Predation risk and the evolution of a vertebrate stress response: Parallel evolution of stress reactivity and sexual dimorphism.

Predation risk is often invoked to explain variation in stress responses. Yet, the answers to several key questions remain elusive, including the following: (1) how predation risk influences the evolution of stress phenotypes, (2) the relative importance of environmental versus genetic factors in stress reactivity and (3) sexual dimorphism in stress physiology. To address these questions, we explored variation in stress reactivity (ventilation frequency) in a post-Pleistocene radiation of live-bearing fish, where Bahamas mosquitofish (Gambusia hubbsi) inhabit isolated blue holes that differ in predation risk.

More than meets the eye: Predator-induced pupil size plasticity in a teleost fish.

Most animals are visually oriented, and their eyes provide their 'window to the world'. Eye size correlates positively with visual performance, because larger eyes can house larger pupils that increase photon catch and contrast discrimination, particularly under dim light, which have positive effects on behaviours that enhance fitness, including predator avoidance and foraging. Recent studies have linked predation risk to selection for larger eyes and pupils, and such changes should be of importance for the majority of teleost fishes as they have a pupil that is fixed in size (eyes lack a pupillary sphincter muscle) and, hence, do not respond to changes in light conditions.

Maladaptive migration behaviour in hybrids links to predator-mediated ecological selection.

Different migratory species have evolved distinct migratory characteristics that improve fitness in their particular ecological niches. However, when such species hybridize, migratory traits from parental species can combine maladaptively and cause hybrids to fall between parental fitness peaks, with potential consequences for hybrid viability and species integrity. Here, we take advantage of a natural cross-breeding incident to study migratory behaviour in naturally occurring hybrids as well as in their parental species and explore links between migratory traits and predation risk.

Defence versus defence: Are crucian carp trading off immune function against predator-induced morphology?

Numerous species adopt inducible defence strategies; that is, they have phenotypically plastic traits that decrease the risk of capture and consumption by potential predators. The benefits of expressing alternative phenotypes in high- vs. low-risk environments are well documented.

Assessing Potential Vulnerability and Response of Fish to Simulated Avian Predation after Exposure to Psychotropic Pharmaceuticals.

Psychotropic pharmaceuticals present in the environment may impact organisms both directly and via interaction strengths with other organisms, including predators; therefore, this study examined the potential effects of pharmaceuticals on behavioral responses of fish to avian predators. Wild-caught juvenile perch () were assayed using a striking bird model after a seven-day exposure to psychotropic pharmaceuticals (the antidepressants fluoxetine or sertraline, or the β-blocker propranolol) under the hypotheses that exposure would increase vulnerability to avian predation via increasing the probability of predator encounter as well as degrading evasive behaviors upon encounter. None of the substances significantly affected swimming activity of the fish, nor did they increase vulnerability by affecting encounter probability or evasive endpoints compared to control treatments.

Branched-chain amino acids increase p70S6k phosphorylation in human skeletal muscle after resistance exercise.

The aim of the study was to investigate the effect of resistance exercise alone or in combination with oral intake of branched-chain amino acids (BCAA) on phosphorylation of the 70-kDa S6 protein kinase (p70(S6k)) and mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase (ERK1/2), and p38 MAPK in skeletal muscle. Seven male subjects performed one session of quadriceps muscle resistance training (4 x 10 repetitions at 80% of one repetition maximum) on two occasions. In a randomized order, double-blind, crossover test, subjects ingested a solution of BCAA or placebo during and after exercise.