Fitting different visual models to behavioral patterns of parasitic egg rejection along a natural egg color gradient in a cavity-nesting host species.

Avian brood parasites lay their eggs in other birds' nests, and hosts can mitigate the fitness cost of raising unrelated offspring by rejecting parasitic eggs. A visually-based cognitive mechanism often thought to be used by hosts to discriminate the foreign egg is to compare it against the hosts' own eggshell by size, shape, maculation, and/or ground coloration (i.e.

Effects of Abdominal Rotation on Jump Performance in the Ant (Hymenoptera, Formicidae).

Jumping is an important form of locomotion, and animals employ a variety of mechanisms to increase jump performance. While jumping is common in insects generally, the ability to jump is rare among ants. An exception is the Neotropical ant (Fabricius 1804) which is well known for jumping to capture prey or escape threats.

Social environment determines the effect of boldness and activity on survival.

Populations of animals are composed of individuals that differ in ecologically relevant behaviors. Building evidence also suggests that individuals occupy different social niches. Here, in a mark-recapture experiment, we show evidence of an interacting effect of behavior and social niche on survival in the wild: bold individuals had higher survival if they were initially captured in groups while shy, inactive individuals had higher survival if they were initially captured when alone.

The evolution of reproductive isolation in Daphnia.

Background: The process by which populations evolve to become new species involves the emergence of various reproductive isolating barriers (RIB). Despite major advancements in understanding this complex process, very little is known about the order in which RIBs evolve or their relative contribution to the total restriction of gene flow during various stages of speciation. This is mainly due to the difficulties of studying reproductive isolation during the early stages of species formation.

An Acoustic Password Enhances Auditory Learning in Juvenile Brood Parasitic Cowbirds.

How does a naive, young animal decide from which adults to learn behavior? Obligate brood parasitic birds, including brown-headed cowbirds (Molothrus ater), face a particular challenge in learning species-specific behaviors; they lay their eggs in the nest of another species, and juveniles are raised without exposure to adult conspecifics. Nevertheless, male cowbirds need to learn a conspecific song to attract appropriate mates, and female cowbirds need to learn to identify conspecific males for mating. Traditionally, it was thought that parasitic bird species rely purely on instinctual species recognition [1-4], but an alternative is that a species-specific trait serves as a "password" [5], a non-learned cue for naive animals that guides decisions regarding from whom to learn.

Complexity, Genetic Causation, and Hereditarianism.

Hereditarians have claimed that recent advances in psychological and psychiatric genetics support their contention that socially important aspects of behavior and cognition in individuals and groups are largely insensitive to environmental context. This has been countered by anti-hereditarians who (correctly) claim that the conclusion of genetic ineluctability is false. Anti-hereditarians, however, sometimes use problematic arguments based on complexity and the ignorance that comes with complexity and a demand for mechanistic, as opposed to variational, explanations for the ways in which genes affect phenotype.

Social interactions do not drive territory aggregation in a grassland songbird.

Understanding the drivers of animal distributions is a fundamental goal of ecology and informs habitat management. The costs and benefits of colonial aggregations in animals are well established, but the factors leading to aggregation in territorial animals remain unclear. Territorial animals might aggregate to facilitate social behavior such as (1) group defense from predators and/or parasites, (2) cooperative care of offspring, (3) extra-pair mating, and/or (4) mitigating costs of extra-pair mating through kin selection.

Do male sticklebacks use visual and/or olfactory cues to assess a potential mate's history with predation risk?

Differential allocation occurs when individuals alter their reproductive investment based on their mate's traits. A previous study showed that male threespine sticklebacks, , reduced courtship towards females that had previously been exposed to predation risk compared to unexposed females. This suggests that males can detect a female's previous history with predation risk, but the mechanisms by which males assess a female's history are unknown.

Greater opportunities for sexual selection in male than in female obligate brood parasitic birds.

Females are expected to have evolved to be more discriminatory in mate choice than males as a result of greater reproductive investment into larger gametes (eggs vs. sperm). In turn, males are predicted to be more promiscuous than females, showing both a larger variance in the number of mates and a greater increase in reproductive success with more mates, yielding more intense sexual selection on males vs.

When are egg-rejection cues perceived? A test using thermochromic eggs in an avian brood parasite host.

At the core of recognition systems research are questions regarding how and when fitness-relevant decisions made. Studying egg-rejection behavior by hosts to reduce the costs of avian brood parasitism has become a productive model to assess cognitive algorithms underlying fitness-relevant decisions. Most of these studies focus on how cues and contexts affect hosts' behavioral responses to foreign eggs; however, the timing of when the cues are perceived for egg-rejection decisions is less understood.

Indirect effects in a planktonic disease system.

Indirect effects, both density- and trait-mediated, have been known to act in tandem with direct effects in the interactions of numerous species. They have been shown to affect populations embedded in competitive and mutualistic networks alike. In this work, we introduce a four-dimensional system of ordinary differential equations and investigate the interplay between direct density-effects and density- and trait-mediated indirect effects that take place in a yeast parasite-zooplankton host-incompetent competitor system embedded in a food web which also includes resources and predators.

Anti-parasitic egg rejection by great reed warblers (Acrocephalus arundinaceus) tracks differences along an eggshell color gradient.

One of the most effective defenses against avian brood parasitism is the rejection of the foreign egg from the host's nest. Until recently, most studies have tested whether hosts discriminate between own and foreign eggs based on the absolute differences in avian-perceivable eggshell coloration and maculation. However, recent studies suggest that hosts may instead contrast egg appearances across a directional eggshell color gradient.

Individual and interactive effects of herbivory on plant fitness: endopolyploidy as a driver of genetic variation in tolerance and resistance.

Previous studies have shown a causal link between mammalian herbivory, tolerance, and chemical defense in Arabidopsis thaliana, driven by the process of endoreduplication (replication of the genome without mitosis). Removal of the apical meristem by mammalian herbivores lowers auxin, which triggers entry into the endocycle. Increasing chromosome number through endoreduplication, and therefore gene copy number, provides a means of increasing gene expression promoting rapid regrowth rates, higher defensive chemistry and enhanced fitness.

Sex differences in cognition and their relationship to male mate choice.

Male cognition has gained recognition as an important potential player in sexual selection. A number of studies have found positive correlations between male sexual signals and cognitive performance and/or female preferences for males with better cognitive performance, although other studies have not found these relationships. Sex roles can differ dramatically, and sex differences in selection on cognition likely follow from the different tasks associated with these sex roles.

Individual variation and the challenge hypothesis.

In this paper I discuss how the challenge hypothesis (Wingfield et al., 1990) influenced the development of ideas about animal personality, and describe particularly promising areas for future study at the intersection of these two topics. I argue that the challenge hypothesis influenced the study of animal personality in at least three specific ways.

Hybridization in human evolution: Insights from other organisms.

During the late Pleistocene, isolated lineages of hominins exchanged genes thus influencing genomic variation in humans in both the past and present. However, the dynamics of this genetic exchange and associated phenotypic consequences through time remain poorly understood. Gene exchange across divergent lineages can result in myriad outcomes arising from these dynamics and the environmental conditions under which it occurs.

Latching of the click beetle (Coleoptera: Elateridae) thoracic hinge enabled by the morphology and mechanics of conformal structures.

Elaterid beetles have evolved to 'click' their bodies in a unique maneuver. When this maneuver is initiated from a stationary position on a solid substrate, it results in a jump not carried out by the traditional means of jointed appendages (i.e.

Neural mechanisms of auditory species recognition in birds.

Auditory communication in humans and other animals frequently takes place in noisy environments with many co-occurring signallers. Receivers are thus challenged to rapidly recognize salient auditory signals and filter out irrelevant sounds. Most bird species produce a variety of complex vocalizations that function to communicate with other members of their own species and behavioural evidence broadly supports preferences for conspecific over heterospecific sounds (auditory species recognition).

A Subsidiary Cell-Localized Glucose Transporter Promotes Stomatal Conductance and Photosynthesis.

It has long been recognized that stomatal movement modulates CO availability and as a consequence the photosynthetic rate of plants, and that this process is feedback-regulated by photoassimilates. However, the genetic components and mechanisms underlying this regulatory loop remain poorly understood, especially in monocot crop species. Here, we report the cloning and functional characterization of a maize () mutant named ().

Variation in multicomponent recognition cues alters egg rejection decisions: a test of the optimal acceptance threshold hypothesis.

The optimal acceptance threshold hypothesis provides a general predictive framework for testing behavioural responses to discrimination challenges. Decision-makers should respond to a stimulus when the perceived difference between that stimulus and a comparison template surpasses an acceptance threshold. We tested how individual components of a relevant recognition cue (experimental eggs) contributed to behavioural responses of chalk-browed mockingbirds, Mimus saturninus, a frequent host of the parasitic shiny cowbird, Molothrus bonariensis.

Overcompensation: a 30-year perspective.

Biomass removal by herbivores usually incurs a fitness cost for the attacked plants, with the total cost per unit lost tissue depending on the value of the removed tissue (i.e., how costly it is to be replaced by regrowth).

Molecular mechanism and history of non-sense to sense evolution of antifreeze glycoprotein gene in northern gadids.

A fundamental question in evolutionary biology is how genetic novelty arises. De novo gene birth is a recently recognized mechanism, but the evolutionary process and function of putative de novo genes remain largely obscure. With a clear life-saving function, the diverse antifreeze proteins of polar fishes are exemplary adaptive innovations and models for investigating new gene evolution.