Meta-analytical evidence for frequency-dependent selection across the tree of life.

Explaining the maintenance of genetic variation in fitness-related traits within populations is a fundamental challenge in ecology and evolutionary biology. Frequency-dependent selection (FDS) is one mechanism that can maintain such variation, especially when selection favours rare variants (negative FDS). However, our general knowledge about the occurrence of FDS, its strength and direction remain fragmented, limiting general inferences about this important evolutionary process.

Population Regulation and Density-Dependent Demography in the Trinidadian Guppy.

AbstractClassic theory for density-dependent selection for delayed maturation requires that a population be regulated through some combination of adult fecundity and/or juvenile survival. We tested whether those demographic conditions were met in four experimental populations of Trinidadian guppies in which delayed maturation of males evolved when the densities of those populations became high. We used monthly mark-recapture data to examine population dynamics and demography in these populations.

Size-Dependent Intraguild Predation, Cannibalism, and Resource Allocation Determine the Outcome of Species Coexistence.

AbstractIntraguild predation (IGP), a system in which species compete for resources and prey on each other, is more common than existing theory predicts. In theory, an IG predator and its prey can coexist if the IG predator is a weaker competitor for a shared resource and the predator directly benefits from consuming the prey. However, many species that are IG predators also consume members of their own species (cannibalism).

Morphological Covariance and Onset of Foot Prehensility as Indicators of Integrated Evolutionary Dynamics in the Herons (Ardeidae).

The ultimate form an organism attains is based, in part, on the rate and timing of developmental trajectories and on compensatory relationships between morphological traits. For example, there is often an inverse correlation between the relative size of an organism's head and the length of its legs. Avian examples with a disproportionately small head and long legs include ostriches (Struthionidae), flamingos (Phoenicopteridae), cranes (Gruidae), and stilts (Recurvirostridae).

Female preference for rare males is maintained by indirect selection in Trinidadian guppies.

When females prefer mates with rare phenotypes, sexual selection can maintain rather than deplete genetic variation. However, there is no consensus on why this widespread and frequently observed preference might evolve and persist. We examine the fitness consequences of female preference for rare male color patterns in a natural population of Trinidadian guppies, using a pedigree that spans 10 generations.

Does the evolution of ontogenetic niche shifts favour species coexistence? An empirical test in Trinidadian streams.

A major question in ecology is how often competing species evolve to reduce competitive interactions and facilitate coexistence. One untested route for a reduction in competitive interactions is through ontogenetic changes in the trophic niche of one or more of the interacting species. In such cases, theory predicts that two species can coexist if the weaker competitor changes its resource niche to a greater degree with increased body size than the superior competitor.

Pathways to global-change effects on biodiversity: new opportunities for dynamically forecasting demography and species interactions.

In structured populations, persistence under environmental change may be particularly threatened when abiotic factors simultaneously negatively affect survival and reproduction of several life cycle stages, as opposed to a single stage. Such effects can then be exacerbated when species interactions generate reciprocal feedbacks between the demographic rates of the different species. Despite the importance of such demographic feedbacks, forecasts that account for them are limited as individual-based data on interacting species are perceived to be essential for such mechanistic forecasting-but are rarely available.

NEOTROPICAL FRESHWATER FISHES: A dataset of occurrence and abundance of freshwater fishes in the Neotropics.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data.

Rapid genomic convergent evolution in experimental populations of Trinidadian guppies ().

Although rapid phenotypic evolution has been documented often, the genomic basis of rapid adaptation to natural environments is largely unknown in multicellular organisms. Population genomic studies of experimental populations of Trinidadian guppies () provide a unique opportunity to study this phenomenon. Guppy populations that were transplanted from high-predation (HP) to low-predation (LP) environments have been shown to evolve toward the phenotypes of naturally colonized LP populations in as few as eight generations.

The evolution of size-dependent competitive interactions promotes species coexistence.

Theory indicates that competing species coexist in a community when intraspecific competition is stronger than interspecific competition. When body size determines the outcome of competitive interactions between individuals, coexistence depends also on how resource use and the ability to compete for these resources change with body size. Testing coexistence theory in size-structured communities, therefore, requires disentangling the effects of size-dependent competitive abilities and niche shifts.

The experimental range extension of guppies (Poecilia reticulata) influences the metabolic activity of tropical streams.

The ecological consequences of biological range extensions reflect the interplay between the functional characteristics of the newly arrived species and their recipient ecosystems. Teasing apart the relative contribution of each component is difficult because most colonization events are studied retrospectively, i.e.

Towards a more precise - and accurate - view of eco-evolution.

Over the past 15 years, the number of papers focused on 'eco-evo dynamics' has increased exponentially (Figure 1). This pattern suggests the rapid growth of a new, integrative discipline. We argue this overstates the case.

Environmental Change, If Unaccounted, Prevents Detection of Cryptic Evolution in a Wild Population.

AbstractDetecting contemporary evolution requires demonstrating that genetic change has occurred. Mixed effects models allow estimation of quantitative genetic parameters and are widely used to study evolution in wild populations. However, predictions of evolution based on these parameters frequently fail to match observations.

On the Origin of Coexisting Species.

Speciation is frequently initiated but rarely completed, a phenomenon hypothesized to arise due to the failure of nascent lineages to persist. Although a failure to persist often has ecological causes, key gaps exist between ecological and evolutionary theories that, if filled, would clarify when and why speciation succeeds or fails. Here, we apply ecological coexistence theory to show how the alignment between different forms of niche opportunity and niche use shape the initiation, progression, and completion of speciation.

Novel parasite invasion leads to rapid demographic compensation and recovery in an experimental population of guppies.

The global movement of pathogens is altering populations and communities through a variety of direct and indirect ecological pathways. The direct effect of a pathogen on a host is reduced survival, which can lead to decreased population densities. However, theory also suggests that increased mortality can lead to no change or even increases in the density of the host.

Individual differences determine the strength of ecological interactions.

Biotic interactions are central to both ecological and evolutionary dynamics. In the vast majority of empirical studies, the strength of intraspecific interactions is estimated by using simple measures of population size. Biologists have long known that these are crude metrics, with experiments and theory suggesting that interactions between individuals should depend on traits, such as body size.

Upper thermal limits are repeatable in Trinidadian guppies.

Measurements of thermal tolerance are critical for predicting species vulnerability to climate change. Critical thermal maximum (CTmax) is a measure of an animal's upper thermal tolerance, but there is limited evidence for how repeatable it is within individuals over time. We measured the CTmax of Trinidadian guppies (Poecilia reticulata) across six consecutive trials, each a week apart.

Eco-Evolutionary Feedbacks Predict the Time Course of Rapid Life-History Evolution.

Organisms can change their environment and in doing so change the selection they experience and how they evolve. Population density is one potential mediator of such interactions because high population densities can impact the ecosystem and reduce resource availability. At present, such interactions are best known from theory and laboratory experiments.

Competitive asymmetry and local adaptation in Trinidadian guppies.

The outcome of competition between individuals often depends on body size. These competitive asymmetries can drive variation in demographic rates, influencing the ecology and evolution of life histories. The magnitude and direction of such asymmetries differ among taxa, yet little is known empirically about how adaptation to resource limitation alters competitive asymmetries.

Nutrients from salmon parents alter selection pressures on their offspring.

Organisms can modify their surrounding environment, but whether these changes are large enough to feed back and alter their evolutionary trajectories is not well understood, particularly in wild populations. Here we show that nutrient pulses from decomposing Atlantic salmon (Salmo salar) parents alter selection pressures on their offspring with important consequences for their phenotypic and genetic diversity. We found a strong survival advantage to larger eggs and faster juvenile metabolic rates in streams lacking carcasses but not in streams containing this parental nutrient input.

Predicting coexistence in species with continuous ontogenetic niche shifts and competitive asymmetry.

A longstanding problem in ecology is whether structured life cycles impede or facilitate coexistence between species. Theory based on populations with only two discrete stages in the life-cycle indicates that for two species to coexist, at least one must shift its niche between stages and each species must be a better competitor in one of the niches. However, in many cases, niche shifts are associated with changes in an underlying continuous trait like body size and we have few predictions concerning conditions for coexistence for such a widespread form of ontogenetic development.

The evolution of coexistence: Reciprocal adaptation promotes the assembly of a simple community.

Species coexistence may result by chance when co-occurring species do not strongly interact or it may be an evolutionary outcome of strongly interacting species adapting to each other. Although patterns like character displacement indicate that coexistence has often been an evolutionary outcome, it is unclear how often the evolution of coexistence represents adaptation in only one species or reciprocal adaptation among all interacting species. Here, we demonstrate a strong role for evolution in the coexistence of guppies and killifish in Trinidadian streams.

The effects of asymmetric competition on the life history of Trinidadian guppies.

The effects of asymmetric interactions on population dynamics has been widely investigated, but there has been little work aimed at understanding how life history parameters like generation time, life expectancy and the variance in lifetime reproductive success are impacted by different types of competition. We develop a new framework for incorporating trait-mediated density-dependence into size-structured models and use Trinidadian guppies to show how different types of competitive interactions impact life history parameters. Our results show the degree of symmetry in competitive interactions can have dramatic effects on the speed of the life history.