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Local-regional (LR) species diversity plots were conceived to assess the contribution of regional and local processes in shaping the patterns of biological diversity, but have been used also to explore the scaling of diversity in terms of its alpha, beta, and gamma components. Here we explore the idea that patterns in the geographical ranges of species over a continent can determine the shape of small region to large region (SRLR) plots, which are equivalent to LR plots when comparing the diversity of sites at two regional scales. To test that idea, we analysed the diversity patterns at two regional scales for the mammals of North America, defined as the mainland from Alaska and Canada to Panama. We developed a theoretical model relating average range size of species over a large-scale region with its average regional point species diversity (RPD). Then, we generated a null model of expected SRLR plots based on theoretical predictions. Species diversities at two scales were modelled using linear and saturation functions for Type I and Type II SRLR relationships, respectively. We applied the models to the case of North American mammals by examining the regional diversity and the RPD for 21 large-scale quadrats (with area equal to 160,000 km2), arranged along a latitudinal gradient. Our model showed that continental and large-scale regional patterns of distribution of species can generate both types of SRLR relationship, and that these patterns can be reflected in LR plots without invoking any kind of local processes. We found that North American nonvolant mammals follow a Type I SRLR relationship, whereas bats follow a Type II pattern. This difference was linked to patterns in which species of the two mammalian groups distribute in geographical space. Traditional LR plots and the new SRLR plots are useful tools in exploring the scaling of species diversity and in showing the relationship between distribution and diversity. Their usefulness in comparing the relative role of local and regional processes is, however, very limited. [ABSTRACT FROM AUTHOR]

The article discusses the significance of citing references in research works pertaining to ecology and the environment. According to the author, research works and such other papers about ecology the foundation of ecological science. The credibility of scientific work depends on its verifiable citations which functions to support the arguments presented in the paper. However, the author argues that there is no existing studies which explore the suitability or even fidelity of citations in ecological journals.

Data are often collected for a single species within an ecological community, so quantitative tools for drawing inferences about the unobserved portions of the community from single-species data are valuable. In this paper, we present and examine a method for estimating community dimension (the number of strongly interacting species or groups) from time series data on a single species. The dynamics of one species can be strongly affected by environmental stochasticity acting not only on itself, but also on other species with which it interacts. By fully accounting for the effects of stochasticity on populations embedded in a community, our approach gives better estimates of community dimension than commonly used methods. Using a combination of time series data and simulations, we show that failing to properly account for stochasticity when attempting to relate population dynamics to attributes of the community can give misleading information about community dimension. [ABSTRACT FROM AUTHOR]

Successful conservation plans are not solely achieved by acquiring optimally designed reserves. Ongoing monitoring and management of the biodiversity in those reserves is an equally important, but often neglected or poorly executed, part of the conservation process. In this paper we address one of the first and most important steps in designing a monitoring program – deciding what to monitor. We present a strategy for prioritizing species for monitoring and management in multispecies conservation plans. We use existing assessments of threatened status, and the degree and spatial and temporal extent of known threats to link the prioritization of species to the overarching goals and objectives of the conservation plan. We consider both broad and localized spatial scales to capture the regional conservation context and the practicalities of local management and monitoring constraints. Spatial scales that are commensurate with available data are selected. We demonstrate the utility of this strategy through application to a set of 85 plants and animals in an established multispecies conservation plan in San Diego County, California, USA. We use the prioritization to identify the most prominent risk factors and the habitats associated with the most threats to species. The protocol highlighted priorities that had not previously been identified and were not necessarily intuitive without systematic application of the criteria; many high-priority species have received no monitoring attention to date, and lower-priority species have. We recommend that in the absence of clear focal species, monitoring threats in highly impacted habitats may be a way to circumvent the need to monitor all the targeted species. [ABSTRACT FROM AUTHOR]

In exploring the relationship between multivariate abundance data and environmental variables, a rarely used approach is to graph raw data separately for each different taxon. It is proposed that such raw data graphs become part of the standard toolset for graphing and analysing multivariate abundances. The key advantage of this approach is that axis scales have quantitative interpretations, enabling quantitative interpretation of patterns in abundance. In contrast, ordinations only present qualitative information. Ordinations are useful for inferring overall, qualitative patterns and raw data graphing is a complementary tool of greater use for answering more specific questions, aimed at a deeper understanding the ecology of a community. It is demonstrated using some well-known examples that our understanding of the nature of associations can be considerably improved by using raw data graphs, even when only plotting a subset of variables. One example describes how an often-cited dataset has been misinterpreted in key methodological papers, because data were interpreted from ordinations alone, with no consideration of plots of the raw data. [ABSTRACT FROM AUTHOR]

Power-law frequency distributions characterize a wide array of natural phenomena. In ecology, biology, and many physical and social sciences, the exponents of these power laws are estimated to draw inference about the processes underlying the phenomenon, to test theoretical models, and to scale up from local observations to global patterns. Therefore, it is essential that these exponents be estimated accurately. Unfortunately, the binning-based methods traditionally used in ecology and other disciplines perform quite poorly. Here we discuss more sophisticated methods for fitting these exponents based on cumulative distribution functions and maximum likelihood estimation. We illustrate their superior performance at estimating known exponents and provide details on how and when ecologists should use them. Our results confirm that maximum likelihood estimation outperforms other methods in both accuracy and precision. Because of the use of biased statistical methods for estimating the exponent, the conclusions of several recently published papers should be revisited. [ABSTRACT FROM AUTHOR]

It has been suggested that alien species with close indigenous relatives in the introduced range may have reduced chances of successful establishment and invasion (Darwin's naturalization hypothesis). Studies trying to test this have in fact been addressing four different hypotheses, and the same data can support some while rejecting others. In this paper, we argue that the phylogenetic pattern will change depending on the spatial and phylogenetic scales considered. Expectations and observations from invasion biology and the study of natural communities are that at the spatial scale relevant to competitive interactions, closely related species will be spatially separated, whereas at the regional scale, species in the same genera or families will tend to co-occur more often than by chance. We also argue that patterns in the relatedness of indigenous and naturalized plants are dependent on the continental/island setting, spatial occupancy levels, and on the group of organisms under scrutiny. Understanding how these factors create a phylogenetic pattern in invasions will help us predict which groups are more likely to invade where, and should contribute to general ecological theory. [ABSTRACT FROM AUTHOR]

This paper explores the effect of spatial processes in a heterogeneous environment on the dynamics of a host-parasitoid interaction. The environment consists of a lattice of favourable (habitat) and hostile (matrix) hexagonal cells, whose spatial distribution is measured by habitat proportion and spatial autocorrelation (inverse of fragmentation). At each time step, a fixed fraction of both populations disperses to the adjacent cells where it reproduces following the Nicholson-Bailey model. Aspects of the dynamics analysed include extinction, stability, cycle period and amplitude, and the spatial patterns emerging from the dynamics. We find that, depending primarily on the fraction of the host population that disperses in each generation and on the landscape geometry, five classes of spatio-temporal dynamics can be objectively distinguished: spatial chaos, spirals, metapopulation, mainland-island and spiral fragments. The first two are commonly found in theoretical studies of homogeneous landscapes. The other three are direct consequences of the heterogeneity and have strong similarities to dynamic patterns observed in real systems (e.g. extinction-recolonisation, source-sink, outbreaks, spreading waves). We discuss the processes that generate these patterns and allow the system to persist. The importance of these results is threefold: first, our model merges into a same theoretical framework dynamics commonly observed in the field that are usually modelled independently. Second, these dynamics and patterns are explained by dispersal rate and common landscape statistics, thus linking in a practical way population ecology to landscape ecology. Third, we show that the landscape geometry has a qualitative effect on the length of the cycles and, in particular, we demonstrate how very long periods can be produced by spatial processes. [ABSTRACT FROM AUTHOR]

1. The fungus-gardening ants and their fungi represent a highly co-evolved, vertically transmitted mutualism. Mutualisms such as these are thought to be reciprocal antagonisms, so that the ants and the fungus can be expected to have some conflicting interests. 2. This paper reports the results from a cultivar switch experiment that documented the effects of switching the native cultivar from the basal ‘higher-attine’ Trachymyrmex septentrionalis with a derived cultivar from the leaf-cutting ant, Atta texana. If the cultivars have been modified significantly during the adaptive radiation of this clade, then they should differ in their ability to produce ant and fungal biomass. If the ants can perceive differences in cultivar performance, then their food preference may also change as a result of the switch. Lastly, if conflict is present in this mutualism, then the sex ratio in the switched colonies should be male biased. 3. Our results showed that food preference was not altered by the new cultivar. The A. texana cultivar did not change the performance of T. septentrionalis colonies relative to colonies that were cultivating conspecific fungal cultivars. Foragers preferred insect faeces and oak staminate flowers over fresh leaves or flowers. Most variation in colony performance was attributable to substrate type. Sex ratio of offspring was not affected by fungal cultivar. With respect to fungal growth, the A. texana cultivar appeared to be more of a generalist, while the T. septentrionalis cultivar performed better on substrates preferred by the ants than those unpreferred. 4. The results of this study indicate that cooperation and not conflict has been more important in shaping the evolutionary ecology of this mutualism. Although the cultivars were certainly genetically and physiologically distinct, these differences did not account for variation in the production of ant biomass or ant behaviour. The emerging picture thus indicates that this mutualism should be viewed as a highly integrated superorganism that is more than the sum of its parts. [ABSTRACT FROM AUTHOR]

Data rarely are available to address the level of predation risk faced by diving animals in different parts of the water column. Consequently, most published research on diving behaviour implicitly assumes – like the proverbial ostrich – that ‘unseen’ predators are functionally unimportant. We argue that failure to consider diving in a predation risk framework may have precluded many insights into the ecology of aquatic foragers that breathe air. Using existing literature and a simple model, we suggest that fear from submerged predators in several systems might be influencing patch residence time, and therefore the duration of other dive cycle components. These analyses, along with an earlier model of predation risk faced by diving animals at the surface, suggest that dive cycle organisation can be modified to increase safety from predators, but only at the cost of reduced energy gain. Theoretical arguments presented here can seed hypotheses on factors contributing to population declines of diving species. For instance, adjustments to the dive cycle that reduce predation risk might be unaffordable if resources are scarce. Thus, if animals are to avoid imminent starvation or substantial loss of reproductive potential, resource declines might indirectly increase predation rates by limiting the extent to which dive cycles can deviate from those that would maximize energy gain. We hope that ideas presented in this paper stimulate other researchers to further develop theory and test predictions on how predation risk might influence diving behaviour and its ecological consequences. [ABSTRACT FROM AUTHOR]

The striking amount of variation in the mating systems of higher plants has stimulated fruitful research by both ecologists and population geneticists. Historically, these two schools of thought have developed independent theoretical treatments and empirical approaches to account for the evolution of such diversity. We highlight the approach adopted by each field. Population geneticists have developed an approach centred on gene properties of individuals and their role on the evolution of self-fertilisation (transmission rules and the deleterious role of mutations), while ecologists have mostly focused on demographic properties of self-fertilisation (seed production, colonisation ability of selfers). As a result, the two approaches sometimes use conflicting notions of fitness. The recent empirical advances on inbreeding depression, a topic typically motivated by population genetic questions, have emphasized the need to adopt a demographical perspective for fitness. In this paper, we suggest generalizing this approach in mating system evolution and we expect further improvements by integrating demographic and genetics perspectives. [ABSTRACT FROM AUTHOR]

Species distributions often show an aggregated pattern, which can be due to a number of endo- and exogenous factors. While autologistic models have been used for modelling such data with statistical rigour, little emphasis has been put on disentangling potential causes of aggregation. In this paper we ask whether it is possible to infer sources of aggregation in species distributions from a single set of occurrence data by comparing the performance of various autologistic models. We create simulated data sets, which show similar occupancy patterns, but differ in the process that causes the aggregation. We model the distribution of these data with various autologistic models, and show how the relative performance of the models is sensitive to the factor causing aggregation in the data. This information can be used when modelling real species data, where causes of aggregation are typically unknown. To illustrate, we use our approach to assess the potential causes of aggregation in data of seven bird species with contrasting statistical patterns. Our findings have important implications for conservation, as understanding the mechanisms that drive population fluctuations in space and time is critical for the development of effective management actions for long-term conservation. [ABSTRACT FROM AUTHOR]

Although the concepts of scale and biological diversity independently have received rapidly increasing attention in the scientific literature since the 1980s, the rate at which the two concepts have been investigated jointly has grown much more slowly. We find that scale considerations have been incorporated explicitly into six broad areas of investigation related to biological diversity: (1) heterogeneity within and among ecosystems, (2) disturbance ecology, (3) conservation and restoration, (4) invasion biology, (5) importance of temporal scale for understanding processes, and (6) species responses to environmental heterogeneity. In addition to placing the papers of this Special Feature within the context of brief summaries of the expanding literature on these six topics, we provide an overview of tools useful for integrating scale considerations into studies of biological diversity. Such tools include hierarchical and structural-equation modelling, kriging, variable-width buffers, k-fold cross-validation, and cascading graph diagrams, among others. Finally, we address some of the major challenges and research frontiers that remain, and conclude with a look to the future. [ABSTRACT FROM AUTHOR]

Although some excellent articles about Lyell's work have been published, they do not explicitly deal with Lyell's biogeographical conceptions. The purpose of this paper is to analyse Lyell's biogeographical model in terms of its own internal structure. Lyell tried to explain the distribution of organisms by appealing to a real cause (climate). However, he was aware that environmental conditions were clearly insufficient to explain the existence of biogeographical regions. Lyell's adherence to ecological determinism generated strong tensions within his biogeographical model. He shifted from granting a secondary weight to dispersal to assigning it a major role. By doing so, Lyell was led into an evident contradiction. A permanent tension in Lyell's ideas was generated by the prevalent explanatory pattern of his time. The explanatory model based on laws did not produce satisfactory results in biology because it did not deal with historical processes. We may conclude that the knowledge of organic distribution interested Lyell as long as it could be explained by the uniformitarian principles of his geological system. The importance of the second volume of the Principles of geology lies in its ample and systematic argumentation about the geographical distribution of organisms. Lyell established, independently from any theory about organic change, the first version of dispersalist biogeography. [ABSTRACT FROM AUTHOR]

The species–time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This pattern has numerous implications for both theory and conservation in much the same way as the species–area relationship (SAR). However, the STR has received much less attention and to date only a handful of papers have been published on the pattern. Here we gather together 984 community time-series, representing 15 study areas and nine taxonomic groups, and evaluate their STRs in order to assess the generality of the STR, its consistency across ecosystems and taxonomic groups, its functional form, and its relationship to local species richness. In general, STRs were surprisingly similar across major taxonomic groups and ecosystem types. STRs tended to be well fit by both power and logarithmic functions, and power function exponents typically ranged between 0.2 and 0.4. Communities with high richness tended to have lower STR exponents, suggesting that factors increasing richness may simultaneously decrease turnover in ecological systems. Our results suggest that the STR is as fundamental an ecological pattern as the SAR, and raise questions about the general processes underlying this pattern. They also highlight the dynamic nature of most species assemblages, and the need to incorporate time scale in both basic and applied research on species richness patterns. [ABSTRACT FROM AUTHOR]

We studied why many diseases has multi-year period in their epidemiological dynamics, whereas a main source of the fluctuation is a seasonality with period of 1 year. Previous studies using a compartment model with seasonality in transmission rate succeed to generate a multi-year epidemiological dynamics, when, in particular, the seasonal difference is large. However, these studies have focused on the dynamical consequence of seasonal forcing in epidemiological dynamics and an adaptation of pathogens in the seasonal environment has been neglected. In this paper, we describe our study of the evolution of pathogen's sensitivity to seasonality and show that a larger fluctuation in the transmission rate can be favored in the life history evolution of pathogens, suggesting that multi-year periodicity may evolve by natural selection. Our result proposes a new aspect of the evolution of multi-year epidemics. [ABSTRACT FROM AUTHOR]

A large number of methods for the analysis of point pattern data have been developed in a wide range of scientific fields. First-order statistics describe large-scale variation in the intensity of points in a study region, whereas second-order characteristics are summary statistics of all point-to-point distances in a mapped area and offer the potential for detecting both different types and scales of patterns. Second-order analysis based on Ripley's K-function is increasingly used in ecology to characterize spatial patterns and to develop hypothesis on underlying processes; however, the full range of available methods has seldomly been applied by ecologists. The aim of this paper is to provide guidance to ecologists with limited experience in second-order analysis to help in the choice of appropriate methods and to point to practical difficulties and pitfalls. We review (1) methods for analytical and numerical implementation of two complementary second-order statistics, Ripley's K and the O-ring statistic, (2) methods for edge correction, (3) methods to account for first-order effects (i.e. heterogeneity) of univariate patterns, and (4) a variety of useful standard and non-standard null models for univariate and bivariate patterns. For illustrative purpose, we analyze examples that deal with non-homogeneous univariate point patterns. We demonstrate that large-scale heterogeneity of a point-pattern biases Ripley's K-function at smaller scales. This bias is difficult to detect without explicitly testing for homogeneity, but we show that it can be removed when applying methods that account for first-order effects. We synthesize our review in a number of step-by-step recommendations that guide the reader through the selection of appropriate methods and we provide a software program that implements most of the methods reviewed and developed here. [ABSTRACT FROM AUTHOR]

The constraint envelope describing the relationship between geographical range size and body size has usually been explained by a minimum viable population size model, furnishing a strong argument for species selection if geographical range size turns out to be ‘heritable’. Recent papers have questioned this assumption of nonzero geographical range heritability at a phylogenetic level, meaning that the logic that constraint envelopes provide support for higher-level selection fails. However, I believe that analysis of constraint envelopes can still furnish insights for the hierarchical expansion of evolutionary theory because the fitness furnished by variation in body size, which is frequently measured as a highly ‘heritable’ trait at the species level, can be partitioned into anagenetic and cladogenetic components. The constraint envelope furnishes an explicit mechanism for large-body biased extinction rates influencing the distribution of body size. More importantly, it is possible to envisage a scenario in which anagenetic trends driving an increase in body size in higher latitudes within species (Bergmann's rule) are counteracted by available habitat area or continental edges constraining overall species distribution in these higher latitudes, increasing the probability of extinction. Under this combined model, faunas at higher latitudes and under habitat constraints may reach equilibrium points between these opposing hierarchical adaptive forces at smaller body size than faunas with less intense higher-level constraints and will tend to be more right-skewed. [ABSTRACT FROM AUTHOR]

Numerous authors have attempted to quantity the physical properties of leaves in relation to aspects of leaf ecology, including decomposition, sclerophylly, herbivory, and leaf function and longevity. This paper examines the relative merits of the punch-and-die, tearing and shearing tests for assessing leaf physical properties. We conducted a series of these three mechanical tests on leaves of Solanum laciniatum, and determined the effect of various test parameters on the measurement of fracture properties. For the punch-and-die test, the parameters considered were machine speed, clearance between the punch and the die, edge definition of the punch, and area of the punch. Aspects of the tearing test examined were notch length, and effects, and length-to width requirements of t est strips, and for shearing tests the effects of blade proximity, angle and sharpness were investigated. All the test parameters investigated were found significantly to affect the assessment of leaf-fracture properties. In addition, fracture properties were found to vary significantly within leaves. Some general principles for designing and implementing tests are outlined. This study suggests that while punching and shearing tests are useful means of quantifying leaf fracture properties, the value of the tearing test may be reduced as it is most constrained by the biological nature of the test material. [ABSTRACT FROM AUTHOR]

The article presents a brief introduction of the paper "Ecosystem alteration modifies the relative strengths of bottom-up and top-down forces in a herbivore population," by G. Moreau and colleagues. It presents the situation in the field of ecology. It offers an overview of the content of the paper of Moreau and colleagues. It shows that by reducing the mortality of larval sawfly, forest thinning practices add to increased outbreak densities of the sawfly. It tells that the authors combined empirical surveys with experimental manipulations.

The author discusses several factors that contribute to the success of "Ecology Letters." The publication features the most recent research of general importance in the ecological, evolutionary and environmental sciences. The author claims that it is the only ecology journal ensuring that every decision on submitted papers is made within published time limits. He also cites guidelines for increasing the chance that a manuscript is reviewed and accepted for publication in the journal.