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Pathogen Dose Infectivity Curves as a Method to Analyze the Distribution of Host Susceptibility: A Quantitative Assessment of Maternal Effects after Food Stress and Pathogen ExposureEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Stress conditions have been found to change the susceptibility of hosts or their offspring to infection. The usual method of testing at just one parasite dose level does not allow conclusions on the distribution of susceptibility. To better understand the epidemiology and evolution of host‐parasite systems, however, knowledge about the distribution of host susceptibility, the parameters that characterize it, and how it changes in response to environmental conditions is required. We investigated transgenerational effects of different st...
Source: The American Naturalist - November 13, 2009 Category: Zoology Tags: article Source Type: journals

Parent‐Offspring Conflict and the Evolution of Dispersal DistanceEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Parent‐offspring conflict emerges in many different contexts, but a rarely emphasized perspective is that of space as a resource that is allocated or acquired through dispersal. Early theoretical work has shown that there are different optima in rates of dispersal between parents and offspring. Here we examine this principle when space is explicitly modeled and dispersal is achieved through a dispersal kernel. We find a consistent pattern that selection favors longer dispersal distances under maternal control of dispersal (e.g., matern...
Source: The American Naturalist - November 13, 2009 Category: Zoology Tags: article Source Type: journals

A Porous Convection Model for Grass PatternsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present a new hypothesis that suggests that fluid convection and chill damage to plants could form vegetation patterns with wavelengths ≈1–2 times the plant height. Previous hypotheses for small‐scale vegetation pattern formation relied on a Turing process driven by competition for water, which is thought to occur in large vegetation patterns. Predictions of the new hypothesis were consistent with properties of natural grass patterns in North Carolina, contradicting the Turing hypothesis. These results indicate that similarities in pattern morphology should not be interpreted as implying similarities in the patter...
Source: The American Naturalist - November 13, 2009 Category: Zoology Tags: article ‐Note Source Type: journals

Plant Water Use Affects Competition for Nitrogen: Why Drought Favors Invasive Species in CaliforniaEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Classic resource competition theory typically treats resource supply rates as independent; however, nutrient supplies can be affected by plants indirectly, with important consequences for model predictions. We demonstrate this general phenomenon by using a model in which competition for nitrogen is mediated by soil moisture, with competitive outcomes including coexistence and multiple stable states as well as competitive exclusion. In the model, soil moisture regulates nitrogen availability through soil moisture dependence of microbial p...
Source: The American Naturalist - November 9, 2009 Category: Zoology Tags: article Source Type: journals

Environmental Dependence of Thermal Reaction Norms: Host Plant Quality Can Reverse the Temperature‐Size RuleEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: The temperature‐size rule, a form of phenotypic plasticity in which decreased temperature increases final size, is one of the most widespread patterns in biology, particularly for ectotherms. Identifying the environmental conditions in which this pattern is reversed is key to understanding the generality of the rule. We use wild and domesticated populations of the tobacco hornworm Manduca sexta and the natural host plants of this species to explore the consequences of resource quality for the temperature‐size rule. Manduca sexta rear...
Source: The American Naturalist - November 9, 2009 Category: Zoology Tags: article Source Type: journals

Testing Spatial Theories of Plant Coexistence: No Consistent Differences in Intra‐ and Interspecific Interaction DistancesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We examined how intraspecific and interspecific competition scales with neighbor distance in a target‐neighbor greenhouse competition experiment. Individuals from co‐occurring forbs from calcareous grasslands were grown in isolation and with single conspecific or heterospecific neighbors at distances of 5, 10, or 15 cm (Plantago lanceolata vs. Plantago media and Hieracium pilosella vs. Prunella grandiflora). Neighbor effects were strong and declined with distance. Interaction distances varied greatly within and between species, but we found no evidence for heteromyopia. Instead, neighbor identity effects were mostly ex...
Source: The American Naturalist - November 6, 2009 Category: Zoology Tags: article Source Type: journals

Pollination Efficiency and the Evolution of Specialized Deceptive Pollination SystemsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: The ultimate causes of evolution of highly specialized pollination systems are little understood. We investigated the relationship between specialization and pollination efficiency, defined as the proportion of pollinated flowers relative to those that experienced pollen removal, using orchids with different pollination strategies as a model system. Rewarding orchids showed the highest pollination efficiency. Sexually deceptive orchids had comparably high pollination efficiency, but food‐deceptive orchids had significantly lower effici...
Source: The American Naturalist - November 6, 2009 Category: Zoology Tags: article Source Type: journals

The Misuse of BLUP in Ecology and EvolutionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Best linear unbiased prediction (BLUP) is a method for obtaining point estimates of a random effect in a mixed effect model. Over the past decade it has been used extensively in ecology and evolutionary biology to predict individual breeding values and reaction norms. These predictions have been used to infer natural selection, evolutionary change, spatial‐genetic patterns, individual reaction norms, and frailties. In this article we show analytically and through simulation and example why BLUP often gives anticonservative and biased e...
Source: The American Naturalist - November 5, 2009 Category: Zoology Tags: article Source Type: journals

Why Do Calypte Hummingbirds “Sing” with Both Their Tail and Their Syrinx? An Apparent Example of Sexual Sensory BiasEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Courtship displays frequently include complex signals that females use to pick a mate. Male Costa’s hummingbirds (Calypte costae) generate two acoustic signals during courtship: a vocal song produced close to a female and a dive‐sound produced during a courtship dive. The song and dive‐sound sound similar, and both were assumed to be produced vocally by the syrinx. Here, we show that they are not; whereas the song is produced by the syrinx, the dive‐sound is produced by high‐frequency fluttering of the outermost tail feathers. ...
Source: The American Naturalist - November 5, 2009 Category: Zoology Tags: article Source Type: journals

Breakdown in Postmating Isolation and the Collapse of a Species Pair through HybridizationEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Species that evolved through ecological speciation and that lack intrinsic genetic incompatibilities may nonetheless be maintained by extrinsic postmating isolating barriers that impose selection against hybrids. These species, however, may be vulnerable to a breakdown in postmating isolation. Here, we investigate a model system for ecological speciation: sympatric limnetic‐benthic pairs of threespine sticklebacks. Recently, stickleback hybrid abundance in Enos Lake has increased. Given that ecological selection against hybrids was his...
Source: The American Naturalist - November 5, 2009 Category: Zoology Tags: article Source Type: journals

The well-temperatured biologist. (American Society of Naturalists Presidential Address).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Temperature provides a powerful theme for exploring environmental adaptation at all levels of biological organization, from molecular kinetics to organismal fitness to global biogeography. First, the thermodynamic properties that underlie biochemical kinetics and protein stability determine the overall thermal sensitivity of rate processes. Consequently, a single quantitative framework can assess variation in thermal sensitivity of ectotherms in terms of single amino acid substitutions, quantitative genetics, and interspecific differences. Thermodynamic considerations predict that higher optimal temperatures will resul...
Source: The American Naturalist - November 5, 2009 Category: Biology Authors: Kingsolver JG Tags: Am Nat Source Type: journals

The maintenance of genetic variation due to asymmetric gene flow in dendritic metapopulations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Dendritic landscapes can have ecological properties that differ importantly from simpler spatial arrangements of habitats. Most dendritic landscapes are structured by elevation, and therefore, migration is likely to be directionally biased. While the population-genetic consequences of both dendritic landscape arrangements and asymmetric migration have begun to be studied, these processes have not been considered together. Simple conceptual models predict that if migration into branch (headwater) populations is limited, such populations can act as reservoirs for potentially unique alleles. As a consequence of the fact t...
Source: The American Naturalist - November 5, 2009 Category: Biology Authors: Morrissey MB, de Kerckhove DT Tags: Am Nat Source Type: journals

Insect rate-temperature relationships: environmental variation and the metabolic theory of ecology.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Much of the recent discussion concerning the form and underlying mechanistic basis of metabolic rate-temperature and development rate-temperature relationships has been precipitated by the development of the metabolic theory of ecology (MTE). Empirical tests of the theory's fundamental equation are an essential component of establishing its validity. Here, we test the temperature component of the fundamental equation of the MTE as it applies to metabolic rate and development rate, using insects as model organisms. Specifically, we test (i) whether mean activation energies, E, approximate the 0.65 eV value proposed by t...
Source: The American Naturalist - November 5, 2009 Category: Biology Authors: Irlich UM, Terblanche JS, Blackburn TM, Chown SL Tags: Am Nat Source Type: journals

Space‐Time Relatedness and Hamilton’s Rule for Long‐Lasting Behaviors in Viscous PopulationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Genes affect not only the behavior and fitness of their carriers but also that of other individuals. According to Hamilton’s rule, whether a mutant gene will spread in the gene pool depends on the effects of its carrier on the fitness of all individuals in the population, each weighted by its relatedness to the carrier. However, social behaviors may affect not only recipients living in the generation of the actor but also individuals living in subsequent generations. In this note, I evaluate space‐time relatedness coefficients for lo...
Source: The American Naturalist - November 4, 2009 Category: Zoology Tags: article Notes and Comments Source Type: journals

Stress and Aversive Learning in a Wild Vertebrate: The Role of Corticosterone in Mediating Escape from a Novel StressorEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Elevated plasma corticosterone during stressful events is linked to rapid changes in behavior in vertebrates and can mediate learning and memory consolidation. We tested the importance of acute corticosterone elevation in aversive learning of a novel stressor by wild male eastern fence lizards (Sceloporus undulatus). We found that inhibiting corticosterone elevation (using metyrapone, a corticosterone synthesis blocker) during an encounter with a novel attacker impaired immediate escape responses and limited learning and recall during fu...
Source: The American Naturalist - November 4, 2009 Category: Zoology Tags: article Source Type: journals

AnnouncementEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 174, Issue 6, Page iii, December 2009. (Source: The American Naturalist)
Source: The American Naturalist - November 2, 2009 Category: Zoology Tags: article Source Type: journals

Treasurer's Report, 2008, American Society of NaturalistsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 174, Issue 6, Page 936, December 2009. (Source: The American Naturalist)
Source: The American Naturalist - November 2, 2009 Category: Zoology Tags: article Source Type: journals

Secretary’s Report, 2009, American Society of NaturalistsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 174, Issue 6, Page 932-935, December 2009. (Source: The American Naturalist)
Source: The American Naturalist - November 2, 2009 Category: Zoology Tags: article Source Type: journals

The Influence of Perenniality and Seed Banks on Polymorphism in Plant‐Parasite InteractionsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Antagonistic interactions, such as diseases, play an important role in natural populations. Understanding the mechanisms that promote long‐term polymorphism at loci that are involved in host‐parasite recognition is a fundamental problem in evolutionary ecology. Coevolution implies the existence of indirect frequency‐dependent selection because the fitnesses of parasite genotypes depend on the frequencies of host genes and vice versa. Polymorphism can be maintained in both organisms if there is also negative, direct, frequency‐dep...
Source: The American Naturalist - October 27, 2009 Category: Zoology Tags: article Source Type: journals

Do Speciation Rates Drive Rates of Body Size Evolution in Mammals?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Recently, it has been shown with large data sets of extinct mammals that large‐bodied lineages experienced higher speciation and extinction rates; with extant mammals, it has been shown that body size evolution is accelerated during speciation. Therefore, it is interesting to investigate whether mammalian body size evolution is faster in large‐bodied lineages. Phylogenetic analysis assuming size‐independent speciation rates suggested that the rate of body size evolution increases with body size, whereas size differences in recent s...
Source: The American Naturalist - October 27, 2009 Category: Zoology Tags: article Source Type: journals

Vegetation, Fire, and Feedbacks: A Disturbance‐Mediated Model of SavannasEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Savanna models that are based on recurrent disturbances such as fire result in nonequilibrium savannas, but these models rarely incorporate vegetation feedbacks on fire frequency or include more than two states (grasses and trees). We develop a disturbance model that includes vegetation‐fire feedbacks, using a system of differential equations to represent three main components of savannas: grasses, fire‐tolerant savanna trees, and fire‐intolerant forest trees. We investigate the stability of savannas in the presence of positive fee...
Source: The American Naturalist - October 27, 2009 Category: Zoology Tags: article Source Type: journals

Putting the Weary Ghost of Clements to Rest: A Brief Response to Brooker et al.’s CommentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. (Source: The American Naturalist)
Source: The American Naturalist - October 27, 2009 Category: Zoology Tags: article Source Type: journals

Don’t Diss Integration: A Comment on Ricklefs’s Disintegrating CommunitiesEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Ricklefs’s recent call to investigate ecological processes at large scales helps focus ecologists’ attention on an undoubtedly important topic. However, we believe that some of his accompanying arguments for the primacy of such work and, in particular, for the need to “disintegrate” the local community concept are flawed. We revisit Ricklefs’s main tenets and demonstrate that research on local communities is a vital part of understanding processes and diversity across a range of spatial and temporal scales. The integration of r...
Source: The American Naturalist - October 27, 2009 Category: Zoology Tags: article Source Type: journals

Putting the Weary Ghost of Clements to Rest: A Brief Response to Brooker et al.'s Comment.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19860538 [PubMed - as supplied by publisher] (Source: The American Naturalist)
Source: The American Naturalist - October 27, 2009 Category: Biology Authors: Ricklefs RE Tags: Am Nat Source Type: journals

Don't Diss Integration: A Comment on Ricklefs's Disintegrating Communities.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Ricklefs's recent call to investigate ecological processes at large scales helps focus ecologists' attention on an undoubtedly important topic. However, we believe that some of his accompanying arguments for the primacy of such work and, in particular, for the need to "disintegrate" the local community concept are flawed. We revisit Ricklefs's main tenets and demonstrate that research on local communities is a vital part of understanding processes and diversity across a range of spatial and temporal scales. The integration of research across spatial scales expands our horizons and understanding of ecology and...
Source: The American Naturalist - October 27, 2009 Category: Biology Authors: Brooker RW, Callaway RM, Cavieres LA, Kikvidze Z, Lortie CJ, Michalet R, Pugnaire FI, Valiente-Banuet A, Whitham TG Tags: Am Nat Source Type: journals

Vegetation, Fire, and Feedbacks: A Disturbance-Mediated Model of Savannas.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Savanna models that are based on recurrent disturbances such as fire result in nonequilibrium savannas, but these models rarely incorporate vegetation feedbacks on fire frequency or include more than two states (grasses and trees). We develop a disturbance model that includes vegetation-fire feedbacks, using a system of differential equations to represent three main components of savannas: grasses, fire-tolerant savanna trees, and fire-intolerant forest trees. We investigate the stability of savannas in the presence of positive feedbacks of fire frequency with (1) grasses, (2) savanna trees, and (3) grasses a...
Source: The American Naturalist - October 27, 2009 Category: Biology Authors: Beckage B, Platt WJ, Gross LJ Tags: Am Nat Source Type: journals

Do Speciation Rates Drive Rates of Body Size Evolution in Mammals?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Recently, it has been shown with large data sets of extinct mammals that large-bodied lineages experienced higher speciation and extinction rates; with extant mammals, it has been shown that body size evolution is accelerated during speciation. Therefore, it is interesting to investigate whether mammalian body size evolution is faster in large-bodied lineages. Phylogenetic analysis assuming size-independent speciation rates suggested that the rate of body size evolution increases with body size, whereas size differences in recent sister species (that are little affected by species turnover) appear to be indep...
Source: The American Naturalist - October 27, 2009 Category: Biology Authors: Monroe MJ, Bokma F Tags: Am Nat Source Type: journals

The Influence of Perenniality and Seed Banks on Polymorphism in Plant-Parasite Interactions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Antagonistic interactions, such as diseases, play an important role in natural populations. Understanding the mechanisms that promote long-term polymorphism at loci that are involved in host-parasite recognition is a fundamental problem in evolutionary ecology. Coevolution implies the existence of indirect frequency-dependent selection because the fitnesses of parasite genotypes depend on the frequencies of host genes and vice versa. Polymorphism can be maintained in both organisms if there is also negative, direct, frequency-dependent selection, when natural selection for host resistance or parasite virulenc...
Source: The American Naturalist - October 27, 2009 Category: Biology Authors: Tellier A, Brown JK Tags: Am Nat Source Type: journals

Island Species Richness Increases with Habitat DiversityEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Species richness is commonly thought to increase with habitat diversity. However, a recent theoretical model aiming to unify niche and island biogeography theories predicted a hump‐shaped relationship between richness and habitat diversity. Given the contradiction between model results and previous knowledge, we examine whether the relationship between species richness and habitat diversity is consistently monotonically increasing and under which circumstances, if at all, such relationships could be hump shaped. We review the empirical...
Source: The American Naturalist - October 26, 2009 Category: Zoology Tags: article ‐Article Source Type: journals

Island Species Richness Increases with Habitat Diversity.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Species richness is commonly thought to increase with habitat diversity. However, a recent theoretical model aiming to unify niche and island biogeography theories predicted a hump-shaped relationship between richness and habitat diversity. Given the contradiction between model results and previous knowledge, we examine whether the relationship between species richness and habitat diversity is consistently monotonically increasing and under which circumstances, if at all, such relationships could be hump shaped. We review the empirical evidence about the shape of such relationships and show that species richn...
Source: The American Naturalist - October 26, 2009 Category: Biology Authors: Hortal J, Triantis KA, Meiri S, Thébault E, Sfenthourakis S Tags: Am Nat Source Type: journals

Inverse‐Gene‐for‐Gene Infection Genetics and Coevolutionary DynamicsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present an alternative model, termed inverse‐gene‐for‐gene (IGFG), where pathogen infectiousness is determined by parasite recognition of host signals and/or receptors or where there is active host searching by parasites. We show that coevolutionary dynamics under IGFG are both qualitatively and quantitatively different from those of the GFG model, and we suggest that this new approach may be applicable to a range of important host‐parasite systems that are not currently catered for by the existing frameworks. (Source: The American Naturalist)
Source: The American Naturalist - October 23, 2009 Category: Zoology Tags: article ‐Note Source Type: journals

Selection, Epistasis, and Parent‐of‐Origin Effects on Deleterious Mutations across Environments in Drosophila melanogasterEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Understanding the nature of selection against deleterious alleles is central to determining how populations are affected by the constant influx of new mutations. Important progress has been made in estimating basic attributes of the distribution of selection coefficients and gene interaction effects (epistasis). Although most aspects of selection are likely to be context dependent, little is known about the effect of stress on selection and epistasis at the level of individual genes, especially in multicellular organisms. Using Drosophil...
Source: The American Naturalist - October 23, 2009 Category: Zoology Tags: article Source Type: journals

Selection, Epistasis, and Parent-of-Origin Effects on Deleterious Mutations across Environments in Drosophila melanogaster.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Understanding the nature of selection against deleterious alleles is central to determining how populations are affected by the constant influx of new mutations. Important progress has been made in estimating basic attributes of the distribution of selection coefficients and gene interaction effects (epistasis). Although most aspects of selection are likely to be context dependent, little is known about the effect of stress on selection and epistasis at the level of individual genes, especially in multicellular organisms. Using Drosophila melanogaster, we measure how selection on 20 mutant alleles is affected...
Source: The American Naturalist - October 23, 2009 Category: Biology Authors: Wang AD, Sharp NP, Spencer CC, Tedman-Aucoin K, Agrawal AF Tags: Am Nat Source Type: journals

Inverse-Gene-for-Gene Infection Genetics and Coevolutionary Dynamics.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We present an alternative model, termed inverse-gene-for-gene (IGFG), where pathogen infectiousness is determined by parasite recognition of host signals and/or receptors or where there is active host searching by parasites. We show that coevolutionary dynamics under IGFG are both qualitatively and quantitatively different from those of the GFG model, and we suggest that this new approach may be applicable to a range of important host-parasite systems that are not currently catered for by the existing frameworks. PMID: 19852618 [PubMed - as supplied by publisher] (Source: The American Naturalist)
Source: The American Naturalist - October 23, 2009 Category: Biology Authors: Fenton A, Antonovics J, Brockhurst MA Tags: Am Nat Source Type: journals

Ecological Opportunity in Adaptive Radiation of Galápagos Endemic Land SnailsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: The classic evolutionary hypothesis of ecological opportunity proposes that both heterogeneity of resources and freedom from enemies promote phenotypic divergence as a response to increased niche availability. Although phenotypic divergence and speciation have often been inferred to be the primary consequences of the release from competition or predation that accompanies a shift to a new adaptive zone, increased phenotypic variation within species is expected to represent the first stage resulting from such a shift. Using measures of int...
Source: The American Naturalist - October 22, 2009 Category: Zoology Tags: article Source Type: journals

Ecological Opportunity in Adaptive Radiation of Galápagos Endemic Land Snails.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ecological Opportunity in Adaptive Radiation of Galápagos Endemic Land Snails. Am Nat. 2009 Oct 22; Authors: Parent CE, Crespi BJ Abstract: The classic evolutionary hypothesis of ecological opportunity proposes that both heterogeneity of resources and freedom from enemies promote phenotypic divergence as a response to increased niche availability. Although phenotypic divergence and speciation have often been inferred to be the primary consequences of the release from competition or predation that accompanies a shift to a new adaptive zone, increased phenotypic variation within species is expected to repres...
Source: The American Naturalist - October 22, 2009 Category: Biology Authors: Parent CE, Crespi BJ Tags: Am Nat Source Type: journals

Reproductive Value and the Stochastic Demography of Age‐Structured PopulationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: The dynamics of an age‐structured population in a fluctuating environment is determined by the stochastic individual contributions from annual survival and fecundity to the total reproductive value of the population the next year. All parameters required to describe the population dynamics are simple properties of the distribution of these individual demographic contributions, which we call individual reproductive value. The asymptotic population growth rate in the average environment and the demographic and environmental variances are...
Source: The American Naturalist - October 20, 2009 Category: Zoology Tags: article Source Type: journals

Reproductive Value and the Stochastic Demography of Age-Structured Populations.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: The dynamics of an age-structured population in a fluctuating environment is determined by the stochastic individual contributions from annual survival and fecundity to the total reproductive value of the population the next year. All parameters required to describe the population dynamics are simple properties of the distribution of these individual demographic contributions, which we call individual reproductive value. The asymptotic population growth rate in the average environment and the demographic and environmental variances are respectively the mean individual reproductive value over individuals throu...
Source: The American Naturalist - October 19, 2009 Category: Biology Authors: Engen S, Lande R, Sæther BE, Dobson FS Tags: Am Nat Source Type: journals

A Linear Model Method for Biodiversity–Ecosystem Functioning ExperimentsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Experiments that manipulate species richness and measure ecosystem functioning attempt to separate the effects of species richness (the number of species) from those of species identity. We introduce an experimental design that ensures that each species is selected the same number of times at each level of species richness. In combination with a linear model analysis, this approach is able to unambiguously partition the variance due to different species identities and the variance due to nonlinear species richness, a proxy measure for in...
Source: The American Naturalist - October 13, 2009 Category: Zoology Tags: article Source Type: journals

The Well‐Temperatured BiologistEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Temperature provides a powerful theme for exploring environmental adaptation at all levels of biological organization, from molecular kinetics to organismal fitness to global biogeography. First, the thermodynamic properties that underlie biochemical kinetics and protein stability determine the overall thermal sensitivity of rate processes. Consequently, a single quantitative framework can assess variation in thermal sensitivity of ectotherms in terms of single amino acid substitutions, quantitative genetics, and interspecific difference...
Source: The American Naturalist - October 13, 2009 Category: Zoology Tags: article Source Type: journals

The Maintenance of Genetic Variation Due to Asymmetric Gene Flow in Dendritic MetapopulationsEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Dendritic landscapes can have ecological properties that differ importantly from simpler spatial arrangements of habitats. Most dendritic landscapes are structured by elevation, and therefore, migration is likely to be directionally biased. While the population‐genetic consequences of both dendritic landscape arrangements and asymmetric migration have begun to be studied, these processes have not been considered together. Simple conceptual models predict that if migration into branch (headwater) populations is limited, such populations...
Source: The American Naturalist - October 13, 2009 Category: Zoology Tags: article Source Type: journals

Demographic and Genetic Constraints on EvolutionEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Populations unable to evolve to selectively favored states are constrained. Genetic constraints occur when additive genetic variance in selectively favored directions is absent (absolute constraints) or present but small (quantitative constraints). Quantitative—unlike absolute—constraints are presumed surmountable given time. This ignores that a population might become extinct before reaching the favored state, in which case demography effectively converts a quantitative into an absolute constraint. Here, we derive criteria for predi...
Source: The American Naturalist - October 13, 2009 Category: Zoology Tags: article ‐Article Source Type: journals

A Linear Model Method for Biodiversity-Ecosystem Functioning Experiments.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Experiments that manipulate species richness and measure ecosystem functioning attempt to separate the effects of species richness (the number of species) from those of species identity. We introduce an experimental design that ensures that each species is selected the same number of times at each level of species richness. In combination with a linear model analysis, this approach is able to unambiguously partition the variance due to different species identities and the variance due to nonlinear species richness, a proxy measure for interactions among species. Our design and analysis provide several advanta...
Source: The American Naturalist - October 12, 2009 Category: Biology Authors: Bell T, Lilley AK, Hector A, Schmid B, King L, Newman JA Tags: Am Nat Source Type: journals

Insect Rate‐Temperature Relationships: Environmental Variation and the Metabolic Theory of EcologyEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Much of the recent discussion concerning the form and underlying mechanistic basis of metabolic rate–temperature and development rate–temperature relationships has been precipitated by the development of the metabolic theory of ecology (MTE). Empirical tests of the theory’s fundamental equation are an essential component of establishing its validity. Here, we test the temperature component of the fundamental equation of the MTE as it applies to metabolic rate and development rate, using insects as model organisms. Specifically, we ...
Source: The American Naturalist - October 12, 2009 Category: Zoology Tags: article Source Type: journals

Selection in Ephemeral NetworksEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: A model of “ephemeral” population structure is presented that applies not only to biological systems in which discrete groups form but also to networks without group boundaries. The evolution of altruistic behaviors is discussed. Nonrandom interaction and nonlinear fitness structures are modeled; together, these factors can produce stable polymorphisms of altruistic and selfish types, as well as bistability. Empirical applications of the model may be found in microbes, marine invertebrates, annual plants, and other organisms. (Source...
Source: The American Naturalist - October 12, 2009 Category: Zoology Tags: article Source Type: journals

Selection in Ephemeral Networks.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: A model of "ephemeral" population structure is presented that applies not only to biological systems in which discrete groups form but also to networks without group boundaries. The evolution of altruistic behaviors is discussed. Nonrandom interaction and nonlinear fitness structures are modeled; together, these factors can produce stable polymorphisms of altruistic and selfish types, as well as bistability. Empirical applications of the model may be found in microbes, marine invertebrates, annual plants, and other organisms. PMID: 19842968 [PubMed - as supplied by publisher] (Source: The American Naturalist)
Source: The American Naturalist - October 11, 2009 Category: Biology Authors: Godfrey-Smith P, Kerr B Tags: Am Nat Source Type: journals

Demographic and Genetic Constraints on Evolution.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Abstract: Populations unable to evolve to selectively favored states are constrained. Genetic constraints occur when additive genetic variance in selectively favored directions is absent (absolute constraints) or present but small (quantitative constraints). Quantitative-unlike absolute-constraints are presumed surmountable given time. This ignores that a population might become extinct before reaching the favored state, in which case demography effectively converts a quantitative into an absolute constraint. Here, we derive criteria for predicting when such conversions occur. We model the demography and evolution of p...
Source: The American Naturalist - October 11, 2009 Category: Biology Authors: Gomulkiewicz R, Houle D Tags: Am Nat Source Type: journals

Eco‐Evolutionary Dynamics of Mutualists and ExploitersEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: With the growing recognition of exploiters as a prominent and enduring feature of many mutualisms, there is a need to understand the ecological and evolutionary dynamics of mutualisms in the context of exploitation. Here, we model coevolution between mutualist and exploiter birth rates, using an obligate pollinating seed parasite mutualism associated with a nonpollinating exploiter as a reference system. In this system, mutualist and exploiter larvae parasitize the host plant, competing for and consuming seeds. Evolution of the mutualist...
Source: The American Naturalist - October 9, 2009 Category: Zoology Tags: article Source Type: journals

Dominant Species and Diversity: Linking Relative Abundance to Controls of Species EstablishmentEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 0, Issue 0, Page 000, Latest Articles. Abstract: Ecological theories make divergent predictions about whether extant species inhibit or promote the establishment of new species and which aspects of community composition determine these interactions; diversity, individual dominant species, and neutral interactions have all been argued to be most important. We experimentally tested these predictions by removing plant biomass (0%, 7%, 100%) from boreal forest understory communities. The 7% removals were restricted to the numerically dominant species, the second most dominant species, or m...
Source: The American Naturalist - October 9, 2009 Category: Zoology Tags: article Source Type: journals

Erratum: ErratumEmail this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The American Naturalist, Volume 174, Issue 5, Page 753, November 2009. (Source: The American Naturalist)
Source: The American Naturalist - October 8, 2009 Category: Zoology Tags: article Source Type: journals