Current Biodiversity Patterns Research Articles

Geophylogenies and the Map of Life

One hundred and fifty years after Charles Darwin wrote these words, two major ongoing Web-based sci entific projects are collating information on the earth's biological diversity. The Encyclopaedia of (EoL; Wilson 2003) provides a single interface through which information on each of the same class can be accessed, whereas The Tree of (ToL) Web project (http://tolweb.org/; Maddison and Schulz 2007; Maddison et al. 2007) places these classes onto an evo lutionary tree. Here, I propose that a third complemen tary project should now be considered, the Map of Life (MoL), in which all we know about the biogeo graphical history of life?including clades, species, their genes, and the communities they are members of?is threaded through a dynamic earth history, capturing the spatiotemporal pathways that underlie current and past patterns of biodiversity. Why, beyond being both intellectually and aestheti cally stimulating to do so, might we want to create such a map and what might be the scientific and societal ben efits? In common with the EoL, creating and analyzing the MoL will stimulate the generation of new scientific hypotheses through the juxtaposition of previously dis parate information (Wilson 2003). Comparative analyses of interspecific biogeographical pattern will facilitate the identification of the geographical and ecological context surrounding the evolution of specific traits, speciose radiations, patterns of extinction, and com munity assemblage. Hypotheses regarding the relative roles of dispersal and vicariance in speciation will be interpretable in a geographically explicit framework. Similarly, analyses of the spatiotemporal history of ge netic variation will link changing landscapes with the frequency and intensity of past population bottlenecks and expansions. Information that is essential to our attempts to predict and manage the effects of habitat fragmentation and climate change, as well as the trajec tories of emergent diseases, genetically modified organ isms, and invasive species, will be made available in an accessible manner. In addition to the scientific rewards, wider societal benefits can be envisaged through the explicit presen tation of the intimate connections between all life in

Phylogeography of the Alcippe morrisonia(Aves: Timaliidae): long population history beyond late Pleistocene glaciations

BackgroundThe role of Pleistocene glacial oscillations in current biodiversity and distribution patterns varies with latitude, physical topology and population life history and has long been a topic of discussion. However, there had been little phylogeographical research in south China, where the geophysical complexity is associated with great biodiversity. A bird endemic in Southeast Asia, the Grey-cheeked Fulvetta, Alcippe morrisonia, has been reported to show deep genetic divergences among its seven subspecies. In the present study, we investigated the phylogeography of A. morrisonia to explore its population structure and evolutionary history, in order to gain insight into the effect of geological events on the speciation and diversity of birds endemic in south China.ResultsMitochondrial genes cytochrome b (Cytb) and cytochrome c oxidase I (COI) were represented by 1236 nucleotide sites from 151 individuals from 29 localities. Phylogenetic analysis showed seven monophyletic clades congruent with the geographically separated groups, which were identified as major sources of molecular variance (90.92%) by AMOVA. TCS analysis revealed four disconnected networks, and that no haplotype was shared among the geographical groups. The common ancestor of these populations was dated to 11.6 Mya and several divergence events were estimated along the population evolutionary history. Isolation by distance was inferred by NCPA to be responsible for the current intra-population genetic pattern and gene flow among geographical groups was interrupted. A late Pleistocene demographic expansion was detected in the eastern geographical groups, while the expansion time (0.2–0.4 Mya) was earlier than the Last Glacial Maximum.ConclusionIt is proposed that the complicated topology preserves high genetic diversity and ancient lineages for geographical groups of A. morrisonia in China mainland and its two major islands, and restricts gene exchange during climate oscillations. Isolation by distance seems to be an important factor of genetic structure formation within geographical populations. Although glacial influence to population fluctuation was observed in late Pleistocene, it seems that populations in eastern China were more susceptible to climate change, and all geographical groups were growing stably through the Last Glacial Maximum. Coalescence analysis suggested that the ancestor of A. morrisonia might be traced back to the late Miocene, and the current phylogeographical structure of A. morrisonia is more likely to be attributable to a series geological events than to Pleistocene glacial cycles.

Bias in freshwater biodiversity sampling: the case of Iberian water beetles

ABSTRACTExtensive distributional data bases are key tools in ecological research, and good‐quality data are required to provide reliable conservation strategies and an understanding of biodiversity patterns and processes. Although the evaluation of data bases requires the incorporation of estimates of sampling effort and bias, no studies have focused on these aspects for freshwater biodiversity data. We used here a comprehensive data base of water beetles from the Iberian Peninsula and the Balearic Islands, and examine whether these data provide an unbiased, reliable picture of their diversity and distribution in the study area. Based on theoretical estimates using the Clench function on the accumulated number of records as a surrogate of sampling effort, about a quarter of the Iberian and Balearic 50 × 50 km Universal Transverse Mercator grid cells can be considered well prospected, with more than 70% of the theoretical species richness actually recorded. These well‐surveyed cells are not evenly distributed across biogeographical and physicoclimatic subregions, reflecting some geographical bias in the distribution of sampling effort. Our results suggest that recording was skewed by relatively simple variables affecting collector activity, such as the perceived ‘attractiveness’ of mountainous landscapes and protected areas with recently described species, and accessibility of sampling sites (distance from main research centres). We emphasize the importance of these evaluation exercises, which are useful to locate areas needed of further sampling as well as to identify potential biases in the distribution of current biodiversity patterns.

Are hotspots of evolutionary potential adequately protected in southern California?

Reserves are often designed to protect rare habitats, or “typical” exemplars of ecoregions and geomorphic provinces. This approach focuses on current patterns of organismal and ecosystem-level biodiversity, but typically ignores the evolutionary processes that control the gain and loss of biodiversity at these and other levels (e.g., genetic, ecological). In order to include evolutionary processes in conservation planning efforts, their spatial components must first be identified and mapped. We describe a GIS-based approach for explicitly mapping patterns of genetic divergence and diversity for multiple species (a “multi-species genetic landscape”). Using this approach, we analyzed mitochondrial DNA datasets from 21 vertebrate and invertebrate species in southern California to identify areas with common phylogeographic breaks and high intrapopulation diversity. The result is an evolutionary framework for southern California within which patterns of genetic diversity can be analyzed in the context of historical processes, future evolutionary potential and current reserve design. Our multi-species genetic landscapes pinpoint six hotspots where interpopulation genetic divergence is consistently high, five evolutionary hotspots within which genetic connectivity is high, and three hotspots where intrapopulation genetic diversity is high. These 14 hotspots can be grouped into eight geographic areas, of which five largely are unprotected at this time. The multi-species genetic landscape approach may provide an avenue to readily incorporate measures of evolutionary process into GIS-based systematic conservation assessment and land-use planning.

Biodiversity dynamics in isolated island communities: interaction between natural and human‐mediated processes

The flora and fauna of oceanic islands have inspired research since the early scientific explorations. Islands can be considered 'nature's test tubes'- simple systems with multiple replicates. Our research has used the simplicity of island systems to understand ecological community dynamics and to compare the properties of island communities with those in more complex mainland systems. Here, we present three topics: (i) current patterns of biodiversity on isolated islands of the Pacific; (ii) current patterns of disturbance and invasion on islands; and (iii) future trajectories inferred from these patterns. We examine features of islands (in particular, topography and isolation) that have allowed for given levels and distribution of endemicity. The extent to which island communities are impacted by, resist or accommodate disturbance and/or invasions by nonindigenous species appears to be dictated to a large extent by properties of the native communities and how these communities were originally assembled. Accordingly, patterns of disturbance and invasion are very different for high (montane) islands that are extremely isolated compared to those that are nearer to a source of natural migrants. As with all biotas, those on islands are dynamic entities. However, the unique aspect of islands is their isolation, and extreme isolation has largely been lost over the course of the last few centuries due to the development of transportation routes. We argue that such a modified dynamic will affect the future of the biota and the processes that gave rise to the biota. Specifically for isolated habitats, ecological processes will become increasingly more likely to generate biodiversity than evolutionary processes which have been relatively more important in the past. In the short term, island biotas and other similar biotas that occur in montane habitats may fare well as species are often abundant locally in the habitat to which they are indigenous, and may demonstrate considerable resistance and resilience to invasion. However, island biotas - and other biotas that show high local endemism - will likely not fare well in the face of prolonged disturbance. The biotas in these areas generally display a relatively low dispersal capacity; therefore, under conditions of long-term habitat modification, isolated biotas are likely to be swamped by non-natives, which - simply because of random processes and higher propagule pressure - will move more readily into available habitats. Thus, despite the importance of incorporating the evolutionary process into conservation efforts, we must also be careful to evaluate the likely form that the processes will take when the context (specifically, extent of isolation) has been highly modified.

Molecular taxonomy in the dark: Evolutionary history, phylogeography, and diversity of cave crayfish in the subgenus Aviticambarus, genus Cambarus

Freshwater crayfish species in the subgenus Aviticambarus (Cambaridae: Cambarus) are restricted to caves along the Cumberland Plateau, the Sequatchie Valley, and the Highland Rim which extend along the Tennessee River in southcentral Tennessee and northern Alabama. Historically, three stygobitic species, Cambarus jonesi, Cambarus hamulatus, and Cambarus veitchorum, comprise this subgenus. We examine species’ boundaries and phylogeographic structure of this imperiled Southern Appalachian assemblage to shed light on patterns of cave colonization. We also provide estimates of genetic diversity for conservation status assessment. Using geologic evidence, phylogeographic analyses, and sequence data from five gene regions (two nuclear: Histone H3 and GAPDH and three mitochondrial: 12S, 16S, and CO1 totaling almost 2700 base pairs), we identify two well-supported cryptic species in addition to the three currently recognized taxa. Four of these taxa exhibit low levels of genetic variation both currently and historically, which may indicate local extirpation events associated with geological and river basin changes. Our results also support other recent findings that pre-Pleistocene paleodrainages may best explain the current patterns of aquatic faunal biodiversity in the Southern Appalachians.

Exploring the Ecology of the Endemic Jackson Lake Spring Snail: Distributions and Interactions with the Invasive New Zealand Mud Snail

Endemic species make a unique contribution to global biodiversity by only existing in one or a few locations. Unfortunately, because of their limited range, endemic species are particularly susceptible to extinction from a range of disturbances, whether anthropogenic or natural. The introduction of non-native species can disrupt community interactions and accelerate extinctions for narrowly endemic species by competing with and/or preying upon native species. On a global scale, community interactions between invasive and native species have changed current patterns of biodiversity and will continue to influence the distribution of biodiversity well into the future.

Using historical ecology to understand patterns of biodiversity in fragmented agricultural landscapes

AbstractAim To enhance current attempts to understand biodiversity patterns by using an historical ecology approach to highlight the over‐riding influence of land‐use history in creating past, current and future patterns of biodiversity in fragmented agricultural landscapes.Methods We develop an integrative conceptual framework for understanding spatial and temporal variations in landscape patterns in fragmented agricultural landscapes by presenting five postulates (hypotheses) which highlight the important role of historical, anthropogenic disturbance regimes. We then illustrate each of these postulates with examples drawn from fragmented woodlands in agricultural areas of south‐eastern Australia, and discuss these findings in an international context. Location examples are drawn from agricultural areas in south‐eastern Australia.Results We conclude that there is limited potential to refine our understanding of patterns of biodiversity in human‐modified landscapes based on traditional concepts of island biogeography, or simple assumptions of ongoing destruction and degradation. Instead, we propose that in agricultural landscapes that were largely cleared over a century ago: (1) present‐day remnant vegetation patterns are not accidental, but are logically arrayed due to historic land‐use decisions, (2) historic anthropogenic disturbances have a major influence on current ecosystem conditions and diversity patterns, and (3) the condition of remnant ecosystems is not necessarily deteriorating rapidly.Main conclusions An historical ecology approach can enhance our understanding of why different species and ecosystem states occur where they do, and can explain internal variations in ecological conditions within remnant ecosystems, too often casually attributed to the ‘mess of history’. This framework emphasizes temporal changes (both past and future) in biotic patterns and processes in fragmented agricultural landscapes. Integration of spatially and temporally explicit historical land‐use information into ecological studies can prove extremely useful to test hypotheses of the effects of changes in landscape processes, and to enhance future research, restoration and conservation management activities.