Evolutionary Physiology

The extent of changes in basic physiological and
demographic traits associated with reproduction was investigated in the highly cultivated haploid–diploid red alga,
Gracilaria chilensis. Sixty individuals bearing vegetative and
reproductive fronds collected in the natural population of
Niebla (39°52′S, 73°23′W), in Chile, were cultivated under
controlled culture conditions. Our results demonstrated that
vegetative fronds have a higher survival rate and a better
growth rate than reproductive ones irrespective of the type of
individual analyzed (male gametophyte, female gametophyte,
and tetrasporophyte). Moreover, the reproductive fronds clearly
showed a decrease in photosynthetic activity compared to nonreproductive ones. In males and tetrasporophytes, the photosynthetic reduction in reproductive individuals could be
explained by a physical effect of reproductive structure development as well as spores release, disrupting the continuity of
the photosynthetic cortical tissues. Translocation of photoassimilates from nearby vegetative tissue or the previous accumulation of photosynthetic products seems to be a prerequisite for reproductive structure development in this species. Altogether, these results document for the first time in G.
chilensis that reproduction has a strong physiological effect
on male, female, and tetrasporophyte fronds. This trade-off
between reproduction, growth, and survival suggest the existence of reproductive costs in the life history of G. chilensis.

Rossier BC, Baker ME, Studer RA. Physiol Rev 95: 297– 340, 2015; doi:10.1152/physrev.00011.2014.
Transcription and translation require a high concentration of potassium across the entire tree of life. The conservation of a high intracellular potassium was an absolute requirement for the evolution of life on Earth. This was achieved by the interplay of P- and V-ATPases that can set up electrochemical gradients across the cell membrane, an energetically costly process requiring the synthesis of ATP by F-ATPases. In animals, the control of an extracellular compartment was achieved by the emergence of multicellular organisms able to produce tight epithelial barriers creating a stable extracellular milieu. Finally, the adaptation to a terrestrian environment was achieved by the evolution of distinct regulatory pathways allowing salt and water conservation. In this review we emphasize the critical and dual role of Na+-K+-ATPase in the control of the ionic composition of the extracellular fluid and the renin-angiotensin-aldosterone system (RAAS) in salt and water conservation in vertebrates. The action of aldosterone on transepithelial sodium transport by activation of the epithelial sodium channel (ENaC) at the apical membrane and that of Na+-K+ATPase at the basolateral membrane may have evolved in lungfish before the emergence of tetrapods. Finally, we discuss the implication of RAAS in the origin of the present pandemia of hypertension and its associated cardiovascular diseases.

Aggression is a common behavioral trait shared in many animals, including both vertebrates and invertebrates. However, the type and intensity of agonistic encounters and displays can vary widely both across and within species, resulting in complicated or subjective interpretations that create difficulties in developing theoretical models that can be widely applied. The need to easily and objectively identify quantifiable behaviors and their associated morphologies becomes especially important when attempting to decipher the neurological mechanisms underlying this complex behavior. Monoamines, neuropeptides, and pheromones have been implicated as important neuromodulators for agonistic displays in both invertebrates and vertebrates. Additionally, recent breakthroughs in insect research have revealed exciting proximate mechanisms important in aggression that may be broadly relevant, due to the relatively high conservation of these neurochemical systems across animal taxa. In this review, we present the latest research demonstrating the importance of monoamines, neuropeptides, and pheromones as neuromodulators for aggression across a variety of insect species. Additionally, we describe the stalk-eyed fly as a model system for studying aggression, which integrates physiological, morphological, and neurochemical approaches in exploring detailed mechanisms responsible for this common yet complex behavior. We conclude with our perspective on the most promising lines of future research aimed at understanding the proximate and ultimate mechanisms underlying aggressive behaviors.

We studied rectal body temperatures of house mice (Mus domesticus) that had been arti®cially selected for high voluntary wheel running. 1. At generation 17, mice from the four replicate selected lines ran, on average, 2.5-times as many revolutions/day as did mice from the four random-bred control lines. 2. During the day, repeatability of individual dierences in body temperature measured 4 days apart was low; at night, repeatability was statistically signi®cant across three time scales (1 day, 1 week, 2 weeks). 3. During the day, body temperatures of selected and control animals did not dier; at night, mice from selected lines had higher body temperatures. However, when amount of wheel running immediately prior to measurement was included as a covariate, the dierence was no longer statistically signi®cant. Higher body temperatures, associated with increased activity, might enhance locomotor abilities through Q10 eects, increase metabolic rate and food requirements, aect sleep patterns, and alter expression of heat-shock proteins.

Mudskippers are amphibious fishes that have developed morphological and physiological adaptations to match their unique lifestyles. Here we perform whole-genome sequencing of four representative mudskippers to elucidate the molecular mechanisms underlying these adaptations. We discover an expansion of innate immune system genes in the mudskippers that may provide defence against terrestrial pathogens. Several genes of the ammonia excretion pathway in the gills have experienced positive selection, suggesting their important roles in mudskippers’ tolerance to environmental ammonia. Some vision-related genes are differentially lost or mutated, illustrating genomic changes associated with aerial vision. Transcriptomic analyses of mudskippers exposed to air highlight regulatory pathways that are up- or down-regulated in response to hypoxia. The present study provides a valuable resource for understanding the molecular mechanisms underlying water-to-land transition of vertebrates.