bluuebunny/crossref_metadata_2025_split huggingface dataset:
Genetic relationships between native and introduced populations of the little fire ant Wasmannia auropunctata
Authors: Mikheyev Alexander S. , Mueller Ulrich G. 
Published: February 2009

AbstractNative to much of Central and South America, the little fire ant Wasmannia auropunctata has been rapidly spreading throughout the world. In its introduced range, W. auropunctata is frequently linked with drastic reductions of ant diversity; anecdotal reports of damaging attacks on vertebrates are also common. As it poses an ever‐increasing threat to biodiversity, W. auropunctata has emerged as a model system for the study of ecological differences between native and invasive ant populations. These studies have been hampered by a lack of information on the genetic relatedness between native and introduced populations. By investigating the genetic structure of W. auropunctata populations, we provide a framework for conducting phylogenetically independent tests of differences between these ants in their native and invasive ranges. Phylogenetic analyses, based on the cox1/cox2 region of mtDNA, revealed at least three separate source populations of W. auropunctata distributed across two large clades. Much of the Caribbean region, presumably part of the native range, is inhabited by a clade of ants sharing very similar or identical mtDNA haplotypes, suggesting the possibility of multiple introductions or high levels of gene flow across that area. Most invasive populations in the Pacific were closely related to these ants. The invasive populations in Gabon and New Caledonia arise from another, relatively distantly related clade. Phylogenetically independent contrasts confirm McGlynn's (1999) observation that invasive W. auropunctata populations are smaller than native populations. Given the complex phylogeographical structure of W. auropunctata populations, future comparative work should correct for phylogenetic effects.
Predicting mountain plant richness and rarity from space using satellite‐derived vegetation indices
Authors: Levin Noam , Shmida Avi , Levanoni Oded , Tamari Hagit , Kark Salit 
Published: February 2009

ABSTRACTCan species richness and rarity be predicted from space? If satellite‐derived vegetation indices can provide us with accurate predictions of richness and rarity in an area, they can serve as an excellent tool in diversity and conservation research, especially in inaccessible areas. The increasing availability of high‐resolution satellite images is enabling us to study this question more carefully. We sampled plant richness and rarity in 34 quadrats (1000 m2) along an elevation gradient between 300 and 2200 m focusing on Mount Hermon as a case study. We then used 10 Landsat, Aster, and QuickBird satellite images ranging over several seasons, going up to very high resolutions, to examine the relationship between plant richness, rarity, and vegetation indices calculated from the images. We used the normalized difference vegetation index (NDVI), one of the most commonly used vegetation indexes, which is strongly correlated to primary production both globally and locally (in more seasonal and in drier and/or colder environments that have wide ranges of NDVI values). All images showed a positive significant correlation between NDVI and both plant species richness and percentage tree cover (with R2 as high as 0.87 between NDVI and total plant richness and 0.89 for annual plant richness). The high resolution images enabled us to examine spatial heterogeneity in NDVI within our quadrats. Plant richness was significantly correlated with the standard deviation of NDVI values (but not with their coefficient of variation) within quadrats and between images. Contrary to richness, relative range size rarity was negatively correlated with NDVI in all images, this result being significant in most cases. Thus, given that they are validated by fieldwork, satellite‐derived indices can shed light on richness and even rarity patterns in mountains, many of which are important biodiversity centres.
Newts under siege: range expansion of Triturus pygmaeus isolates populations of its sister species
Authors: Themudo G. Espregueira , Arntzen J. W. 
Published: February 2009

ABSTRACTThe newt species Triturus marmoratus and Triturus pygmaeus are both present in central Portugal where they have parapatric distributions. We used four genetic markers to determine which species was present in 31 populations. In the centre of the study area we found a T. marmoratus enclave. Despite small interpopulation distances, hybridization is locally rare. We built several models to try to explain this distribution using environmental data. The best model, chosen by Akaike's Information Criterion, relates the presence of T. marmoratus with the temperature in July, the relief of the landscape, and a higher use of the land for orchards. The current distribution can best be explained by T. pygmaeus expanding north and replacing T. marmoratus, the latter only persisting where ecological conditions are relatively favourable.
Invasive exotic aoudad (Ammotragus lervia) as a major threat to native Iberian ibex (Capra pyrenaica): a habitat suitability model approach
Authors: Acevedo Pelayo , Cassinello Jorge , Hortal Joaquín , Gortázar Christian 
Published: February 2009

ABSTRACTThe introduction of alien species to new environments is one of the main threats to the conservation of biodiversity. One particularly problematic example is that of wild ungulates which are increasingly being established in regions outside their natural distribution range due to human hunting interests. Unfortunately, we know little of the effects these large herbivores may have on the host ecosystems. This study deals with a first comparative analysis of the habitat requirements of two ungulate species that may be facing competition for resources in the south of Europe: the native Iberian ibex (Capra pyrenaica) and the exotic aoudad (Ammotragus lervia). The aoudad is a North African caprid introduced in 1970 as a game species in south‐eastern Spain. It has adapted well, and populations have been freely expanding since then. Ecological Niche Factor Analysis is used to describe the realized niche of both species where their distribution ranges merge. Both species occupy marginal areas of rugged terrain in the region. Marginality is higher for the Iberian ibex, which also presents a higher tolerance of secondary environmental gradients than the aoudad. Highly suitable areas for each species are secondarily suitable for the other. Reclassified and cross‐tabulated habitat suitability maps showing the areas of potential spatial coexistence and differences in ecological traits between both species are provided. The results obtained do not allow inferring resource competition between these species. However, current aoudad expansion could result in it invading the favoured habitats of the ibex. Inadequate hunting policy and monitoring, and increasing climatic resemblance of the study region to the native aoudad areas, due to a strong desertification process, are facilitating a high rate of expansion. We strongly recommend to eradicate or, at least, monitor these exotic populations, and promote active conservation practices, if one wants to preserve the unique natural resources present in this European region.
Developing products for conservation decision‐making: lessons from a spatial biodiversity assessment for South Africa
Authors: Reyers B. , Rouget M. , Jonas Z. , Cowling R. M. , Driver A. , Maze K. , Desmet P. 
Published: February 2009

ABSTRACTSouth Africa's first national assessment of spatial priorities for biodiversity conservation, released in 2005, aimed to identify conservation priority areas for mainstreaming into all sectors at national and provincial scales. This National Spatial Biodiversity Assessment (NSBA) was based on a planning for implementation approach in order to deliver defensible products useful to decision‐makers. The NSBA aimed to produce a map of broad‐scale priority areas for future finer‐scale assessment and conservation action. This map summarized information on species, ecosystems, ecological processes, and the pressures they face from human activities. Owing to the complexity of the priority area map, two additional user‐friendly products — maps of ecosystem status and protection levels — were developed. These products represented the habitat loss and protected area coverage of South Africa's ecosystems relative to their conservation targets. A year after release, we reflect on the NSBA process, products and uptake by implementing agencies (with a specific focus on the terrestrial biodiversity assessment) in order to contribute to the growing body of documented best practice in conservation planning. The ecosystem status product has been widely used at national and provincial scales due in large to its clear and compelling message. The protection level and overall priority map have also witnessed uptake, the former in guiding the expansion of protected areas and the latter as an integrated map of national biodiversity status. The strong collaboration of local planners and implementers with in‐depth experience of biodiversity assessment, using a systematic approach and focusing on communicating a few high level messages, appears to have contributed to the initial, successful uptake of the NSBA. We conclude with a call to address data and monitoring shortcomings before the next NSBA in 2010.
An index to compare geographical distributions of species
Authors: Erni Birgit , Altwegg Res , Underhill Les G. 
Published: February 2009

AbstractWe present an index for the dissimilarity/distance between geographical distributions based on reporting rates recorded on a regular lattice. Reporting rate data are common, for example, in bird atlas projects where observers fill in check lists of encountered species in a particular area. Our index is a variation of the Euclidean distance, with the contribution of each grid cell weighted by the number of checklists collected for the grid cell, and a scaling factor to ensure that the dissimilarity ranges between zero and one. Reporting rates were transformed to ordered percentile classes to make species with different mean reporting rates comparable. The index was developed for the comparison of distributions of The Atlas of Southern African Birds. We illustrate the dissimilarity index comparing distributions of whydahs and indigobirds (widowfinches), which are specialized brood parasites, to the distributions of their hosts: waxbills and other finches.
How does the knowledge about the spatial distribution of Iberian dung beetle species accumulate over time?
Authors: Lobo Jorge M. , Baselga Andrés , Hortal Joaquín , Jiménez‐Valverde Alberto , Gómez Jose F. 
Published: February 2009

ABSTRACTDifferent distribution maps can be obtained for the same species if localities where species are present are mapped at different times. We analysed the accumulation of information over time for a group of dung beetle species in the Iberian Peninsula. To do this, we used all available information about the distribution of the group as well as data on selected species to examine if the process of discovery of species distribution has occurred in a climatically or spatially structured fashion. Our results show the existence of a well‐defined pattern of temporal growth in distributional information; due to this, the date of capture of each specimen can be explained by the environmental and spatial variables associated to the collection sites. We hypothesize that such temporal biases could be the rule rather than the exception in most distributional data. These biases could affect the weighting of environmental factors that influence species distributions, as well as the accuracy of predictive distribution models. Systematic surveys should be a priority for the description of species geographical ranges in order to make robust predictions about the consequences of habitat and climate change for their persistence and conservation.
Regional patterns of recruitment success and failure in two endemic California oaks
Authors: Zavaleta Erika S. , Hulvey Kristin B. , Fulfrost Brian 
Published: February 2009

ABSTRACTOak woodlands and savannas are key defining landscapes in the California Floristic Province, making up almost a quarter of the region's forests and woodlands. Two endemic Californian oak species, valley oak (Quercus lobata Neé) and blue oak (Quercus douglasii Hook. & Arn.), are widely considered at risk of decline from persistent recruitment failures in the last century. However, decades of research have produced no definitive conclusion about the existence, extent, or causes of this ‘regeneration problem’. Underlying causes of perceived recruitment failure are unclear and could include drivers at distribution‐wide to local scales including climate and atmospheric changes, habitat fragmentation, altered herbivore populations, changing fire regimes, exotic plant and animal invasions, livestock grazing, and soil conditions altered by past land uses. We performed meta‐analyses of existing stand‐scale data from the published and grey literatures on seedling and sapling recruitment in blue and valley oaks throughout each of their distributions. We sought to evaluate whether distribution‐wide regeneration ‘problems’ exist for either species and to assess what factors correlate with distribution‐wide recruitment patterns. Nearly 80% of sites surveyed for blue oaks but fewer than 50% of sites surveyed for valley oaks contained some evidence of seedling or sapling recruitment. A majority of sites surveyed for both species appear to have insufficient recruitment to replace adult populations, though further demographic work would be required to quantify minimum replacement recruitment rates. Reserve sites were seven times more likely than non‐reserve sites to contain valley oak populations with evidence of recruitment. Blue oak recruitment patterns were weakly related to climate and geographical factors and strongly variable at subregional scales. We suggest several lines of additional research that could fill gaps in the existing literature and clarify the patterns emerging from this analysis.
Will hotspots conserve extra primate and carnivore evolutionary history?
Authors: Spathelf Miles , Waite T. A. 
Published: February 2009

ABSTRACTSetting aside biodiversity hotspots would be especially compelling if they contained not just enormous numbers of species but also excessive evolutionary history. A recent study seemed to provide evidence for this incentive for hotspot conservation.Sechrestet al. (2002) reported that hotspots contain more endemic phylogenetic diversity (PD) than expected based on the numbers of primate and carnivore species they contain. We extend their analysis and revise some of their claims. For primates and threatened carnivores, we show that the original analysis was driven by a single hotspot (Madagascar) that contains an ancient endemic clade. The remaining hotspots harbour less rather than significantly more endemic PD than expected. Thus, while one hotspot contains an enormous excess of evolutionary history, the remaining hotspots do not. Our analysis reveals that the overriding influence of a single hotspot can create the misleading impression that hotspots generally contain excessive evolutionary history. Justification for the hotspot initiative should be based on robust evidence. We join others in endorsing an increased role for detailed phylogenetic analysis in conservation planning.
Land use changes affect distributional patterns of desert birds in the Baja California peninsula, Mexico
Authors: Rodríguez‐Estrella Ricardo 
Published: February 2009

AbstractReliable plans for desert bird conservation will depend on accurate prediction of habitat change effects on their distribution and abundance patterns. Predictive models can help highlight relationships between human‐related and other environmental variables and the presence of desert bird species. Presence/absence of 30 desert bird species of Baja California peninsula was modelled on the basis of explanatory variables taken from the field, maps, and digital imagery. Generalized linear models were fit to each bird species using both variables representing human activity and other environmental factors as predictors that might influence distribution. Probability of species presence was used as a habitat suitability index to evaluate the effect of human activity when the model contained a significant human activity variable. No differences were found in bird species richness between natural sites and those transformed by agriculture or urbanization. Of 59 bird species recorded in surveys, 34% were positively or negatively associated with human‐transformed habitats. Fourteen species seem to benefit from transformation of natural vegetation by agriculture or urbanization, while six were negatively affected. Sensitivity analyses of final models indicated all were robust. Results suggest that the occurrence of a large percentage of bird species inhabiting scrub habitats is sensitive to human habitat transformation. This finding has important conservation implications at regional scale as fragmentation and conversion of desert ecosystems into agricultural and urban areas affect the distribution of species that are highly selective for scrub habitat. Land use and anthropogenic activities seem to change ecological patterns at large spatial scales, but other factors could drive species richness distribution too (i.e. individual species response, species–energy relationships). The spatial modelling approach at regional scale used in this study can be useful for designing natural resource management plans in the Sonoran desert scrub.
Regional assessment of the impact of climatic change on the distribution of a tropical conifer in the lowlands of South America
Authors: Ledru Marie‐Pierre , Salatino Maria Luisa Ferraz , Ceccantini Gregorio , Salatino Antonio , Pinheiro Fabio , Pintaud Jean‐Christophe 
Published: February 2009

AbstractFor decades, palynologists working in tropical South America are using the genus Podocarpus as a climate indicator although without referring to any modern data concerning its distribution and limiting factors. With the aim to characterize the modern and past distribution of the southern conifer Podocarpus in Brazil and to obtain new information on the distribution of the Atlantic rainforest during the Quaternary, we examined herbarium data to locate the populations of three Brazilian endemic Podocarpus species: P. sellowii, P. lambertii, and P. brasiliensis, and extracted DNA from fresh leaves from 26 populations. Our conclusions are drawn in the light of the combination of these three disciplines: botany, palynology, and genetics. We find that the modern distribution of endemic Podocarpus populations shows that they are widely dispersed in eastern Brazil, from north to south and reveals that the expansion of Podocarpus recorded in single Amazonian pollen records may have come from either western or eastern populations. Genetic analysis enabled us to delimit regional expansion: between 5° and 15° S grouping northern and central populations of P. sellowii expanded c. 16,000 years ago; between 15° and 23° S populations of either P. lambertii or sellowii expanded at different times since at least the last glaciation; and between 23° and 30° S, P. lambertii appeared during the recent expansion of the Araucaria forest. The combination of botany, pollen, and molecular analysis proved to be a rapid tool for inferring distribution borders for sparse populations and their regional evolution within tropical ecosystems. Today the refugia of rainforest communities we identified are crucial hotspots to allow the Atlantic forest to survive under unfavourable climatic conditions and, as such, offer the only possible opportunity for this type of forest to expand in the event of a future climate change.
A changing climate is eroding the geographical range of the Namib Desert tree Aloe through population declines and dispersal lags
Authors: Foden Wendy , Midgley Guy F. , Hughes Greg , Bond William J. , Thuiller Wilfried , Hoffman M. Timm , Kaleme Prince , Underhill Les G. , Rebelo Anthony , Hannah Lee 
Published: February 2009

ABSTRACTWhile poleward species migration in response to recent climatic warming is widely documented, few studies have examined entire range responses of broadly distributed sessile organisms, including changes on both the trailing (equatorward) and the leading (poleward) range edges. From a detailed population census throughout the entire geographical range of Aloe dichotoma Masson, a long‐lived Namib Desert tree, together with data from repeat photographs, we present strong evidence that a developing range shift in this species is a ‘fingerprint’ of anthropogenic climate change. This is explained at a high level of statistical significance by population level impacts of observed regional warming and resulting water balance constraints. Generalized linear models suggest that greater mortalities and population declines in equatorward populations are virtually certainly the result, due to anthropogenic climate change, of the progressive exceedance of critical climate thresholds that are relatively closer to the species’ tolerance limits in equatorward sites. Equatorward population declines are also broadly consistent with bioclimatically modelled projections under anticipated anthropogenic climate change but, as yet, there is no evidence of poleward range expansion into the area predicted to become suitable in future, despite good evidence for positive population growth trends in poleward populations. This study is among the first to show a marked lag between trailing edge population extinction and leading edge range expansion in a species experiencing anthropogenic climate change impacts, a pattern likely to apply to most sessile and poorly dispersed organisms. This provides support for conservative assumptions of species’ migration rates when modelling climate change impacts for such species. Aloe dichotoma's response to climate change suggests that desert ecosystems may be more sensitive to climate change than previously suspected.
The chytrid fungusBatrachochytrium dendrobatidisis non‐randomly distributed across amphibian breeding habitats
Authors: Kriger Kerry M. , Hero Jean‐Marc 
Published: February 2009

ABSTRACTThe chytrid fungusBatrachochytrium dendrobatidishas been implicated as the causative agent of mass mortalities, population declines, and the extinctions of stream‐breeding amphibian species worldwide. While the factors that limit the distribution and abundance ofB. dendrobatidisacross large geographical regions are fairly well understood, little is known about the distribution of the fungus within localized areas such as individual catchments. The accurate identification of amphibian populations likely to be exposed to the fungus is urgently required for effective disease management. We conducted disease surveys of frogs representing five ecological guilds in south‐east Queensland, Australia, and hypothesized that ifB. dendrobatidiswere responsible for the disappearance of stream‐breeding amphibian populations, infection prevalence and intensity would be greatest in frogs breeding in permanent, flowing water. Overall, 30.3% of the 519 frogs we sampled were infected withB. dendrobatidis. However, infections were not evenly distributed across the ecological guilds, being almost completely restricted to frogs breeding at permanent waterbodies. Of these, stream breeders were significantly more likely to be infected than were pond breeders, though the intensity of frogs’ infections did not differ significantly between the two guilds.Batrachochytrium dendrobatidiswas detected on only one of the 117 frogs that were found at ephemeral ponds, ephemeral streams, or terrestrial sites. These findings provide strong support for the hypothesis thatB. dendrobatidiswas responsible for many of the unexplained disappearances of stream‐breeding amphibian populations in recent decades, and will enable wildlife managers to more accurately focus conservation efforts on those species at highest risk of disease‐related decline.