The partitioning of Africa: statistically defined biogeographical regions in sub‐Saharan Africa

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.     

Reconciling approaches to biogeographical regionalization: a systematic and generic framework examined with a case study of the Australian continent

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.     

A framework for delineating biogeographical regions based on species distributions

Aim Biogeographical regionalizations, such as zoogeographical regions, floristic kingdoms or ecoregions, represent categorizations central to many basic and applied questions in biogeography, ecology, evolution and conservation. Traditionally established by experts based on qualitative evidence, the lack of transparency and quantitative support has set constraints on their utility. The recent availability of global species range maps, novel multivariate techniques and enhanced computational power now enable a quantitative scrutiny and extension of biogeographical regionalizations that will facilitate new and more rigorous uses. In this paper we develop and illustrate a methodological roadmap for species‐level biogeographical regionalizations at the global scale and apply it to mammals. Location Global. Methods We explore the relative usefulness of ordination and clustering methods and validation techniques. The performance of nine different clustering algorithms is tested at different taxonomic levels. The grain of regionalization (i.e. the number of clusters) will usually be driven by the purpose of the study, but we present several approaches that provide guidance. Results Non‐metric multidimensional scaling offers a valuable first step in identifying and illustrating biogeographical transition zones. For the clustering of regions, the nine different hierarchical clustering methods varied greatly in utility, with UPGMA (unweighted pair‐group method using arithmetic averages) agglomerative hierarchical clustering having consistently the best performance. The UPGMA approach allows a tree‐like phenetic representation of the relative distances of regions and can be applied at different levels of taxonomic resolution. We find that the new quantitative biogeographical regions exhibit both striking similarities to and differences from the classic primary geographical divisions of the world’s biota. Specifically, our results provide evidence that the Sahara, northern Africa, the Arabian Peninsula and parts of the Middle East should be regarded as part of the Afrotropics. Further, the position of the New Guinean continental shelf, Lydekker’s Line, is supported as an appropriate border to separate the Oriental and Australian regions. Main conclusions We propose that this sort of new, quantitative delineation and relationship assessment across taxonomic and geographical grains is likely to offer opportunities for more rigorous inference in historical and ecological biogeography and conservation.     

Regionalization of the avifauna of the Baja California Peninsula, Mexico: a parsimony analysis of endemicity and distributional modelling approach

Aim To analyse the distributional patterns of the Baja California Peninsula's resident avifauna, and to generate a regionalization based on a method that uses a parsimony analysis (parsimony analysis of endemicity, PAE) of point data and modelled potential distributions. Location The Baja California Peninsula, Mexico. Methods A data base was constructed containing records of 113 species of resident terrestrial birds present in the Baja California Peninsula. Records and localities were obtained from the literature and from specimens housed in scientific collections world‐wide. Raw data points and potential distribution maps obtained using the software Genetic Algorithms for Rule‐set Prediction (GARP), were analysed with PAE. Results The data base consisted of 4164 unique records (only one combination of species/locality) belonging to 113 terrestrial resident bird species, in a total of 809 localities. From the point distribution matrix, the analysis generated 500 equally parsimonious trees, from which a strict consensus cladogram with 967 steps was obtained. The cladogram shows a basal polytomy and some geographical correspondence of a few resolved groups obtained in the analysis. These results do not allow the recognition of areas defined by avifaunistic associations. From the potential distribution matrix, the analysis generated 501 equally parsimonious trees, and a strict consensus cladogram of 516 steps was obtained. The cladogram shows a higher resolution because of the number of resolved groups with better geographical correspondence and therefore regions are well‐defined. Main conclusions The correspondence of some groupings of species suggest their validity as areas with biogeographical (historical and/or ecological) meaning. This regionalization in the Baja California avifauna seems to be consistent with previous regionalizations for other groups. Hence, PAE is a useful tool for area categorization if reliable point records and prediction tools are available. Our results suggest that the geographical definition is much better using potential data generated by GARP, particularly when they are contrasted with the results from point data. Thus, this is an excellent alternative for developing biogeographical studies, as well as for improving the use of data from scientific collections and other sources of biodiversity information.     

中国自然保护综合地理区划

综合自然地理区划可以为生物多样性保护和自然保护区体系建设等提供基础资料,为区域生物多样性政策的制定提供科学依据。随着我国自然保护区事业的不断发展,自然保护综合地理区划成为自然地理区划的重要研究内容之一。虽然我国自然保护区体系已经初步建立,但仍然没有一个同时依据生物因素和非生物因素分布规律,确定的自然保护综合地理区划方案,为生物多样性保护和自然保护区建设服务。利用GIS技术和PC-ORD4.0软件中的双向指示种分析(TWINSPAN)方法,将中国版图划分出3489个基本地理单元,并对这些地理单元进行了数量化分类。然后,根据这个分类结果,参考植被区划和地貌区划等,提出了中国自然保护综合地理区划方案。中国自然保护综合地理区划方案包括了8个自然保护地理大区、37个自然保护地理地区和117个自然保护地理亚地区。该区划具有以下特点:(1)利用TWINSPAN的数量分类方法进行地理区划的探索是区划方法上的创新,为自然地理区划的研究提供了新的研究途径。(2)选取的数量化指标是在结合已有专项区划资料提出的,有助于避免动植物分布指标的人为选择偏差,可以综合反映区域自然地理特征,对生物多样性就地保护和自然保护区体系建设具有较好的指导作用。(3)量化分析保证了地理区划的客观性,同时定性分析避免了量化分析过程中的误差,使区划结果更准确。     

Methods for comparison of biotic regionalizations: the case of pteridophytes in the Iberian Peninsula

We made several regionalizations of the Iberian Peninsula based on the distributions of the pteridophyte flora to see whether the regionalization depended on the type and scale of lattice or the similarity index considered. We used five types of lattice in which the scale also varied: river basins, mountains and plains, natural regions, physiographic and geological regions, and administrative provinces; and two similarity indices: those of Jaccard and of Baroni-Urbani and Buser. The regionalizations varied according to the type of lattice, the grain size, and the similarity index used. To assess the different regionalizations we used four methods: 1) the coefficient of variation of the size of sites in each lattice. 2) the bestblock method, which considers as the hest lattice that which maximizes the number of matches between presences over all pairwise site comparisons. 3) the Mantel test, to assess the statistical significance of the regionalizations obtained, and 4) mapability, which considers the most contiguous regionalization to be the best. The best regionalization according to our four criteria was that based on administrative provinces and Jaccard's index. This yielded a small central region and three large regions: northern, western, and eastern.     

Biogeography at the limits of life: Do extremophilic microbial communities show biogeographical regionalization?

Aim

Biogeographical regions are the fundamental geographical units for grouping Earth's biodiversity. Biogeographical regionalization has been demonstrated for many higher taxa, such as terrestrial plants and vertebrates, but not in microbial communities. Therefore, we sought to test empirically whether microbial communities, or taxa, show patterns consistent with biogeographical regionalization.

Location

Within halite (NaCl) crystals from coastal solar salterns of western Europe, the Mediterranean and east Africa.

Time period

Modern (2006–2013).

Major taxa studied

Archaea.

Methods

Using high‐throughput Illumina amplicon sequencing, we generated the most high‐resolution characterization of halite‐associated archaeal communities to date, using samples from 17 locations. We grouped communities into biogeographical clusters based on community turnover to test whether these communities show biogeographical regionalization. To examine whether individual taxa, rather than communities, show biogeographical patterns, we also tested whether the relative abundance of individual genera may be indicative of a community's biogeographical origins using machine learning methods, specifically random forest classification.

Results

We found that the rate of community turnover was greatest over subregional spatial scales (< 500 km), whereas at regional spatial scales the turnover was independent of geographical distance. Biogeographical clusters of communities were either not statistically robust or lacked spatial coherence, inconsistent with biogeographical regionalization. However, we identified several archaeal genera that were good indicators of biogeographical origin, providing classification error rates of < 10%.

Main conclusions

Overall, our results provide little support for the concept of biogeographical regions in these extremophilic microbial communities, despite the fact that some taxa do show biogeographical patterns. We suggest that variable dispersal ability among the halite‐associated Archaea may disrupt biogeographical patterns at the community level, preventing the formation of biogeographical regions. This means that the processes that lead to the formation of biogeographical regions operate differentially on individual microbial taxa rather than on entire communities.     

Historical biogeographical patterns in continental Australia: congruence among areas of endemism of two major clades of eucalypts

Published phylogenies of two eucalypt clades, red bloodwoods Corymbia subgenus Corymbia and eudesmids Eucalyptus subgenus Eudesmia (Myrtaceae), were combined for an analysis of historical biogeographical area relationships within continental Australia. The method of paralogy‐free subtree analysis was used to eliminate geographical paralogy; the paralogy‐free subtrees were coded as characters for parsimony analysis to find the minimal and area cladogram, which proved to be informative of a continent‐wide pattern. The eucalypt fossil record and molecular dating studies allow an interpretation of the biogeographical history in terms of major vicariance events that date from the early Paleogene. The summary area cladogram shows the wet jarrah forest region of South‐West Western Australia, a region of high endemism, as the earliest to differentiate from all other areas, isolated by marine inundation across southern Australia and climatic cooling in the Late Eocene–Early Oligocene. From about this time, regionalization continued, with warmer conditions and monsoonal climate developing in central and northern Australia, and cooling in the south‐east. Northern and eastern humid and semi‐humid areas were related as a track, but with increased aridity in the interior of the continent, the monsoonal climate contracted northwards. The Australian Monsoon Tropics (AMT: Kimberley, Top End, Arnhem, Cape York and inland north‐east Queensland) differentiated from eastern areas (Queensland wet tropics to McPherson–Macleay). Our results also show all arid and semi‐arid regions as related, suggestive of a historically cohesive interior biota rather than repeated colonizations of the interior from the periphery of the continent. Climate largely differentiates hot arid areas in the north (Pilbara, Northern and Central deserts) from arid areas in the south (south‐west interzone, Wheatbelt, Goldfields and Great Victoria Desert). © The Willi Hennig Society 2010.     

Biogeographic regions of North American mammals based on endemism

Since the 19th Century, two regions have been recognized for North American mammals, which overlap in Mexico. The Nearctic region corresponds to the northern areas and the Neotropical region corresponds to the southern ones. There are no recent regionalizations for these regions under the criterion of endemism. In the present study, we integrate two methods to regionalize North America, using species distribution models of mammals: endemicity analysis (EA) and parsimony analysis of endemicity (PAE). EA was used to obtain areas of endemism and PAE was used to hierarchize them. We found 76 consensus areas from 329 sets classified in 146 cladograms, and the strict consensus cladogram shows a basal polytomy with 14 areas and 16 clades. The final regionalization recognizes two regions (Nearctic and Neotropical) and a transition zone (Mexican Transition Zone), six subregions (Canadian, Alleghanian, Californian‐Rocky Mountain, Pacific Central America, Mexican Gulf‐Central America, and Central America), two dominions (Californian and Rocky Mountain), and 23 provinces. Our analysis show that North America is probably more complex than previously assumed. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110 , 485–499.     

Biogeographical regions of the Iberian peninsula based on freshwater fish and amphibian distributions

We classified the main Iberian river basins based on the presence and absence of freshwater fishes and amphibians. For both taxonomic groups we analysed three data sets; 1) endemic species only, to search for biotic boundaries related to historical events, 2) indigenous species, which include endemic ones, to search for biotic boundaries related to ecological factors, 3) indigenous and well-established introduced species, to assess the influence of man in the current biogeographical patterns of fishes and amphibians. We used both phenetic and cladistic methods, followed by a consensus analysis to provide an overall biogeographical pattern. Based on all fish distributions, the Iberian Peninsula is divided into three biogeographical regions: Cantabrian, Atlantic and Mediterranean, No boundary existed between the Cantabrian and Atlantic regions when only indigenous fish species were considered. This suggests that this boundary has been induced by man, probably through the differential introduction of fish species into reservoirs at one or other side of the boundary. Run-off and the size of the river basins are the environmental factors that distinguished the Atlantic and Mediterranean regions. However, regionalization based only on endemic freshwater fishes showed a latitudinal pattern that agrees with the paleogeographic events of the Upper Oligocene-Lower Miocene period. By contrast, one northern and one southern region were distinguished based on all amphibian distributions and on indigenous amphibians only, which suggests that human activity has not significantly affected the overall biogeographical pattern of amphibians in the Iberian Peninsula. Interannual predictability of precipitation best accounts for this regionalization. Based on endemic amphibians, the Iberian Peninsula is divided into three regions that closely resemble the three separate land areas of the Upper Eocene-Lower Oligocene period. The consensus between the biogeographical regions based on fishes and amphibians yields five pairs of basins. Geological origin of the basins seems to better explain the consensus between the biogeographical patterns of fishes and amphibians, whereas ecological factors probably contribute to the differences between them.     

Biogeography of helminth parasites of freshwater fishes in Mexico: the search for patterns and processes

Aim To uncover and describe patterns of biogeography of helminth parasites in freshwater fishes of Mexico, and to understand processes that determine them. Three predictions about host‐specificity, faunal exchange in transitional areas, and the biogeographical ‘core’ fauna, are evaluated, all of which follow from a fundamental hypothesis: that parasites show characteristic associations with particular host clades. The parasite fauna of the southern Mexican cichlids and of the fishes of the Mesa Central are examined as case studies that reflect Neotropical and Nearctic historical influences. Location The region covered in this study includes most of Mexico, with emphasis on six biogeographical areas: the Yucatán Peninsula (area 1), the Grijalva‐Usumacinta drainage (area 2), the Papaloapan and Pánuco drainages (area 3), the Balsas drainage (area 4), the Lerma‐Santiago drainage (area 5), and the Bravo drainage (area 6). Methods A parasite data base containing all the records of helminth parasites of freshwater fishes of Mexico was filtered to extract records of adult helminth parasites in freshwater fishes from the six biogeographical areas designated in this study. Jaccard's similarity coefficients and cluster analyses (using upgma ) were used to analyse the extent of faunal similarity between the designated biogeographical areas and between host (fish) families. Taxonomic composition of parasite assemblages in different host groups was also qualitatively compared from summary data. These data were used to test the three main predictions. Results To date, 184 species of helminths (120 as adults) have been recorded from 127 freshwater fishes in Mexico (almost 33% of the total fish diversity of Mexico). Of these parasite species, 69 are digenetic flukes, 51 are nematodes, 33 are monogeneans, 25 are tapeworms, and only six are acanthocephalans. The data and analyses from the six biogeographical areas corroborate the predictions that: (1) the adult parasite fauna is largely circumscribed by higher levels of monophyletic host taxa (families, orders, etc.), and that this pattern is independent of areas; (2) areas within a certain biogeographical region, and consequently with similar fish composition (e.g. areas 1, 2 and 3) have more similar parasite faunas compared to areas with less similar fish faunal composition; and (3) ‘core’ parasite faunas persist to some extent in transitional areas with limited host‐sharing. Main conclusions Helminth biodiversity in Mexican freshwater fishes is determined by the historical and contemporary biogeography of their hosts. Host lineage specificity, mainly at the level of the host family, appears to be an important factor in the distribution of the parasites. Most fish families (Characidae, Cichlidae, Pimelodidae, Ictaluridae, Catsotomidae, Goodeidae, Atherinidae) possess their own characteristic ‘core’ helminth fauna, with limited host‐sharing in transitional areas (e.g. areas 3 and 4). A re‐evaluation of the helminth fauna of Mexican cichlids questions the hypothesis that cichlids lost parasites during the colonization of Mexico from South America. The evidence supports the idea that they acquired new parasites by host switching, possibly from marine or brackish‐water percomorphs. In contrast, the parasite fauna of the Mesa Central remains enigmatic and reflects the region's history of endemicity with historical marine and Nearctic connections.     

Parsimony analysis of endemicity (PAE) of Mexican terrestrial mammals at different area units: when size matters

Abstract Aim Parsimony analysis of endemicity (PAE) is a biogeographical method that uses a parsimony algorithm to obtain an area cladogram, based on taxa inhabiting the study areas. We compare its performance at different geographical units (½° and 1° quadrats, ecoregions and biogeographical provinces) to analyse distributional patterns of Mexican terrestrial mammals, in order to assess the importance of the size of area units. Location The area analysed corresponds to Mexico. Methods Parsimony analyses were based on 56,859 collection records, corresponding to 703 genera, species and subspecies. Four data matrices were constructed for: (1) 716 quadrats of ½° latitude × ½° longitude, (2) 230 quadrats of 1° latitude × 1° longitude, (3) forty‐five ecoregions and (4) fourteen biogeographical provinces. Results For the ½° quadrat matrix, we obtained six cladograms of 17,138 steps. For the 1° quadrat matrix, we obtained five cladograms (strict consensus with 9394 steps). For the matrix of ecoregions, we obtained twelve cladograms (strict consensus cladogram with 3009 steps). For the provinces, we obtained a single cladogram with 1603 steps. Main conclusions The best results were obtained with natural areas instead of quadrats. There seems to exist a trend to decrease the absolute number of steps and an increase in the absolute and relative number of synapomorphies as the size of the area units decreases, although this does not necessarily occur for the number of cladograms.     

The biogeography of seaweeds in Southeast Alaska

Aim This article reviews the history of seaweed collections in Southeast Alaska from the early Russian explorers to contemporary efforts. It summarizes other studies of Southeast Alaskan seaweeds from a biogeographical perspective, and compares the known seaweed flora near three population centres (Ketchikan, Sitka and Juneau) with those of other regions within Alaska, and with nearby regions. Location For this article, Southeast Alaska includes all inside and outside waters of the Alexander Archipelago from Dixon Entrance (54°40′ N, 133°00′ W) to Icy Point (58°23′10″ N, 137°04′20″ W). Methods The literature on seaweeds occurring in Southeast Alaska is reviewed from a biogeographical perspective, and herbarium records for Southeast Alaska from the Alaska Seaweed Database project are used to provide an overview of the biogeography of the area. Records for the population centres of Ketchikan, Sitka and Juneau are compared with records from other areas within Alaska and with nearby regions to determine floristic similarities. Results Southeast Alaska has the most diverse seaweed flora of any region of Alaska. A list of species known to occur in Southeast Alaska is appended (in Supplementary Material) and includes their reported occurrences in three population centres (Juneau, Ketchikan and Sitka). Recognition of at least three distinct biogeographical areas associated with these three centres is supported by a comparison of their floras with those of other regions in the North Pacific. A close relationship of some species with conspecifics in the north‐west Atlantic is also noted. In contrast, ecological, physiological and genetic differentiation of Southeast Alaskan seaweeds from conspecifics in Washington State or even from different areas of Southeast Alaska are documented. A ShoreZone coastal habitat system, which is being implemented to inventory and map the entire shoreline of Southeast Alaska, is defining new biogeographical units called ‘bioareas’ on the basis of the distribution of canopy kelps and lower intertidal algal assemblages. Main conclusions Southeast Alaska has the most diverse seaweed flora of any region of Alaska. This is a reflection of its extensive coastline, with varied past and present environmental conditions. Different parts of Southeast Alaska show similarities to different areas outside Southeast Alaska. Despite this, much remains to be learned about the biogeography of seaweeds in Southeast Alaska, and many questions remain to be answered.     

Gauging the effects of sampling failure in biogeographical analysis

Aim Various methods are employed to recover patterns of area relationships in extinct and extant clades. The fidelity of these patterns can be adversely affected by sampling error in the form of missing data. Here we use simulation studies to evaluate the sensitivity of an analytical biogeographical method, namely tree reconciliation analysis (TRA), to this form of sampling failure. Location Simulation study. Methods To approximate varying degrees of taxonomic sampling failure within phylogenies varying in size and in redundancy of biogeographical signal, we applied sequential pruning protocols to artificial taxon–area cladograms displaying congruent patterns of area relationships. Initial trials assumed equal probability of sampling failure among all areas. Additional trials assigned weighted probabilities to each of the areas in order to explore the effects of uneven geographical sampling. Pruned taxon–area cladograms were then analysed with TRA to determine if the optimal area cladograms recovered match the original biogeographical signal, or if they represent false, ambiguous or uninformative signals. Results The results indicate a period of consistently accurate recovery of the true biogeographical signal, followed by a nonlinear decrease in signal recovery as more taxa are pruned. At high levels of sampling failure, false biogeographical signals are more likely to be recovered than the true signal. However, randomization testing for statistical significance greatly decreases the chance of accepting false signals. The primary inflection of the signal recovery curve, and its steepness and slope depend upon taxon–area cladogram size and area redundancy, as well as on the evenness of sampling. Uneven sampling across geographical areas is found to have serious deleterious effects on TRA, with the accuracy of recovery of biogeographical signal varying by an order of magnitude or more across different sampling regimes. Main conclusions These simulations reiterate the importance of taxon sampling in biogeographical analysis, and attest to the importance of considering geographical, as well as overall, sampling failure when interpreting the robustness of biogeographical signals. In addition to randomization testing for significance, we suggest the use of randomized sequential taxon deletions and the construction of signal decay curves as a means to assess the robustness of biogeographical signals for empirical data sets.     

Panbiogeographical analysis of the genus Bomarea (Alstroemeriaceae)

Aim  A panbiogeographical analysis of the genus Bomarea was undertaken in order to determine generalized tracks and biogeographical nodes, and to evaluate the current distribution of the genus based on the available tectonic information and the biogeographical regionalization of Latin America.
Location  The Neotropical region from northern Mexico to northern Argentina, and the Nearctic and Andean regions.
Method  A total of 2205 records of 101 species were analysed, representing 95% of the species assigned to Bomarea . Localities were represented on maps and their individual tracks were drawn. Based on their comparison, generalized tracks were detected and mapped. Nodes were identified in the areas where different generalized tracks were superimposed.
Results  Five generalized tracks were recovered. One is located in the Eastern Central America and Western Panamanian Isthmus provinces (Caribbean subregion, Neotropical region), which was supported by three species of Central American distribution. The four remaining generalized tracks were located in South America, in the North Andean Paramo, Cauca and Puna biogeographical provinces. These tracks were supported by species of Bomarea with an Andean distribution. Biogeographical nodes were established in the Central Andean region of Colombia, central Ecuador and central Peru.
Main conclusions  The nodes obtained for Bomarea support a hybrid origin for the Andean region, which presents diverse components from both northern and southern South America. Likewise, the track recovered between Colombia and Ecuador includes Andean and Neotropical areas, providing further support for this hypothesis. The nodes obtained are coherent with vicariant elements evident for Bomarea. Species of three clades proposed for Bomarea are distributed in specific generalized tracks.     

基于自组织特征映射模型(SOFM)网络的中国自然资源生态安全区划

自然资源生态安全是国家安全的重要组成部分,自然资源生态安全区划对保障区域可持续发展提供了重要途径。基于自然资源数据、生态环境数据和相关区划资料,从生态敏感性与生态服务重要性角度构建了自然资源生态安全评价指标体系,进而揭示了中国自然资源生态安全的空间格局;通过建立区划的原则和指标,按照一级区主要反映自然资源空间分布格局,二级区主要揭示自然资源生态安全水平的差异,采用SOFM网络制订了中国自然资源生态安全区划方案。结果显示：(1)中国自然资源生态安全水平整体偏低,以中警与重警状态区域为主,安全和较安全状态的区域仅占24.22%,其中低安全等级区多分布于400mm等降水量线以西的干旱、半干旱区,高安全等级区则集中分布于水热资源与生物资源较为丰富的东南部地区;(2)中国自然资源生态安全区划方案包括8个一级区与27个二级区,总结归纳各大区自然资源的特征和威胁生态安全的问题,并针对二级区自然资源生态安全状况提出了对策建议。研究结果可为分区、分类推进全国自然资源可持续利用和国土空间优化提供理论支持与决策依据。     

Functional Differences Among Benthic Macroinvertebrate Communities in Reference Streams of Same Order in a Given Biogeographic Area

Ecological theory (Southwood, 1977. Journal of Animal Ecology 46: 337–365, 1988. Oikos 52: 3–18; Townsend, 1989. Journal of the North American Benthological Society 8: 36–50; Townsend & Hildrew, 1994. Freshwater Biology 31: 265–275) considers that spatio-temporal variations in habitats act as evolutionary forces on organisms, selecting for traits that maximize fitness. As a consequence, communities developed under same environmental conditions should present the same combination of species bio-ecological characteristics. The objective was to verify, using data from the same biogeographical zone, (1) if there was a unique suite of bio-ecological profiles for reference macrobenthic communities of `comparable' rivers or (2) if the distribution of bio-ecological traits within reference communities was significantly influenced by geology. The variability of 22 bio-ecological traits in 12 different sites was tested to evaluate the potential influence of geological substrate on biological and ecological features of reference stream communities. Observed patterns suggested that communities displayed highly stable bio-ecological profiles among sites (within a given biogeographical zone) whatever the substrate was, even if communities on clayey substrate exhibited slightly different bio/ecological characteristics than on others geologies. Nevertheless, the functional structure of macrobenthic communities in reference sites was quite stable in this biogeographical area. This study was restricted to the selected stream types and its results may not directly be transferred to other biogeographical areas and stream types. However, the perspective of a unique functional reference for streams of the same order in a given biogeographical area, improve functional comparison between observed vs. reference communities. This could simplify and objectively define the ecological status of a given site.     

Do phytogeographic patterns reveal biomes or biotic regions?

We present the largest comparative biogeographical analysis that has complete coverage of Australia's geography (20 phytogeographical subregions), using the most complete published molecular phylogenies to date of large Australian plant clades (Acacia, Banksia and the eucalypts). Two distinct sets of areas within the Australian flora were recovered, using distributional data from the Australasian Virtual Herbarium (AVH) and the Atlas of Living Australia (ALA): younger Temperate, Eremaean and Monsoonal biomes, and older southwest + west, southeast and northern historical biogeographical regions. The analyses showed that by partitioning the data into two sets, using either a Majority or a Frequency method to select taxon distributions, two equally valid results were found. The dataset that used a Frequency method discovered general area cladograms that resolved patterns of the Australian biomes, whereas if widespread taxa (Majority method, with >50% of occurrences outside a single subregion) were removed the analysis then recovered historical biogeographical regions. The study highlights the need for caution when processing taxon distributions prior to analysis as, in the case of the history of Australian phytogeography, the validity of both biomes and historical areas have been called into question.     

Phytogeography of upwelling areas in the Arabian Sea

Aim The identification of the marine plant communities of two islands from different upwelling areas of the Arabian Sea, with a similar diversity in biotopes. A comparison of the species composition of these macroalgal communities and their biogeographical affinities within the Indian Ocean should give insight into the biogeographical position of the Arabian Sea within the larger Indian Ocean. The incorporation of environmental parameters in the analysis is instructive in understanding their importance in shaping the diverse marine assemblages of the Arabian Sea. Location Arabian Sea: (1) the Socotra Archipelago (Yemen; 12.47° N, 53.87° E) in the Somali upwelling area, (2) Masirah Island (Oman; 20.42° N, 58.79° E) in the upwelling area of the southern Arabian Peninsula. Methods The marine flora of different biotopes around both islands were examined by means of qualitative assessments. Ordination analysis [detrended correspondence analysis (DCA)] was used to identify the different plant communities and to correlate these with environmental parameters. The species composition of the identified communities were compared (tripartite similarity index) and their biogeographical affinity with nations bordering the Indian Ocean was determined. Indicator species analyses were performed to identify the characteristic species of the different plant communities and their biotopes. Results The DCA analysis shows a clustering of sites (plant communities) corresponding with their geographical position, linked in turn to the prevailing environmental conditions of the different coastal areas. The combined interpretation of the ordination, similarity and biogeographical analyses results in the aggregation of similar plant communities of both upwelling areas into four biotopes. Main conclusions The north coast communities of Socotra and the west coast communities of Masirah can be grouped into three biotopes related to the degree of exposure (to upwelling) and sedimentation. These biotopes are typified by indicator species, characteristic for specific substrata, and have a high biogeographical affinity with the East African coast. The plant communities of Socotra's south coast and Masirah's east coast constitute a fourth biotope, being diverse and species rich, typified by a large proportion of red macroalgae including the characteristic species of the unique Arabian Sea flora. This biotope has a pronounced biogeographical affinity with distant regions (disjunctly distributed taxa) as South Africa's East Coast and Western Australia. Within the different biotopes, the communities of Masirah are more divergent from an East African flora in comparison to Socotra, the latter being a stepping stone between the East African and Arabian Sea flora.