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Evolutionary Ecology (evolutionary + ecology)
Selected AbstractsA review of Evolutionary Ecology of Parasites, by Robert PoulinEVOLUTION AND DEVELOPMENT, Issue 5 2007Oliver Balmer No abstract is available for this article. [source] Evolutionary ecology, sexual conflict, and behavioral differentiation among baboon populationsEVOLUTIONARY ANTHROPOLOGY, Issue 5 2003Peter Henzi Abstract A central assumption of baboon socio-ecological models is that all populations have the same capacity to react to different environments. The burden of our argument is that this assumption needs to be reconsidered. Data suggest not only that hamadryas, but chacma as well, differ in interesting ways from the stock baboon model that has been derived, in the main, from earlier work on anubis and cynocephalus. Although environmental factors are behind these differences, much of their influence is a consequence of their effect on restricted ancestral populations, where selection for appropriate responses to the social challenges set by local conditions now constrains the nature of individual responses to contemporary environments. Available genetic evidence suggess a southern African origin for Papio at a time when climatic conditions were certainly no better than they are now and when temperatures, if nothing else, were probably lower. In light of this, a reconstruction of how climate has structured the sexual conflict between males and female charcma, which itself hinges on infanticide, can help explain not only the East African pattern, but also how the apparently anomalous hamadryas pattern has been derived. [source] Evolutionary ecology of insect adaptation to Bt cropsEVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 5-6 2010Yves Carrière Abstract Transgenic crops producing Bacillus thuringiensis (Bt) toxins are used worldwide to control major pests of corn and cotton. Development of strategies to delay the evolution of pest resistance to Bt crops requires an understanding of factors affecting responses to natural selection, which include variation in survival on Bt crops, heritability of resistance, and fitness advantages associated with resistance mutations. The two main strategies adopted for delaying resistance are the refuge and pyramid strategies. Both can reduce heritability of resistance, but pyramids can also delay resistance by reducing genetic variation for resistance. Seasonal declines in the concentration of Bt toxins in transgenic cultivars, however, can increase the heritability of resistance. The fitness advantages associated with resistance mutations can be reduced by agronomic practices, including increasing refuge size, manipulating refuges to increase fitness costs, and manipulating Bt cultivars to reduce fitness of resistant individuals. Manipulating costs and fitness of resistant individuals on transgenic insecticidal crops may be especially important for thwarting evolution of resistance in haplodiploid and parthenogenetic pests. Field-evolved resistance to Bt crops in only five pests during the last 14 years suggests that the refuge strategy has successfully delayed resistance, but the accumulation of resistant pests could accelerate. [source] Genome-wide SNP detection in the great tit Parus major using high throughput sequencingMOLECULAR ECOLOGY, Issue 2010NIKKIE E. M. VAN BERS Abstract Identifying genes that underlie ecological traits will open exiting possibilities to study gene,environment interactions in shaping phenotypes and in measuring natural selection on genes. Evolutionary ecology has been pursuing these objectives for decades, but they come into reach now that next generation sequencing technologies have dramatically lowered the costs to obtain the genomic sequence information that is currently lacking for most ecologically important species. Here we describe how we generated over 2 billion basepairs of novel sequence information for an ecological model species, the great tit Parus major. We used over 16 million short sequence reads for the de novo assembly of a reference sequence consisting of 550 000 contigs, covering 2.5% of the genome of the great tit. This reference sequence was used as the scaffold for mapping of the sequence reads, which allowed for the detection of over 20 000 novel single nucleotide polymorphisms. Contigs harbouring 4272 of the single nucleotide polymorphisms could be mapped to a unique location on the recently sequenced zebra finch genome. Of all the great tit contigs, significantly more were mapped to the microchromosomes than to the intermediate and the macrochromosomes of the zebra finch, indicating a higher overall level of sequence conservation on the microchromosomes than on the other types of chromosomes. The large number of great tit contigs that can be aligned to the zebra finch genome shows that this genome provides a valuable framework for large scale genetics, e.g. QTL mapping or whole genome association studies, in passerines. [source] Reconstructing ancestral ecologies: challenges and possible solutionsDIVERSITY AND DISTRIBUTIONS, Issue 1 2006Christopher R. Hardy ABSTRACT There are several ways to extract information about the evolutionary ecology of clades from their phylogenies. Of these, character state optimization and ,ancestor reconstruction' are perhaps the most widely used despite their being fraught with assumptions and potential pitfalls. Requirements for robust inferences of ancestral traits in general (i.e. those applicable to all types of characters) include accurate and robust phylogenetic hypotheses, complete species-level sampling and the appropriate choice of optimality criterion. Ecological characters, however, also require careful consideration of methods for accounting for intraspecific variability. Such methods include ,Presence Coding' and ,Polymorphism Coding' for discrete ecological characters, and ,Range Coding' and ,MaxMin Coding' for continuously variable characters. Ultimately, however, historical inferences such as these are, as with phylogenetic inference itself, associated with a degree of uncertainty. Statistically based uncertainty estimates are available within the context of model-based inference (e.g. maximum likelihood and Bayesian); however, these measures are only as reliable as the chosen model is appropriate. Although generally thought to preclude the possibility of measuring relative uncertainty or support for alternative possible reconstructions, certain useful non-statistical support measures (i.e. ,Sharkey support' and ,Parsimony support') are applicable to parsimony reconstructions. [source] Parasite loads are higher in the tropics: temperate to tropical variation in a single host-parasite systemECOGRAPHY, Issue 4 2008Daniel J. Salkeld Parasites are important selective forces upon the evolutionary ecology of their hosts. At least one hypothesis suggests that high species diversity in the tropics is associated with higher parasite abundance in tropical climates. Few studies, however, have directly assessed whether parasite abundance is higher in the tropics. To address this question, it is ideal, although seldom achievable, to compare parasite abundance in a single species that occurs over a geographical area including both temperate and tropical regions. We examined variation in blood parasite abundance in seven populations of a single lizard host species (Eulamprus quoyii) using a transect that spans temperate and tropical climates. Parasite prevalence (proportion of the host population infected) showed no geographical pattern. Interestingly though, parasite load was higher in lizard populations in the tropics, and was related to mean annual temperature, but not to rainfall. We speculate that in this system the relationship between latitude and parasite load is most likely due to variation in host life history over their geographic range. [source] The evolutionary ecology of PlasmodiumECOLOGY LETTERS, Issue 9 2003R. E. L. Paul Abstract Plasmodium, the aetiological agent of malaria, imposes a substantial public health burden on human society and one that is likely to deteriorate. Hitherto, the recent Darwinian medicine movement has promoted the important role evolutionary biology can play in issues of public health. Recasting the malaria parasite two-host life cycle within an evolutionary framework has generated considerable insight into how the parasite has adapted to life within both vertebrate and insect hosts. Coupled with the rapid advances in the molecular basis to host,parasite interactions, exploration of the evolutionary ecology of Plasmodium will enable identification of key steps in the life cycle and highlight fruitful avenues of research for developing malaria control strategies. In addition, elucidating the extent to which Plasmodium can respond to short- and long-term changes in selection pressures, i.e. its adaptive capacity, is even more crucial in predicting how the burden of malaria will alter with our rapidly evolving ecology. [source] GENOMICS IN THE LIGHT OF EVOLUTIONARY TRANSITIONSEVOLUTION, Issue 6 2010Pierre M. Durand Molecular biology has entrenched the gene as the basic hereditary unit and genomes are often considered little more than collections of genes. However, new concepts and genomic data have emerged, which suggest that the genome has a unique place in the hierarchy of life. Despite this, a framework for the genome as a major evolutionary transition has not been fully developed. Instead, genome origin and evolution are frequently considered as a series of neutral or nonadaptive events. In this article, we argue for a Darwinian multilevel selection interpretation for the origin of the genome. We base our arguments on the multilevel selection theory of hypercycles of cooperative interacting genes and predictions that gene-level trade-offs in viability and reproduction can help drive evolutionary transitions. We consider genomic data involving mobile genetic elements as a test case of our view. A new concept of the genome as a discrete evolutionary unit emerges and the gene,genome juncture is positioned as a major evolutionary transition in individuality. This framework offers a fresh perspective on the origin of macromolecular life and sets the scene for a new, emerging line of inquiry,the evolutionary ecology of the genome. [source] PERSPECTIVE ARTICLE: Why do adaptive immune responses cross-react?EVOLUTIONARY APPLICATIONS (ELECTRONIC), Issue 1 2009Karen J. Fairlie-Clarke Abstract Antigen specificity of adaptive immune responses is often in the host's best interests, but with important and as yet unpredictable exceptions. For example, antibodies that bind to multiple flaviviral or malarial species can provide hosts with simultaneous protection against many parasite genotypes. Vaccinology often aims to harness such imprecision, because cross-reactive antibodies might provide broad-spectrum protection in the face of antigenic variation by parasites. However, the causes of cross-reactivity among immune responses are not always known, and here, we explore potential proximate and evolutionary explanations for cross-reactivity. We particularly consider whether cross-reactivity is the result of constraints on the ability of the immune system to process information about the world of antigens, or whether an intermediate level of cross-reactivity may instead represent an evolutionary optimum. We conclude with a series of open questions for future interdisciplinary research, including the suggestion that the evolutionary ecology of information processing might benefit from close examination of immunological data. [source] Effect of tick parasitism on the health status of a passerine birdFUNCTIONAL ECOLOGY, Issue 6 2008D. J. A. Heylen Summary 1Little information is available on the ecological interactions between ticks and their hosts under natural conditions, and particularly so for avian hosts. To understand this host,parasite interaction it is necessary to assess the physiological harm ticks can do to their host. 2We combined observational and experimental (field and laboratory) data to examine the effects of a common tick species with major economic importance, the sheep tick (Ixodes ricinus), on the health status of a common passerine bird, the great tit (Parus major). 3In the laboratory experiment a parallel group design was carried out in which the birds of the experimental group were infested with 3,10 nymphs, whereas the birds of the control group were kept free of ticks and received a sham treatment. Both groups were stratified according to age and sex. Health parameters were measured the day before and 3 days after infestation or sham treatment: haematocrit level, erythrocyte sedimentation rate, leucocyte concentration and general body condition (body mass corrected for body size). 4No effects of age were observed on any of the health parameters. The decrease in haematocrit level in the experimental group was significantly greater than in the control group. Moreover, infested males suffered more blood depletion than infested females. The increase in sedimentation rate was greater in the experimental group than in the control group. Surprisingly, no treatment effects were found on leucocyte concentrations, which may indicate immunoregulation by the ticks on components of the birds' cellular immune response. Also no difference in general body condition between the treatment groups was found. None of the infested birds died during infestation. 5Lower haematocrit levels in infested birds, but unaffected leucocyte concentrations and general body condition are confirmed by field data (experimental and observational) of adult birds during breeding season. 6Neither haematocrit level nor general body condition was associated with parasite intensity among infested birds, suggesting that immature Ixodes ricinus are not resource limited at high natural densities. Still, the measurable direct harm caused by sheep tick infestations calls for further study on its importance for the evolutionary ecology of passerine hosts. [source] The evolutionary ecology of senescenceFUNCTIONAL ECOLOGY, Issue 3 2008P. Monaghan Summary 1Research on senescence has largely focused on its underlying causes, and is concentrated on humans and relatively few model organisms in laboratory conditions. To understand the evolutionary ecology of senescence, research on a broader taxonomic range is needed, incorporating field, and, where possible, longitudinal studies. 2Senescence is generally considered to involve progressive deterioration in performance, and it is important to distinguish this from other age-related phenotypic changes. We outline and discuss the main explanations of why selection has not eliminated senescence, and summarise the principal mechanisms thought to be involved. 3The main focus of research on senescence is on age-related changes in mortality risk. However, evolutionary biologists focus on fitness, of which survival is only one component. To understand the selective pressures shaping senescence patterns, more attention needs to be devoted to age-related changes in fecundity. 4Both genetic and environmental factors influence the rate of senescence. However, a much clearer distinction needs to be drawn between life span and senescence rate, and between factors that alter the overall risk of death, and factors that alter the rate of senescence. This is particularly important when considering the potential reversibility and plasticity of senescence, and environmental effects, such as circumstances early in life. 5There is a need to reconcile the different approaches to studying senescence, and to integrate theories to explain the evolution of senescence with other evolutionary theories such as sexual and kin selection. [source] Reproductive modes in lizards: measuring fitness consequences of the duration of uterine retention of eggsFUNCTIONAL ECOLOGY, Issue 2 2008R. S. Radder Summary 1One of the primary axes of life-history variation involves the proportion of embryonic development for which the offspring is retained within its parent's body; understanding trade-offs associated with prolonging that period thus is a critical challenge for evolutionary ecology. 2Prior to oviposition, most oviparous squamate reptiles retain developing eggs in utero for about one-third of embryogenesis; the strong conservatism in this trait is a major puzzle in reptilian reproduction. To clarify fitness consequences of this prolonged uterine retention, we need to experimentally modify the trait and examine the effects of our manipulation. 3We used transdermal application of corticosterone to induce gravid scincid lizards (Bassiana duperreyi) to lay their eggs ,prematurely', with relatively undeveloped embryos. Corticosterone application induced females to oviposit sooner (mean of 5·41 ± 0·51 days post-treatment) at earlier embryonic developmental stage (27 ± 0·21) than did controls (13·2 ± 1·22 days; embryonic stage 30·4 ± 0·16). 4Corticosterone levels in the egg yolk were unaffected by maternal treatment, so effects of earlier oviposition should not be confounded by endocrine disruption of embryogenesis. Nonetheless, early oviposition reduced hatchling fitness. Hatching success was lower, incubation periods post-laying were increased, and neonates from eggs laid at earlier embryonic stages were smaller and slower. 5These results suggest that retention of developing eggs in utero by oviparous squamates enhances maternal fitness, and does so via modifications to offspring phenotypes rather than (for example) due to accelerated developmental rates of eggs in utero compared to in the nest. 6More generally, our data support optimality models that interpret interspecific variation in the duration of maternal,offspring contact in terms of the selective forces that result from earlier vs. later termination of that maternal investment. [source] The Marriage of Marx and Darwin?HISTORY AND THEORY, Issue 1 2002Doyne Dawson Recent attempts to develop scientific research strategies for cultural evolution have mostly drawn upon evolutionary biology, but within anthropology there is also an influential tradition of non-biological evolutionary thought whose basic principle is adaptation to the environment. This article is mainly concerned with the "cultural materialist" school of Marvin Harris, but also treats the recent attempt of Jared Diamond to create a more radical model of evolutionary ecology. I argue that the ecological tradition does not represent a real alternative to neo-Darwinism and is in fact a pseudo-Darwinist theory. I also suggest that the bias in favor of materialistic explanation in cultural evolution may not be justified. [source] Timing is everything: flexible phenology and shifting selection in a colonial seabirdJOURNAL OF ANIMAL ECOLOGY, Issue 2 2009Thomas E. Reed Summary 1In order to reproduce successfully in a temporally varying environment, iteroparous animals must exhibit considerable behavioural flexibility across their lifetimes. By adjusting timing of breeding each year, parents can ensure optimal overlap between the energy intensive period of offspring production and the seasonal peak in favourable environmental conditions, thereby increasing their chances of successfully rearing young. 2Few studies investigate variation among individuals in how they respond to fluctuating conditions, or how selection acts on these individual differences, but this information is essential for understanding how populations will cope with rapid environmental change. 3We explored inter-annual trends in breeding time and individual responses to environmental variability in common guillemots Uria aalge, an important marine top predator in the highly variable California Current System. Complex, nonlinear relationships between phenology and oceanic and climate variables were found at the population level. Using a novel application of a statistical technique called random regression, we showed that individual females responded in a nonlinear fashion to environmental variability, and that reaction norm shape differed among females. 4The pattern and strength of selection varied substantially over a 34-year period, but in general, earlier laying was favoured. Females deviating significantly from the population mean laying date each year also suffered reduced breeding success, with the strength of nonlinear selection varying in relation to environmental conditions. 5We discuss our results in the wider context of an emerging literature on the evolutionary ecology of individual-level plasticity in the wild. Better understanding of how species-specific factors and local habitat features affect the timing and success of breeding will improve our ability to predict how populations will respond to climate change. [source] Peppers and poisons: the evolutionary ecology of bad tasteJOURNAL OF ANIMAL ECOLOGY, Issue 5 2006GRAEME D. RUXTON No abstract is available for this article. [source] Effects of predator landscapes on the evolutionary ecology of routing, timing and molt by long-distance migrantsJOURNAL OF AVIAN BIOLOGY, Issue 5 2007Ronald C. Ydenberg [source] Empirical tests of life-history evolution theory using phylogenetic analysis of plant demographyJOURNAL OF ECOLOGY, Issue 2 2010Jean H. Burns Summary 1. A primary goal of evolutionary ecology is to understand factors selecting for the diversity of life histories. Life-history components, such as time-to-reproduction, adult survivorship and fecundity, might differ among species because of variation in direct and indirect benefits of these life histories in different environments or might have lower-than-expected variability because of phylogenetic constraints. Here, we present a phylogenetic examination of demography and life histories using a data base of 204 terrestrial plant species. 2. Overall, statistical models without phylogeny were preferred to models with phylogeny for vital rates and elasticities, suggesting that they lacked phylogenetic signal and are evolutionarily labile. However, the effect of phylogeny was significant in models including sensitivities, suggesting that sensitivities exhibit greater phylogenetic signal than vital rates or elasticities. 3. Species with a greater age at first reproduction had lower fecundity, consistent with a cost of delayed reproduction, but only in some habitats (e.g. grassland). We found no evidence for an indirect benefit of delayed reproduction via a decrease in variation in fecundity with age to first reproduction. 4. The greater sensitivity and lower variation in survival than in fecundity was consistent with buffering of more important vital rates, as others have also found. This suggests that studies of life-history evolution should include survival, rather than only fecundity, for the majority of species. 5.Synthesis. Demographic matrix models can provide informative tests of life-history theory because of their shared construction and outputs and their widespread use among plant ecologists. Our comparative analysis suggested that there is a cost of delayed reproduction and that more important vital rates exhibit lower variability. The absolute importance of vital rates to population growth rates (sensitivities) exhibited phylogenetic signal, suggesting that a thorough understanding of life-history evolution might require an understanding of the importance of vital rates, not just their means, and the role of phylogenetic history. [source] The evolutionary ecology of vegetative dormancy in mature herbaceous perennial plantsJOURNAL OF ECOLOGY, Issue 5 2009Richard P. Shefferson Summary 1.,I present an evolutionary ecology interpretation of vegetative dormancy in mature herbaceous perennials. This kind of vegetative dormancy has been noted for at least 40 years, but has only recently become a topic of study. 2.,Vegetative dormancy may be considered in a life-history context. Both vegetative dormancy and mortality typically decrease with increasing size. Vegetative dormancy's relationship to reproduction is more complex, because some species increase flowering and fruiting after dormancy while others do the opposite. 3.,If vegetative dormancy is adaptive, then it is most likely a bet-hedging trait. Dormancy-prone plants are often long-lived, and in such organisms, bet-hedging traits should counter the effects of environmental stochasticity on adult survival. This adaptive context may vary by life span, because in shorter-lived plants, fitness is most sensitive to changes in reproduction rather than survival. 4.,Vegetative dormancy could evolve if the costs of sprouting ever outweigh the benefits. The benefits of sprouting include: (i) photosynthesis and (ii) the opportunity to flower and reproduce. The costs include: (i) greater chance of herbivory, (ii) greater need for limiting nutrients, and (iii) greater maintenance costs. The many losses of photosynthesis among plants suggest that these benefits may not always outweigh the costs. 5.,Vegetative dormancy may be an evolutionary step towards the loss of photosynthesis. Many non-photosynthetic plants acquire carbon from their mycorrhizal fungi. Many autotrophic, dormancy-prone plants also acquire some carbon from their mycorrhizal fungi. Further, non-photosynthetic plants often become dormant to an even greater extent than autotrophic, dormancy-prone plants. 6.Synthesis,Vegetative dormancy often occurs in clades with non-photosynthetic, myco-heterotrophic plants, with implications for the evolution of traits involved in carbon nutrition. The links between vegetative dormancy, other life-history traits, mycorrhizas and the loss of photosynthesis should provide exciting directions for further research in plant evolutionary ecology. Particularly needed is an assessment of the physiology of vegetative dormancy, including whether the mycorrhiza is a carbon source in all dormancy-prone plant species. Equally important is a better understanding of the genetic relationships among photosynthesis, myco-heterotrophy and dormancy. [source] Habitat saturation and the spatial evolutionary ecology of altruismJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 7 2009S. LION Abstract Under which ecological conditions should individuals help their neighbours? We investigate the effect of habitat saturation on the evolution of helping behaviours in a spatially structured population. We combine the formalisms of population genetics and spatial moment equations to tease out the effects of various physiological (direct benefits and costs of helping) and ecological parameters (such as the density of empty sites) on the selection gradient on helping. Our analysis highlights the crucial importance of demography for the evolution of helping behaviours. It shows that habitat saturation can have contrasting effects, depending on the form of competition (direct vs. indirect competition) and on the conditionality of helping. In our attempt to bridge the gap between spatial ecology and population genetics, we derive an expression for relatedness that takes into account both habitat saturation and the spatial structure of genetic variation. This analysis helps clarify discrepancies in the results obtained by previous theoretical studies. It also provides a theoretical framework taking into account the interplay between demography and kin selection, in which new biological questions can be explored. [source] Pathogen fitness components and genotypes differ in their sensitivity to nutrient and temperature variation in a wild plant,pathogen associationJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2007A.-L. LAINE Abstract Understanding processes maintaining variation in pathogen life-history stages affecting infectivity and reproduction is a key challenge in evolutionary ecology. Models of host,parasite coevolution are based on the assumption that genetic variation for host,parasite interactions is a significant cause of variation in infection, and that variation in environmental conditions does not overwhelm the genetic basis. However, surprisingly little is known about the stability of genotype,genotype interactions under variable environmental conditions. Here, using a naturally occurring plant,pathogen interaction, I tested whether the two distinct aspects of the infection process , infectivity and transmission potential , vary over realistic nutrient and temperature gradients. I show that the initial pathogen infectivity and host resistance responses are robust over the environmental gradients. However, for compatible responses there were striking differences in how different pathogen life-history stages and host and pathogen genotypes responded to environmental variation. For some pathogen genotypes even slight changes in temperature arrested spore production, rendering the developing infection ineffectual. The response of pathogen genotypes to environmental gradients varied in magnitude and even direction, so that their rankings changed across the abiotic gradients. Hence, the variable environment of spatially structured host,parasite interactions may strongly influence the maintenance of polymorphism in pathogen life-history stages governing transmission, whereas evolutionary trajectories of infectivity may be unaffected by the surrounding environment. [source] Conflicting selection pressures on seed size: evolutionary ecology of fruit size in a bird-dispersed tree, Olea europaeaJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 6 2003J. M. Alcántara Abstract Recent evidence indicates that fruit size has evolved according to dispersers' size. This is hypothesized to result from a balance between factors favouring large seeds and dispersers setting the maximum fruit size. This hypothesis assumes that (1) the size of fruits that can be consumed by dispersers is limited, (2) fruit and seed size are positively correlated, and (3) the result of multiple selection pressures on seed size is positive. Our studies on the seed dispersal mutualism of Olea europaea have supported the first and second assumptions, but valid tests of the third assumption are still lacking. Here we confirm the third assumption. Using multiplicative fitness components, we show that conflicting selection pressures on seed size during and after dispersal reverse the negative pattern of selection exerted by dispersers. [source] Xmrks the spot: life history tradeoffs, sexual selection and the evolutionary ecology of oncogenesisMOLECULAR ECOLOGY, Issue 15 2010KYLE SUMMERS In a classic paper, George Williams (1957) argued that alleles promoting reproductive success early in life may be favoured by selection, even if they reduce the lifespan of individuals that bear the allele. A variety of evidence supports the theory that such ,antagonistic pleiotropy' is a major factor contributing to the evolution of senescence (Ljubuncic & Reznick 2009), but examples of specific alleles known to fulfil Williams' criteria remain rare, in both humans and other animals (e.g. Alexander et al. 2007; Kulminski et al. 2010). An intriguing example in this issue of Molecular Ecology (Fernandez & Bowser 2010) demonstrates that both natural and sexual selection may favour melanoma-promoting oncogene alleles in the fish genus Xiphophorus. [source] Deferred Harvests: The Transition from Hunting to Animal HusbandryAMERICAN ANTHROPOLOGIST, Issue 2 2001Michael S. Alvard We define animal husbandry as prey conservation. Conservation is rare among extant hunters and only likely to occur when prey are highly valued, private goods. The long-term discounted deferred returns from husbandry must also be greater than the short-term returns from hunting. We compare the returns from hunting and husbanding strategies as a function of prey body size. Returns from husbanding are estimated using a maximum sustainable yield (MSY) model. Following Charnov (1993), allometric analyses show that the MSY is nearly independent of prey body size. The opportunity costs of husbanding are measured as prey standing biomass times the discount rate. Since standing biomass scales positively with body size, the opportunity costs of husbanding are greater for larger animals. An evolutionary discount rate is estimated following Rogers (1994) to be between 2.4% and 6%. Using these values, the prey body size for which hunting and meat-only husbanding provide the same return is approximately 40kg. Animals greater than 40kg are predicted to be hunted, [animal husbandry, evolutionary ecology, allometry, hunting, Neolithic transition] [source] Survival in a long-lived territorial migrant: effects of life-history traits and ecological conditions in wintering and breeding areasOIKOS, Issue 4 2009Juan M. Grande Despite its key role in population dynamics and evolutionary ecology, little is known about factors shaping survival in long-lived territorial species. Here, we assessed several hypotheses that might explain variability in survival in a migratory Spanish population of a long-lived territorial species, the Egyptian vulture Neophron percnopterus, using a 16-year monitoring period and live-encounter histories of 835 individually marked birds. Cormack-Jolly-Seber capture,recapture models showed no evidence for effects of sex or nestling body condition on survival. However, the normalized difference vegetation index (NDVI; an indicator of primary productivity) of natal territories had positive effects on juvenile survival, indicating that environmental conditions experienced early in life can determine survival prospects. Survival increased with age (0.73±0.02 in the first 2 years to 0.78±0.03 in years 3 and 4) to later decrease when birds were five years old (0.60±0.05), the age at which they acquire the adult plumage, abandon the communal lifestyle of juveniles, and may look for a breeding territory. At older ages, survival was higher for non-breeding (0.75±0.02) and breeding adults (0.83±0.02). Among the latter, birds that recruited into better territories had higher survival prospects. Age-specific variation in survival in this species may be related to behavioural changes linked to dispersal and recruitment into the breeding population, while survival prospects of adult birds strongly depend on breeding territory selection. These results suggest a tradeoff between recruiting soon, and thus reducing mortality costs of a long and extensive dispersal period, and trying to recruit into a good quality territory. Finally, annual survival rates for birds of all age classes were positively related with the NDVI in their African wintering grounds. Although this relationship was probably mediated by food availability, further research is needed to properly identify the limiting factors that are affecting trans-Saharan migrants, especially in light of global climate change. [source] When is a maternal effect adaptive?OIKOS, Issue 12 2007Dustin J. Marshall Maternal effects have become an important field of study in evolutionary ecology and there is an ongoing debate regarding their adaptive significance. Some maternal effects can act to increase offspring fitness and are called ,adaptive maternal effects'. However, other maternal effects decrease offspring fitness and there is confusion regarding whether certain maternal effects are indeed adaptive or merely physiological inevitabilities. Here we suggest that the focus on the consequences of maternal effects for offspring fitness only and the use of ,snapshot' estimates of fitness have misdirected our effort to understand the evolution of maternal effects. We suggest that selection typically acts on maternal effects to maximise maternal rather than (or in addition to) offspring fitness. We highlight the importance of considering how maternal effects influence maternal fitness across a mother's lifetime and describe four broad types of maternal effects using an outcome-based approach. Overall, we suggest that many maternal effects will have an adaptive basis for mothers, regardless of whether these effects increase or decrease survival or reproductive success of individual offspring. [source] Toward a stoichiometric framework for evolutionary biologyOIKOS, Issue 1 2005Adam D. Kay Ecological stoichiometry, the study of the balance of energy and materials in living systems, may serve as a useful synthetic framework for evolutionary biology. Here, we review recent work that illustrates the power of a stoichiometric approach to evolution across multiple scales, and then point to important open questions that may chart the way forward in this new field. At the molecular level, stoichiometry links hereditary changes in the molecular composition of organisms to key phenotypic functions. At the level of evolutionary ecology, a simultaneous focus on the energetic and material underpinnings of evolutionary tradeoffs and transactions highlights the relationship between the cost of resource acquisition and the functional consequences of biochemical composition. At the macroevolutionary level, a stoichiometric perspective can better operationalize models of adaptive radiation and escalation, and elucidate links between evolutionary innovation and the development of global biogeochemical cycles. Because ecological stoichiometry focuses on the interaction of energetic and multiple material currencies, it should provide new opportunities for coupling evolutionary dynamics across scales from genomes to the biosphere. [source] Gene function beyond the single trait: natural variation, gene effects, and evolutionary ecology in Arabidopsis thalianaPLANT CELL & ENVIRONMENT, Issue 1 2005S. J. TONSOR ABSTRACT The purpose of plant functional genomics is to describe the patterns of gene expression and internal plant function underlying the ecological functions that sustain plant growth and reproduction. Plants function as integrated systems in which metabolic and developmental pathways draw on common resource pools and respond to a relatively small number of signal/response systems. Plants are also integrated with their environment, exchanging energy and matter with their surroundings and are consequently sensitive to changes in energy and resource fluxes. These two levels of integration complicate the description of gene function. Internal integration results in single genes often affecting multiple characteristics (pleiotropy) and interacting with multiple other genes (epistasis). Integration with the external environment leads to gene expression and the genes' phenotypic effects varying across environmental backgrounds (gene,environment interaction). An accurate description of the function of all genes requires an augmentation, already underway, of the study of isolated developmental and metabolic pathways to a more integrated approach involving the study of genetic effects across scales of variation usually regarded as the purview of ecological and evolutionary research. Since the evolution of gene function also depends on this complex of gene effects, progress in evolutionary genetics will also require understanding the nature of gene interactions and pleiotropy and the constraints and patterns they impose on adaptive evolution. Studying gene function in the context of the integrated organism is a major challenge, best met by developing co-ordinated research efforts in model systems. This review highlights natural variation in A. thaliana as a system for understanding integrated gene function in an ecological and evolutionary context. The current state of this research integration in A. thaliana is described by summarizing relevant approaches, current knowledge, and some potentially fruitful future studies. By introducing some of the fundamental questions of ecological and evolutionary research, experimental approaches and systems that can reveal new facets of gene function and gene effect are also described. A glossary is included in the Appendix. [source] Carotenoids in evolutionary ecology: re-evaluating the antioxidant roleBIOESSAYS, Issue 10 2009Lorenzo Pérez-Rodríguez Abstract The antioxidant role of carotenoids in the living organism was proposed as a possible basis for the honesty of carotenoid-based signals. However, recent studies have questioned the relevance of carotenoids as powerful antioxidants in vivo. Current evidence does not seem to support the "antioxidant role" hypothesis, but it does not allow us to reject it either. This paper proposes some steps to solve this controversy, such as taking a dynamic approach to antioxidant responses, designing protocols that expose individuals to oxidative challenges, analyzing tissues other than blood, and obtaining measures of antioxidant capacity and oxidative damage simultaneously. However, it should be considered that, irrespective of their antioxidant potential, carotenoids might still give information on oxidative stress levels if they are particularly sensitive to free radicals. Finally, lumping together the immunostimulatory and antioxidant roles of carotenoids should be avoided as these functions are not necessarily associated. [source] Rising starlet: the starlet sea anemone, Nematostella vectensisBIOESSAYS, Issue 2 2005John A. Darling In recent years, a handful of model systems from the basal metazoan phylum Cnidaria have emerged to challenge long-held views on the evolution of animal complexity. The most-recent, and in many ways most-promising addition to this group is the starlet sea anemone, Nematostella vectensis. The remarkable amenability of this species to laboratory manipulation has already made it a productive system for exploring cnidarian development, and a proliferation of molecular and genomic tools, including the currently ongoing Nematostella genome project, further enhances the promise of this species. In addition, the facility with which Nematostella populations can be investigated within their natural ecological context suggests that this model may be profitably expanded to address important questions in molecular and evolutionary ecology. In this review, we explore the traits that make Nematostella exceptionally attractive as a model organism, summarize recent research demonstrating the utility of Nematostella in several different contexts, and highlight a number of developments likely to further increase that utility in the near future. BioEssays 27:211,221, 2005. © 2005 Wiley Periodicals, Inc. [source] Haplotype diversity of the nematode Pristionchus pacificus on Réunion in the Indian Ocean suggests multiple independent invasionsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2010MATTHIAS HERRMANN Pristionchus pacificus has been established as a nematode model system in evolutionary developmental biology and evolutionary ecology. Field studies in North and South America, Asia, Africa and Europe indicated that nematodes of the genus Pristionchus live in association with scarab beetles. Here, we describe the first account of soil- and beetle-associated nematodes on an island setting by investigating the island of Réunion in the Indian Ocean. Réunion has high numbers of endemic insects and is one among several attractive islands for biodiversity studies. Being of volcanic origin, Réunion is 2,3 million years old, making it the youngest of the Mascareigne islands. We show that beetle- and soil-derived nematodes on Réunion are nearly exclusively hermaphroditic, suggesting that selfing is favoured over gonochorism (outcrossing) during island colonization. Among members of four nematode genera observed on Réunion, Pristionchus pacificus was the most prevalent species. A total of 76 isolates, in association with five different scarab beetles, has been obtained for this cosmopolitan nematode. A detailed mitochondrial haplotype analysis indicates that the Réunion isolates of P. pacificus cover all four worldwide clades of the species. This extraordinary haplotype diversity suggests multiple independent invasions, most likely in association with different scarab beetles. Together, we establish Réunion as a case study for nematode island biogeography, in which the analysis of nematode population genetics and population dynamics can provide insight into evolutionary and ecological processes. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 170,179. [source] | ||||||||||||||||||||||||||||