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Non-uniform rates of morphological evolution and evolutionary increases in organismal complexity, captured in metaphors like “adaptive zones”, “punctuated equilibrium” and “blunderbuss patterns”, require more elaborate explanations than a simple gradual accumulation of mutations. Here we argue that non-uniform evolutionary increases in phenotypic complexity can be caused by a threshold-like response to growing ecological pressures resulting from evolutionary diversification at a given level of complexity. Acquisition of a new phenotypic feature allows an evolving species to escape this pressure but can typically be expected to carry significant physiological costs. Therefore, the ecological pressure should exceed a certain level to make such an acquisition evolutionarily successful. We present a detailed quantitative description of this process using a microevolutionary competition model as an example. The model exhibits sequential increases in phenotypic complexity driven by diversification at existing levels of complexity and a resulting increase in competitive pressure, which can push an evolving species over the barrier of physiological costs of new phenotypic features. [ABSTRACT FROM AUTHOR]

In the absence of constraints, preference for larger mates is expected to evolve, as larger individuals are typical of higher potential fitness. Large females are often more fecund and carry larger eggs (which result in higher number and better quality of offspring), whereas large males usually have more conspicuous ornaments and are better at defending resources. However, intrasexual competition can constrain the access to larger partners, especially when opportunities for mate takeover abound. Here we investigate the relationship between individual’s size and mate choice in relation to one’s own size and their respective mate’s size using the sailfin tetra, a sexually dimorphic Amazonian fish species. We show that ornaments of larger males are exponentially more conspicuous, and larger females are more fecund and carry larger eggs. Contrary to expectation, neither males nor females associated for longer with the larger of two offered potential mates. Instead, individuals of both genders chose opposite-sex individuals of similar sizes to themselves. Additionally, similar-sized pairs were more likely to spawn than couples with higher size asymmetries. Grounded on field observations, we propose that prudent choice should be particularly important in this system, since courtship is long (often taking several days), which offers opportunities for mate takeover. Intrasexual competition, however, cannot readily explain female choice for similar-sized males. We thus suggest that such preference might be best explained by avoidance of filial cannibalism. [ABSTRACT FROM AUTHOR]

Previous research revealed the feline skin bacterial microbiota to be site-specific and the fungal microbiota to be individual-specific. The effect of other factors, such as genotype and environment, have not yet been studied in cats, but have been shown to be potentially important in shaping the cutaneous microbiota of other animals. Therefore, the objectives of this study were to evaluate the effect of these factors on the bacterial and fungal microbiota of feline skin and oral cavity. The influence of genotype was assessed through the analysis of different cat breeds, and the influence of environment through comparison of indoor and outdoor cats. DNA was extracted from skin and oral swabs, and bacterial and fungal next-generation sequencing were performed. Analysis of the skin microbiota of different cat breeds revealed significant differences in alpha diversity, with Sphynx and Bengal cats having the most diverse communities. Many taxa were found to be differentially abundant between cat breeds, including Veillonellaceae and Malassezia spp. Outdoor environment exposure had considerable influence on beta diversity, especially in the oral cavity, and resulted in numerous differentially abundant taxa. Our findings indicate that the oral bacterial microbiota and both fungal and bacterial microbiota of feline skin are influenced by breed, and to a lesser degree, environment. [ABSTRACT FROM AUTHOR]

Objective: To examine how stratifying persons born outside Canada according to tuberculosis (TB) incidence in their birth country and other demographic factors refines our understanding of TB epidemiology and local TB transmission. Background: Population-level TB surveillance programs and research studies in low incidence settings often report all persons born outside the country in which the study is conducted as “foreign-born”–a single label for a highly diverse population with variable TB risks. This may mask important TB epidemiologic trends and not accurately reflect local transmission patterns. Methods: We used population-level data from two large cohorts in British Columbia (BC), Canada: an immigration cohort (n = 337,492 permanent residents to BC) and a genotyping cohort (n = 2290 culture-confirmed active TB cases). We stratified active TB case counts, incidence rates, and genotypic clustering (an indicator of TB transmission) in BC by birth country TB incidence, age at immigration, and years since arrival. Results: Persons from high-incidence countries had a 12-fold higher TB incidence than those emigrating from low-incidence settings. Estimates of local transmission, as captured by genotyping, versus reactivation of latent TB infection acquired outside Canada varied when data were stratified by birthplace TB incidence, as did patient-level characteristics of individuals in each group, such as age and years between immigration and diagnosis. Conclusion: Categorizing persons beyond simply “foreign-born”, particularly in the context of TB epidemiologic and molecular data, is needed for a more accurate understanding of TB rates and patterns of transmission. [ABSTRACT FROM AUTHOR]

Atractaspidines are poorly studied, fossorial snakes that are found throughout Africa and western Asia, including the Middle East. We employed concatenated gene-tree analyses and divergence dating approaches to investigate evolutionary relationships and biogeographic patterns of atractaspidines with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). We sampled 91 individuals from both atractaspidine genera (Atractaspis and Homoroselaps). Additionally, we used ancestral-state reconstructions to investigate fang and diet evolution within Atractaspidinae and its sister lineage (Aparallactinae). Our results indicated that current classification of atractaspidines underestimates diversity within the group. Diversification occurred predominantly between the Miocene and Pliocene. Ancestral-state reconstructions suggest that snake dentition in these taxa might be highly plastic within relatively short periods of time to facilitate adaptations to dynamic foraging and life-history strategies. [ABSTRACT FROM AUTHOR]

The article offers discussion on the biosphere, industriosphere and their interaction. The biosphere is the thin, discontinuous mantle of life which surrounds the earth and includes natural ecosystems, agricultural ecosystems and man while the industriosphere which is located within, and supported by the biosphere is the series of fossil-fuel powered patches of human industrial activity. To maintain their respective systems and produce goods and services useful to man, both the biosphere and industriosphere use energy, principally derive from the sun to rearrange the chemicals of the Earth's crust. However, the uncontrolled growth and development of industriosphere has degraded human existence through pollution and industrial squalor and threatened the productivity of the biosphere.

The article presents a discussion of the role of the scientist in relation to environmental problems. The problems of the environment are found at the interface between the biosphere and the technosphere. Some of the duties of a natural scientist include undertaking research oriented towards the improvement of the human environment, acting as a scientist in public environmental issues, maintaining and renewing the ethics of scientific research, and contributing to the development of a new social ethics.

The characterization and quantification of ecological interactions and the construction of species' distributions and their associated ecological niches are of fundamental theoretical and practical importance. In this paper, we discuss a Bayesian inference framework, which, using spatial data, offers a general formalism within which ecological interactions may be characterized and quantified. Interactions are identified through deviations of the spatial distribution of co-occurrences of spatial variables relative to a benchmark for the non-interacting system and based on a statistical ensemble of spatial cells. The formalism allows for the integration of both biotic and abiotic factors of arbitrary resolution. We concentrate on the conceptual and mathematical underpinnings of the formalism, showing how, using the naive Bayes approximation, it can be used to not only compare and contrast the relative contribution from each variable, but also to construct species' distributions and ecological niches based on an arbitrary variable type. We also show how non-linear interactions between distinct niche variables can be identified and the degree of confounding between variables accounted for. [ABSTRACT FROM AUTHOR]

In the present study, we investigated the optimum length of prolonged dormancy (developmental arrest extending over favourable periods) of organisms under uncertain environmental conditions. We used an artificial life model to simulate the evolution of suspended development in the ontogenesis of organisms inhabiting unpredictably changing habitats. A virtual population of semelparous parthenogenetic individuals that varied in a duration of developmental arrest competed for limited resources. At a constant level of available resources, uninterrupted development was the superior life strategy. Once population fluctuations appeared (generated by the stochastic variability of available resources), temporal developmental arrest became more advantageous than continuous development. We did not observe the selection of the optimum length of dormancy, but rather the evolution of a diversified period of developmental arrest. The fittest organisms employed bet-hedging strategy and produced diversified dormant forms postponing development for a different number of generations (from 0 to several generations, in decreasing or equal proportions). The maximum length of suspended development increased asymptotically with increasing environmental variability and was inversely related to the mortality of dormant forms. The prolonged dormancy may appear beneficial not only in erratic habitats but also in seasonal ones that are exposed to long-term variability of environmental conditions during the growing seasons. In light of our simulations the phenomenon of very long diapause (VLD), lasting tens to thousands of generations, which is occasionally observed in ontogenesis of some living creatures, may not be explained by the benefits of bet-hedging revival strategies. We propose an alternative reasoning for the expression of VLD. [ABSTRACT FROM AUTHOR]

Islands are pieces of land entirely surrounded by sea on which terrestrial and marine organisms live as little as a few metres apart. Yet, in contrast to terrestrial species, marine species have attracted little attention in studies of island theory. The experimental and conceptual origins of this dichotomy date back to the 1970s, although the apposition has softened in the early 2000s, in part a consequence of phylogeographic analyses and the discovery of new marine environments. Here, I explore the possible range of island and island-like settings in the marine realm and find good evidence, albeit in short supply, for integrating marine with terrestrial perspectives during the current transition from equilibrium to general dynamic models of island biogeography. This integration of marine systems into island theory will be facilitated by three advances: (1) development of many descriptive marine studies to reduce the current deficit, (2) design of rigorous comparative studies within and across realms, and (3) modification of conceptual models to unite seemingly disparate situations, for example describing islands in terms of ecological-evolutionary processes. Marine island biogeography is in its infancy; it may present situations that are uncommon in the existing literature, but not rare in nature, and thus contribute substantially to the new dynamic outlook on a half-century-old theme. [ABSTRACT FROM AUTHOR]

: This paper presents the first mathematical model that attempts to represent the biology and behavior of all individual organisms globally, taking us a step closer to holistic ecological and conservation science founded on mechanistic predictions. [ABSTRACT FROM AUTHOR]

The article discusses a study on the evolution of the beetles and other species. It provides an overview of the categories of explanation regarding the distributions of species which includes random chance, ecological opportunity and key innovations of species. It also emphasizes the dramatic differences among species and its statistical similarities which shows random chance in combination with the multiplicative nature of the process of extinction and speciation.

This article is an inquiry into how analysts and psychotherapists can respond to the environmental crisis within the context of the analytic process. It addresses a perspective on individual and cultural defenses that separate us from a relational context within the matrix of life. A view is presented that regards humans as integral with the natural world, emphasizing the wild nature of psyche, embodiment, and the analytic process as a way of learning to engage this wildness. Building on Thomas Berry's idea that hope for our future lies in our human participation in the dream of the earth, case vignettes introduce the truth telling of the imaginal, proposing that we listen for how dreaming unfolds within one's self, between one's self and another, and between ourselves and the earth. [ABSTRACT FROM AUTHOR]

A trade-off between reproduction and survival is one of the most consistent empirical aspects of life-history diversification. One explanation for this interspecific pattern is evolved differences in the balance of allocation to reproduction versus individual maintenance and survival. The same pattern is expected, however, simply as a result of differences among species in body size. We tested these alternatives using original data from 44 species of albatrosses and petrels, long-lived seabirds that breed very slowly. After application of regression techniques to remove the effects of body size and phylogeny, annual reproduction and survival exhibited a significant trade-off. Our measures of reproductive effort also exhibited significant trade-offs with age at maturity, the latter strongly associated with survival. Feeding rate of chicks, success at fledging chicks, and annual chick production were also significantly associated. In conclusion, after removing the effects of body size, we found a significant trade-off of reproduction and survival, in spite of the fact that these long-lived birds lay only one egg at a time. Our examination of the pattern among life-history traits of these slow breeders and their pelagic feeding ecology provide support for the evolutionary explanation of a trade-off of reproduction and survival. Le compromis entre la reproduction et la survie est l'un des aspects empiriques les plus cohérents de la diversification des cycles biologiques. Une explication de ce patron interspécifique est l'évolution de différences dans l'équilibre entre les allocations à la reproduction par rapport au maintien individuel et à la survie. On s'attend, cependant, à ce que le même patron soit simplement dû à des différences de taille corporelle entre les espèces. Nous testons ces explications de rechange à l'aide de données originales sur 44 espèces d'albatros et de pétrels, des oiseaux marins à grande longévité et à reproduction très étalée. Une fois retirés les effets de la taille et de la phylogénie par des techniques de régression, il existe un important compromis entre la reproduction annuelle et la survie. Il y a aussi des compromis significatifs entre nos mesures de l'effort reproductif et l'âge à la maturité et ce dernier est fortement associé à la survie. Le taux d'alimentation des petits, le succès de l'envol des petits et la production annuelle de petits sont aussi associés de manière significative. En somme, une fois les effets de la taille retirés, il existe un compromis significatif entre la reproduction et la survie, malgré le fait que ces oiseaux longévifs pondent une seul œuf à la fois. Notre examen du patron entre les traits du cycle biologiques de ces oiseaux à reproduction étalée et notre étude de leur écologie alimentaire pélagique viennent renforcer l'explication évolutive de l'existence d'un compromis entre la reproduction et la survie. [ABSTRACT FROM AUTHOR]

Recent advances in nutritional ecology, particularly arising from Ecological Stoichiometry and the Geometric Framework for nutrition, have resulted in greater theoretical coherence and increasingly incisive empirical methodologies that in combination allow for the consideration of nutrient-related processes at many levels of biological complexity. However, these advances have not been consistently integrated into the study of sexual differences in reproductive investment, despite contemporary emphasis on the material costs associated with sexually selected traits (e.g. condition-dependence of exaggerated ornaments). Nutritional ecology suggests that material costs related to sex-specific reproductive traits should be linked to quantifiable underlying differences in the relationship between individuals of each sex and their foods. Here, we argue that applying nutritionally-explicit thought to the study of sexual reproduction should both deepen current understanding of sex-specific phenomena and broaden the tractable frontiers of sexual selection research. In support of this general argument, we examine the causes and consequences of sex-specific nutritional differences, from food selection and nutrient processing to sex-specific reproductive traits. At each level of biological organization, we highlight how a nutritionally-explicit perspective may provide new insights and help to identify new directions. Based on predictions derived at the individual level, we then consider how sex-specific nutrient limitation might influence population growth, and thus potentially broader patterns of life history evolution, using a simple population dynamics model. We conclude by highlighting new avenues of research that may be more accessible from this integrative perspective. [ABSTRACT FROM AUTHOR]

Reproductive rate is a key demographic parameter of life history and population ecology. In traditional population-ecology studies of small mammals, this and other vital rates are inferred from capture-mark-recapture (CMR) data. However, CMR assumes that immigrants at first capture can be distinguished from unmarked locally born offspring, an assumption not always met. We verified CMR estimates of locally born red squirrel ( Sciurus vulgaris) offspring as a measure of reproductive rate, with candidate offspring (CO)–candidate parent (mothers, CPs) assignment by CERVUS, using ten DNA microsatellite loci. Seventy-two of 122 candidate offspring (59%) were assigned to 52 of 125 CPs in six populations. Estimates of mean litter size were 1.5 young (range 1–3). The 50 CO (41%) not assigned to a reproducing female in the study site were considered immigrants. Parentage assignment also provided evidence of dispersal between two of our sites. Overall, CMR and CERVUS agreed in 77% of cases. Considering only the 55 juveniles determined as locally born by CMR, 50 (91%) were also assigned as local offspring with CERVUS. The main discrepancy between the two methods was that 22 subadult squirrels classified immigrants by CMR, were assigned by CERVUS to females which had reproduced in our sites. It is concluded that although in our study system agreement between CMR and CERVUS in determining local offspring was high, using genetic parentage assignment helped to correctly classify some subadults, considered immigrants by CMR, as locally born. Hence, in large-scale demographic studies, combining CMR with parentage assignment will allow more precise estimates of reproduction and dispersal. [ABSTRACT FROM AUTHOR]

Recently, Eskola and Geritz (Bull. Math. Biol. 69:329-346, 2007) showed that several discrete-time population models can be derived mechanistically within a single ecological framework by varying the within-season patterns of reproduction and interindividual aggression. However, these models do not have the Allee effect. In this paper, we modify the original modelling framework by adding different mate finding processes, and thus derive mechanistically several population models with the Allee effect. [ABSTRACT FROM AUTHOR]

This article reviews the subject of resource choice by consumers. It is concerned with how such choice has been and should be represented in quantitative ecological models. This requires consideration of the dynamics of behavioral change and the fitness consequences of different resource intake rates. The topic is important because of the impact of choice on the functional response of the consumer to each of the resources it consumes. A variety of open questions related to choice are addressed. These include: the relationship between optimal diet choice and switching; the relationship between adaptive choice of two or resources and type-3 functional responses to a single resource; whether switching behavior requires choice and whether choice always results in switching behavior; why partial preferences are observed; whether choice between habitats is fundamentally different from choice within habitats; how between-individual variation in parameters related to resource use alters functional responses measured at the population level. The impacts of choice on stability are discussed briefly. The costs of increased resource use and the type of nutritional interactions between resources are particularly important determinants of adaptive resource choice, and are considered in some detail. [ABSTRACT FROM AUTHOR]

1. Life-history theorists have long observed that fast growth and high reproduction tend to be associated with short life span, suggesting that greater investment in such traits may trade off with self-maintenance. The immune system plays an integral role in self-maintenance and has been proposed as a mediator of life-history trade-offs. 2. Ecoimmunologists have predicted that fast-living organisms should rely more heavily on constitutive innate immunity than slow-living organisms, as constitutive innate defences are thought to be relatively inexpensive to develop and can provide a rapid, general response to pathogens. 3. We present the first study to examine this hypothesis in an ectothermic vertebrate, by testing for differences in three aspects of constitutive innate immunity in replicate populations of two life-history ecotypes of the garter snake Thamnophis elegans, one fast-living and one slow-living. 4. As predicted, free-ranging snakes from the fast-living ecotype had higher levels of all three measures of constitutive innate immunity than the slow-living ecotype. These differences in immunity were not explained by parasite loads measured. Furthermore, both ecotypes exhibited a positive relationship between innate immunity and body size/age, which we discuss in the context of ectotherm physiology and ecotype differences in developmental rates. [ABSTRACT FROM AUTHOR]

Ecologists have recognized for decades the importance of spatial scale in ecological processes and patterns, as well as the complications scale poses for understanding ecological mechanisms. Here we highlight the opportunity attention to scale offers experimental ecology. Despite many advantages to considering scale, a review of the literature indicates that multi-scale experimental studies are rare. Although much work has focused on scale as a primary factor (e.g. island size), we draw attention to scale as a ‘lurking’ variable: one which influences the relationship between two or more variables that are not usually understood to be scale-dependent. We highlight three basic observations from which scale-dependence arises: abundance increases with area, environmental conditions vary across space, and the effect of an organism on its environment is spatially limited. From these arise first-order scale-dependence, which relates an ecological variable of interest to a measure of scale. Combining first-order relationships together, we can produce second-order scale-dependencies, which occur when the relationship between two or more variables is mediated by scale. It is these relationships that are of particular interest, as they have the potential to confound experimental results. Most ecological experiments have incorporated scale either implicitly or not at all. We suggest that an explicit consideration of scale could help resolve some long-standing debates when scale is turned from a lurking variable into a working variable. Finally, we review and evaluate four different experimental sampling designs and corresponding statistical analyses that can be used to address the effects of scale in ecological experiments. [ABSTRACT FROM AUTHOR]

We examine the proposal that the high levels of ecological specialization seen in many animals has been driven by benefits in decision accuracy that accrue from this resource-use strategy. Using artificial analogs of real neural processing (artificial neural networks), we examine the relationship between decision accuracy, level of ecological specialization/generalization, and the punishment/reward for selecting non-host resources. We demonstrate that specialists make more accurate resource-use decisions than generalists when the consequences of using a non-host are neutral or positive but not very positive. Pronounced unsuitability of non-host resources in fact promotes higher decision accuracy in generalists. These unusual predictions can be explained by the special properties of neural processing systems and are entirely consistent with patterns of performance of many specialists in nature, where non-used resources are, curiously, often quite suitable for growth and reproduction. They potentially reconcile the long-observed discrepancy between the presence of high levels of ecological specialization in many animal groups and the absence of strong negative fitness correlations across resources. The strong theoretical support obtained here, and the equally good support in experimental studies elsewhere, should bring the "neural limitations" hypothesis to the forefront of research on the evolutionary determinants of ecological range. [ABSTRACT FROM AUTHOR]

The behavior of organisms can contribute to the transformation of their environments. When organismal impacts on the environment feed back to influence organismal density, viability, fertility, or persistence, the environment can be construed as an extension of the organism. This process of fitness-enhancing environmental transformation has been called niche construction. We focus on the relationship of niche construction with species or strain diversity and on the variability of investment in niche construction versus reproduction. We demonstrate a fundamental dilemma of niche construction, whereby the construction of a shared resource leads to a tragedy of the commons, with competition tending to eliminate niche construction strategies. The ability to monopolize a niche, either through spatial proximity or through preferential exploitation, can stabilize niche construction and promote ecological coexistence among polymorphic constructors. We consider both sympatric and allopatric origins of niche construction. Under a variety of different construction mechanisms, variability in the investment in niche construction versus reproduction suggests reproductive altruism but is fully consistent with selfish behavior. We discuss the implications of niche-construction theory on the evolution of life cycles and development, behavioral plasticity, the division of labor, and long-term macroevolutionary trends. [ABSTRACT FROM AUTHOR]

The populations of the Laperrine’s olive ( Olea europaea subsp. laperrinei) are located in three main areas corresponding to the mountains of northern Niger (Aïr), southern Algeria (Hoggar), and north-western Sudan (western Darfur). The populations native of Niger were found to occur in very fragmented patches from 1550 to 1850 m in five isolated mountains with population sizes not exceeding 100 trees each, except in the Tamgak. Samples in the Tamgak and the Bagzane mountains were studied by combining field observations with identification of genets (using highly variable DNA marker analyzes). Trees were relatively small and multi-stemmed like those in the Hoggar, and were associated with some tropical species as in the western Darfur. They were found on borders of “wadis”, i.e., temporary water courses, in ravines and on hillsides. They were unable to rely on sexual reproduction, which was found to be ineffective. In contrast, 28% of the genetic profiles found ( n genet = 98) were represented with two or more trees without aboveground connections. Molecular and morphological data both demonstrated that the populations used clonal growth (CG) to survive in the current unfavorable period of hyper-aridity, and thus are likely to be remnant populations. Signs of human-related disturbances, recorded on 43% of the sampled trees, should be a determining factor of distribution as well. In the Bagzane mountains especially, where human activities are more intense than in the Tamgak mountains, trees developed preferentially on hillsides and ravines with low access rather than on wadi borders with better edaphic conditions but easier access for livestock/people. CG may be therefore, a survival strategy both against aridity and human-related disturbances. Sexual reproduction may be triggered during a less arid period, following the model of multiple demographic strategies, widespread in arid environments. However, survival would be affected by browsing and cuttings. Lastly, the absence of an efficient sexual strategy coupled with the high fragmentation of very small populations and a narrow altitudinal range of distribution indicates that today the populations of O. e. laperrinei in the Aïr mountain range are more endangered than those from southern Algeria and north-western Sudan. [ABSTRACT FROM AUTHOR]

Most population models assume that individuals have equal opportunities for survival and reproduction, although many natural populations consist of individuals with different vital parameters that remain different over time. Individual heterogeneity in vital parameters, which may depend on age or stage, can alter many population characteristics compared with a homogeneous population, affecting both deterministic and stochastic properties of the population process. Demographic variance is an important parameter influenced by heterogeneity. However, whether heterogeneity leads to increased or decreased demographic variance has been an unresolved question, except for special cases. Here, we present a general stochastic matrix model for a heterogeneous population that allows us to examine effects of heterogeneity on population dynamics, even when the degree of heterogeneity depends on age. Using this model, we found that the demographic variance may increase, decrease, or remain unaltered compared with a homogeneous comparison model, depending on the vital parameter values and on how these are distributed among individuals at each time step. Furthermore, if the reproductive value is the same for all individuals, heterogeneity has no effect on the demographic variance. Thus, we provide a general theoretical framework for analyzing how individual heterogeneity caused by different biological mechanisms affects fluctuations of especially small populations. [ABSTRACT FROM AUTHOR]

To study the oribatid mite community inhabiting microhabitats in the canopy of montane Abies amabilis [(Douglas ex D. Don) Lindl.] and Tsuga heterophylla [(Raf.) Sarg] tree species across five elevational sites, we collected 180 branch tips and 180 foliose/crustose lichen samples over three time periods. Thirty-three species of oribatid mites were identified from the study area. Mite species richness and abundance was significantly affected by microhabitat, and this association was independent of sampling time. At the microhabitat scale, distinct species assemblages were associated with lichen and branch tip habitats, and to a lesser degree, tree species. Conifer specificity was most apparent in the closely related species of Jugatala, where Jugatala tuberosa Ewing was only found on branch tips from A. amabilis and Jugatala sp. was primarily found on branch tips from T. heterophylla. Microhabitat specificity was most pronounced in Dendrozetes sp. where most individuals were found on branch tips and Anachiperia geminus Lindo et al. that occurred primarily on lichens. Principal components analysis of oribatid mite community composition further showed a high degree of association with microhabitat and tree species. Habitat profiles are difficult to discern for many species because tree, microhabitat, and elevation preferences confound distribution patterns. Given the significant tree-microhabitat associations in species composition in this montane canopy study, we suggest that sampling multiple microhabitats across elevations to look for patterns in community structure offers opportunities to explicitly test organizing principles in community ecology. [ABSTRACT FROM AUTHOR]

Spiders are a megadiverse group that can be useful indicators of the overall species richness and health of biotic communities. The spider diversity in subtropical forests of the Neotropical region are not yet well known, especially in Argentinean subtropical forests where systematic fieldwork has not been done until recently. The Great Chaco is very important as the unique dry subtropical forest of the earth, but it is suffering increasing degradation by the advance of agriculture. Spider communities have been shown to be more directly influenced by vegetation architecture than vegetation species composition. In this study, we aim to assess whether spider diversity and assemblages change in adjacent habitats with different types of vegetation. We compare the diversity and spider assemblages in two different contiguous protected habitats (hygrophilous woodland and savannah parkland) of the Mburucuyá National Park, (Humid Chaco ecoregion). Seasonal samples were obtained using three types of sampling methods: pitfall trapping, beating, and manual litter extraction. The spider assemblages were different in the studied areas, and the abundance, diversity, evenness, and species richness were higher in the hygrophilous woodland than the savannah parkland. These differences in spider diversity and assemblages indicate that both types of habitats are important if the biodiversity is to be conserved in the Chaco ecoregion, where different types of habitat are shown as a patchy distribution. [ABSTRACT FROM AUTHOR]

The ecological and economic advantages of preventing introduction of species likely to become invasive have increased interest in implementing effective screening tools. We compared the accuracy of the Australian Weed Risk Assessment (WRA) system with that across the six geographies in which it has been tested (New Zealand, Hawaii, Hawaii and Pacific Islands, Czech Republic, Bonin Islands and Florida). Inclusion in four of the tests of a secondary screening tool, developed to reduce the number of species requiring further evaluation, decreased the number of species with that outcome by over 60% on average. Averaging across all tests demonstrated that the WRA system accurately identified major invaders 90%, and non-invaders 70%, of the time. Examined differently, a species of unknown invasive potential is on average likely to be correctly accepted or rejected over 80% of the time for all of these geographies when minor invaders are categorized as invasive. Whereas increasing consistency in definitions and implementation would facilitate understanding of the general application of the WRA system, we believe that this tool functions similarly across islands and continents in tropical and temperate climates and has been sufficiently tested to be adopted as an initial screen for plant species proposed for introduction to a new geography. [ABSTRACT FROM AUTHOR]

We tested the hypothesis that providing high-quality food and water would increase reproduction, survival and population size in house mice living in a semi-arid cropping environment in the mallee region of western Victoria, Australia, where outbreaks of house mice ( Mus domesticus) occur irregularly. We employed a factorial design and applied treatments along internal fencelines (16 sites), adjacent to cropping areas, from November 2003 to July 2004. Population abundance was low during the experiment (0–26 mice per site), and the summer rainfall was below average. We confirmed that mice used the supplementary food and water through a reduction in weight of food containers over time and for water through the presence of Rhodamine B in blood samples and positive bands in whiskers. Abundant food was also available through grain spilt on the ground after harvest of the wheat and barley crops. There was some evidence of increased breeding on sites where water was added, but no effect of food or food and water in combination. Sites where free water was available had marginally higher populations over summer (∼2 more mice on average; P = 0.07). This difference was well below any biologically meaningful effect. Mice were 0.9 g heavier on sites where water was added ( P = 0.04), and were in better condition ( P = 0.03). The addition of high-quality food did not affect mouse population dynamics, and the addition of water resulted in only marginal responses for some demographic characteristics. We conclude that other factors appear to be important for limiting mouse population growth in summer and autumn. [ABSTRACT FROM AUTHOR]

Abstract: The question of whether changes in glucocorticoid concentrations reflect consistent changes in physiology associated with transitions between different stages of reproduction, or whether they reflect responses to environmental conditions, is one the central issues in field endocrinology studies. We examined the temporal and spatial dynamics of corticosterone (CORT, baseline, and acute stress-induced) and corticosterone binding globulin (CBG) concentrations in blood of Black-legged Kittiwakes (Rissa tridactyla) breeding at four major colonies in the Bering Sea, Alaska, during 1999–2005. We found that total CORT, free CORT, and CBG capacity varied inconsistently among reproductive stages, colonies, and years. Total CORT levels were positively correlated with CBG capacity. Variation in free CORT was largely driven by variation in total CORT. Results suggest that the adrenocortical function and CBG in breeding kittiwakes do not vary as a consequence of stage-specific modulation associated with a particular reproductive stage as in some short-lived passerine birds. Rather, in accord with predictions for a long-lived species, the lack of consistent colony, year, and reproductive stage patterns in baseline and maximum CORT, and CBG indicates that environmental factors, probably local dynamics of food availability, drive variation in these factors. [Copyright &y& Elsevier]

1. Much of the literature on the relationship between species richness or functional group richness and measures of ecosystem function focuses on a restricted set of ecosystem function measures and taxonomic groups. Few such studies have been carried out under realistic levels of diversity in the field, particularly in high diversity ecosystems such as tropical forests. 2. We used exclusion experiments to study the effects of dung beetle functional group richness and composition on two interlinked and functionally important ecological processes, dung removal and secondary seed dispersal, in evergreen tropical forest in Sabah, Malaysian Borneo. 3. Overall, both dung and seed removal increased with dung beetle functional group richness. However, levels of ecosystem functioning were idiosyncratic depending on the identity of the functional groups present, indicating an important role for functional group composition. There was no evidence for interference or competition among functional groups. 4. We found strong evidence for overyielding and transgressive overyielding, suggesting complementarity or facilitation among functional groups. Not all mixtures showed transgressive overyielding, so that complementarity was restricted to particular functional group combinations. 5. Beetles in a single functional group (large nocturnal tunnellers) had a disproportionate influence on measures of ecosystem function: in their absence dung removal is reduced by approximately 75%. However, a full complement of functional groups is required to maximize ecosystem functioning. 6. This study highlights the importance of both functional group identity and species composition in determining the ecosystem consequences of extinctions or altered patterns in the relative abundance of species. [ABSTRACT FROM AUTHOR]

Resting egg banks of microcrustaceans have been used to reconstruct the evolutionary and ecological history of species. However, recent studies provided evidence for a discrepancy between dormant propagules in the sediment and the planktonic population. This pattern raises two questions: First, what is the value of data on resting egg banks for population dynamics over time and second, which component of the reproductive cycle causes the observed inconsistency? In our study we focussed on the second question by comparing the taxon composition of a resting egg bank with the reproductive success of ex-ephippial hatchlings. Species and interspecific hybrid identification of dormant and hatched stages was achieved through the application of restriction fragment length polymorphism analysis of an internal transcribed spacer region. We found no significant deviation between the proportion of hatched Daphnia galeata, D. galeata × hyalina and D. hyalina individuals and the observed taxon composition of the resting egg bank. However, species and hybrids differed in their mode and relative success of reproduction. We conclude that the components of reproductive success in Daphnia contribute differentially to the fitness of species and interspecific hybrids. The discrepancy between resting egg banks and “active” planktonic populations results not from differential hatching of species but from the reproductive success of ex-ephippial females and the timing and frequency of sexual reproduction of the different taxa. [ABSTRACT FROM AUTHOR]

Immune activity is variable within and among vertebrates despite the potentially large fitness costs of pathogens to their hosts. From the perspective of life history theory, immunological variability may be the consequence of counterbalancing investments in immune defense against other expensive physiological processes, namely, reproduction. In the present study, we tested the hypothesis that immune defense among captive-bred, disease-free Peromyscus mice would be influenced by their reproductive life history strategies. Specifically, we expected that small species that reproduce prolifically and mature rapidly (i.e., fast pace of life) would favor inexpensive, nonspecific immune defenses to promote reproductive proclivity. Alternatively, we expected that large species that mature slowly and invest modestly in reproduction over multiple events (i.e., slow pace of life) would favor developmentally expensive, specific immune defenses and avoid cheap, nonspecific ones because such defenses are predisposed to self-damage. We found that species exhibited either strong ability to kill (gram-negative) bacteria, a developmentally inexpensive defense, or strong ability to produce antibodies against a novel protein, a developmentally expensive defense, but not both. Cell- mediated inflammation also varied significantly among species, but in a unique fashion relative to bacteria killing or antibody production; wound healing was comparatively similar among species. These results indicate that Peroniyscus species use immune strategies that are con- strained to a dominant axis, but this axis is not determined solely by reproductive pace of life. Further comparisons, ideally with broader phylogenetic coverage, could identify what ecological and evolutionary forces produce the pattern we detected. Importantly, our study indicates that species may not be differentially immunocompetent; rather, they use unique defense strategies to prevent infection. [ABSTRACT FROM AUTHOR]

1. In this study we address how growth rate in consumers may be regulated by nitrogen (N)- and phosphorus (P)- limitation of ribonucleic acid (RNA), using the rotifer Brachionus calyciflorus as the model organism. 2. Growth rate, RNA and weight-specific concentrations of carbon (C), N and P were analyzed in B. calyciflorus fed algae with different C : N, C : P and N : P ratios. 3. Growth rate correlated negatively with food C : N, but not with C : P or N : P, strongly suggesting N-limited growth. Growth rate also strongly correlated with tissue concentrations of RNA and P, in support of the growth rate hypothesis which states that specific P-content of organisms reflects their RNA-content and thus capacity for protein synthesis. 4. Food C : N rather than C : P regulated the growth, RNA and P in this consumer under the food conditions applied. This suggests that availability of N can also be an important regulator of cellular acquisition of P and build-up of ribosomes in that animals released from N-limitation have an increased demand for the P-rich cellular machinery for protein synthesis. 5. The data suggest a strong reciprocal regulation of consumer demands and their C : N : P stoichiometry via the intimate connections between ribosome allocation and protein synthesis and also lend support to the view that reduced protein synthesis efficiency under high growth rates may affect stoichiometry of the consumer. [ABSTRACT FROM AUTHOR]

1. We investigated age-related changes in two reproductive traits (laying date and annual fecundity) in barn swallows Hirundo rustica L. using a mixed model approach to di-stinguish among between- and within-individual changes in breeding performance with age. 2. We tested predictions of age-related improvements of competence (i.e. constraint hypothesis) and age-related progressive disappearance of poor-quality breeders (i.e. selection hypothesis) to explain age-related increase in breeding performance in early life. 3. Reproductive success increased in early life, reaching a plateau at middle age (e.g. at 3 years of age) and decreasing at older age (> 4 years). Age-related changes in breeding success were due mainly to an effect of female age. 4. Age of both female and male affected timing of reproduction. Final linear mixed effect models (LME) for laying date included main and quadratic terms for female and male age, suggesting a deterioration in reproductive performance at older age for both males and females. 5. We found evidence supporting the constraints hypothesis that increases in competence within individuals, with ageing being the most probable cause of the observed increase in breeding performance with age in early life. Two mechanisms were implicated: (1) advance in male arrival date with age provided middle-aged males with better access to mates. Yearling males arrived later to the breeding grounds and therefore had limited access to high-quality mates. (2) Breeding pairs maintaining bonds for 2 consecutive years (experienced pairs) had higher fecundity than newly formed inexperienced breeding pairs. 6. There was no support for the selection hypothesis because breeding performance was not correlated with life span. 7. We found a within-individual deterioration in breeding and migratory performance (arrival date) in the oldest age-classes consistent with senescence in these reproductive and migratory traits. [ABSTRACT FROM AUTHOR]

The article discusses the reproduction, ecology, and evolution of the Indo-Pacific limpet Scutellastra flexuosa. The section reports the results of a multi-year study of the patellogastropod limpet Scutellastra flexuosa on Moorea, Society Islands, French Polynesia. It examines the ecological and life history characteristics of Scutellastra flexuosa with other patellid species, using a standardized list of ecological and life history characters, which was developed during George M. Branch's study of intraspecific competition in southern African Patella.

Laboratory studies were conducted to measure selected life history traits and the functional response of the parasitoid Pseudapanteles dignus (Muesebeck), a major enemy of Tuta absoluta (Meyrick) in tomato crops in South America. Newly mated P. dignus females were individually exposed to 10 host larvae in mines for 24 h. We determined developmental time from egg to pupal formation and pupal stage duration, female adult life span, fecundity, reproductive period, daily parasitism rate, and sex ratio of offspring. For the functional response experiment, treatments consisted of six host densities: 3, 5, 7, 10, 15, 20, or 30 larvae. The number and proportion of parasitized hosts were calculated for each density. The shape of the functional response curve was analyzed by logistic regression. P. clignus females attacked hosts daily, exhibiting modest lifetime fecundity (≈32 parasitized hosts per female) and a female-biased offspring sex ratio. Female adult life span was 36 d. P. dignus showed a type I functional response within the range of host densities tested. We observed that females detect and parasitize the host within a wide range of densities, including low densities. The functional response curve reached an asymptote at a mean density of six hosts per day and seemed not to be egg-limited. Percent parasitism was ≈30%. The ecological implications of the results in relation to the potential of P. dignus for the biological control of T. absoluta in tomato are discussed. [ABSTRACT FROM AUTHOR]

Laboratory clip-cage studies were conducted to quantify the temperature-dependent development, survivorship, and reproduction and to generate life history characteristics and population growth parameters of the cotton aphid, Aphis gossypii Clover, on phenologically standardized greenhouse-grown cottons at 10,15,20,25,30, and 35°C. The developmental thresholds were estimated to be 6.3, 6.7, 5.9, 5.9, and 6.3°C for first to fourth instars and for total nymphal development, respectively. The maximum rate of development were estimated to occur at 32.2, 30.8, 30.4, 30.0, and 30.2°C for first to fourth instars and for total nymphal development, respectively. Increased temperature resulted in more rapid decline in survivorship, which was particularly sharp at 35°C, dropping from 94 to 17% in 5 d. Number of days elapsed until first deposition of progeny increased progressively and sharply at temperatures 10 (26 d) to 15 (15 d) to 20°C (8 d) and stabilized at 5 d for 25, 30, and 35°C. Average lifetime fecundity of females rose from a low of 9.76 progeny at 10°C to a peak of 58.9 progeny at 30°C and declined sharply to 17.3 at 35°C. Finite rate of population growth was highest at 25°C and lowest at 10°C. Although stage-specific developmental maxima occurred between 30 and 32°C, a nonlinear regression model estimated 28.6°C to be the optimum temperature for overall cotton aphid development, reproduction, and population increase. [ABSTRACT FROM AUTHOR]

Development, survival, and reproduction of the predatory mite Kampimodromus aberrans Oudemans were studied at constant temperatures in the range from 15 to 35°C under laboratory conditions. Larval developmental rate for both males and females increased gradually from 15 to 35°C and decreased at higher temperatures. Lactin's nonlinear model described with adequate accuracy the relationship between developmental rate and temperature. The model predicted that lower and upper threshold temperatures for preimaginal development ranged from 9.8 to 11.8°C and from 37.2 to 39.8°C, respectively. The intrinsic rate of population increase (rm) at the different temperatures ranged from 0.0442 to 0.1575, with the highest value recorded at 25°C. At 33°C a negative rm, value was estimated. The rm values determined at different temperatures were fitted to Lactin's nonlinear model, and the lower and upper threshold and the optimal temperatures for population increase were 10.5, 32.4, and 27.6°C, respectively. These data indicate that K. aberrans may be better adapted to intermediate temperatures around 27°C and, therefore, could be a useful biocontrol agent of spider mites during spring and early summer when such temperatures are prevalent in northern Greece. The results could also be useful in developing a population model for K. aberrans under field conditions. [ABSTRACT FROM AUTHOR]

The recently proposed metabolic theory of ecology (MTE) claims to provide a mechanistic explanation for long known allometric relationships between mass and metabolic rate. The MTE postulates that these patterns of allometry are driven by the primary selective constraint of transport of energy and materials. However, recent evidence along several different lines has called into question both the adequacy and the universality of this mechanism. We review the accumulating body of literature on this subject, adding our own concerns and criticisms. In addition to other difficulties, we argue that MTE fails as a mechanistic explanation of mass versus metabolic rate allometries because: 1) circulatory cost minimization is not a tenable criterion for evolutionary optimization, 2) the Boltzmann type relationships on which MTE depends are inadequate descriptors of complex metabolic pathways, and 3) most of the hypotheses advanced by the MTE do not, in fact, depend on the proposed mechanism and therefore cannot be used to test the theory. We conclude that the MTE should be abandoned as a monolithic explanation for allometric patterns, and that a more realistic path toward a better understanding of allometry would be to consider multiple explanatory mechanisms for physiological allometries. [ABSTRACT FROM AUTHOR]

The article presents an alternative model called the Island Immaturity Speciation Pulse which cites that the opportunities for speciation have a broadly predictable relationship to the life cycle of oceanic islands. As islands mature, both richness and endemism increase in tandem, but as islands decline in their old age, opportunities for speciation diminish, in tandem with a reduced carrying capacity. Numerous analyses of species richness variation provide broad support for the idea of an environmentally-determined carrying capacity (K) for richness on islands.

1. Geostatistical models based on Euclidean distance fail to represent the spatial configuration, connectivity, and directionality of sites in a stream network and may not be ecologically relevant for many chemical, physical and biological studies of freshwater streams. Functional distance measures, such as symmetric and asymmetric hydrologic distance, more accurately represent the transfer of organisms, material and energy through stream networks. However, calculating the hydrologic distances for a large study area remains challenging and substituting hydrologic distance for Euclidean distance may violate geostatistical modelling assumptions. 2. We provide a review of geostatistical modelling assumptions and discuss the statistical and ecological consequences of substituting hydrologic distance measures for Euclidean distance. We also describe a new family of autocovariance models that we developed for stream networks, which are based on hydrologic distance measures. 3. We describe the geographical information system (GIS) methodology used to generate spatial data necessary for geostatistical modelling in stream networks. We also provide an example that illustrates the methodology used to create a valid covariance matrix based on asymmetric hydrologic distance and weighted by discharge volume, which can be incorporated into common geostatistical models. 4. The methodology and tools described supply ecologically meaningful and statistically valid geostatistical models for stream networks. They also provide stream ecologists with the opportunity to develop their own functional measures of distance and connectivity, which will improve geostatistical models developed for stream networks in the future. 5. The GIS tools presented here are being made available in order to facilitate the application of valid geostatistical modelling in freshwater ecology. [ABSTRACT FROM AUTHOR]

Background: Among the long-standing conundrums of evolutionary theory, obligatory sex is one of the hardest. Current theory suggests multiple factors that might explain the benefits of sex when compared with complete asexuality, but no satisfactory explanation for the prevalence of obligatory sex in the face of facultative sexual reproduction. Results and Conclusion: We show that when sexual selection is present obligatory sex can evolve and be maintained even against facultative sex, under common scenarios of deleterious mutations and environmental changes. [ABSTRACT FROM AUTHOR]

In this paper I will attempt to answer the question of who or what can have moral status in the environment in the sense that we show direct moral concern and respect toward them. The traditional answer to this question has been anthropocentric, where moral status is ascribed only to human beings, all or some. I shall argue against this position and in favour of a nonanthropocentric position that ascribes moral status to all individual organisms, as well as to certain kinds of supra-individual wholes such as species-populations, ecosystems, and the biosphere as a whole. This corresponds to a combined biocentric and ecocentric position. The argument is constructed in part as a Spinozistic argument using the conceptual apparatus of Baruch Spinoza's systematic philosophy, but it introduces some additional premises as well. [ABSTRACT FROM AUTHOR]

Estimates of carbon fluxes and turnover in ecosystems are key elements in the understanding of climate change and in predicting the accumulation of trace elements in the biosphere. In this paper we present estimates of carbon fluxes and turnover times for five terrestrial ecosystems using a modeling approach. Multiple criteria of acceptance were used to parameterize the model, thus incorporating large amounts of multi-faceted empirical data in the simulations in a standardized manner. Mean turnover times of carbon were found to be rather similar between systems with a few exceptions, even though the size of both the pools and the fluxes varied substantially. Depending on the route of the carbon through the ecosystem, turnover times varied from less than one year to more than one hundred, which may be of importance when considering trace element transport and retention. The parameterization method was useful both in the estimation of unknown parameters, and to identify variability in carbon turnover in the selected ecosystems. [ABSTRACT FROM AUTHOR]

The discovery of Earth-sized extrasolar planets orbiting distant stars will merit an expansion of the sphere of entities worthy of moral consideration. Although it will be a long time, if ever, before humans visit these planets, it is nevertheless worthwhile to develop an environmental ethic that encompasses these planets, as this ethic reflects on our view of life on Earth and elsewhere. A particularly significant case would be a planet that displays spectroscopic signatures of life, although the discovery of many lifeless planets might itself intensify the value of life on Earth. A derivation of Schweitzer's general principle of "reverence for life" and similar frameworks are appropriate ethics with which to view extrasolar planets. The development of an ethical framework for extrasolar planets might provide a means to fashion a deeper and more effective environmental ethic for Earth's biosphere. [ABSTRACT FROM AUTHOR]

Efforts to anticipate threats to biodiversity take the form of species richness predictions (SRPs) based on simple correlations with current climate and habitat area. We review the major approaches that have been used for SRP, species area curves and climate envelopes, and suggest that alternative research efforts may provide more understanding and guidance for management. Extinction prediction suffers from a number of limitations related to data and the novelty of future environments. We suggest additional attention to (1) identification of variables related to biodiversity that are diagnostic and potentially more predictable than extinction, (2) constraints on species dispersal and reproduction that wilt determine population persistence and range shifts, including limited sources or potential immigrants for many regions, and (3) changes in biotic interactions and phenology. We suggest combinations of observational and experimental approaches within a framework available for ingesting heterogeneous data sources. Together, these recommendations amount to a shift in emphasis from prediction of extinction numbers to identification of vulnerabilities and leading indicators of change, as well as suggestions for surveillance tools needed to evaluate important variables and the experiments likely to provide most insight. [ABSTRACT FROM AUTHOR]