Biogeographical Attributes Research Articles

Evaluating ecosystem protection and fragmentation of the world's major mountain regions.

Conserving mountains is important for protecting biodiversity because they have high beta diversity and endemicity, facilitate species movement, and provide numerous ecosystem benefits for people. Mountains are often thought to have lower levels of human modification and contain more protected area than surrounding lowlands. To examine this, we compared biogeographic attributes of the largest, contiguous, mountainous region on each continent. In each region, we generated detailed ecosystems based on Köppen-Geiger climate regions, ecoregions, and detailed landforms. We quantified anthropogenic fragmentation of these ecosystems based on human modification classes of large wild areas, shared lands, and cities and farms. Human modification for half the mountainous regions approached the global average, and fragmentation reduced the ecological integrity of mountain ecosystems up to 40%. Only one-third of the major mountainous regions currently meet the Kunming-Montreal Global Biodiversity Framework target of 30% coverage for all protected areas; furthermore, the vast majority of ecosystem types present in mountains were underrepresented in protected areas. By measuring ecological integrity and human-caused fragmentation with a detailed representation of mountain ecosystems, our approach facilitates tracking progress toward achieving conservation goals and better informs mountain conservation.

Structural, ecological and biogeographical attributes of European vegetation alliances

AbstractThe first comprehensive phytosociological classification of all vegetation types in Europe (EuroVegChecklist; Applied Vegetation Science, 2016, 19, 3–264) contained brief descriptions of each type. However, these descriptions were not standardized and mentioned only the most distinct features of each vegetation type. The practical application of the vegetation classification system could be enhanced if users had the option to select sets of vegetation types based on various combinations of structural, ecological, and biogeographical attributes. Based on a literature review and expert knowledge, we created a new database that assigns standardized categorical attributes of 12 variables to each of the 1106 alliances dominated by vascular plants defined in EuroVegChecklist. These variables include dominant life form, phenological optimum, substrate moisture, substrate reaction, salinity, nutrient status, soil organic matter, vegetation region, elevational vegetation belt, azonality, successional status and naturalness. The new database has the potential to enhance the usefulness of phytosociological classification for researchers and practitioners and to help understand this classification to non‐specialists.

Revisiting a speciation classic: Comparative analyses support sharp but leaky transitions between Bombina toads

AbstractAimThe amount of gene flow between parapatric species can be greatly variable depending on how species boundaries are maintained in respect to numerous genetic and ecological factors that affect the strength of reproductive isolation. We quantified this variability to understand its effect on the genetic integrity of a well‐studied pair of hybridizing amphibians.LocationCentral and Eastern Europe.TaxaThe fire‐ and yellow‐bellied toads Bombina bombina and B. variegata.MethodsWe first complemented the mitochondrial phylogeography of European Bombina by barcoding additional populations and built MaxEnt species distribution models to identify the routes of post‐glacial colonization that led to hybrid zone formation. Second, we targeted the areas of parapatry in Poland and Ukraine to assess nuclear admixture by population genetics (PCA, Bayesian clustering) of allozyme and genomic markers (RAD‐seq). Third, we harvested the rich Bombina literature to thoroughly compare the extent of geographical introgression across 11 transitions altogether, using cline analyses when possible.ResultsWe found sharp (2–11 km wide) but leaky transitions (geographically extensive traces of introgression) in all parapatric areas, either measured from a few allozymes or thousands of species‐diagnostic SNPs, and irrespective of the intraspecific lineages involved or the relative ages since first contact.Main conclusionBombina species are permeable to gene flow despite selection against hybrids that retards but cannot ultimately prevent putatively neutral introgression into the parental gene pools. Although local hybrid swarms face genetic assimilation, the species’ integrities remain intact due to their large geographical ranges and ecological differentiation that enforces tight boundaries regardless of the biogeographical attributes of the contacts. Opposing the great variability of introgression patterns found between cryptic species, these results support that gene flow should not be viewed as a force of despeciation when reproductive isolation involves multiple intrinsic and extrinsic barriers.

Nature representation in South American protected areas: country contrasts and conservation priorities.

BackgroundSouth America faces strong environmental pressures as a result of agriculture and infrastructure expansion and also of demographic growth, demanding immediate action to preserve natural assets by establishing protected areas. Currently, 7.1% of the (sub)continent is under strict conservation categories (I to IV, IUCN), but the spatial distribution of these 1.3 × 106 km2 is poorly understood. We evaluated the representation of nature within the networks of protected areas, map conservation priorities and assess demographic, economic or geopolitical causes of existing protection patterns.MethodsWe characterized nature representation by looking at two components: the extent and the equality of protection. The first refers to the fraction of territory under protection, while the second refers to the homogeneity in the distribution along natural conditions of this protected fraction. We characterized natural conditions by either 113 biogeographical units (specifically, ecoregions) or a series of limited and significant climatic, topographic and edaphic traits. We analyzed representation every ten years since 1960 at national and continental levels. In the physical approach, histograms allowed us to map the degree of conservation priorities. Finally, we ranked the importance of different economic or geopolitical variables driving the observed distributions with a random forest technique.ResultsNature representation varied across countries in spite of its priority in conservation agendas. In Brazil, Peru and Argentina there are still natural conditions with no formal protection, while in Bolivia and Venezuela, protected areas incorporate the natural diversity in a more balanced manner. As protected networks have increased their extent, so did their equality across and within countries over time. Our maps revealed as top continental priorities the southern temperate, subhumid and fertile lowland environments, and other country-specific areas. Protection extent was generally driven by a low population density and isolation, while other variables like distance to frontiers, were relevant only locally (e.g., in Argentina).DiscussionOur description of the spatial distribution of protected areas can help societies and governments to improve the allocation of conservation efforts. We identified the main limitations that future conservation efforts will face, as protection was generally driven by the opportunities provided by low population density and isolation. From a methodological perspective, the physical approach reveals new properties of protection and provides tools to explore nature representation at different spatial, temporal and conceptual levels, complementing the traditional ones based on biodiversity or biogeographical attributes.

Stable but fragile: long-term dynamics of arctic benthic macrofauna in Baydaratskaya Bay (the Kara Sea)

Climate change and direct impacts of human activity are often considered among the main drivers of ecosystem dynamics; however, their relative importance for high-Arctic marine systems is not clearly understood. The Baydaratskaya Bay (southwestern part of the Kara Sea) was not subject to any human activity until 2011, when the construction of the underwater portion of a gas pipeline began; thus, it is a good place to investigate this issue. We used data on the macrobenthos from 1945 to 2013 to assess temporal variability and reveal either decadal-scale trends or construction impacts on the ecosystem. Until 2013, no evidence of long-term changes was detected in biomass, diversity, species composition, functional structure, and biogeographic attributes of the fauna. The ecological status was permanently evaluated as undisturbed. In 2013, however, an extensive shift occurred in the deep-sea area close to the pipeline trench. Benthic biomass and diversity decreased abruptly; while total abundance increased. The functional structure changed. Large bivalves almost completely disappeared, abundance of gastropods and amphipods dropped sharply, while the abundance of small opportunistic polychaetes increased abruptly. Benthic quality assessment indices indicated the deterioration of the community. The most likely reason for such catastrophic changes was the direct impact of dredging and dumping of sediments during pipeline burial from 2012 to 2013. We conclude that the benthic macrofauna in Baydaratskaya Bay has remained relatively stable over the last several decades without any signs of climate-driven borealization. Recent human activity, however, caused local but rapid and strong response, indicating the high sensitivity and vulnerability of this ecosystem.

Evolution in Extremis: The When, How, and Why of Hawaiian Carabid Beetles

The Hawaiian Archipelago is the most isolated oceanic island system in the World, separated from the nearest source areas by more than 4000 km. Five independent colonization events have resulted in diversification of a native carabid beetle fauna in excess of 400 known species. This diverse assemblage is disharmonic, with the major radiations restricted to the platynine genus Blackburnia Sharp (139 species), the subgenus Nesocidium Sharp of Bembidion Latreille (21 species), and the moriomorphine genus Mecyclothorax Sharp (239 species). Biogeographical, ecological, and evolutionary attributes of these three radiations are compared in order to determine factors crucial to carabid beetle diversification in this most-isolated situation. Biogeographical attributes include the age of origin of the constituent radiation, the island likely colonized by its common ancestor, and the biological characteristics, where known, of the colonizing ancestors for each independent radiation. Ecological attributes include the amount of habitat specialization undergone during each radiation, taking into account the primordial habitat colonized and the subsequent pattern of occupation of different habitat types during diversification. Evolutionary attributes include brachyptery, body-size evolution, sexual selection, and the evolution of specialized body conformations. It is shown that ecological specialization—i.e., occupation of a diverse array of ecological zones and microhabitats—in concert with reduced dispersal ability brought on by evolution of brachyptery are positively associated with enhanced levels of diversification. Comparing sympatric island faunas, it is shown that the latter operates synergistically with body size, as the smaller-bodied Mecyclothorax beetles speciate much more rapidly than the larger-bodied Blackburnia on Maui and Hawai῾i Island. Nonetheless, small body size does not gaurantee high diversity, as Bembidion beetles attain body sizes similar to Mecyclothorax beetles. Age of origin of a radiation is a subsidiary criterion for diversification given that the Mecyclothorax radiation commenced only 1.2 Ma, whereas it is hypothesized that Blackburnia have been resident in the Hawaiian archipelago for upwards of 28 Ma. Thus especially for Blackburnia we are constrained in our ability to know all of the evolutionary products of the radiation due to extinction of presumably all or nearly all species that occupied the now-sunken islands northwest of the oldest high island of Kauai. We are fortunate to know of several extinct Blackburnia species discovered in lowland subfossil deposits in Kauai, and these species provide crucial information now regarding future patterns of extinction. Sexual selection can be demonstrated for the Bembidion subgenus Nesocidium, and is a likely explanation for genitalic evolution over parts of the Mecyclothorax radiation, but it is not a phenomenon pervasively associated with increased levels of speciation.

Classification and comparison of five estuaries in the southeast Gulf of California based on environmental variables and fish assemblages

Estuarine systems in subtropical and tropical areas of the Mexican Pacific are characterized by specific hydrological, biological, and anthropogenic conditions. Using multivariate analyses of geomorphic, biological, and anthropogenic variables, five of the largest estuarine systems of the southeastern Gulf of California were classified into estuary type using a similar classification method to that employed in New South Wales, Australia. Three estuary types were identified: tide-dominated, wave-dominated, and intermittently-closed. The characteristics of each estuary type were related to the fish assemblages from every system, using catch per unit effort to make results comparable among all estuaries. Our results demonstrated that intrinsic estuarine characteristics, such as geomorphologic, biological, physicochemical, anthropogenic, and biogeographical attributes, are likely to have a strong influence on the diversity and structure of fish assemblages, but more information is needed on the ecology and biology of the fish fauna to understand how these variables affect the different fish species.

Beyond a Climate-Centric View of Plant Distribution: Edaphic Variables Add Value to Distribution Models

Both climatic and edaphic conditions determine plant distribution, however many species distribution models do not include edaphic variables especially over large geographical extent. Using an exceptional database of vegetation plots (n = 4839) covering an extent of ∼55000 km2, we tested whether the inclusion of fine scale edaphic variables would improve model predictions of plant distribution compared to models using only climate predictors. We also tested how well these edaphic variables could predict distribution on their own, to evaluate the assumption that at large extents, distribution is governed largely by climate. We also hypothesized that the relative contribution of edaphic and climatic data would vary among species depending on their growth forms and biogeographical attributes within the study area. We modelled 128 native plant species from diverse taxa using four statistical model types and three sets of abiotic predictors: climate, edaphic, and edaphic-climate. Model predictive accuracy and variable importance were compared among these models and for species' characteristics describing growth form, range boundaries within the study area, and prevalence. For many species both the climate-only and edaphic-only models performed well, however the edaphic-climate models generally performed best. The three sets of predictors differed in the spatial information provided about habitat suitability, with climate models able to distinguish range edges, but edaphic models able to better distinguish within-range variation. Model predictive accuracy was generally lower for species without a range boundary within the study area and for common species, but these effects were buffered by including both edaphic and climatic predictors. The relative importance of edaphic and climatic variables varied with growth forms, with trees being more related to climate whereas lower growth forms were more related to edaphic conditions. Our study identifies the potential for non-climate aspects of the environment to pose a constraint to range expansion under climate change.

Book review: Avian history is written by the winners

news and update book review Avian history is written by the winners Avian survivors: The history and biogeography of Palearctic birds, by Clive Finlayson, 2011, T & AD Poyser Ltd., 304 pp. £50 (Hardback) ISBN: 9780713688658; http://www.acblack.com/naturalhistory/ This is a difficult book to review fairly, because it is not a book to read through, nor is its intention easily discerned. It is a profound and deeply detailed compilation, assessing the climatic, historical and biogeographical attributes of the bird fauna of the Western Palaearctic. Its intention is to understand how this particular constellation of species survived through the climatic vicissitudes of the Tertiary Period, and especially the last 2 million years of the Pleistocene climatic fluctuations, to be combined as the extant fauna. Finlayson was inspired by the remarkably diverse faunas that appear in the caves of Gibraltar, at the extreme southern tip of the Western Palaearctic. At different times these included northern species such as Great Auk and Velvet Scoter, at others southern species such as Lammergeier and Crag Martin. Those that still occur in the Palaearctic are the survivors of his title. He starts with a short outline of the climatic, geographical and ecological changes that affected the region during the Tertiary, as Africa and India shifted north to collide with Europe and Asia, so closing the Mediterranean, and causing the uplift of the mountain ranges across central Europe and Asia that changed the climate, especially the strength and direction of rain-bearing winds. Grasses evolved in this period, and grasslands, replacing tropical forests, became more widespread. His analysis of the times of origin of bird genera that, at present, include migratory species, especially Trans-Saharan migrants, suggests that many of them evolved in the Miocene, as the grasslands appeared. Popular, perhaps superficial, opinion has assumed that the glacial-interglacial cycles of the Pleistocene prompted the evolution of the migratory habit, but this analysis strongly suggests that it was already well established. The majority of the book is a detailed examination of each family, genus and species that is currently represented in the Palaearctic. It assesses their climatic limits, habitat requirements and likely history. Much modern work on genetic phylogeny is used to assess the zoogeographic origins of such taxa, when they migrated into the Palaearctic, and how their climatic requirements have persisted, along with the taxa themselves. Each is assigned to its climatic and latitudinal tolerance ranges, and to its migratory group (sedentary, partial migrant, Trans-Saharan migrant). For instance, Finlayson interprets the history of the Corvidae as probably evolving in Australia, and migrating into the tropical forests of Southeast Asia, where a great diversity of basal genera still occur; but one, the Choughs (Pyrrhocorax) migrated out along the great mountain chain right across Asia and Europe in the Miocene, as mountain uplift created their drier upland habitat. However, most corvids remained essentially forest species, and migrated west along the forest belts south (mostly deciduous) or north (mostly coniferous) of the mountains. Corvids reside mostly in more humid climatic zones, and few show much migratory behaviour. Fossil corvids are represented in Europe by Middle Miocene times; two modern genera are present by the Early Pliocene (Pyrrhocorax, Pica, two more by Middle Pliocene (Garrulus, Nucifraga) and all by Early Pleistocene. Sometimes the detailed evidence on which such histories are based is clearly indicated. The fossil record is largely quoting the compilation by Mlikovský (2002), and the phylogenetic references are well cited. However, much of the story is informed speculation, of probable histories and probable spreads, based upon known climatic and geographical changes, and the known broad ecological requirements of the taxa. Given the number of taxa involved, this amounts to quite a lot of speculation accumulated over the book as a whole. This is not to suggest that it is wrong, nor does it deny its value. A lot of diverse information frontiers of biogeography 4.1, 2012 — © 2012 the authors; journal compilation © 2012 The International Biogeography Society

Strong human association with plant invasion success for Trifolium introductions to New Zealand

It has proven difficult, when focused only on biological determinants, to explain why some plant species become naturalized in or invade new locations, whereas others fail. We analyzed the invasion of Trifolium (true clover) species into New Zealand, assessing a range of human, biogeographic, and biological influences at three key invasion stages: introduction, naturalization, and spread. We used sparse principal component analysis (SPCA) to define suites of related attributes and aggregated boosted trees to model relationships with invasion outcomes. Human and biogeographic attributes were strongly associated with success at all stages. Whereas biogeographic attributes, notably large native range, were consistently associated with success, different human factors appeared to favor success at different stages, such as presence in early trade/immigration hotspots (introduction), intentional large-scale planting (naturalization), and frequent presence as a seed contaminant (relative spread rate). Biological traits were less strongly associated with success for introduction and spread and little if at all for naturalization; we found that tall perennials with long flowering periods were more frequently selected for introduction, whereas species with extended flowering in New Zealand spread more rapidly. In addition to causal relationships, the importance of human factors may reflect indirect associations, including ecological traits associated with both human use and invasion. Nevertheless, our results highlight key roles that humans can play in facilitating plant invasion via two pathways: (i) commercial introduction leading to widespread planting and concomitant naturalization and spread and (ii) unintentional introduction and spread of species associated with human activities, such as seed contaminants.

Diversification in the Tropical Pacific: Comparisons Between Marine and Terrestrial Systems and the Importance of Founder Speciation

Patterns of distribution and processes of differentiation have often been contrasted between terrestrial and marine biotas. The islands of Oceania offer an excellent setting to explore this contrast, because the geographic setting for terrestrial and shallow-water, benthic, marine organisms are the same: the myriad islands strewn across the vast Pacific. The size of species ranges and the geographic distribution of endemism are two biogeographic attributes that are thought to differ markedly between terrestrial and marine biotas in the Pacific. While terrestrial species are frequently confined to single islands or archipelagoes throughout Oceania, marine species tend to have wide to very wide distributions, and are rarely restricted to single island groups except for the most isolated archipelagoes. We explore the conditions under which species can reach an island by dispersal and differentiate. Genetic differentiation can occur either through founder speciation or vicariance; these processes are requisite ends of a continuum. We show that founder speciation is most likely when few propagules enter the dispersal medium and survive well while they travel far. We argue that conditions favorable to founder speciation are common in marine as well as terrestrial systems, and that terrestrial-type, archipelagic-level endemism is likely common in marine taxa. We give examples of marine groups that show archipelagic level endemism on most Pacific island groups as well as of terrestrial species that are widespread. Thus both the patterns and processes of insular diversification are variable, and overlap more between land and sea than previously considered.

Biostratigraphic and biogeographic constraints on the Carboniferous to Jurassic Cache Creek Terrane in central British Columbia

Conodonts, radiolarians, foraminiferids, and corals provide constraints on the geology and tectonics of the Nechako region. They also support the notion that the Cache Creek Terrane is allochthonous with respect to the North American craton. The 177 conodont collections, assigned to 20 faunas, range in age from Bashkirian (Late Carboniferous) to Norian (Late Triassic); 70 radiolarian collections representing 12 zones range from Gzhelian (Late Carboniferous) to Toarcian (Early Jurassic); 335 collections assigned to 11 fusulinacean assemblages (with associated foram-algal associations) range from Bashkirian to Wordian (Middle Permian); and two coral faunas are of Bashkirian and Wordian age. The fossils document a long but sporadic history of sedimentary events within the Cache Creek Complex that included two major carbonate buildups in the Late Carboniferous (Pope limestone) and Middle Permian (Copley limestone), punctuated by intervening Early Permian deepening; basaltic eruptions during the mid Carboniferous and mid Permian; the onset of oceanic chert sedimentation close to the Carboniferous–Permian boundary and its persistence through the Late Triassic (Sowchea succession); latest Permian and Early Triassic mixed clastics and volcanics (Kloch Lake succession); Middle and Late Triassic reworking of carbonates (Whitefish limestone), including cavity fill in older limestones (Necoslie breccia), and fine-grained clastic sedimentation extending into the Early Jurassic (Tezzeron succession). Tethyan, eastern Pacific, and (or) low-latitude biogeographic attributes of the faunas are noted in the Gzhelian (fusulines), Artinskian (conodonts, fusulines), Wordian (fusulines, corals, conodonts), and Ladinian (conodonts, radiolarians). The Cache Creek Terrane lay far to the west of the North American continent during these times.

The effects of isolation, habitat fragmentation and degradation by livestock grazing on the use by birds of patches of Gimlet Eucalyptus salubris woodland in the wheatbelt of Western Australia

The numbers of species, and the frequency of occurrence of individual species, in patches of Gimlet Eucalyptus salubris woodland in remnants of native vegetation in the central wheatbelt of Western Australia were recorded over a year. These values were examined in relation to the structural characteristics of the patches and the biogeographic attributes of the remnants (i.e., size and various indices of isolation from other native vegetation). There were five patches in large remnants (>100 ha) and 24 patches in small remnants (0.5?27.0 ha). Most of the small remnants were grazed by livestock and had lost much or all of the shrub understorey. The Galah Cacatua roseicapilla and Port Lincoln Ringnecked Parrot Platycercus zonarius were found in all patches, but the remaining large species of birds (Australian Raven Corvus coronoides,Pied Butcherbird Cracticus nigroregularis, Crested Pigeon Ocyphaps lophotes, and Yellow-throated Miner Manorina flavigula) were found more frequently in patches in small remnants. Conversely, with the exception of the Striated Pardalote Pardalotus striatus, small passerine species were found less frequently in patches in small remnants. Remnant size was significantly negatively correlated with frequency of occurrence of six of the eight common large species, indicating that these species concentrated in patches in small remnants, and significantly positively correlated with frequency of occurrence of two of four small passerine species. Having taken out the effect of remnant area, a stepwise regression procedure was used to see whether other biogeographic attributes of the remnants or habitat structure in the patches influenced the frequency of occurrence of individual species and species richness. As area of native vegetation within a 5 km radius increased so did the frequency of occurrence of the Galah and Port Lincoln Parrot, indicating that local numbers of the species affects their presence. Of the large birds only the Yellowthroated Miner was influenced by patch structural attributes whereas all species of small passerines showed responses to various structural attributes of the patches. Frequency of occurrence of the Striated Pardalote and the number of species of small passerines in a patch decreased with increasing distance to the nearest native vegatation. Overall frequency of occurence of small passerines increased with the number of linear strips of native vegetation linked to a remnant. In this study a majority of the small remnants were too small to support resident birds. The Gimlet patches, if used, would be part of a home range. Loss of the shrub understorey through grazing and loss of canopy cover through tree deaths had a significant impact on numbers of species of small passerines using the Gimlet patches. The conservation value of the patches in small remnants would be enhanced by increasing remnant size and by the linking of remnants to nearby native vegetation.

Predicting Invasions of Woody Plants Introduced into North America

Plant species continue to be introduced in North America for various purposes. If the trend continues, it is probable that some will escape cultivation and become invasive in native ecosystems. We present a retrospective analysis of several structural, life history, and biogeographical attributes of woody plants introduced in North America to determine which traits characterize species that have and have not invaded. Predictive models derived from discriminant analysis correctly classified 86.2% of the species in cross‐validation, whereas those derived from classification and regression trees classified 76% correctly. From these models we created a hierarchical predictive tree that allows the user to divide species into three categories: admit (low risk of invasiveness), deny admission (high risk of invasiveness), or delay admission for further analyses and/or monitor intensively (risk cannot adequately be assessed based on only the included attributes). We recommend that species that are highly invasive elsewhere not be allowed into the U.S. and that a more conservative introduction policy using a hierarchical predictive method be employed.