A dimensão espacial e temporal da diversidade de peixes da zona litoral vegetada de lagoas marginais da planície de inundação do rio Cuiabá, Pantanal, Brasil

The spatial distribution of bats in Burkina Faso is little-known. Previous studies have only described the bat species’ richness in Burkina Faso. This study was conducted to highlight bat species’ richness distribution within Burkina Faso and environmental variables that influence this distribution with the aim to give support for protection and further sampling for biodiversity. The Species Distribution Models (SDMs) were used to perform this study. To do that, species occurrences were collected throughout literature and field sampling and correlated to environmental variables through the Maxent software (Maximum Entropy). Our modeling variables included climate, vegetation cover, topography and hydrography data. The Jackknife test was performed to determine the importance of environmental variables that influence the species distribution model. The results showed that bats are present in all areas of vegetation in Burkina Faso. Species richness varies across the country. The species richness for major families increases from North to South. The total annual precipitation and topography are the main variables that positively influence bats distribution in Burkina Faso but the bare ground cover and standard deviation of the maximum temperature negatively influence this distribution. This modeling approach of bat species richness is important for policies makers and represents an invaluable tool in ecological management, particularly in the current context of climate change.

The statistical framework of rarefaction curves and asymptotic estimators allows for an effective standardization of biodiversity measures. However, most statistical analyses still consist of point comparisons of diversity estimators for a particular sampling level. We introduce new randomization methods that incorporate sampling variability encompassing the entire length of the rarefaction curve and allow for statistical comparison of i ≥2 individual‐based, sample‐based, or coverage‐based rarefaction curves. These methods distinguish between two distinct null hypotheses: the ecological null hypothesis (H0eco) and the biogeographical null hypothesis (H0biog).H0eco states that the i samples were drawn from a single assemblage, and any differences among them in species richness, composition, or relative abundance reflect only sampling effects. H0biog states that the i samples were drawn from assemblages that differ in their species composition but share similar species richness and species abundance distributions. To test H0eco, we created a composite rarefaction curve by summing the abundances of all species from the i samples. We then calculated a test statistic Zeco, the (cumulative) summed areas of difference between each of the i individual curves and the composite curve. For H0biog, the test statistic Zbiog was calculated by summing the area of difference between all possible pairs of the i individual curves. Bootstrap sampling from the composite curve (H0eco) or random sampling from different simulated assemblages using alternative abundance distributions (H0biog) was used to create the null distribution of Z, and to provide a frequentist test of Z | H0. Rejection of H0eco does not pinpoint whether the samples differ in species richness, species composition, and/or relative abundance.In benchmark comparisons, both tests performed satisfactorily against artificial data sets randomly drawn from a single assemblage (low Type I error). In benchmark comparisons with different species abundance distributions and richness, the tests had adequate power to detect differences among curves (low Type II error), although power diminished at small sample sizes and for small differences among underlying species rank abundances.

Experiments and theory in single trophic level systems dominate biodiversity and ecosystem functioning research and recent debates. All natural ecosystems contain communities with multiple trophic levels, however, and this can have important effects on ecosystem structure and functioning. Furthermore, many experiments compare assembled communities, rather than examining loss of species directly. We identify three questions around which to organise an investigation of how species loss affects the structure and functioning of multitrophic systems. 1) What is the distribution of species richness among trophic levels; 2) from which trophic levels are species most often lost; and 3) does loss of species from different trophic levels influence ecosystem functioning differently? Our analyses show that: 1) Relatively few high‐quality data are available concerning the distribution of species richness among trophic levels. A new data‐set provides evidence of a decrease in species richness as trophic height increases. 2) Multiple lines of evidence indicate that species are lost from higher trophic levels more frequently than lower trophic levels. 3) A theoretical model suggests that both the structure of food webs (occurrence of omnivory and the distribution of species richness among trophic levels) and the trophic level from which species are lost determines the impact of species loss on ecosystem functioning, which can even vary in the sign of the effect. These results indicate that, at least for aquatic systems, models of single trophic level ecosystems are insufficient for understanding the functional consequences of extinctions. Knowledge is required of food web structure, which species are likely to be lost, and also whether cascading extinctions will occur.

Evidence for significant losses of species richness or biodiversity, even within protected natural areas, is mounting. Managers are increasingly being asked to monitor biodiversity, yet estimating biodiversity is often prohibitively expensive. As a cost-effective option, we estimated the spatial and temporal distribution of species richness for four taxonomic groups (birds, mammals, herpetofauna (reptiles and amphibians), and plants) within Sequoia and Kings Canyon National Parks using only existing biological studies undertaken within the Parks and the Parks' long-term wildlife observation database. We used a rarefaction approach to model species richness for the four taxonomic groups and analyzed those groups by habitat type, elevation zone, and time period. We then mapped the spatial distributions of species richness values for the four taxonomic groups, as well as total species richness, for the Parks. We also estimated changes in species richness for birds, mammals, and herpetofauna since 1980. The modeled patterns of species richness either peaked at mid elevations (mammals, plants, and total species richness) or declined consistently with increasing elevation (herpetofauna and birds). Plants reached maximum species richness values at much higher elevations than did vertebrate taxa, and non-flying mammals reached maximum species richness values at higher elevations than did birds. Alpine plant communities, including sagebrush, had higher species richness values than did subalpine plant communities located below them in elevation. These results are supported by other papers published in the scientific literature. Perhaps reflecting climate change: birds and herpetofauna displayed declines in species richness since 1980 at low and middle elevations and mammals displayed declines in species richness since 1980 at all elevations.

Predictable geographic patterns in the distribution of species richness, especially the latitudinal gradient, are intriguing because they suggest that if we knew what the controlling factors were we could predict species richness where empirical data is lacking (e.g. tropics). Based on analyses of the macro‐scale distribution of woody plant species richness in Southern Africa, one controlling factor appears to be climate‐based water‐energy dynamics. Using the regression models of climate's relationship to species richness in Southern Africa, I was able to describe an Interim General Model (IGM) and to predict first‐order macro‐scale geographic variations in woody plant species richness for the continent of Africa, as well as elsewhere in the world—exemplified using South America, the United States and China.In all cases, the geographic pattern of variation in species richness is in accord with geographic variations in vegetation (visual comparison with vegetation maps) and net primary productivity. What validation was possible (Africa and U.S.A.) suggests that the IGM provides ‘reasonable’ estimates for actual woody plant species richness where species richness is in relative equilibrium with climate. Areas of over‐ or under‐prediction support the contention of earlier workers that edaphic, topographic, historical, and dispersal factors need to be considered in a more complete explanation for spatio‐temporal variations in species richness.In addition to providing a means for systematically estimating woody plant species richness where present‐day empirical data is lacking, the Interim General Model may prove useful for modelling the effects of climate change (past/future) on species richness (and, by association, the vegetation).

Apparent regular variation in the distributions of organisms along geographical gradients has always fascinated ecologists. Variation in species richness with latitude has received the most attention, of course, but variation in species richness with elevation also has been of considerable interest and study. Precisely how and why species richness varies with elevation remains controversial (Wolda 1987, McCoy 1990, Colwell and Hurtt 1994, Rahbek 1995, 1997, Fleishman et al. 1998). Part of the reason for the continuing controversy is the fact that species richness is only an index, a manageable substitute for the set of distributions of individual species along an elevational gradient. Any explanation proposed for apparent regular variation in species richness with elevation can be, at best, only a loose reflection of the complicated autecological relationships between the individual species and elevation. The more species the proposed explanation is able to accommodate, the closer it will come to explaining variation in species richness, but any single explanation may not be suitable for a wide range of species (Lawton 1996). Another part of the reason for the continuing controversy about how and why species richness varies with elevation involves sampling problems (McCoy 1990, Rahbek 1995). Simply comparing species richness from one location to another can involve many sampling problems (Gotelli and Colwell 2001), but when such comparisons are made along gradients, the problems multiply. Understanding the causes of variation in species richness with elevation may have been hampered, for example, because different studies typically do not encompass the same elevational range and because the elevation of true maximum species richness sometimes occurs outside the sampled range (McCoy 1990). Ultimately, sampling problems even could lead to erroneous views of how species richness varies along elevational gradients (Rahbek 1995). Sampling problems such as those just described for studies of variation in species richness along elevational gradients are instances of a general problem in ecology that I term gradients. Veiled gradients arise from the fact that the outcome of any examination of a local gradient elevation, in this case is contingent upon the temporal and spatial frameworks employed. Over short time periods or across small geographical scales, only a portion of the gradient is likely to be revealed, the remainder of the gradient being veiled in time or space. Failure to realize that only a portion of the gradient is likely to be revealed in studies that are temporally or spatially restricted could obscure any true relationship that might exist (Allen and Starr 1982, McCoy 1990, McCoy and Bell 1991, Korner 2000). A ready example of how veiled gradients can influence interpretation of the variation in species richness with elevation can be found in the recent literature. Fleishman et al. (2000) determined that butterfly species richness increased with elevation in one of the canyons they studied but decreased in the other (Fig. 1). They attributed the apparent difference in the distribution of species richness with elevation to differences in climatic severity between the two canyons. The elevational ranges that were sampled were not the same in the two canyons, however, raising the possibility of a sampling problem. Samples (n = 102) from the first canyon (Toiyabe Range) spanned an elevational range of 1917-3272 m, whereas samples (n = 49) from the second canyon (Toquima Range) spanned an elevational range of 1872-2750 m. Ideally, we would like to unveil the distribution of species richness with elevation by extending the gradient in the Toquima Range to 3272 m, but we cannot do so with the available data. We can find out what the distribution of species richness with elevation would look like if the gradient in the Toiyabe Range were veiled to 2750 m, however. Examining changes in richness with elevation when the gradients are of the same length dramatically alters the interpretation of the relationship (Fig. 1). The apparent decline in species richness with elevation in the Toiyabe Range essentially disappears. Furthermore, an alternative interpretation of the data now suggests itself: that

Biological diversity analysis is among the most informative approaches to describe communities and regional species compositions. Soil ecosystems include large numbers of invertebrates, among which soil bugs (Crustacea, Isopoda, Oniscidea) play significant ecological roles. The aim of this study was to provide advices to optimize the sampling effort, to efficiently monitor the diversity of this taxon, to analyze its seasonal patterns of species composition, and ultimately to understand better the coexistence of so many species over a relatively small area. Terrestrial isopods were collected at the Natural Reserve "Saline di Trapani e Paceco" (Italy), using pitfall traps monthly monitored over 2years. We analyzed parameters of α- and β-diversity and calculated a number of indexes and measures to disentangle diversity patterns. We also used various approaches to analyze changes in biodiversity over time, such as distributions of species abundances and accumulation and rarefaction curves. As concerns species richness and total abundance of individuals, spring resulted the best season to monitor Isopoda, to reduce sampling efforts, and to save resources without losing information, while in both years abundances were maximum between summer and autumn. This suggests that evaluations of β-diversity are maximized if samples are first collected during the spring and then between summer and autumn. Sampling during these coupled seasons allows to collect a number of species close to the γ-diversity (24 species) of the area. Finally, our results show that seasonal shifts in community composition (i.e., dynamic fluctuations in species abundances during the four seasons) may minimize competitive interactions, contribute to stabilize total abundances, and allow the coexistence of phylogenetically close species within the ecosystem.

BackgroundThe guppy fish (Poecilia reticulata) is a tropical fish ancestrally linked to northern South America and the Caribbean. It is known to be very tolerant of and adaptable to new environments, and able to consume multiple food sources, including mosquito larvae. Consequently, guppies have been frequently introduced to non-native ecosystems to control mosquito populations, resulting in near-global distribution. Indeed, due to the increasing need for mosquito-borne disease control, guppy releases will likely continue, however there are concerns about potential adverse impacts on other species, biodiversity, and certain ecosystem functions. The most significant of these is local species extinction, and by extension, reduced biodiversity. Yet, the extent of these impacts has not been evaluated by scientific review. Accordingly, this study will examine and evaluate whether anthropogenic introduction of guppy fish (Poecilia reticulata) has impacts on faunal species diversity and abundance in natural aquatic habitats. The results of this review may have implications for environmental management and policy and inform ecosystem-based integrated vector management and public health policy.MethodsRelevant scientific articles will be identified by searching electronic databases. Articles will be included if they report changes or differences, associated with guppy fish introduction, in at least one of these population parameters: (1) abundance of individuals in any species, (2) total abundance of individuals in all species present, (3) species richness, (4) species diversity, and (5) community evenness. Each article will be assessed by at least two independent reviewers against pre-defined inclusion/exclusion criteria. Snowballing reference lists of included articles will be conducted. At least two reviewers will critically appraise all included studies using the Collaboration for Environmental Evidence Critical Appraisal Tool (CEECAT) and any discrepancies will be resolved by discussion between the two or adjudication by a third author if agreement is not reached. Each study will also be subjected to data extraction against pre-defined qualitative and quantitative outcomes and results will be tabulated/presented in figures where appropriate. A meta-analysis will be carried out on outcome parameters with sufficient evidence.

O objetivo deste trabalho foi determinar a distribuição da riqueza de espécies e a preferência pelo habitat de Carabidae e Staphylinidae (Coleoptera), em áreas com rotação de soja e milho, em plantio direto e convencional, e em áreas adjacentes a estas com fragmento florestal e povoamento de pínus, respectivamente. Os besouros foram amostrados por meio de armadilhas de solo distribuídas em dois transectos de 100 m de comprimento. A distribuição da riqueza de espécies nas culturas, no fragmento florestal e no pínus foi avaliada por meio de análise de regressão linear. A análise de agrupamento foi empregada para identificar as espécies quanto à preferência pelos habitats: fragmento florestal, pínus, cultura e interface. A distribuição da riqueza de espécies de Carabidae e Staphylinidae não variou em relação à posição no transecto, enquanto a riqueza de espécies observada nas interfaces foi elevada em comparação com a encontrada nos demais habitats. A ocorrência de espécies de Carabidae diferiu conforme o tipo de cobertura vegetal: Megacephala sp. e Scarites sp. preferiram áreas cultivadas em sistema de rotação soja-milho; Odontochila nodicornis (Dejean) preferiu o fragmento florestal e o povoamento de pínus. A espécie Abaris basistriatus Chaudoir caracterizou-se como generalista quanto à preferência pelo habitat.

The spatial distribution of alien species richness often correlates positively with native species richness, and reflects the role of human density and activity, and primary productivity and habitat heterogeneity, in facilitating the establishment and spread of alien species. Here, we investigate the relationship between the spatial distribution of alien bird species, human density, and anthropogenic and natural environmental conditions. Next, we examined the relationship between the spatial distribution of alien bird species and native bird species richness. We examined alien species richness as a response variable, using correlative analyses that take spatial autocorrelation into account. Further, each alien bird species was examined as a response variable, using logistic regression procedures based on binary presence–absence data. A combination of human density and natural habitat heterogeneity best explained the spatial distribution of alien species richness. This contrasts with the results for individual alien species and with previous studies on other non-native taxa showing the importance of primary productivity and anthropogenic habitat modification as explanatory variables. In general, native species richness is an important correlate of the spatial distribution of alien species richness and individual alien species, with alien species being more similar to common species than to rare species.

Aim To evaluate the relative importance of water–energy, land‐cover, environmental heterogeneity and spatial variables on the regional distribution of Red‐Listed and common vascular plant species richness.Location Trento Province (c. 6200 km2) on the southern border of the European Alps (Italy), subdivided regularly into 228 3′ × 5′ quadrants.Methods Data from a floristic inventory were separated into two subsets, representing Red‐Listed and common (i.e. all except Red‐Listed) plant species richness. Both subsets were separately related to water–energy, land‐cover and environmental heterogeneity variables. We simultaneously applied ordinary least squares regression with variation partitioning and hierarchical partitioning, attempting to identify the most important factors controlling species richness. We combined the analysis of environmental variables with a trend surface analysis and a spatial autocorrelation analysis.Results At the regional scale, plant species richness of both Red‐Listed and common species was primarily related to energy availability and land cover, whereas environmental heterogeneity had a lesser effect. The greatest number of species of both subsets was found in quadrants with the largest energy availability and the greatest degree of urbanization. These findings suggest that the elevation range within our study region imposes an energy‐driven control on the distribution of species richness, which resembles that of the broader latitude gradient. Overall, the two species subsets had similar trends concerning the relative importance of water–energy, land cover and environmental heterogeneity, showing a few differences regarding the selection of some predictors of secondary importance. The incorporation of spatial variables did not improve the explanatory power of the environmental models and the high original spatial autocorrelation in the response variables was reduced drastically by including the selected environmental variables.Main conclusions Water–energy and land cover showed significant pure effects in explaining plant species richness, indicating that climate and land cover should both be included as explanatory variables in modelling species richness in human‐affected landscapes. However, the high degree of shared variation between the two groups made the relative effects difficult to separate. The relatively low range of variation in the environmental heterogeneity variables within our sampling domain might have caused the low importance of this complex factor.

The goal of elucidating the primary mechanisms constraining the assembly and distribution of biodiversity remains among the central unresolved challenges facing the field of ecology. Simulation studies and experimental manipulations have focused on how patterns in community assembly result from bivariate relationships along productivity or environmental gradients. However, the joint influence of multiple resource gradients on the distribution of species richness in natural communities remains understudied. Using data from a large network of multiscale vegetation plots across forests and woodlands of the southeastern United States, we find significant evidence for the scale-dependent, joint constraints of forest structure and soil resources on the distribution of vascular plant species richness. In addition to their significant partial effects on species richness, understory light levels and soil fertility positively interact, suggesting a trade-off between the two limiting resources with species richness peaking both in high-light, low-fertility conditions as well as low-light, high-fertility settings. This finding provides a novel perspective on the biodiversity-productivity relationship that suggests a transition in limiting resources from soil nutrients to light availability when enhanced productivity results in reduced light resources for subordinate individuals. Results likewise have meaningful implications for our understanding of scale-dependent community assembly processes as size-asymmetric competition replaces environmental filtering as the primary assembly mechanism structuring temperate forest communities along an increasing soil fertility gradient.

Probability distributions of extinction times, species richness, and immigration and extinction rates in neutral ecological models

ABSTRACTAims Tests of the energy hypothesis for the large‐scale distribution of species richness have largely been concerned with the influence of two alternative forms of environmental energy, temperature and energy from primary productivity, both of which (at least in terrestrial systems) peak within the tropics. Taxa showing extra‐tropical diversity peaks present a potential challenge to the generality of species–energy theory. One such group are pelagic seabirds of the order Procellariiformes that show not only an extra‐tropical diversity peak but one confined to the Southern Ocean, hence a highly asymmetric one. They are distinct in being exceptionally adapted to take advantage of wind energy, which they may rely on for long‐distance ocean foraging for the patchy resources needed to meet their energetic needs. Wind represents a readily available source of kinetic energy, shows a strong latitudinal gradient, and has been largely omitted from species–energy theory. Moreover, maximal benefits of wind are likely to be afforded in areas of greatest available contiguous ocean extent. We compare the relative importance of wind speed, ocean productivity (chlorophyll concentration), air temperature and available ocean extent (distance) in explaining large‐scale global distribution of procellariiform species richness across the world's oceans.Location Global, oceanic.Methods Hierarchical partitioning, model selection, ordinary least squares (OLS) and spatial generalized least squares (GLS) regression.Results Hierarchical partitioning of non‐spatial regression models indicates that ocean distance is the most important predictor of procellariiform species richness followed by wind speed and then temperature. In contrast, that of spatial regression models indicates the roughly equal importance of ocean distance and temperature, followed by wind speed. Although contributing additional model fit, ocean productivity is consistently the weakest predictor. Best‐fit models include all four predictors and explain 67% of observed variation. The species–productivity relationship is negative overall, while the species–temperature relationship is hump‐shaped. In contrast, ocean distance and wind speed are positively associated with species richness.Conclusions Large‐scale procellariiform species richness distribution may represent a trade‐off in the use of different energy forms, being highest in Southern Ocean areas where productive energy and temperature are relatively low, but where available ocean foraging extent and wind energy required to utilize it are near‐maximal.

Temporal dynamics of local assemblages depend on the species richness and the total abundance of individuals as well as local departure and arrival rates of species. We used urban bird survey data collected from the same 31 study plots and methods during three winters (1991–1992; 1999–2000 and 2009–2010) to analyze the temporal relationship between bird species richness and total number of individuals (abundance). We also evaluated local departures and arrivals of species in each assemblage. In total, 13,812 individuals of 35 species were detected. The temporal variation in bird species richness followed the variation in the total number of individuals. The numbers of local departure and arrival events were similar. Also, the mean number of individuals of the recently arrived species (8.6) was almost the same as the mean number of individuals of the departed species (8.2). Risk of species departure was inversely related to number of individuals. Local species richness increased by one species when the total abundance of individuals increased by around 125 individuals and vice versa. Our results highlight the important role of local population departures and arrivals in determining the local species richness-abundance dynamics in human-dominated landscapes. Local species richness patterns depend on the total number of individuals as well as both the departure-arrival dynamics of individual species as well as the dynamics of all the species together. Our results support the more individuals hypothesis, which suggests that individual-rich assemblages have more species.