – contemporary climate and vegetation type – constraining the distributions of low-rank taxa. Previous results at the continental scale have also demonstrated that biogeographical units for vertebrate groups based on species are partly determined by climate and habitat (Heikinheimo et al., 2007; Rueda et al., 2010), which also suggests linkages between biological traits and patterns of regionalization at finer spatial and taxonomic scales. For example, limited dispersal ability and ectothermy probably make amphibians more susceptible to climatic conditions and generate more localized clusters of species than for birds or mammals (Rueda et al., 2010). ...
Article
Aim When dividing the world into zoogeographical regions, Alfred Russel Wallace stipulated a set of criteria by which regions should be determined, foremost the use of generic rather than species distributions. Yet, recent updates of Wallace’s scheme have not followed his reasoning, probably explain- ing in part the discrepancies found. Using a recently developed quantitative method, we evaluated the world’s zoogeographical regions following his criteria as closely as possible. Location Global. Methods We subjected presence–absence data from range maps of birds, mammals and amphibians to an innovative clustering algorithm, affinity prop- agation. We used genera as our taxonomic rank, although species and familial ranks were also assessed, to evaluate how divergence from Wallace’s criteria influences the results. We also accepted Wallace’s argument that bats and migratory birds should be excluded (although he was contradictory about the birds) and devised a procedure to determine the optimal number of regions to eliminate subjectivity in delimiting the number of regions. Results Regions attained using genera (eight for mammals and birds and six for amphibians) strongly coincided with the regions proposed by Wallace. The regions for amphibians were nearly identical to Wallace’s scheme, whereas we obtained two new ‘regions’ for mammals and two for birds that largely coin- cide with Wallace’s subregions. As argued by Wallace, there are strong reasons not to consider these as being equivalent to the six main regions. Species distri- butions generated many small regions related to contemporary climate and vegetation patterns, whereas at the familial rank regions were very broad. The differences between our generic maps and Wallace’s all involve areas which he identified as being uncertain in his regionalization. Main conclusions Despite more than 135 years of additional knowledge of distributions, the shuffling of generic concepts, and the development of com- puters and complex analytical techniques, Wallace’s zoogeographical regions appear to be no less valid than they were when he proposed them. Recent studies re-evaluating Wallace’s scheme should not be considered updates as such because they have not followed Wallace’s reasoning, and all computer- based analyses, including this one, are subject to the vagaries of the particular methods used.
... In particular, the partitioning techniques such as k-means have recently been employed in biogeographic analysis (e.g. Foukal and Thomas 2014;Rueda et al. 2010;Heikinheimo et al. 2007;Valdés et al. 2006). This technique has the advantage of avoiding the use of subjective phenom lines (Sneath and Sokal 1973), but it requires the user to specify the number of k clusters. ...
Article
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The Iberian flora has a high degree of originality (1328 endemic species, 24% of endemism), comparable to other regions in the Mediterranean Basin. The richness of Iberian endemic species is unevenly distributed; the greatest diversity is found in the main mountain ranges although the southwestern Atlantic coast and specially the Balearic Islands are rich in range-restricted endemic species. The largest number of endemic genera is found in the northwestern mountains, which might have acted as a refugium area. The Baetic System, which includes nearly half (46%) of the total Iberian endemic species, is by far the richest region of the territory. Its endemic flora is characterized by the great richness of narrow endemics and the high species turnover rate. The k-means partitioning analysis enables us to identify 11 units, generally well defined by the natural geographic features. The clusters including the northwestern mountains, the Cantabrian Mountains, the southwestern coast and especially the Balearic Islands, the Pyrenees and the Baetic System are compact and consist of a high proportion of diagnostic species, and can therefore be considered areas of endemism on a large scale. The regionalization reflects a primary longitudinal division of Iberia between a basic eastern and an acidic western region, but also partly reveals a climatic division between Eurosiberian and Mediterranean regions. Southeastern Iberia seems to be an important center of differentiation for several typically Mediterranean genera (e.g. Centaurea, Linaria, Armeria, Teucrium and Thymus), but other large genera are also highly diversified.
... Although such delineation of biogeographical regions has been based for a long time on expert knowledge of qualitative data collection the increasing availability of species-level distribution data and recent technological advances have allowed for the development of more rigorous frameworks (Kreft & Jetz, 2010). Multivariate methods, such as hierarchical clustering algorithms, have thus been successfully applied in a wide range of studies, from the spatial clustering of Europe on the basis of fauna and flora distributional patterns (Heikinheimo et al., 2007;Mateo et al., 2013;Moreno Saiz et al., 2013;Rueda et al., 2010) and the biogeographical regionalization for plants and vertebrates in sub-Saharan Africa (Linder et al., 2012) to the delineation of zoogeographical and phytogeographical regions in China (He et al., 2016;Zhang et al., 2016) to name but a few. The production of detailed cartographic outputs portraying the differentiation of vegetation into distinct homogeneous biogeographical regions remains difficult, especially where spatial heterogeneity of assemblages is associated with complex environmental gradients (Mikolajczak et al., 2015). ...
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Aim. We performed a network analysis of the spatial distribution patterns of plant species using a network approach in order to analyse the biogeographical structure of the French Mediterranean flora. Location. South of France (Languedoc-Roussillon and Provence-Alpes-Côte d'Azur). Methods. We used a network approach to identify and characterize biogeographical regions in southern France, based on a large database consisting in millions of geolocalized plant samples corresponding to more than 3, 500 plant species. This methodology is performed following five steps, from the biogeographical bipartite network construction, to the identification of biogeographical regions under the form of spatial network communities, the analysis of their interactions and the identification of clusters of plant species based on the species contribution to the biogeographical regions. Results. The French Mediterranean area is divided into eight statistically significant biogeograph-ical regions that are highly connected spatially. Mediterranean and temperate sub-networks can be distinguished. Main conclusions. The proposed network approach provides a characterization of the biogeo-graphical structure which confirms some previously recognized floristic regions in southern France, while providing more precise insights into the relationships between them. This approach sheds light on the ecological mechanisms shaping the distribution of Mediterranean biota, and exemplify why fragmented distributions are common in the Mediterranean region.
... Although such delineation of biogeographical regions has been based for a long time on expert knowledge of qualitative data collection the increasing availability of species-level distribution data and recent technological advances have allowed for the development of more rigorous frameworks (Kreft & Jetz, 2010). Multivariate methods, such as hierarchical clustering algorithms, have thus been successfully applied in a wide range of studies, from the spatial clustering of Europe on the basis of fauna and flora distributional patterns (Heikinheimo et al., 2007;Mateo et al., 2013;Moreno Saiz et al., 2013;Rueda et al., 2010) and the biogeographical regionalization for plants and vertebrates in sub-Saharan Africa (Linder et al., 2012) to the delineation of zoogeographical and phytogeographical regions in China (He et al., 2016;Zhang et al., 2016) to name but a few. The production of detailed cartographic outputs portraying the differentiation of vegetation into distinct homogeneous biogeographical regions remains difficult, especially where spatial heterogeneity of assemblages is associated with complex environmental gradients arXiv:1803.05275v1 ...
Article
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The delimitation of bioregions helps to understand historical and ecological drivers of species distribution. In this work, we performed a network analysis of the spatial distribution patterns of plants in south of France (Languedoc‐Roussillon and Provence‐Alpes‐Côte d'Azur) to analyze the biogeographical structure of the French Mediterranean flora at different scales. We used a network approach to identify and characterize biogeographical regions, based on a large database containing 2.5 million of geolocalized plant records corresponding to more than 3,500 plant species. This methodology is performed following five steps, from the biogeographical bipartite network construction to the identification of biogeographical regions under the form of spatial network communities, the analysis of their interactions, and the identification of clusters of plant species based on the species contribution to the biogeographical regions. First, we identified two sub‐networks that distinguish Mediterranean and temperate biota. Then, we separated eight statistically significant bioregions that present a complex spatial structure. Some of them are spatially well delimited and match with particular geological entities. On the other hand, fuzzy transitions arise between adjacent bioregions that share a common geological setting, but are spread along a climatic gradient. The proposed network approach illustrates the biogeographical structure of the flora in southern France and provides precise insights into the relationships between bioregions. This approach sheds light on ecological drivers shaping the distribution of Mediterranean biota: The interplay between a climatic gradient and geological substrate shapes biodiversity patterns. Finally, this work exemplifies why fragmented distributions are common in the Mediterranean region, isolating groups of species that share a similar eco‐evolutionary history.
... analyses require explicit geographical delimitations (Barve et al. 2011). The Iberian Peninsula, separated from north Africa by the Strait of Gibraltar and from the rest of Europe by the Pyrenees, has been described as an ''almost-island'' (Loidi 2017) and constitutes a unique biogeographical unit (Rueda et al. 2010;Olivero et al. 2013). The Iberian Peninsula represents a natural, neat and self-evident geographical extent for niche analyses. ...
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The ecological niches of the three Iberian Argiope species have not been studied in quantitative detail, and recently developed approaches for assessing niche overlap have rarely been applied to invertebrates. This study aimed to quantify the climatic niche differences between Argiope bruennichi (Scopoli, 1772), A. lobata (Pallas, 1772) and A. trifasciata (Forsskål, 1775) in the Iberian Peninsula. An extensive occurrence database for the three species was compiled from the literature, a citizen science project (Biodiversidad Virtual) and a social network (Flickr). Niche comparison and recursive partitioning analyses were used to compare and characterize the niches of these species using regional climatic information. The three Argiope species had different distribution patterns within the Iberian Peninsula with a clear degree of sympatry. Despite an appreciable niche overlap, the three species had significantly different climatic niches. A. bruennichi was present in colder and more humid environments, while A. lobata and A. trifasciata selected warmer, drier environments. A. trifasciata preferred areas with higher minimum temperatures than A. lobata and avoided continental environments that the two other species tolerated. Despite these differences, the Iberian Peninsula contained a broad range of suitable environments where more than one species co-occurred. Further studies are needed to explore these species relationships, particularly given the trend of ranges shifting north due to global warming. Considering both the results of this study and the increasingly xeric conditions in the Iberian Peninsula, A. lobata and A. trifasciata may benefit at the expense of a retraction of A. bruennichi.
... In Europe and Africa computer analyses of flowering plant and animal distribution data have been used to determine if there is a common biogeographical region. Common regions was found in subSaharan Africa with mammal, bird, amphibian, reptile, and vascular plants (Linder et al. 2012), but common regions were not found in Europe (Rueda et al. 2010). ...
Article
This paper presents an integrated model of the variation over a continental landmass of myxomycetes, a single-celled organism in the phylum Amoebozoa. Bark samples were collected on long traverses across Australia, and cultivated in Petri dishes by the moist chamber technique to obtain large assemblages of common species. The results of this survey and previous surveys are consistent with there being four major myxomycete assemblages: Tropical, Northern Arid, Southern Arid and Temperate. Where mapped, these species assemblage regions are consistent with the Australian phytogeographical regions. The myxomycetes differ between arid and non-arid areas; the arid areas have slightly higher productivity per wetting event, with members of the Physarales and Liceales relatively important and the Stemonitidales, Trichiales and Cribrariales less important. When the bark samples are placed in a moist culture there is a myxomycete growth cycle and then the population declines to resting phases. The population increase during a growth phase can be modelled by a linear plot of log(abundance) against species rank, where abundance is total harvested spore volume of a species. The population decline appears to be linear from two weeks after watering, declining to negligible activity 4 weeks after watering.
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The hectad (10610 km square) distributions of the 1405 native British and Irish vascular plants were classified by the SPHERIKM cluster analysis program into 20 clusters, each of which is characterised by the key species used to initiate the cluster. The clusters reflect the influence of climate, altitude, geology, and habitat on distribution patterns at this scale. Clusters with restricted distributions have high concentrations of threatened species, particularly the Medicago sativa cluster, centred on Breckland (55% of the species are threatened in Britain, although only 29% are regarded as priorities for conservation), and the Carex atrata cluster of montane species (45% threatened, and 49% conservation priority species). Some clusters are composed predominantly of species with similar European distributions whereas others are much more phytogeographically heterogeneous. A comparison with a similar analysis of the distribution of British and Irish mosses and liverworts reveals many similarities, especially between the vascular plants and the mosses, although there are many more common vascular plants than bryophytes and many more coastal species.
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The first biogeographical division of the Carpathians, the second largest mountain range in Europe, was based on qualitative observational floristic data > 100 years ago and has also been applied for the regional zoogeography. In this study, the recent availability of detailed quantitative data allowed us to perform a more powerful evaluation of the classical biogeographical regions of the area. Thus, we analysed updated distribution patterns of 137 Orthoptera species native to the Carpathian Mountains and, by using published species range maps, we compiled data on species presence or absence within 2576 cells of a 10 km × 10 km universal transverse mercator grid in the area. Pattern analysis of the data was based on non-metric multidimensional scaling and clustering using six different algorithms applied to a β sim dissimilarity matrix. The unweighted pair-group method using arithmetic averages, which gave the best performance in the analysis of species turnover, delineated four regions. Environmental variables and species richness were used in logistic regression as predictors of delineated clusters, and indicator species were identified for each of the inferred regions. The pattern can be explained, in part, by environmental variables and species richness (34.2%) and was also influenced by connections with the orthopterofauna from adjacent areas. The observed discrepancy between regionalization based on expert knowledge and the pattern revealed using quantitative data provides a warning that the biogeography of the Carpathians might also have been revised in other taxa, where only classical qualitative regionalization exists.
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A precise knowledge of the spatial distribution of taxa is essential for decision-making processes in land management and biodiversity conservation, both for present and under future global change scenarios. This is a key base for several scientific disciplines (e.g. macro-ecology, biogeography, evolutionary biology, spatial planning, or environmental impact assessment) that rely on species distribution maps. An atlas summarizing the distribution of European amphibians and reptiles with 50 × 50 km resolution maps based on ca. 85 000 grid records was published by the Societas Europaea Herpetologica (SEH) in 1997. Since then, more detailed species distribution maps covering large parts of Europe became available, while taxonomic progress has led to a plethora of taxonomic changes including new species descriptions. To account for these progresses, we compiled information from different data sources: published in books and websites, ongoing national atlases, personal data kindly provided to the SEH, the 1997 European Atlas, and the Global Biodiversity Information Facility (GBIF). Databases were homogenised, deleting all information except species names and coordinates, projected to the same coordinate system (WGS84) and transformed into a 50 × 50 km grid. The newly compiled database comprises more than 384 000 grid and locality records distributed across 40 countries. We calculated species richness maps as well as maps of Corrected Weighted Endemism and defined species distribution types (i.e. groups of species with similar distribution patterns) by hierarchical cluster analysis using Jaccard’s index as association measure. Our analysis serves as a preliminary step towards an interactive, dynamic and online distributed database system (NA2RE system) of the current spatial distribution of European amphibians and reptiles. The NA2RE system will serve as well to monitor potential temporal changes in their distributions. Grid maps of all species are made available along with this paper as a tool for decision-making and conservation-related studies and actions. We also identify taxonomic and geographic gaps of knowledge that need to be filled, and we highlight the need to add temporal and altitudinal data for all records, to allow tracking potential species distribution changes as well as detailed modelling of the impacts of land use and climate change on European amphibians and reptiles.
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We used ecological niche modelling projected as species' potential (based on the original vegetation map) and extant (based on the 2000 land use and vegetation map) distributions to analyse changes on patterns of endemism of terrestrial mammals occurring in Mexico. Based on the biogeographic method of Parsimony Analysis of Endemicity, we obtained cladograms under scenarios of species' potential distribution (t1) and extant distributions (t2). We found that the resolution of consensus cladogram in t2 was poorer, while there were more geographic synapomorphies in t1, and more autapomorphies in t2 due to a reduction of species' distributions as a consequence of deforestation. We defined a hierarchical regionalization with two regions with the cladogram of t1; a transitional zone, two subregions, five dominions, and 15 provinces. Conversely, the consensus cladogram of t2 had a basal trichotomy, and the position of the Sierra Madre Occidental changed compared with t1. In t1 and t2, the Yucatán Peninsula+Chiapas+Isthmus of Tehuantepec clade was maintained, although in t2 it was separated from the remaining areas of the country. The impact of deforestation on species distributions strongly affected the biogeographic regionalization of terrestrial mammals in Mexico.
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It is often claimed that we do not understand the forces driving the global diversity gradient. However, an extensive literature suggests that contemporary climate constrains terrestrial taxonomic richness over broad geographic extents. Here, we review the empirical literature to examine the nature and form of the relationship between climate and richness. Our goals were to document the support for the climatically based energy hypothesis, and within the constraints imposed by correlative analyses, to evaluate two versions of the hypothesis: the productivity and ambient energy hypotheses. Focusing on studies extending over 800 km, we found that measures of energy, water, or water-energy balance explain spatial variation in richness better than other climatic and non-climatic variables in 82 of 85 cases. Even when considered individually and in isolation, water/ energy variables explain on average over 60% of the variation in the richness of a wide range of plant and animal groups. Further, water variables usually represent the strongest predictors in the tropics, subtropics, and warm temperate zones, whereas energy variables (for animals) or water-energy variables (for plants) dominate in high latitudes. We conclude that the interaction between water and energy, either directly or indirectly (via plant pro- ductivity), provides a strong explanation for globally extensive plant and animal diversity gradients, but for animals there also is a latitudinal shift in the relative importance of ambient energy vs. water moving from the poles to the equator. Although contemporary climate is not the only factor influencing species richness and may not explain the diversity pattern for all taxonomic groups, it is clear that understanding water-energy dynamics is critical to future biodiversity research. Analyses that do not include water-energy variables are missing a key component for explaining broad-scale patterns of diversity.
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The use of analytical techniques to delineate biogeographical regions is becoming increasingly popular. One recent example, Heikinheimo et al. (Journal of Biogeography, 2007, 34, 1053–1064), applied the k-means clustering algorithm to define the biogeography of the European land mammal fauna. However, they used the Euclidean distance measure to cluster grid cells described by species-occurrence data, which is inappropriate. The Euclidian distance yields misleading results when applied to species-occurrence data because of the double-zero problem and the species-abundance paradox. We repeat their analysis using the Hellinger distance, a measure appropriate for species-occurrence data and which has been shown to outperform other such measures. Our results differ substantially from those presented by Heikinheimo et al. We argue that the rigorous application of appropriate statistical techniques is of crucial concern within conservation biogeography.
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Aim Both floral kingdoms and faunal regions have so far been intuitively defined. This study was conducted to compare these with an analytical regionalization based on cluster analyses in a fairly homogeneous, globally distributed group of organisms: the bats (order Chiroptera). This comparison was used to discuss the possibilities of employing clustering techniques in global biogeography.Location The study considered bat distributions world-wide.Methods Analyses were conducted both for presence/absence of genera and species, and for the number of species in each genus. Clusters distinguished at selected dissimilarity values were mapped.Results A set of c. 10 regional clusters recurred in the analyses, broadly corresponding not only to the world's accepted faunal regions and subregions, but also to the floral kingdoms and subkingdoms.Main conclusions This study is an analytical confirmation of the fact that similar global distribution patterns are to be found in different groups of organisms. Cluster analyses can be used to refine global regionalization schemes, and, with the accumulation of such data for different taxa and ecologically defined groups, shared patterns can be used to draft one common global biogeographical regionalization. At the same time, differences between the regionalization schemes derived for different groups can be used to partial out the role of dispersal abilities, body size, evolutionary age, etc., in determining global distribution patterns.
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1. The habitat templet approach depends on defining templet axes appropriate to the organism(s) of interest, predicting the traits of species associated with different parts of the templet, and testing these predictions in a range of habitats whose positions in the templet have been determined. 2. In this study of thirty-five benthic insect taxa at fifty-four tributary sites of the Taieri River on the South Island of New Zealand, we chose as the temporal axis the intensity/frequency of disturbance, defined in terms of bed movement during high discharge events. As the spatial axis, we postulated that three features would provide refugia and therefore ameliorate disturbance—percentage of the bed with low shear stress, percentage of the bed made up of large substratum particles and availability of interstitial space in the bed—from which we derived a combined multivariate refugium axis. 3. More disturbed communities contained a significantly higher percentage of individuals possessing the following traits: small size, high adult mobility, habitat generalist (each predicted to confer resilience in response to disturbance), clinger, streamlined/flattened and with two or more life stages outside the stream (each predicted to confer resistance in the face of disturbance). When analyses were performed on the percentage of taxa having particular traits, the predicted positive relationships with average bed movement were found for high adult mobility and habitat generalist traits. 4. The percentage of variance in trait scores explained by intensity of disturbance was generally higher in sites with less refugia available and lower in sites further from the headwaters. The percentage of variance explained was higher in sites recently subject to a major high discharge disturbance, suggesting that disturbances tend to strengthen the pattern of preponderance of resilience/resistance traits. 5. We mapped insect taxa onto the two-dimensional templet, following Grime et al.’s triangular terrestrial plant classification. The full variety of resistance and resilience traits were represented in insect species throughout the templet, but taxa associated with more disturbed conditions generally displayed a larger number of resilience and resistance traits, combined, than taxa associated with more stable stream beds.
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Plant functional types have been identified by the International Geosphere Biosphere Program as functionally similar basic plant types, especially trees, as needed for global ecological modeling. Based to some extent on an earlier set of pheno-physiognomically defined plant types, a Global Biome Model was produced but has not satisfied all the desired functional criteria posed by IGBP physiologists and modelers. This paper asks two questions: what are the main environmental factors which limit terrestrial plant types, especially tree types; and how many types of potential vegetation are needed to cover the world's terrestrial vegetation patterns? Based on the main environmental factors recognized, a model of world potential dominant vegetation types was produced and used to estimate the minimal number of vegetation types needed. The resulting set of 40 potential dominant vegetation types may serve as an initial basis for a structural-functionally based set of world plant functional types.
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This paper examines how to obtain species biplots in unconstrained or constrained ordination without resorting to the Euclidean distance [used in principal-component analysis (PCA) and redundancy analysis (RDA)] or the chi-square distance [preserved in correspondence analysis (CA) and canonical correspondence analysis (CCA)] which are not always appropriate for the analysis of community composition data. To achieve this goal, transformations are proposed for species data tables. They allow ecologists to use ordination methods such as PCA and RDA, which are Euclidean-based, for the analysis of community data, while circumventing the problems associated with the Euclidean distance, and avoiding CA and CCA which present problems of their own in some cases. This allows the use of the original (transformed) species data in RDA carried out to test for relationships with explanatory variables (i.e. environmental variables, or factors of a multifactorial analysis-of-variance model); ecologists can then draw biplots displaying the relationships of the species to the explanatory variables. Another application allows the use of species data in other methods of multivariate data analysis which optimize a least-squares loss function; an example is K-means partitioning.
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In genomic studies, thousands of features are collected on relatively few samples. One of the goals of these studies is to build classifiers to predict the outcome of future observations. There are three inherent steps to this process: feature selection, model selection and prediction assessment. With a focus on prediction assessment, we compare several methods for estimating the 'true' prediction error of a prediction model in the presence of feature selection. For small studies where features are selected from thousands of candidates, the resubstitution and simple split-sample estimates are seriously biased. In these small samples, leave-one-out cross-validation (LOOCV), 10-fold cross-validation (CV) and the .632+ bootstrap have the smallest bias for diagonal discriminant analysis, nearest neighbor and classification trees. LOOCV and 10-fold CV have the smallest bias for linear discriminant analysis. Additionally, LOOCV, 5- and 10-fold CV, and the .632+ bootstrap have the lowest mean square error. The .632+ bootstrap is quite biased in small sample sizes with strong signal-to-noise ratios. Differences in performance among resampling methods are reduced as the number of specimens available increase. A complete compilation of results and R code for simulations and analyses are available in Molinaro et al. (2005) (http://linus.nci.nih.gov/brb/TechReport.htm).
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The global data sets with half-degree resolution of monthly evapotranspiration and water balance were produced using simplified water balance model and published global data set. Results are compared with information obtained by previous investigations that used different data sets and analytical approaches. In general, the quantitative features of hydrologic regimes at the earth's surface are successfully simulated. The value of water balance components at the terrestrial area also agrees well with those obtained by Baumgartner and Reichel. Particularly, the good correlation (r=0.89-0.95) was obtained from the comparison results between the computed annual evapotranspiration and observed values. The comparison of the latitudinal distribution shows that the large amount of water surplus in 45°N-75°N and deficit in 10°S-30°S rather than those of Legates and Mather. On the other hand, the latitudinal distribution of annual evapotranspiration shows very similar, except in middle-high latitudes region. Preliminary results suggest possible solutions to the problem of the evaluation of national water resources using these developed data sets.
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The distribution of southern Africa's woody flora (N = 1372 species) describes a west-to-east pattern of increasing species richness, being lowest in arid to semi-arid areas and highest in mesic to humid areas. Climate accounts for 77.8% of the variation; species richness is greatest where the amount and duration of energy is optimized and moisture maximized, and decreases as the amount or duration of energy moves above or below optimal conditions, or as moisture decreases. Given the perpetual and necessary relationship between climate and plant photosynthesis, climate provides a first-order, albeit partial, explanation for the persistence of pattern (especially latitudinal and elevation gradients) in the distribution of woody plant species richness over space and time. -Author
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The paper reviews current concepts that relate particular life-history strategies to habitat characteristics. The strategy selection system is described: through effects on the fitness of individual organisms in ecological time certain combinations of adaptations for survival and reproduction are selected. These combinations arise through trade-offs between different tactics. The author's hypothesis that the habitat provides the templet on which evolution forges characteristic life-history strategies is further explored and related to similar concepts proposed by others. It is shown that in general these formulations define habitat along two axes: one being the frequency of disturbances and the other the general level adversity or harshness. When these axes and the orientation of the figures are made to correspond, the predictions from the different approaches have many similarities. Although the habitat may be defined in terms of two abiotic axes, the scaling of these in time and space must be appropriate to the temporal (e.g. generation time) and spatial (e.g. trivial range) scales of the organism being considered. It is pointed out that the pattern of trade-offs will be constrained by the available genetic variability (a reflection of the organism's phylogenetic history) and there may be more than one stable strategy for a particular environment. The templet constrains the range of life-history strategies, but it does not impose uniformity. The extent of variation may correspond to the dichotomy between high risk and low risk strategies recently explored by Ellner.
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This paper aims to explore how well numerical techniques that are commonly used at ecological scales, perform at broad biogeographical scales in detecting and explaining major distributional patterns of species within the genus Salix at the European continental scale. The occurrences of the sixty-five native Salix species in 484 grid squares comprising Europe, were recorded on the basis of distributional maps in Atlas Florae Europaeae. Distributional patterns were described numerically by means of two-way indicator species analysis and detrended correspondence analysis, and were related numerically to thirteen climatic and geographic variables recorded for each of the 484 grid squares by means of simple discriminant functions and canonical correspondence analysis. Regional climate, mainly related to summer temperature, largely accounts for the major distributional patterns of Salix in Europe. The number of species in each grid was related numerically to the same thirteen climatic and geographic variables. Area, regional climatic variability, and latitude were the most important predictors for the broad-scale diversity within Salix. An attempt was made to relate the distributional patterns to the habitat preferences and morphology of each species. The results suggest that some distributional types can be related to species occurrences in certain habitats and altitudes, possibly because of the temperature tolerances of these species.
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Evapotranspiration is a key element in climate related studies on all spatial and temporal scales. Recent studies have shown that evapotranspiration can be estimated with some degree of precision using semiempirical and analytical models. By this study, a method for the estimation of evapotranspiration using the available global data sets has been proposed.Monthly global potential evapotranspiration (PET) on 30-minute latitude-longitude grid was estimated based on the Priestley-Taylor method using global data sets including air temperature, albedo, cloudiness, elevation, which are parts of Global Ecosystems Database supplied by NOAA-EPA.
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Actual evapotranspiration (AE) is shown to be a highly significant predictor of the net annual above-ground productivity in mature terrestrial plant communities. Communities included ranged from deserts and tundra to tropical forests. It is hypothesized that the relationship of AE to productivity is due to the fact that AE measures the simultaneous availability of water and solar energy, the most important rate-limiting resources in photosynthesis. 27 references, 1 figure, 1 table.
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Aim We analyse the geographical distribution of 1911 Afrotropical bird species using indices of three simple biogeographic patterns. The first index, the frequency of species with range edges (Te), is formulated to map directly the density of species distribution limits, for comparison with the results of traditional biogeographical classification and ordination procedures, in order to show variations in the strength and breadth of transition zones. The other two indices are formulated to seek to distinguish as directly as possible between two components within these transition-zone patterns: contributions from gradients in species richness (Tg); and contributions from replacements among species (Tr). We test the ability of these indices to discover the same boundaries among Afrotropical bird faunas as one popular procedure for classifying areas (TWINSPAN) and then use them to look for geographical trends in the different kinds of transition zones.
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The distribution of 144 species of pteridophyte in sixty-five areas within Europe was analysed by minimum-variance cluster analysis and principal co-ordinates analysis. Fifteen floristic regions and twenty-one floristic elements were delimited, and the distribution and composition of these are described. Inter-relationships between the elements and regions are demonstrated, and the major floristic divisions revealed within Europe are discussed. Possible ecological and historical causes for these patterns are considered.
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Nature is the international weekly journal of science: a magazine style journal that publishes full-length research papers in all disciplines of science, as well as News and Views, reviews, news, features, commentaries, web focuses and more, covering all branches of science and how science impacts upon all aspects of society and life.
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The physical characteristics of two contrasting streams, and habitat types within these streams, are described in terms of a two-dimenisonal physical habitat templet in which disturbance frequency and the availability of spatial refugia are the temporal and spatial axes. A lower median substrate particle size and higher shear stress regime in Timber Creek were indicative of a higher disturbance frequency than in the Kyeburn. Substrate diversity was lower in Timber Creek than in the Kyeburn and indicated that the availability of refugia was lower in Timber Creek. In both streams, pools had a higher disturbance frequency and lower availability of refugia than riffles. Invertebrate species diversity, the biomass of epilithic algae and particulate organic matter and the representation of sedentary species, filter feeders and shredders were higher in the more temporally stable and spatially heterogeneous Kyeburn. The community of Timber Creek, frequently disturbed and having low refuge availability, had a high proportion of mobile and weedy species, with the highly mobile, generalist-feeding Deleatidium spp. (Ephemeroptera: Leptophlebiidae) being the most dominant organisms. -from Authors
Article
Aim The aim of this paper is to determine the optimal methods for delimiting areas of endemism for Elegia L. (Restionaceae), an endemic genus of the Cape Floristic Region. We assess two methods of scoring the data (presence–absence in regular grids, or in irregular eco-geographical regions) and three methods for locating biogeographical centres or areas of endemism, and evaluate one method for locating biotic elements. Location The Cape Floristic Region (CFR), South Africa. Methods The distribution of all 48 species of Elegia was mapped as presence–absence data on a quarter-degree grid and on broad habitat units (eco-geographical areas). Three methods to delimit areas of endemism were applied: parsimony analysis of endemism (PAE), phenetic cluster analysis, and NDM (‘endemism’). In addition, we used presence–absence clustering (‘Prabclus’) to delimit biotic elements. The performances of these methods in elucidating the geographical patterns in Elegia were compared, for both types of input data, by evaluating their efficacy in maximizing the proportion of endemics and the number of areas of endemism. Results Eco-geographical areas perform better than quarter-degree grids. The eco-geographical areas are potentially more likely to track the distribution of species. The phenetic approach performed best in terms of its ability to delimit areas of endemism in the study area. The species richness and the richness of range-restricted species are each highest in the south-western part of the CFR, decreasing to the north and east. The phytogeographical centres identified in the present study are the northern mountains, the southern mountains (inclusive of the Riviersonderend Mountains and the Cape Peninsula), the Langeberg range, the south coast, the Cape flats, and the west coast. Main conclusions This study demonstrates that (1) eco-geographical areas should be preferred over a grid overlay in the study of biogeographical patterns, (2) phenetic clustering is the most suitable analytical method for finding areas of endemism, and (3) delimiting biotic elements does not contribute to an understanding of the biogeographical pattern in Elegia. The areas of endemism in Elegia are largely similar to those described in other studies, but there are many detailed differences.
Article
Aim  To develop a systematic and generic framework for biogeographical regionalizations that can assist in reconciling different approaches and advance their application as a research tool.Location  The Australian continent is used as a case study.Methods  A review of approaches to biogeographical regionalization revealed two basic methodologies: the integrated survey method and the parametric approach. To help reconcile these different approaches, we propose a simple, four-step, flexible and generic framework. (1) Identification of the thematic foci from the three main themes (composition and evolutionary legacy; ecosystem drivers; ecosystem responses). (2) Proposal of a theory defining the purpose. (3) Application of a numeric agglomerative classification procedure that requires the user to make explicit assumptions about attributes, the number of classification groups, the spatial unit of analysis, and the metric for measuring the similarity of these units based on their attribute values. (4) Acquisition of spatial estimates of the required input attribute data. For this case study, an agglomerative classification strategy was applied using the functions within patn 3.03, a software package facilitating large-scale, multivariate pattern analysis. The input data to the classifications were continental coverages of 11 environmental variables and three indices of gross primary productivity stored at a grid cell resolution of c. 250 m. The spatial units of analysis were surface hydrological units (SHU), which were derived from a continental digital elevation model based on the contributing areas to stream segments or the area draining into a local sink where there is no organized drainage. The Minkowski series (Euclidean distance) was selected as the association measure to allow weightings to be applied to the variables.Results  Two new biogeographical regionalizations of the Australian continent were generated. The first was an environmental domain classification, based on 11 climatic, terrain and soil attributes. This regionalization can be used to address hypotheses about the relationship between environmental distance and evolutionary processes. The classification produced 151 environmental groups. The second was a classification of primary productivity regimes based on estimates of the gross primary productivity of the vegetation cover calculated from moderate resolution imaging spectroradiometer (MODIS) normalized difference vegetation index (NDVI) data and estimates of radiation. This classification produced 50 groups, and can be used to examine hypotheses concerning productivity regimes and animal life-history strategies. The productivity classification does not capture all the properties related to biological carrying capacity, process rates and differences in the characteristic biodiversity of ecosystems. Some of these ecologically significant properties are captured by the environmental domain classification.Main conclusions  Our framework can be applied to all terrestrial regions, and the necessary data for the analyses presented here are now available at global scales. As the spatial predictions generated by the classifications can be tested by comparison with independent data, the approach facilitates exploratory analysis and further hypothesis generation. Integration of the three themes in our framework will contribute to a more comprehensive approach to biogeography.
Article
Aim To identify floristic elements in the European flora by an analysis of the distributions of species and species groups mapped in Atlas Florae Europaeae. Location Europe, as defined by Flora Europaea. Methods We analysed the native distributions of 2762 species and 33 species’ aggregates from 79 families, which represent c. 20% of the European flora. The distributional data base, derived from Atlas Florae Europaeae, includes records from 4420 50 × 50-km UTM grid squares. We classified species into floristic elements by a three-stage clustering procedure, which consisted of: (1) constructing a dissimilarity hierarchy by complete linkage clustering, using a distance measure based on Jaccard’s coefficient; (2) cutting the hierarchical tree at the 0.95 level to create initial clusters, and forcing small clusters to link with larger ones until the sum of within-group pairwise distances exceeded a threshold value; and (3) checking the allocation of all species to the redefined clusters and reassigning species if appropriate, using the cosine of the angle between the species and cluster centres to measure the similarity of species to clusters. Results The clustering procedure classified 2793 taxa into 18 floristic elements, which included between 66 and 289 taxa; two species had unique, non-overlapping distributions and could not be classified. Main conclusions The analysis highlights the floristic diversity of the mountains of central and southern Europe, and of the Mediterranean region. The floristic elements of northern latitudes and the temperate lowlands tend to be composed of wide-ranging species and include only a low proportion of European endemics. The montane elements, including those centred on montane areas in the Mediterranean region, are composed predominantly of perennial species and include high or very high proportions of European endemics. Classifications that recognize one ‘Alpine’ and one ‘Mediterranean’ biogeographical zone in Europe fail to reflect this floristic diversity.
Article
The latitudinal diversity gradient is the largest scale, and longest known, pattern in ecology. We examined the applicability of three versions of the energy hypothesis, the habitat heterogeneity hypothesis, and historical contingency to the gradient of terrestrial birds. The productivity version of the energy hypothesis, tested using actual evapotrans-piration, a water–energy variable closely associated with plant productivity, accounted for 72% of the variance in a model of global extent. An historical contingency model based on biogeographic region explained 58% of the variance. A combined climate–region model accounted for 78% of the variance, but 52% comprised the overlap between these effects. This suggests that further resolution of contemporary vs. historical processes at the global level will require the inclusion of phylogenetic information. Regional-extent regression models suggest a latitudinal shift in constraints on diversity; measures of ambient energy (potential evapotranspiration and mean annual temperature) best predicted the diversity gradient at high latitudes, whereas water-related variables (actual evapotranspiration and annual rainfall) best predicted richness in low-latitude, high-energy regions. Intraregional spatial autocorrelation analysis confirmed that climatic models ad-equately describe geographic richness patterns at all but the smallest spatial scales resolved by the analysis. We conclude that the ''water–energy dynamics'' hypothesis, originally developed for plant diversity gradients, offers a parsimonious explanation for bird diversity patterns as well, presumably operating via plant productivity. However, more refined tests of historical factors are needed to fully resolve their influences on the gradient.
Article
Aims To describe the pattern of mean body size of native mammals in Europe, and to investigate its relationships with environmental predictors related to four hypotheses: (1) dispersal; (2) heat conservation; (3) heat dissipation; and (4) resource availability. Location Continental western Europe and Great Britain. Methods We used range maps to estimate the mean body size (average log mass) of mammals in 386 cells of 12,100 km2 each. Environmental conditions in each cell were quantified using nine historical, climatic and primary production variables. We attempted to tease apart the effects of these variables using correlation, multiple regression and spatial autocorrelation analyses. Results In the part of the continent covered by ice during the Pleistocene, body mass decreases southwards, and annual average temperature explains 73% of the variance in body size, consistent with the heat-conservation hypothesis. However, in warmer, non-glaciated areas the best predictor is an estimate of seasonality in plant production, but it explains only 18% of the variance. Carnivores, omnivores and herbivores show similar relationships, but the pattern for herbivores is substantially weaker than for the other groups. Main conclusions Overall, the relationship between mean body size and temperature is non-linear, being strong in cold environments but virtually disappearing above a temperature threshold.
Article
The length of time land has been available for colonization by plants and other organisms could provide a partial explanation of the contemporary richness gradients of trees. According to this hypothesis, increasing times of land availability entail higher chances of recolonization, which eventually have positive effects on tree richness. To test this, we generated a dataset of the Holarctic trees and evaluated the influence of cell age, a measure of the time since an area became free of ice, on the observed tree richness gradients. We found that cell age is associated with richness in both Europe and North America, after controlling for contemporary climate patterns, suggesting that the historical pattern of glacial retreat in response to post-Pleistocene global warming has left a signal still detectable after at least 14 000 yr. The results were consistent using a range of modelling approaches or whether Europe and North America were analyzed separately or in concert. We conclude that, although secondary to contemporary climate, the post-glacial recolonization hypothesis is broadly supported at temperate latitudes.
Article
Aim To predict French Scarabaeidae dung beetle species richness distribution, and to determine the possible underlying causal factors. Location The entire French territory has been studied by dividing it into 301 grid cells of 0.72 × 0.36 degrees. Method Species richness distribution was predicted using generalized linear models to relate the number of species with spatial, topographic and climate variables in grid squares previously identified as well sampled (n = 66). The predictive function includes the curvilinear relationship between variables, interaction terms and the significant third-degree polynomial terms of latitude and longitude. The final model was validated by a jack-knife procedure. The underlying causal factors were investigated by partial regression analysis, decomposing the variation in species richness among spatial, topographic and climate type variables. Results The final model accounts for 86.2% of total deviance, with a mean jack-knife predictive error of 17.7%. The species richness map obtained highlights the Mediterranean as the region richest in species, and the less well-explored south-western region as also being species-rich. The largest fraction of variability (38%) in the number of species is accounted for by the combined effect of the three groups of explanatory variables. The spatially structured climate component explains 21% of variation, while the pure climate and pure spatial components explain 14% and 11%, respectively. The effect of topography was negligible. Conclusions Delimiting the adequately inventoried areas and elaborating forecasting models using simple environmental variables can rapidly produce an estimate of the species richness distribution. Scarabaeidae species richness distribution seems to be mainly influenced by temperature. Minimum mean temperature is the most influential variable on a local scale, while maximum and mean temperature are the most important spatially structured variables. We suggest that species richness variation is mainly conditioned by the failure of many species to go beyond determined temperature range limits.
Article
Aim To use Monmonier’s algorithm, a spatially explicit technique, to elucidate positions of biogeographical boundaries in the northern Neotropics. Location The northern Neotropics (Isthmus of Tehuantepec, Mexico, south to trans-Andean Colombia). Methods We compiled avifaunal lists for 36 forested sites from the literature, museum records, field notes, and web sources. We constructed distance matrices as inverse Jaccard’s similarity, used Monmonier’s algorithm to place biogeographical boundaries, and created bootstrap matrices to determine the relative strength of boundaries. Results Biogeographical boundaries with the best support separated lowland (< 1000 m) and montane sites and areas with a distinct historical background, such as seaways, suture zones, volcanic peaks, and former islands. Main conclusions Monmonier’s algorithm used with distance (dissimilarity) data effectively identified biogeographical boundaries consistent with historical processes and with past research. Montane sites tended to be circumscribed by sharp boundaries, emphasizing their isolation and higher endemism. Lowland sites, by contrast, tended to be homogeneous, suggesting that dispersal has played a much larger role at low elevations. Former seaways, as in the Nicaraguan Depression and extended Bay of Urabá, yielded boundaries, but typically for highland avifauna only. In addition to providing a rigorous (bootstrap support) and heuristic (direct mapping) means of locating biotic boundaries, Monmonier’s algorithm can be a valuable tool for conservation planning.
Article
Aim To produce a statistical stratification of the European environment, suitable for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent, and to provide strata for modelling exercises and reporting. Location A ‘Greater European Window’ with the following boundaries: 11° W, 32° E, 34° N, 72° N. Methods Twenty of the most relevant available environmental variables were selected, based on experience from previous studies. Principal components analysis (PCA) was used to explain 88% of the variation into three dimensions, which were subsequently clustered using an ISODATA clustering routine. The mean first principal component values of the classification variables were used to aggregate the strata into Environmental Zones and to provide a basis for consistent nomenclature. Results The Environmental Stratification of Europe (EnS) consists of 84 strata, which have been aggregated into 13 Environmental Zones. The stratification has a 1 km2 resolution. Aggregations of the strata have been compared to other European classifications using the Kappa statistic, and show ‘good’ comparisons. The individual strata have been described using data from available environmental databases. The EnS is available for noncommercial use by applying to the corresponding author. Main conclusions The Environmental Stratification of Europe has been constructed using tried and tested statistical procedures. It forms an appropriate stratification for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent and for the provision of strata for modelling exercises and reporting at the European scale.
Article
Aim  To produce a spatial clustering of Europe on the basis of species occurrence data for the land mammal fauna.Location  Europe defined by the following boundaries: 11°W, 32°E, 71°N, 35°N.Methods  Presence/absence records of mammal species collected by the Societas Europaea Mammalogica with a resolution of 50 × 50 km were used in the analysis. After pre-processing, the data provide information on 124 species in 2183 grid cells. The data were clustered using the k-means and probabilistic expectation maximization (EM) clustering algorithms. The resulting geographical pattern of clusters was compared against climate variables and against an environmental stratification of Europe based on climate, geomorphology and soil characteristics (EnS).Results  The mammalian presence/absence data divide naturally into clusters, which are highly connected spatially and most strongly determined by the small mammals with the highest grid cell incidence. The clusters reflect major physiographic and environmental features and differ significantly in the values of basic climate variables. The geographical pattern is a fair match for the EnS stratification and is robust between non-overlapping subsets of the data, such as trophic groups.Main conclusions  The pattern of clusters is regarded as reflecting the spatial expression of biologically distinct, metacommunity-like entities influenced by deterministic forces ultimately related to the physical environment. Small mammals give the most spatially coherent clusters of any subgroup, while large mammals show stronger relationships to climate variables. The spatial pattern is mainly due to small mammals with high grid cell incidence and is robust to noise from other subsets. The results support the use of spatially resolved environmental reconstructions based on fossil mammal data, especially when based on species with the highest incidence.
Article
The spatial heterogeneity of populations and communities plays a central role in many ecological theories, for instance the theories of succession, adaptation, maintenance of species diversity, community stability, competition, predator-prey interactions, parasitism, epidemics and other natural catastrophes, ergoclines, and so on. This paper will review how the spatial structure of biological populations and communities can be studied. We first demonstrate that many of the basic statistical methods used in ecological studies are impaired by autocorrelated data. Most if not all environmental data fall in this category. We will look briefly at ways of performing valid statistical tests in the presence of spatial autocorrelation. Methods now available for analysing the spatial structure of biological populations are described, and illustrated by vegetation data. These include various methods to test for the presence of spatial autocorrelation in the data: univariate methods (all-directional and two-dimensional spatial correlograms, and two-dimensional spectral analysis), and the multivariate Mantel test and Mantel correlogram; other descriptive methods of spatial structure: the univariate variogram, and the multivariate methods of clustering with spatial contiguity constraint; the partial Mantel test, presented here as a way of studying causal models that include space as an explanatory variable; and finally, various methods for mapping ecological variables and producing either univariate maps (interpolation, trend surface analysis, kriging) or maps of truly multivariate data (produced by constrained clustering). A table shows the methods classified in terms of the ecological questions they allow to resolve. Reference is made to available computer programs.
Article
We used published data of individuals moving among habitat patches to answer questions pertaining to frequency of interpatch movements and subsequent effects on population dynamics. A review of 415 published articles produced data for 89 species-system combinations where movements were recorded in sufficient detail to include in our analysis. The percentage of individuals in a population that moved among habitat patches ranged from 0.00 to 93.00%, with a mean of 16.84%. Scaling this statistic by generation time yielded a mean movement rate of 15.45 3.27% per generation. The relatively low movement rates suggest that subpopulations, except those of invertebrates, should not be highly integrated. Less than half of the empirical studies reported on the population effects of interpatch movement. Of these, thirty-three studies yielded population effects on 34 individual species in 45 species-systems. They reported movement having a positive effect 28 times, a negative effect twice and a neutral effect 14 times. Despite its importance, relatively few studies document rates of interpatch movement and far fewer determine population level consequences of these movements. This deficiency limits our ability to understand the dynamics of spatially structured populations and apply that knowledge to conservation efforts.
Article
We used regression analyses to examine the relationships between reptile and amphibian species richness in Europe and 11 environmental variables related to five hypotheses for geographical patterns of species richness: (1) productivity; (2) ambient energy; (3) water–energy balance, (4) habitat heterogeneity; and (5) climatic variability. For reptiles, annual potential evapotranspiration (PET), a measure of the amount of atmospheric energy, explained 71% of the variance, with variability in log elevation explaining an additional 6%. For amphibians, annual actual evapotranspiration (AET), a measure of the joint availability of energy and water in the environment, and the global vegetation index, an estimate of plant biomass generated through satellite remote sensing, both described similar proportions of the variance (61% and 60%, respectively) and had partially independent effects on richness as indicated by multiple regression. The two-factor environmental models successfully removed most of the statistically detectable spatial autocorrelation in the richness data of both groups. Our results are consistent with reptile and amphibian environmental requirements, where the former depend strongly on solar energy and the latter require both warmth and moisture for reproduction. We conclude that ambient energy explains the reptile richness pattern, whereas for amphibians a combination of water–energy balance and productivity best explain the pattern.
Book
This is the third edition of the premier professional reference on the subject of data mining, expanding and updating the previous market leading edition. This was the first (and is still the best and most popular) of its kind. Combines sound theory with truly practical applications to prepare students for real-world challenges in data mining. Like the first and second editions, Data Mining: Concepts and Techniques, 3rd Edition equips professionals with a sound understanding of data mining principles and teaches proven methods for knowledge discovery in large corporate databases. The first and second editions also established itself as the market leader for courses in data mining, data analytics, and knowledge discovery. Revisions incorporate input from instructors, changes in the field, and new and important topics such as data warehouse and data cube technology, mining stream data, mining social networks, and mining spatial, multimedia and other complex data. This book begins with a conceptual introduction followed by a comprehensive and state-of-the-art coverage of concepts and techniques. Each chapter is a stand-alone guide to a critical topic, presenting proven algorithms and sound implementations ready to be used directly or with strategic modification against live data. Wherever possible, the authors raise and answer questions of utility, feasibility, optimization, and scalability. relational data. -- A comprehensive, practical look at the concepts and techniques you need to get the most out of real business data. -- Updates that incorporate input from readers, changes in the field, and more material on statistics and machine learning, -- Scores of algorithms and implementation examples, all in easily understood pseudo-code and suitable for use in real-world, large-scale data mining projects. -- Complete classroom support for instructors as well as bonus content available at the companion website. A comprehensive and practical look at the concepts and techniques you need in the area of data mining and knowledge discovery.
Article
Aim To produce a statistical stratification of the European environment, suitable for stratified random sampling of ecological resources, the selection of sites for representative studies across the continent, and to provide strata for modelling exercises and reporting.
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