Minimum Adequate Models Research Articles

Does competition management improve the ecophysiological response to water shortage of mixed woodland species of North Patagonia?

Globally, the increasing forests vulnerability and drought-induced forest mortality events, extended to a larger scale, may have the potential to rapidly alter forest functioning and the provision of ecosystem services. Patagonian forests in Southern South America constitute an extensive reservoir of wildlife, but at the same time they have high productive potential. These low-mixed forests are composed of co-dominant species that are highly disturbed by local population, both for cattle raising and wood extraction; and different efforts are being dedicated to improve their management. Very little is known about the response of their different woody species to climatic variation, particularly to severe drought in particular, that may guide management strategies to improve productivity and resilience in context of drought stress and climate change. The present study aimed at characterizing the physiological strategies of response to drought to identify the most vulnerable and most resilient species to drought and how they respond under different competition levels. The response of four species of the Andean Patagonian low mixed forest was quantified at three moments of the 2018–2019 growing season in three sites through measurements of the net carbon exchange, vulnerability to xylem cavitation, tissue water relations, and damage of the photosynthetic apparatus. Additionally, records of average monthly values of precipitation and air temperature were used to calculate a standardized precipitation-evapotranspiration index. The normal climatic conditions of NW Patagonia region are characterized by water deficits during the spring-summer growing season, but the studied season presented lower values of standardized precipitation-evapotranspiration index respect to the historical mean values, indicating drier than normal conditions. Analysis of the tissue water relations showed that, in all cases, competition had no effect over the different studied parameters. There were species-specific differences in the models fitted to the vulnerability to cavitation curves; as a whole, all the species differed from each other. Overall, for all the physiological response traits studied, the Site, Species, and Season factors were important predictors in the minimum adequate model. Although there is an effect of competition on the individual annual growth, that effect is not evidenced in physiological variables of punctual measurement. Our results suggest that the effect of summer drought cannot be modulated by density management. The productivity of the species of interest can be improved, but not their adaptability, at least to severe events such as the one of the year of study.

Species Richness and Taxonomic Distinctness of Zooplankton in Ponds and Small Lakes from Albania and North Macedonia: The Role of Bioclimatic Factors

Resolving the contribution to biodiversity patterns of regional-scale environmental drivers is, to date, essential in the implementation of effective conservation strategies. Here, we assessed the species richness S and taxonomic distinctness Δ+ (used a proxy of phylogenetic diversity) of crustacean zooplankton assemblages from 40 ponds and small lakes located in Albania and North Macedonia and tested whether they could be predicted by waterbodies’ landscape characteristics (area, perimeter, and altitude), together with local bioclimatic conditions that were derived from Wordclim and MODIS databases. The results showed that a minimum adequate model, including the positive effects of non-arboreal vegetation cover and temperature seasonality, together with the negative influence of the mean temperature of the wettest quarter, effectively predicted assemblages’ variation in species richness. In contrast, taxonomic distinctness did not predictably respond to landscape or bioclimatic factors. Noticeably, waterbodies’ area showed a generally low prediction power for both S and Δ+. Additionally, an in-depth analysis of assemblages’ species composition indicated the occurrence of two distinct groups of waterbodies characterized by different species and different precipitation and temperature regimes. Our findings indicated that the classical species-area relationship hypothesis is inadequate in explaining the diversity of crustacean zooplankton assemblages characterizing the waterbodies under analysis. In contrast, local bioclimatic factors might affect the species richness and composition, but not their phylogenetic diversity, the latter likely to be influenced by long-term adaptation mechanisms.

Rapoport's rule and determinants of species range size in snakes

AbstractAimUnderstanding determinants of species' range size is paramount to explaining global ecological patterns and estimating extinction risk of species. Here, we examined whether a sample of 536 snake species exhibits a latitudinal gradient of range size in support of Rapoport's rule, and determined predictors of range size from a set of environmental and biological factors.LocationGlobal.MethodsBased on a priori hypotheses about the effects of latitude, environmental and biological factors on species' range, we calculated mid‐latitudes of species ranges, and collected data on environmental factors (altitude, temperature, precipitation, size and number of ecoregions occupied) and biological traits (body size, fecundity, habitat breadth and species age) to construct multivariate models of snake range size. We used a recently published dated consensus phylogeny to determine minimum adequate models of range size using phylogenetic generalized least squares models and establish correlations between range size and time since species' description.ResultsRange size increased significantly with latitude, consistent with Rapoport's rule, especially across mid‐ and high latitudes in the Northern Hemisphere. Habitat breadth, body size and altitudinal range had a significant positive effect on range size, with minor negative effects on range size from mean altitude and reproductive output. Biological variables explained more variation in range size than environmental variables. Species' range size had a significant effect on species' description, with larger‐ranged species having been described earlier.Main conclusionsPrediction of range size in lesser‐known species such as snakes relies on a suite of factors. Species with restricted habitat breadth, small body size and at high altitudes generally have smaller ranges, and are thus likely to have higher extinction risk. [Correction added on 10 October 2017, after first online publication: The preceding sentence has been rephrased for clarity.] Our work illustrates that it is these species we are likely to under‐report in extinction risk assessments.

Biological responses to recent eutrophication and hydrologic changes in Xingyun Lake, southwest China

The synergistic influence of multiple environmental stressors on lake ecosystems has typically been evaluated paleolimnologically, through examination of a single biological indicator. Aquatic organisms, however, may display heterogeneous responses because of differences in their ecological sensitivity, and/or because of ecological consequences caused by strong interactions among multiple stressors. We applied paleolimnological methods to compare patterns of algal and invertebrate response to multiple stressors in a large, shallow lake in southwest China over the last two centuries. Our multi-proxy records show a clear trajectory of lake eutrophication (greater total nitrogen) and increasing lake productivity (greater sediment Chlorophyll-a concentration) during the last century. Nutrient enrichment and lake productivity played significant, but different roles, in structuring diatom and cladoceran assemblages, accounting for 31.4 and 77.3% of the total variance in the communities, respectively. Furthermore, there was a pronounced influx of the endemic diatom species Cyclotella rhomboideo-elliptica Skuja, which was strongly associated with the second axis of a diatom PCA (Principal Component Analysis). This occurred synchronously with a documented reversal of hydrological connectivity with a downstream, nutrient-poor lake during the early twentieth century, suggesting a role for species dispersal in modulating community reorganization. There are also strong differences between the two organism groups in their sensitivity to hydrological fluctuations, as hydrodynamics, indicated by sand content, was a significant driver for cladocerans (>25%), but showed only minor influence on diatom assemblages in our selection of minimum adequate models. The proportion of the total variance explained by our measured variables (<30%) was much lower for diatom assemblages than for both cladoceran assemblage and accumulation data (~77%), reflecting differences in community reorganization between the two biological indicators. The sediment-based evaluation of community responses revealed the differential impact of eutrophication and hydrological fluctuations on the biota of this large, shallow lake. Therefore, multiple biological indicators should be evaluated in limnological surveys to assess the full scope of ecological changes in highly stressed lake systems targeted for conservation or restoration.

Quick model of septic shock in rats

Modeling septic shock by means of administration of living bacteria is a minimum invasive adequate model for reproduction of this pathologic process, however there is a few data on effectiveness of this model in rats on the basis of direct measurement of hemodynamic parameters. The goal of the study was to elaborate a simple and convenient model of septic shock by intravenous infusion of living bifidobacteria. Indexes of central hemodynamics evaluated by direct method were analyzed in the study as well as endothelial function of blood vessels assessed by measuring concentration of NO, vessels' endothelial growth factor-A and tissue plasminogen activator. Dysfunction of hemostasis was also estimated by measuring fibrinogen level and soluble complexes of fibrin monomer. Intravenous infusion of living bifidobacteria caused development of severe septic shock by 15th minute after administration with valid decrease of all systemic hemodynamics' parameters. Marked hemodynamic disturbancies combined with development of endothelial dysfunction and hemostatic mechanisms' increased activity. The present model is absolutely safe; it can be easily reproduced in a research or training laboratory and it can be used for fundamental research of septic shock, for pre-clinical tests of drugs as well as for educational purposes.

Geographical variation and environmental correlates of functional trait distributions in palms (Arecaceae) across the New World

Functional traits play a key role in driving biodiversity effects on ecosystem functioning. Here, we examine the geographical distributions of three key functional traits in New World palms (Arecaceae), an ecologically important plant group, and their relationships with current climate, soil and glacial-interglacial climate change. We combined range maps for the New World (N = 541 palm species) with data on traits (leaf size, stem height and fruit size), representing the leaf-height-seed plant strategy scheme of Westoby, to estimate median trait values for palm species assemblages in 110 × 110-km grid cells. Spatial and non-spatial multi-predictor regressions were used with the Akaike Information Criterion to identify minimum adequate models. Present-day seasonality in temperature and precipitation played a major role in explaining geographical variation of all traits. Mean annual temperature and annual precipitation were additionally important for median leaf size. Glacial-interglacial temperature change was the most important predictor for median fruit size. Large-scale soil gradients played only a minor role overall. These results suggest that current climate (larger median trait values with increasing seasonality) and glacial-interglacial temperature change (larger median fruit size with increasing Quaternary temperature anomaly) are important drivers for functional trait distributions of New World palms.

Display behaviour and dewlap colour as predictors of contest success in brown anoles

Many animals display visual signals in male contests for access to females and territories. These visual signals can be multimodal and stimulate different aspects of a signal receiver’s visual system. Over two summers, we tested whether aspects of behaviour and dewlap colour might function as signals that predict contest success when males compete for access to either mates or territories in male brown anole lizards. We found that behaviour (PC1, a correlated composite of head-bob, push-up, and dewlap extension frequency) and an aspect of dewlap colour (PC3, the relative amounts of ultraviolet, yellow, orange, and red of the dewlap margin) were retained in the minimum adequate model predicting contest success across years and social contexts. Winners showed significant differences in behaviour (winners displayed more) and dewlap margin PC3 (winners had lower PC3 scores) compared to contest losers. These findings suggest that display behaviour and dewlap colour might serve as signals indicating a male’s ability to win contests for access to females and territories. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111, 646–655. ADDITIONAL KEYWORDS: lizard.

Abiotic surrogates for temperate rocky reef biodiversity: implications for marine protected areas

AbstractAimTo examine the potential of remotely sensed abiotic measures as surrogates for the abundance, diversity and community composition of temperate rocky reef fishes and sessile invertebrates.LocationBatemans Marine Park, south‐eastern Australia.MethodsWe used high‐resolution bathymetric side‐scan sonar imagery to quantify abiotic measures of rocky reef habitat, within a marine protected area (MPA), and examine the relationship between abiotic measures and (1) sessile invertebrate abundance, (2) sessile invertebrate species richness, (3) total fish abundance, (4) fish species richness, and (5) Monacanthidae abundance using generalized additive mixed models (GAMMs). We chose GAMMs as the preferred statistical analysis to account for the spatial autocorrelation present in our data.ResultsWe found a strong positive relationship between abiotic measures and sessile invertebrate abundance and diversity (r2 &gt; 0.64). By far the most important predictor was vertical relief within a 75 m radii seascape surrounding the faunal survey. Overall, abiotic measures were poor predictors of total fish abundance (r2 = 0.175) and fish species richness (r2 = 0.276), with minimum adequate models producing low explanatory power. In contrast, Monacanthids exhibited a strong positive relationship with abiotic variables (r2 = 0.385), with increased abundance associated with greater depth and distance from soft sediment.Main conclusionsRemotely sensed abiotic measures are important predictors in describing the spatial patterns of sessile invertebrate abundance and diversity and Monacanthid abundance. In contrast, abiotic variables were poor predictors of total fish abundance and diversity. Habitat could be a useful cost‐effective surrogate to determine areas of conservation value for certain temperate rocky reef assemblages. This information is valuable for future MPA development and design.

Regional context affects native and alien plant species richness across habitat types

AbstractQuestionHow does large‐scale context affect native and alien species richness across different habitat types?LocationCatalonia, NE Spain.MethodsWe analysed a set of 5309 vegetation plots from the BDBC (Biodiversity Data Bank of Catalonia) database, organized following the UTM (Universal Transverse Mercator) 10 km × 10 km grid. Plots were assigned to the first or second hierarchy of EUNIS (European Nature Information System) habitat classification. For each plot, the number of native plants (including archaeophytes, i.e. alien plants introduced before 1500 ad) and neophytes (alien plants introduced after 1500 ad) was recorded. Neophytes were classified according their Raunkiaer's life form. For each UTM we selected eight predictors related to land cover composition, anthropogenic context and climate. The association of neophyte and native species richness with these predictor variables was explored by generalized linear mixed models for each terrestrial habitat type after controlling for plot area.ResultsA total of 77 different neophyte species were found distributed among the eight habitat types with fitted models. Minimum adequate models on both neophyte and native species richness were highly variable. In general, native species richness responded more to climatic variables, while neophyte species richness was associated more with human landscape factors such as distance to main roads and, secondarily, cropland cover.ConclusionsContext factors defined on a large scale (10 km) have a significant effect on local native and neophyte species richness for many habitat types in Catalonia. Our results highlight the major influence of climatic context on native species richness and the influence of human landscape context on neophyte species richness in the study region. The inconsistency of results between habitat types suggests that this large‐scale effect might be highly idiosyncratic and dependent on species ecology and life form.

Frog community responses to recent American bullfrog invasions

Abstract Native species may decline quickly when confronted with an exotic species to which they are not adapted. The extent of decline may depend on the abundance of an invader and the length of time since it first arrived in the community (residence time), and the interaction between these two variables. We tested these effects using data on the effects of American bullfrog Lithobates catesbeianus invasion on native frog communities in 65 permanent lentic waters on islands in the Zhoushan Archipelago, China. We examined variation in native frog abundance and species richness in relation to features of the American bullfrog invasion, habitat disturbance, characteristics of the water body and fish communities and the presence of red swamp crayfish. Bullfrog invaded sites had lower native frog density and species richness, higher submerged vegetation cover and greater frequency of repairs to the water body than did non-invaded sites. The minimum adequate general linear mixed models showed that both native frog density and species richness were negatively related to post-metamorphosis bullfrog density, and that native frog species richness was also positively related to the vegetation cover. There was no effect on either native frog density or species richness of residence time or its interaction with bullfrog density, or of the abundance of bullfrog tadpoles. The results suggested that post-metamorphosis bullfrogs had impacts on native frog communities in the islands, and that the extents of these impacts are proportional to post-metamorphosis bullfrog density.

The combined effect of waterlogging, extractable P and soil pH on α-diversity: a case study on mesotrophic grasslands in the UK

Developing a strategy for evidence-based conservation is often problematic where a given habitat is found on relatively few small sites. Here, we investigate the important environmental variables that control species α-diversity in wet mesotrophic grasslands in lowland England. We analysed data on species richness and three soils variables from 10 mesotrophic grasslands to test the following hypothesis: is species diversity related to these soil factors, and if so, which is the most important? Generalised linear modelling was used to derive minimum adequate models of these relationships. The analysis identified degree of waterlogging and its interaction with both soil available phosphorus and soil pH as significant. Species diversity decreased with increasing waterlogging and available phosphorus. If species richness is to be conserved in these mesotrophic grasslands, it would be best done by maintaining low levels of waterlogging (0–1 m weeks), and low available phosphorus concentrations (<10 μg P g−1). However, this approach may predicate against specialist wetland species. Our results will help develop sound conservation strategies for these mesotrophic grasslands, and points the way for further investigative research.

Comparative nest habitat characteristics of sympatric White‐tailed Haliaeetus albicilla and Golden Eagles Aquila chrysaetos in western Scotland

Capsule Golden and White‐tailed Eagles selected different habitats for nesting. Aim To investigate differences in nesting habitat used by sympatrically breeding eagles in western Scotland, following reintroduction of White‐tailed Eagles from 1975 onwards. Methods Nest‐site locations from national surveys in 2003–05 were entered into a geographical information system (GIS) in order to measure a set of geographic parameters for each nest site. Binary logistic regression with backwards deletion of non‐significant terms was used to derive minimum adequate models at two spatial scales of the likelihood of an eagle nest belonging to one species or the other. We compared changes in occupancy between 1992 and 2003 of Golden Eagle territories inside and outside a GIS model of potential White‐tailed Eagle habitat and according to proximity to White‐tailed Eagle nests. Results White‐tailed Eagles nested at lower altitudes than Golden Eagles, in more wooded habitats with more open water close by, tending to nest in trees where these were present. There were 3359 km2 of potential White‐tailed Eagle nesting habitat within 25 km of existing White‐tailed Eagle nests, containing 54 Golden Eagle territory centres, but we found no difference in change of occupancy for Golden Eagle territories close to White‐tailed Eagles compared with those further away. Conclusion White‐tailed and Golden Eagles appear to partition nesting habitat in the west of Scotland by altitude. This corresponds with behaviour in western Norway and with the situation described in historical accounts of nest‐sites in western Scotland prior to extinction of White‐tailed Eagles. It is also consistent with recent studies showing little overlap in breeding season diet of Golden and White‐tailed Eagles in western Scotland, and likely partitioning of foraging habitat by altitude. We conclude that the likelihood of competitive exclusion is less than previously suggested.

Synchrony of butterfly populations across species' geographic ranges

Understanding the mechanisms by which global climate change and habitat loss impact upon biodiversity is essential in order to mitigate any negative impacts. One such impact may be changes to population synchrony (defined as correlated fluctuations in the density of separate populations). It is well established that synchrony depends on both dispersal ability and correlated environmental conditions, for example shared climate. However, what is not clear is whether differences in habitat or position within a species' range also mediate synchrony. Since synchronous metapopulations are thought to be more extinction-prone, establishing the drivers of synchrony has clear conservation implications. Using three butterfly species (Maniola jurtina, Pyronia tithonus and Aphantopus hyperantus) we investigated the effects of habitat similarity and range position on population synchrony, after accounting for the effects of distance and climate. Range position was present in all minimum adequate models, though non-significant using Mantel randomization tests in one case. We show that M. jurtina and P. tithonus synchrony is not consistent across species' ranges, with marginal populations showing more synchronous dynamics. Increased climatic constraints on marginal populations, leading to a narrower range of suitable microhabitats may be responsible for this, which is supported by the result that habitat similarity between sites was also positively correlated with population synchrony. As the landscape becomes increasingly homogeneous, overall population synchrony may be expected to rise. We conclude that habitat modification and climate change have the capacity to drive changes in population synchrony that could make species more vulnerable to extinction.

Taxonomic scale-dependence of habitat niche partitioning and biotic neighbourhood on survival of tropical tree seedlings

In order to differentiate between mechanisms of species coexistence, we examined the relative importance of local biotic neighbourhood, abiotic habitat factors and species differences as factors influencing the survival of 2330 spatially mapped tropical tree seedlings of 15 species of Myristicaceae in two separate analyses in which individuals were identified first to species and then to genus. Using likelihood methods, we selected the most parsimonious candidate models as predictors of 3 year seedling survival in both sets of analyses. We found evidence for differential effects of abiotic niche and neighbourhood processes on individual survival between analyses at the genus and species levels. Niche partitioning (defined as an interaction of taxonomic identity and abiotic neighbourhood) was significant in analyses at the genus level, but did not differentiate among species in models of individual seedling survival. By contrast, conspecific and congeneric seedling and adult density were retained in the minimum adequate models of seedling survival at species and genus levels, respectively. We conclude that abiotic niche effects express differences in seedling survival among genera but not among species, and that, within genera, community and/or local variation in adult and seedling abundance drives variation in seedling survival. These data suggest that different mechanisms of coexistence among tropical tree taxa may function at different taxonomic or phylogenetic scales. This perspective helps to reconcile perceived differences of importance in the various non-mutually exclusive mechanisms of species coexistence in hyper-diverse tropical forests.

Aquaculture Enclosures Relate to the Establishment of Feral Populations of Introduced Species

Many species introduced by humans for social and economic benefits have invaded new ranges by escaping from captivity. Such invasive species can negatively affect biodiversity and economies. Understanding the factors that relate to the establishment of feral populations of introduced species is therefore of great importance for managing introduced species. The American Bullfrog (Lithobates catesbeianus) is one species that has escaped from farms, and it is now found in the wild in China. In this study, we examined influences of two types of bullfrog farm (termed simple and elaborate farm enclosures) on the establishment of feral populations of this species in 137 water bodies in 66 plots in four provinces of China. The likelihood of establishment of bullfrog populations in water bodies in plots with simple enclosures (49/89 = 55.1%) was higher than those with elaborate enclosures (3/48 = 6.3%). Based on the Akaike Information Criterion, the minimum adequate model of generalized linear mixed models with a binomial error structure and a logit link function showed that the establishment or failure of bullfrog populations in water bodies was positively correlated with the presence of a simple enclosure, the number of bullfrogs raised and the presence of permanent water in a plot, but negatively correlated with distance from a bullfrog farm and the occurrence of frequent hunting. Results therefore suggest that a simple farm enclosure can increase the establishment of feral bullfrog populations compared with an elaborate enclosure. Our findings are the first to quantify the importance of improving farming enclosures to control and minimize the risk from introduced species.

Model selection and information theory in geographical ecology

ABSTRACTAim Although parameter estimates are not as affected by spatial autocorrelation as Type I errors, the change from classical null hypothesis significance testing to model selection under an information theoretic approach does not completely avoid problems caused by spatial autocorrelation. Here we briefly review the model selection approach based on the Akaike information criterion (AIC) and present a new routine for Spatial Analysis in Macroecology (SAM) software that helps establishing minimum adequate models in the presence of spatial autocorrelation.Innovation We illustrate how a model selection approach based on the AIC can be used in geographical data by modelling patterns of mammal species in South America represented in a grid system (n = 383) with 2° of resolution, as a function of five environmental explanatory variables, performing an exhaustive search of minimum adequate models considering three regression methods: non‐spatial ordinary least squares (OLS), spatial eigenvector mapping and the autoregressive (lagged‐response) model. The models selected by spatial methods included a smaller number of explanatory variables than the one selected by OLS, and minimum adequate models contain different explanatory variables, although model averaging revealed a similar rank of explanatory variables.Main conclusions We stress that the AIC is sensitive to the presence of spatial autocorrelation, generating unstable and overfitted minimum adequate models to describe macroecological data based on non‐spatial OLS regression. Alternative regression techniques provided different minimum adequate models and have different uncertainty levels. Despite this, the averaged model based on Akaike weights generates consistent and robust results across different methods and may be the best approach for understanding of macroecological patterns.

Um Estudo sobre as Publicações de Investimentos em Meio Ambiente do Setor Empresarial com Base no Balanço Social

Nos últimos anos tem sido freqüente o interesse da sociedade em conhecer os investimentos das empresas em responsabilidade social e meio ambiente. Um desses exemplos pode ser observado ao se conhecer a carta empresarial para o desenvolvimento sustentável da Câmara de Comércio Internacional (CCI), divulgada em 1991, que sugere várias ações que as empresas devem tomar a fim de se prepararem para a nova realidade advinda das questões ambientais. Sendo assim, a preocupação com o meio ambiente, alardeada em todas as esferas da sociedade, deu espaço a dois temas de grande repercussão nos ambientes internos e externos das organizações: a responsabilidade social e a preocupação com o meio ambiente. Nesse contexto, a demonstração que pode fornecer aos stakeholders informações de natureza ambiental é o Balanço Social, que tem por objetivo demonstrar o resultado da interação da empresa com o meio. Diante dessa exposição, a pergunta que se faz é: apesar de todo o empenho da sociedade, pode-se dizer que as empresas vêm gradativamente ampliando seus investimentos relacionados ao meio ambiente? A justificativa desse tema se apóia no fato de as empresas utilizarem as aplicações em meio ambiente e responsabilidade social para fins mercadológicos; entretanto, os valores aplicados e seu verdadeiro comprometimento agregando essas informações às suas demonstrações financeiras só podem ser identificados por ocasião dessas publicações. O objetivo deste trabalho se concentrou em levantar o número de empresas que publicaram informações de natureza social e ambiental, em 2005 e 2006, por meio do Balanço Social e, em seguida, verificar o comportamento dos indicadores ambientais divulgados nos referidos balanços e relacionados à produção. O presente trabalho foi desenvolvido por meio de pesquisa descritiva e documental com base nas demonstrações financeiras publicadas em meios específicos. Em resposta à pergunta formulada, analisando o intervalo delimitado na pesquisa, observase que, apesar de existirem modelos minimamente adequados para que as empresas revelem seus verdadeiros interesses em relação ao desenvolvimento sustentável, não se pode dizer que as empresas estão ampliando seus investimentos relacionados à produção visando à sustentabilidade.

Macroecology and extinction risk correlates of frogs

ABSTRACTAim Our aim was to test whether extinction risk of frog species could be predicted from their body size, fecundity or geographical range size. Because small geographical range size is a correlate of extinction risk in many taxa, we also tested hypotheses about correlates of range size in frogs.Location Global.Methods Using a large comparative data set (n = 527 species) compiled from the literature, we performed bivariate and multiple regressions through the origin of independent contrasts to test proposed macroecological patterns and correlates of extinction risk in frogs. We also created minimum adequate models to predict snout–vent length, clutch size, geographical range size and IUCN Red List status in frogs. Parallel non‐phylogenetic analyses were also conducted. We verified the results of the phylogenetic analyses using gridded data accounting for spatial autocorrelation.Results The most threatened frog species tend to have small geographical ranges, although the relationship between range and extinction risk is not linear. In addition, tropical frogs with small clutches have the smallest ranges. Clutch size was strongly positively correlated with geographical range size (r2 = 0.22) and body size (r2 = 0.28).Main conclusions Our results suggest that body size and fecundity only affect extinction risk indirectly through their effect on geographical range size. Thus, although large frogs with small clutches tend to be endangered, there is no comparative evidence that this relationship is direct. If correct, this inference has consequences for conservation strategy: it would be inefficient to allocate conservation resources on the basis of low fecundity or large body size; instead it would be better to protect areas that contain many frog species with small geographical ranges.

The influence of territory characteristics and food supply on the breeding performance of the Red‐backed Shrike (Lanius collurio) in an extensively farmed region of eastern Poland

AbstractThe breeding performance of the Red‐backed Shrike (Lanius collurio) in relation to the territory characteristics was investigated. The study was conducted in an area of high agricultural land use, characterised by small field size, a more mosaic habitat and low use of mineral fertilisers in comparison to Western European countries. The influence of habitat structure and composition in the territory on the date of clutch initiation, nest predation and clutch size in the Red‐backed Shrike was not found, but such an influence on the number of nestlings was shown. The minimum adequate model explained 18.3% of the variation between territories in nestling's number. The number of fledglings was positively correlated with the area of pastures, meadows, orchards and fallows within territories, and negatively correlated with length of overhead transmission lines. The number of fledglings was correlated with food abundance within territories, based on to the results from pitfall traps. There was no correlation between territory food abundance and the size of clutch. The presence of pastures, meadows and fallows, which are foraging places, thus seems to be crucial for the protection of the Red‐backed Shrike.

Modelling introduced predator and herbivore distribution in the Tanami Desert, Australia

This paper examines the pattern of introduced herbivore and predator distribution in the Tanami Desert and tests a series of propositions put forward by Stafford Smith and Morton [1990. A framework for the ecology of arid Australia. Journal of Arid Environments 18, 255–278]. regarding the functioning of arid Australian environments. These authors proposed that introduced herbivore and predator species would be largely restricted to and reliant on productive refugia. We collected occurrence data on introduced and naturalized predators and herbivores at 227 plots stratified by substrate and fire age class across a study area of 700×400 km. We also collected data from 16 repetitively sampled transects stratified by substrate and latitude over a 4 year period. Each of the predator species was associated with different landscape parameters and the proposition that predator diversity and abundance would be greatest in the productive habitats was not supported. There was support for the proposition that introduced feral herbivores would be concentrated in the productive habitats. Overall, the parameters reflecting the climatic gradient were the most important determinants of introduced species distribution in the Tanami Desert. Substrate-related variables or episodic variables such as fire age were of secondary importance at the scale considered. Furthermore, the variables that reflected episodic rainfall or periods of rainfall deviance did not form a significant component of the minimum adequate models for any of the species.