Migratory-derived resources induce elongated food chains through middle-up food web effects.

Background: Seasonal movements of animals often result in the transfer of large amounts of energy and nutrients across ecosystem boundaries, which may have large consequences on local food webs through various pathways. While this is known for both terrestrial- and aquatic organisms, quantitative estimates on its effects on food web structure and identification of key pathways are scarce, due to the difficulty in obtaining replication on ecosystem level with negative control, i.e.

Ecological character displacement among Nothobranchius annual killifishes in Tanzania.

Divergent ecological character displacement (ECD) is the competition-driven divergence in resource use-related phenotypic traits between coexisting species. It is considered one of the primary drivers of ecological diversification and adaptive radiation. We analyzed phenotypic and ecological variation in 2 African annual killifish species of the genus Nothobranchius: N.

Seasonality and competition select for variable germination behavior in perennials.

The occurrence of within-population variation in germination behavior and associated traits such as seed size has long fascinated evolutionary ecologists. In annuals, unpredictable environments are known to select for bet-hedging strategies causing variation in dormancy duration and germination strategies. Variation in germination timing and associated traits is also commonly observed in perennials and often tracks gradients of environmental predictability.

Competition among small individuals hinders adaptive radiation despite ecological opportunity.

Ontogenetic diet shifts, where individuals change their resource use during development, are the rule rather than the exception in the animal world. Here, we aim to understand how such changes in diet during development affect the conditions for an adaptive radiation in the presence of ecological opportunity. We use a size-structured consumer-resource model and the adaptive dynamics approach to study the ecological conditions for speciation.

Disentangling Verbal Arguments: Intralocus Sexual Conflict in Haplodiploids.

AbstractIn haplodiploids, (1) alleles spend twice as many generations in females as in males, (2) males are never heterozygous and therefore express recessive alleles, and (3) males sire daughters but not sons. Intralocus sexual conflict therefore operates differently in haplodiploids than in diploids and shares strong similarities with loci on X (or Z) chromosomes. The common co-occurrence of all three features makes it difficult to pinpoint their respective roles.

Habitat deterioration promotes the evolution of direct development in metamorphosing species.

Although metamorphosis is widespread in the animal kingdom, several species have evolved life-cycle modifications to avoid complete metamorphosis. Some species, for example, many salamanders and newts, have deleted the adult stage via a process called paedomorphosis. Others, for example, some frog species and marine invertebrates, no longer have a distinct larval stage and reach maturation via direct development.

Optimal germination timing in unpredictable environments: the importance of dormancy for both among- and within-season variation.

For organisms living in unpredictable environments, timing important life-history events is challenging. One way to deal with uncertainty is to spread the emergence of offspring across multiple years via dormancy. However, timing of emergence is not only important among years, but also within each growing season.

The Evolutionary Ecology of Metamorphosis.

Almost all animal species undergo metamorphosis, even though empirical data show that this life-history strategy evolved only a few times. Why is metamorphosis so widespread, and why has it evolved? Here we study the evolution of metamorphosis by using a fully size-structured population model in conjunction with the adaptive-dynamics approach. We assume that individuals compete for two food sources; one of these, the primary food source, is available to individuals of all sizes.

Large-amplitude consumer-resource cycles allow for the evolution of ontogenetic niche shifts in consumer life history.

In many size-structured populations individuals change resources during the course of their ontogenetic development. Different resources often require different adaptations to be effectively exploited. This leads to a trade-off between small and large individuals in direct developing species.

A Parent-Offspring Trade-Off Limits the Evolution of an Ontogenetic Niche Shift.

Many free-living animal species, including the majority of fish, insects, and amphibians, change their food and habitat during their life. Even though these ontogenetic changes in niche are common, it is not well understood which ecological conditions have favored the evolution of these shifts. Using an adaptive dynamics approach, we show that it is evolutionarily advantageous to switch to an alternative food source in the course of ontogeny when this results in a higher intake rate for the switching consumers.

Do intraspecific or interspecific interactions determine responses to predators feeding on a shared size-structured prey community?

Coexistence of predators that share the same prey is common. This is still the case in size-structured predator communities where predators consume prey species of different sizes (interspecific prey responses) or consume different size classes of the same species of prey (intraspecific prey responses). A mechanism has recently been proposed to explain coexistence between predators that differ in size but share the same prey species, emergent facilitation, which is dependent on strong intraspecific responses from one or more prey species.