Second Sahelian amphibian endemism suggested by phylogeography of Groove crowned Bullfrog (Hoplobatrachus occipitalis) in western Sahel and hints of polyploid species formation

Several studies have assessed the phylogeographic patterns of vertebrates in North Africa and Sahara–Sahel, but most of the phylogeographic knowledge on amphibians comes from the Mediterranean region while the southern Sahara and Sahel remain poorly studied. Here, we assess the phylogeography of the African Groove crowned frog Hoplobatrachus occipitalis, with a focus on western Sahel in order to better understand the biogeographic patterns of semi-aquatic species in this arid region. Using mitochondrial and nuclear markers, we have assessed the species’ genetic structure, distribution of genetic diversity, and the presence of cryptic diversity. We found evidence of a recent (re-)colonization of the mountains in its northernmost distribution, but also for the role of southern Mauritanian mountains and large rivers as refugia. Two major lineages were detected, one perhaps endemic to Mauritania and the other widespread in Africa. The first lineage possibly constitutes the second Sahelian amphibian endemic; the latter may have originated through an allopolyploidy event, with the Mauritanian lineage being one of the parental ones.     

Do hotspots fall within protected areas? A Geographic Approach to Planning analysis of regional freshwater biodiversity

相似文献   

The role of the uplift of the Qinghai‐Tibetan Plateau for the evolution of Tibetan biotas

Biodiversity is unevenly distributed on Earth and hotspots of biodiversity are often associated with areas that have undergone orogenic activity during recent geological history (i.e. tens of millions of years). Understanding the underlying processes that have driven the accumulation of species in some areas and not in others may help guide prioritization in conservation and may facilitate forecasts on ecosystem services under future climate conditions. Consequently, the study of the origin and evolution of biodiversity in mountain systems has motivated growing scientific interest. Despite an increasing number of studies, the origin and evolution of diversity hotspots associated with the Qinghai‐Tibetan Plateau (QTP) remains poorly understood. We review literature related to the diversification of organisms linked to the uplift of the QTP. To promote hypothesis‐based research, we provide a geological and palaeoclimatic scenario for the region of the QTP and argue that further studies would benefit from providing a complete set of complementary analyses (molecular dating, biogeographic, and diversification rates analyses) to test for a link between organismic diversification and past geological and climatic changes in this region. In general, we found that the contribution of biological interchange between the QTP and other hotspots of biodiversity has not been sufficiently studied to date. Finally, we suggest that the biological consequences of the uplift of the QTP would be best understood using a meta‐analysis approach, encompassing studies on a variety of organisms (plants and animals) from diverse habitats (forests, meadows, rivers), and thermal belts (montane, subalpine, alpine, nival). Since the species diversity in the QTP region is better documented for some organismic groups than for others, we suggest that baseline taxonomic work should be promoted.     

Glacial refugia influence plant diversity patterns in the Mediterranean Basin

Aim The aims of this study were to assess the distribution of putative Mediterranean refugia of plants, to compare the locations of refugia and those of regional hotspots of plant biodiversity, and to provide a critical analysis of the Mediterranean refugium paradigm. Furthermore, we consider how biogeographical and genetic results can be combined to guide global conservation strategies. Location The Mediterranean region. Methods We started from a detailed analysis of the scientific literature (1993–2007) in order to identify refugia in the Mediterranean region, based on intra‐specific phylogeographical studies of plant species. We used population locations together with gene‐pool identity to establish the database, comparing patterns of phylogeographical concordance with the locations of Mediterranean refugia. We then tested the biogeographical congruence between two biodiversity components, namely phylogeographical refugia and regional hotspots. Results We identified 52 refugia in the Mediterranean bioclimatic region and confirmed the role played by the three major peninsulas, with a shared total of 25 refugia. We emphasize the importance of areas that have previously been attributed a lesser role (large Mediterranean islands, North Africa, Turkey, Catalonia). Of the 52 refugia identified, 33 are situated in the western Mediterranean Basin and 19 in the eastern part. The locations of the phylogeographically defined refugia are significantly associated with the 10 regional hotspots of plant biodiversity, with 26 of these refugia (i.e. 50%) occurring within the hotspots. Main conclusions The locations of refugia are determined by complex historical and environmental factors, the cumulative effects of which need to be considered because they have occurred since the Tertiary, rather than solely during the last glacial period. Refugia represent climatically stable areas and constitute a high conservation priority as key areas for the long‐term persistence of species and genetic diversity, especially given the threat posed by the extensive environmental change processes operating in the Mediterranean region. The refugia defined here represent ‘phylogeographical hotspots’; that is, significant reservoirs of unique genetic diversity favourable to the evolutionary processes of Mediterranean plant species.     

黄河流域被子植物和陆栖脊椎动物丰富度格局及其影响因子

生物多样性的大尺度空间分布格局及其形成机制一直是生态学和生物地理学的核心内容。黄河流域是我国重要的生态屏障, 明确该区域动植物多样性分布格局及其影响因素, 对我国黄河流域生态保护和高质量发展具有重要意义。本研究通过收集黄河流域被子植物和陆栖脊椎动物分布数据, 结合气候、环境异质性和人类活动等信息, 探讨了黄河流域被子植物和陆栖脊椎动物物种丰富度格局及其主要影响因素。结果表明, 黄河流域被子植物和陆栖脊椎动物物种丰富度在区域尺度具有相似的分布格局: 南部山地动植物物种丰富度最高, 而东部高寒区和北部干旱区物种丰富度最低。回归树模型表明, 冠层高度范围和净初级生产力范围分别是黄河流域被子植物和陆栖脊椎动物物种丰富度最重要的预测因子; 当移除空间自相关影响后, 环境异质性和气候因子依然对区域尺度的动植物物种丰富度具有较高且相似的解释度。表明环境异质性和气候共同决定了黄河流域被子植物和陆栖脊椎动物物种丰富度格局, 而人类使用土地面积并不是影响黄河流域动植物物种丰富度格局的主要因子。因此, 在未来的研究中若针对不同区域筛选出更精准的环境驱动因子或选用更多不同类别的环境异质性因子进行分析, 将有助于更深入理解物种多样性格局的成因。     

Fiddling in biodiversity hotspots while deserts burn? Collapse of the Sahara's megafauna

Biodiversity hotspots understandably attract considerable conservation attention. However, deserts are rarely viewed as conservation priority areas, due to their relatively low productivity, yet these systems are home to unique species, adapted to harsh and highly variable environments. While global attention has been focused on hotspots, the world's largest tropical desert, the Sahara, has suffered a catastrophic decline in megafauna. Of 14 large vertebrates that have historically occurred in the region, four are now extinct in the wild, including the iconic scimitar‐horned oryx (Oryx dammah). The majority has disappeared from more than 90% of their Saharan range, including addax (Addax nasomaculatus), dama gazelle (Nanger dama) and Saharan cheetah (Acinonyx jubatus hecki) – all now on the brink of extinction. Greater conservation support and scientific attention for the region might have helped to avert these catastrophic declines. The Sahara serves as an example of a wider historical neglect of deserts and the human communities who depend on them. The scientific community can make an important contribution to conservation in deserts by establishing baseline information on biodiversity and developing new approaches to sustainable management of desert species and ecosystems. Such approaches must accommodate mobility of both people and wildlife so that they can use resources most efficiently in the face of low and unpredictable rainfall. This is needed to enable governments to deliver on their commitments to halt further degradation of deserts and to improve their status for both biodiversity conservation and human well‐being. Only by so‐doing will deserts be able to support resilient ecosystems and communities that are best able to adapt to climate change.     

Fragmented habitats and Pleistocene climate shaped diversification of the hoary bamboo rat (Rhizomys pruinosus) in the mountainous plateau of SW China

The southwest mountainous region of China has been characterized as one of the worldwide biodiversity hotspots, but mechanisms underlying diversification of organisms in this region are still not clear. We assessed whether fragmented mountainous habitats and Pleistocene climate changes impacted the genetic diversity and diversification patterns of the hoary bamboo rat (Rhizomys pruinosus Blyth), a widely distributed species of rodent in SW China. Genetic diversity analyses were undertaken based on four mitochondrial DNA regions and 12 nuclear microsatellite loci (simple sequence repeats), representing 153 individuals from 24 populations across SW China. Moreover, we investigated correlations between genotype and geographical components, and predicted species distribution models for R. pruinosus under the historical and present climate conditions. Both mitochondrial DNA and simple sequence repeat markers revealed substantial genetic diversity and strong differentiation between populations. Phylogeographical analyses revealed two phylogenetic clades that were consistent with their geographical distributions (eastern and western clades). We inferred that the divergence of R. pruinosus was largely driven by Quaternary climatic oscillations and regionally fragmented mountainous habitats with environmental and geographical heterogeneity. Overall, our study revealed diversification patterns of R. pruinosus—patterns that may be shared by small alpine vertebrates in SW China.     

A spider diversity model for the Caucasus Ecoregion

Precise information on spatial patterns of species richness and endemic species distribution is important for effective species conservation. In the Caucasus Ecoregion such information is virtually non-existent for invertebrate taxa. Using occurrence data from a large database we calculated species distribution models with the GARP algorithm for 471 spider species to visualize the diversity distribution of spider species in this region. Overall species diversity was highest in mountain forests of the North Caucasus, east-central Georgia, the southern slopes of the eastern Great Caucasus and south-east Azerbaijan. A regression tree analysis Chi squared automatic interaction detector method revealed the mean temperature of the driest quarter and precipitation parameters to be the main environmental factors shaping these patterns. Diversity of endemic species was correlated with overall species diversity but hotspots of endemic species (10+ percent of all species) exists in high-mountain areas, suggesting post-glacial speciation events in the high mountains as the main sources of high endemism in Caucasus. Further information on the spatial distribution of species diversity of invertebrate taxa in the Caucasus Ecoregion is needed to improve conservation efforts in this biodiversity hotspot.     

Phylogeny of North African Agama lizards (Reptilia: Agamidae) and the role of the Sahara desert in vertebrate speciation

The origin of Saharan biodiversity is poorly understood, in part because the geological and paleoclimatic events that presumably shaped species diversity are still controversial, but also because few studies have explored causal explanations for the origin of Saharan diversity using a phylogenetic framework. Here, we use mtDNA (16S and ND4 genes) and nDNA (MC1R and CMOS genes) to infer the relationships and biogeographic history of North African agamas (genus Agama). Agamas are conspicuous, diverse and abundant African lizards that also occur in the Saharan xeric and mesic environments. Our results revealed the presence of three Agama lineages in North Africa: one Afrotropical, one Sahelo-Saharan, and one broadly distributed in North Africa and mainly Saharan. Southern Mauritania contains the highest known diversity, with all three lineages present. Results suggest that agamas colonized the Sahara twice, but only one lineage was able to radiate and diversify there. Species in the Saharan lineage are mostly allopatric, and their splitting, genetic diversity and distribution are greatly explained by mountain ranges. One species in this lineage has colonized the Mediterranean climatic zone (A. impalearis), and another one the Sahel savannah (A. boueti). The other lineage to colonize the Sahara corresponds to A. boulengeri, an eminently Sahelian species that also inhabits Saharan mountain ranges in Mauritania and Mali. Phylogenetic analyses indicate that allopatric montane populations within some currently recognized species are also genetically divergent. Our study therefore concludes that vicariant speciation is a leading motor of species diversification in the area: Inside the Sahara, associated to mountain-ranges isolated by dune seas and bare plains; outside, associated to less harsh climates to the North and South. Paleoclimatic oscillations are suggested as causal explanations of the vicariant distribution and origin of species. Agamas are thought to have colonized northern Africa during wet periods, with subsequent dry periods fragmenting species distribution and leading to allopatric populations associated to milder and wetter climates in the Mediterranean, Sahel, and in Saharan mountains, in an island-model fashion. Finally, our results support the synonymization of A. castroviejoi with A. boueti, the reciprocal monophyly of all other North African agamas, and suggest one candidate species within A. boulengeri.     

Overlooked Mountain Rock Pools in Deserts Are Critical Local Hotspots of Biodiversity

BackgroundThe world is undergoing exceptional biodiversity loss. Most conservation efforts target biodiversity hotspots at large scales. Such approach overlooks small-sized local hotspots, which may be rich in endemic and highly threatened species. We explore the importance of mountain rock pools (gueltas) as local biodiversity hotspots in the Sahara-Sahel. Specifically, we considered how many vertebrates (total and endemics) use gueltas, what factors predict species richness, and which gueltas are of most priority for conservation. We expected to provide management recommendations, improve local biodiversity conservation, and simultaneously contribute with a framework for future enhancement of local communities’ economy. The identification of local hotspots of biodiversity is important for revaluating global conservation priorities.Conclusion/SignificanceGueltas are crucial for local biodiversity conservation and human activities. They require urgent management plans in Mauritania’s mountains. They could provide refugia under climate change being important for long-term conservation of Sahara-Sahel biodiversity. Given their disproportional importance in relation to their size, they are local hotspots of biodiversity deserving global attention.     

Plant species diversity and grazing in the Scandinavian mountains - patterns and processes at different spatial scales

There is a long tradition of grazing by semi‐domestic reindeer and sheep in alpine and sub‐alpine Scandinavian habitats, but present management regimes are questioned from a conservation point of view. In this review we discuss plant diversity patterns in the Scandinavian mountains in a global, regional and local perspective. The main objective was to identify processes that influence diversity at different spatial scales with a particular focus on grazing. In a global perspective the species pool of the Scandinavian mountains is limited. partly reflecting the general latitudinal decline of species but also historical and ecological factors operating after the latest glaciation. At the local scale, both productivity and disturbance are primary factors structuring diversity, but abiotic factors such as soil pH, snow distribution and temperature are also important. Although evidence is scarce, grazing favours local species richness in productive habitats, whereas species richness decreases with grazing when productivity is low. Regional patterns of plant diversity is set by, 1) the species pool. 2) the heterogeneity and fragmentation of communities, and 3) local diversity of each plant community. We suggest that local shifts in community composition depend both on the local grazing frequency and the return‐time of the plant community after a grazing session. In addition, an increasing number of grazing‐modified local patches homogenises the vegetation and is likely to reduce the regional plant diversity. The time scale of local shifts in community composition depends on plant colonisation and persistence, From a mechanistic point of view, diversity patterns at a regional scale also depend on the regional dynamics of single species. Colonisation is usually a slow and irregular process in alpine environments, whereas the capacity for extended local persistence is generally high. Although the poor knowledge of plant regional dynamics restricts our understanding of how grazing influences plant diversity, we conclude that grazing is a key process for maintaining biodiversity in the Scandinavian mountains.     

Aquatic biodiversity in the mediterranean region of South Africa

The Cape mediterranean region, part of South Africa’s Cape Floristic Realm (CFR), is recognised for its rich diversity and high degree of endemism of terrestrial vegetation. We review the biodiversity of the aquatic flora and fauna using literature sources and museum data. Geological, palaeohistorical and climate data are examined in relation to the formation of the winter-rainfall regime. Prehistoric humans had minimal impact on the aquatic biotas. Patterns and processes relating to the present-day climate, ecosystem status, distribution and diversity of plants, invertebrates and vertebrates in the CFR are reviewed. The proportion of endemic CFR species relative to the total number of species known from southern Africa is estimated. Observed distribution patterns are evaluated against temperate Gondwana vicariance, old African migrations, the role of the ancient Cape fold mountains and Pangaea. The lack of Pleistocene glaciations in Africa, the oligotrophic nature of the river systems and the palaeohistorical origin and distribution of taxa are considered when assessing reasons for disjunct distribution patterns. Impacts of anthropogenic interference with aquatic ecosystems are evaluated. Fragmented jurisdiction of nature conservation authorities is seen as a problem for attaining adequate conservation of CFR aquatic ecosystems. Systematic conservation planning is under way for the region.     

汶川地震灾区生物多样性热点地区分析

汶川地震灾区位于长江上游,是我国大熊猫(Ailuropoda melanoleuca)的主要分布区,被保护国际认定的25个全球生物多样性热点地区之一.2008年5月12日发生的汶川大地震导致该区域生态环境遭受严重破坏,需要识别生物多样性热点地区,指导灾后生物多样性保护.选取物种生境质量、植被景观多样性指数和物种多样性指数作为评价指标,其中生境质量采用InVEST生物多样性模型计算,然后利用空间相关分析中G系数进行热点地区分析,探测出灾区生物多样性的热点区,并在此基础上与现有保护区分布、物种生境分布以及Marxan模型计算出的优先区进行对比验证.结果显示:热点区范围涉及到现有76％的保护区,且保护区内的热点区面积达到灾区所有保护区面积的55％;在选取的69个指示物种中有60个物种位于热点区的生境面积占这些物种在灾区的总生境面积的50％以上,有32个物种在80％左右,热点区内的所有指示物种生境总面积占整个灾区指示物种生境总面积的70％以上.基于空间相关分析方法得出的热点地区基本上与Marxan模型输出的优先保护区范围结果基本一致.但空间相关分析的热点区划分克服了Marxan模型优先保护区分布过于离散,孤岛效应明显的不足.     

Assessment of a new hotspot for plant biodiversity in the Mediterranean basin (North Africa)

The concept of biodiversity hotspot at the regional and global scale has contributed to the improvement of the conservation strategies. The need for precise evaluation is often hampered by lapses of knowledge in some Mediterranean regional hotspots. The objective of the present work is to analyse the diversity of endemic and rare flora in the northern part of Algeria. According to the bibliographical data that are available, the most remarkable areas for endemism are the Oran's coast, the Great Kabylia, and the Small Kabylia. As far as rare species are concerned, coastal Numidia comes first, then the Algiers surroundings. This group 'Kabylias-Numidia-Kroumiria' comprises an unrecognised regional hotspot, made of forests, mountains and coastal ecosystems and threatened by human activities. In the face of growing threats, it is urgent to reinforce national and international policies of conservation and to cooperate for a better floristic knowledge of all the areas mentioned above.     

Genetic Divergence During Long‐term Isolation in Highly Diverse Populations of Tropical Trees Across the Eastern Arc Mountains of Tanzania

The Eastern Arc Mountains are believed to support some of the oldest tropical forest in the world. The current distribution of this forest is highly fragmented due to a combination of long‐term effects of past changes in global climate and more recent deforestation. We sought to explore the hypothesized antiquity and long‐term isolation of the Eastern Arc montane forests based on an assessment of the geographical distribution and interspecies similarity of chloroplast DNA sequence variation in five forest trees. Data were used to investigate regional patterns of diversity and population structure based on intraspecific phylogenies, and results were interpreted against hypotheses on ecosystem age and connectivity. Regional diversity was high, with up to 22 chloroplast DNA haplotypes being recorded within a species across the sampled populations. Geographical concordance of genetic and geographic structure was weak to absent in all species and there was little similarity of genetic structure between species. Haplotype sharing between mountain blocks was extremely limited. The generally weak phylogeographical structure, in conjunction with high regional diversity and genetic uniqueness of individual mountain forests does not support the assumption of widespread genetic connectivity of the mountain forests, indicating instead a pattern of past isolation and ongoing diversification. Our findings substantially add to understanding patterns of diversity in this region and lend weight to calls to use more sophisticated biodiversity assessments when setting regional conservation and research funding priorities.     

Arthropods in biodiversity hotspots: the case of the Phytoseiidae (Acari: Mesostigmata)

The biodiversity hotspot concept was defined by Myers in 1988 to determine priority areas for conservation. They have high endemism levels and have lost more than 70% of their original vegetated area. To date, there is little information on arthropod diversity in these zones. This work focuses on the biodiversity of the Phytoseiidae (Acari), one of the best known among the order Mesostigmata, in these threatened areas. These mites are usually predators and they are worldwide spread. Geographic distribution of phytoseiids in 27 biodiversity hostspots was assessed from data of the last world catalogue published in 2004. One thousand two hundred and thirty species are reported from at least one hotspot (62% of the total species number) and 604 species (30% of the total species number) are endemic to the 27 hotspots considered. The number of reports/publication in hotspot areas (2.6) is higher than in non-hotspot zones (1.5). Hotspots areas could be thus considered as a great reservoir of the Phytoseiidae diversity, just as they are for vertebrates and plants. Correlations between plant, vertebrate, mite diversity and endemism, as well as congruence rates between endemism levels of these three organisms suggest that the biodiversity patterns of plants and vertebrates mirror well those of the Phytoseiidae (both for endemicity and species richness). More intense conservation efforts in biodiversity hotspots would thus be assumed to affect plant and vertebrate biodiversity, as already known, but also arthropod biodiversity, as it was assumed. These results further support thus the importance of these zones in biodiversity conservation, even for organisms like mites, very small and poorly studied in this regards. More data on arthropods are, however, required to confirm these preliminary observations.     

Geostatistical modelling of regional bird species richness: exploring environmental proxies for conservation purpose

Identifying spatial patterns in species diversity represents an essential task to be accounted for when establishing conservation strategies or monitoring programs. Predicting patterns of species richness by a model-based approach has recently been recognised as a significant component of conservation planning. Finding those environmental predictors which are related to these patterns is crucial since they may represent surrogates of biodiversity, indicating in a fast and cheap way the spatial location of biodiversity hotspots and, consequently, where conservation efforts should be addressed. Predictive models based on classical multiple linear regression or generalised linear models crowded the recent ecological literature. However, very often, problems related with spatial autocorrelation in observed data were not adequately considered. Here, a spatially-explicit data-set on birds presence and distribution across the whole Tuscany region was analysed. Species richness was calculated within 1 × 1 km grid cells and 10 environmental predictors (e.g. altitude, habitat diversity and satellite-derived landscape heterogeneity indices) were included in the analysis. Integrating spatial components of variation with predictive ecological factors, i.e. using geostatistical models, a general model of bird species richness was developed and used to obtain predictive regional maps of bird diversity hotspots. A meaningful subset of environmental predictors, namely habitat productivity, habitat heterogeneity, combined with topographic and geographic information, were included in the final geostatistical model. Conservation strategies based on the predicted hotspots as well as directions for increasing sampling effort efficiency could be extrapolated by the proposed model.     

The contribution of geographically common and rare species to the spatial distribution of biodiversity

Motivation and aim

Mapping the spatial distribution of biodiversity is critical for understanding its fundamental drivers (e.g. speciation, environmental filtering) as well as for conservation assessment. An important dimension of this topic is how the distributions of subsets of species contribute to the overall distribution of biodiversity. Although studies have previously investigated the role of geographically common and rare species in determining these patterns, their respective contributions appear to vary between studies. Knowing which species contribute disproportionately to the spatial distribution of biodiversity enables the identification of key indicator species for biodiversity assessments across large areas and is important for prioritising areas for conservation actions. An extensive review of the literature was carried out to synthesise research on how geographic rarity contributes to spatial patterns of biodiversity. We identify potential explanations for the discrepancies in findings between studies and identify opportunities for further research.

Results

Many studies on the contribution of geographic commonness and rarity to the spatial distribution of biodiversity focus on species richness. A prevalent view is that common (widespread) species contribute disproportionately, although this is not ubiquitous across studies due to factors such as the geographic extent from which relative rarity is quantified. We identify research pathways that will further improve our knowledge of how geographically common and rare species shape the spatial distribution of biodiversity including the impact of spatial scale on species contributions and the incorporation of biodiversity components beyond taxonomic alpha diversity, that is functional and phylogenetic diversity.

Main conclusions

Future research should incorporate multiple biodiversity components and model scale dependency. This will further our knowledge on the underlying processes that shape the spatial variation of biodiversity across the planet and help inform biological surveys and conservation activities.     

基于系统发育的黄土高原地区木本植物多样性及特有性格局

黄土高原地区植被类型多样, 森林、草原和荒漠在此交汇并逐渐过渡。由于水热条件限制和人类活动加剧, 该地区生态环境脆弱, 生物多样性保护面临的形势日益严峻, 因此获取该区域物种多样性的空间分布格局并阐明其影响因素成为该地区生物多样性保护的首要任务。本研究首先结合标本采集记录与环境因子, 利用物种分布模型获取了293种木本植物的潜在分布区, 分析了物种丰富度和物种加权特有性的空间格局。其次, 引入系统发育信息, 分析系统发育多样性和系统发育特有性的空间格局, 并进一步利用环境因子对上述格局分别进行解释。最后, 对黄土高原地区的特有中心性质和显著性进行分析。结果表明, 生物多样性热点地区均出现在黄土高原南部水热条件较好的地区, 即秦岭和中条山一带。本区域的生物多样性空间格局由年平均降水量和最冷月最低温主导, 符合植物区系交汇带的特点。特有中心集中在南部地区和青海省, 由南向北分别是古特有中心和混合特有中心, 不存在单独的新特有中心。黄土高原地区木本植物起源较为古老, 生物多样性格局的形成以来源于热带或亚热带的物种扩散为主, 物种的分化不占主导地位。上述结果表明了将植物的进化历史纳入生物多样性保护的重要性。