Evolutionary Physiology

Thermal tolerance underpins most biogeographical patterns in ectothermic animals. Macroevolutionary patterns of thermal limits have been historically evaluated, but a role for the phylogenetic component in physiological variation has been neglected. Three marine zoogeographical provinces are recognized throughout the Neotropical region based on mean seawater temperature (T m ): the Brazilian (T m = 26 °C), Argentinian (T m = 15 °C), and Magellanic (T m = 9 °C) provinces. Microhabitat temperature (MHT) was measured, and the upper (UL 50 ) and lower (LL 50 ) critical thermal limits were established for 12 eubrachyuran crab species from intertidal zones within these three provinces. A molecular phylogenetic analysis was performed by maximum likelihood using the 16S mitochondrial gene, also considering other representative species to enable comparative evaluations. We tested for: (1) phylogenetic pattern of MHT, UL 50 , and LL 50 ; (2) effect of zoogeographical province on the evolution of both limits; and (3) evolutionary correlation between MHT and thermal limits. MHT and UL 50 showed strong phylogenetic signal at the species level while LL 50 was unrelated to phylogeny, suggesting a more plastic evolution. Province seems to have affected the evolution of thermal tolerance, and only UL 50 was dependent on MHT. UL 50 was similar between the two northern provinces compared to the southernmost while LL 50 differed markedly among provinces. Apparently, critical limits are subject to different environmental pressures and thus manifest unique evolutionary histories. An asymmetrical macroevolutionary scenario for eubrachyuran thermal tolerance seems likely, as the critical thermal limits are differentially inherited and environmentally driven.

Through functional analyses, integrative physiology is able to link molecular biology with ecology as well as evolutionary biology and is thereby expected to provide access to the evolution of molecular, cellular, and organismic functions; the genetic basis of adaptability; and the shaping of ecological patterns. This paper compiles several exemplary studies of thermal physiology and ecology, carried out at various levels of biological organization from single genes (proteins) to ecosystems.

Predicting species responses to global warming is the holy grail of climate change science. As temperature directly affects physiological rates, it is clear that a mechanistic understanding of species vulnerability should be grounded in organismal physiology. Here, we review what respiratory physiology can offer the field of thermal ecology, showcasing different perspectives on how respiratory physiology can help explain thermal niches. In water, maintaining adequate oxygen delivery to fuel the higher metabolic rates under warming conditions can become the weakest link, setting thermal tolerance limits. This has repercussions for growth and scaling of metabolic rate. On land, water loss is more likely to become problematic as long as O2 delivery and pH balance can be maintained, potentially constraining species in their normal activity. Therefore, high temperatures need not be lethal, but can still affect the energy intake of an animal, with concomitant consequences for long-term fi...

In culture and in situ the parasitic red alga Gardneriella tuberifera Kylin undergoes a life history in which gametes, c. arpospores, tetraspores and uninucleate and binucleate bispores are produced. In culture, carpospores infect the host Agardhiella gaudichaudii (Montagne) Silva et Papenfuss resulting in the formulation of pustules which produce binucleate bi spores and infrequently tetraspores. These spores infect additional host tissue resulting in the formation of gametes and carposporophytes. Infection by the uninucleate bispores results in the formation of binucleate bispores. The uninucleate bispores which are the dominant spore type in situ, provide an asexual alternative in this life history. In sexually reproducing individuals, the binucleate bispore carries two genotypes into a host. Culture studies reveal that both male and female gametophytes may develop within the tissues of a single host plant infected by a single binucleate bispore. The gametes are self-compatible. The capacity to establish both male and female gametophytes from a single spore infection may provide an important mechanism to insure the proximity of gametes in populations of this parasite.

Male crickets Gryllus bimaculatus are known to exhibit intensive aggressive behavior towards other males. These crickets are often used as an experimental model in aggression researches. We establish a real-time recording system and behavior manipulation system using a small robot that can elicit aggressive behavior in a test cricket.

Thermal tolerance underpins most biogeographical patterns in ectothermic animals. Macroevolutionary patterns of thermal limits have been historically evaluated, but a role for the phylogenetic component in physiological variation has been neglected. Three marine zoogeographical provinces are recognized throughout the Neotropical region based on mean seawater temperature (T m ): the Brazilian (T m = 26 °C), Argentinian (T m = 15 °C), and Magellanic (T m = 9 °C) provinces. Microhabitat temperature (MHT) was measured, and the upper (UL 50 ) and lower (LL 50 ) critical thermal limits were established for 12 eubrachyuran crab species from intertidal zones within these three provinces. A molecular phylogenetic analysis was performed by maximum likelihood using the 16S mitochondrial gene, also considering other representative species to enable comparative evaluations. We tested for: (1) phylogenetic pattern of MHT, UL 50 , and LL 50 ; (2) effect of zoogeographical province on the evolution of both limits; and (3) evolutionary correlation between MHT and thermal limits. MHT and UL 50 showed strong phylogenetic signal at the species level while LL 50 was unrelated to phylogeny, suggesting a more plastic evolution. Province seems to have affected the evolution of thermal tolerance, and only UL 50 was dependent on MHT. UL 50 was similar between the two northern provinces compared to the southernmost while LL 50 differed markedly among provinces. Apparently, critical limits are subject to different environmental pressures and thus manifest unique evolutionary histories. An asymmetrical macroevolutionary scenario for eubrachyuran thermal tolerance seems likely, as the critical thermal limits are differentially inherited and environmentally driven.

Salinity is the primary driver of osmoregulatory evolution in decapods, and may have influenced their diversification into different osmotic niches. In semi-terrestrial crabs, hyper-osmoregulatory ability favors sojourns into burrows and dilute media, and provides a safeguard against hemolymph dilution; hypo-osmoregulatory ability underlies emersion capability and a life more removed from water sources. However, most comparative studies have neglected the roles of the phylogenetic and environmental components of inter-specific physiological variation, hindering evaluation of phylogenetic patterns and the adaptive nature of osmoregulatory evolution. Semi-terrestrial fiddler crabs (Uca) inhabit fresh to hyper-saline waters, with species from the Americas occupying higher intertidal habitats than Indo-west Pacific species mainly found in the low intertidal zone. Here, we characterize numerous osmoregulatory traits in all ten fiddler crabs found along the Atlantic coast of Brazil, and w...

In anisogamous species, sexual selection is expected to be stronger in males. Bateman's principles state that the variance in (i) reproductive and (ii) mating success is greater for males, and (iii) the relationship between reproductive success and mating success (the Bateman gradient) is also stronger for males than for females. Sexual selection, based on Bateman's principles, has been demonstrated in animals and some angiosperms, but never in a seaweed. Here we focus on the oogamous haploid-diploid rhodophyte Gracilaria gracilis in which previous studies have shown evidence for non-random mating, suggesting the existence of male–male competition and female choice. We estimated mating and reproductive success using paternity analyses in a natural population where up to 92% of fertilizations occurred between partners of that population. The results show that the variance in mating success is significantly greater in males than in females and that the Bateman gradient is posi...

The history of comparative and evolutionary physiology since the early XIX century is given; 2) The methods of evolutionary physiology are described; 3) Principles of the evolution of function are discussed at every level of physiological organization (cellular, functional units of the organ, the organ itself, functional systems) as they apply to the kidney and to the regulation of salt and water balance; and 4) General questions of evolutionary physiology covering physico-chemical factors in evolution of functions, the development of the integrity of an organism, the origin of physiological adaptation, the development of interconnection of physiological systems are discussed. comp biochem physiol 118A;1:63-79, 1997.

The long-held belief that animal-mediated pollination is absent in the sea has recently been contradicted in seagrasses, motivating investigations of other marine phyla. This is particularly relevant in red algae, in which female gametes are not liberated and male gametes are not flagellated. Using experiments with the isopod Idotea balthica and the red alga Gracilaria gracilis , we demonstrate that biotic interactions dramatically increase the fertilization success of the alga through animal transport of spermatia on their body. This discovery suggests that animal-mediated fertilization could have evolved independently in terrestrial and marine environments and raises the possibility of its emergence in the sea before plants moved ashore.

Adaptation to increasingly warmer environments may be critical to avoid extinction. Whether and how these adaptive responses can arise is under debate. Though several studies have tackled evolutionary responses under different thermal selective regimes, very few have specifically addressed the underlying patterns of thermal adaptation under scenarios of progressive warming conditions. Also, considering how much past history affects such evolutionary response is critical. Here, we report a long-term experimental evolution study addressing the adaptive response of Drosophila subobscura populations with distinct biogeographical history to two thermal regimes. Our results showed clear differences between the historically differentiated populations, with adaptation to the warming conditions only evident in the low latitude populations. Furthermore, this adaptation was only detected after more than 30 generations of thermal evolution. Our findings show some evolutionary potential of Droso...

Roughgarden has produced a personal synthesis of the theories in the converging fields of genetics and ecology. Half of the chapters, identified by Roughgarden with asterisks, could be used as a primer on the theories of population biology. Most

Air‐breathing and amphibious fishes are essential study organisms to shed insight into the required physiological shifts that supported the full transition from aquatic water‐breathing fishes to terrestrial air‐breathing tetrapods. While the origin of air‐breathing in the evolutionary history of the tetrapods has received considerable focus, much less is known about the evolutionary physiology of air‐breathing among fishes. This review summarizes recent advances within the field with specific emphasis on the cardiorespiratory regulation associated with air‐breathing and terrestrial excursions, and how respiratory physiology of these living transitional forms are affected by development and personality. Finally, we provide a detailed and re‐evaluated model of the evolution of air‐breathing among fishes that serves as a framework for addressing new questions on the cardiorespiratory changes associated with it. This review highlights the importance of combining detailed studies on pisc...

19-Nordeoxycorticosterone (19~nor-Dot), a potent mineralocorticoid, was found to be synthesized by the isolated rat kidney perfused by an adrenal precursor (19-0x0-Doe). To determine if this bioconversion is a function of renal tubular cells, various adrenal precursors of 19-nor-Dot were added separately to rat kidney inner medullaty collecting duct cells culture media at a concentration of 10 nM. While 4.6% 2 IA?% of 19-0x0-Doe In = 3) and 14.4% * 1.4% of 19-oic-Doe (n = 3) were converted to 19~nor-Dot after 24 hours of incubation, Dot, and IPOH-Doe were not converted. This represents further evidence that Dot has to be metabolized to f9-0x0-Dot or I9-oic-Dot fl9-carboxy-Doe) before it can be converted by the kidney inner medullary collecting duct cells to 19-nor-Dot.

The plant khat "Catha Edulis Forsk" is widely distributed among most East African countries, Yemen and many other areas of the world. Administration of khat extract by the intragastric route in rabbits affected the metabolism of erythrocytes. There is a significant decrease in pyruvate kinase and the level of reduced glutathione (P < O.OOl), and a highly significant increase in both glucosed-phosphate dehydrogenase and glutathione reductase activities (P < 0.001) in khat-fed rabbits as compared to controls. On the other hand the activity of uridyl transferase as well as the concentration of 2,3-diphosphoglycerate were not significantly changed in experimental khat-fed rabbits (P > 0.5).

Aggression is an innate behavior that likely evolved in the framework of defending or obtaining resources. This complex social behavior is influenced by genetic, environmental, and internal factors. Drosophila melanogaster remains an effective and exciting model organism to unravel the mechanistic basis of aggression due to its small but sophisticated brain, an impressive array of neurogenetic tools, and robust stereotypical behavioral patterns. The investigations of many laboratories have led to the identification of external and internal state factors that promote aggression, sex differences in the patterns and outcome of aggression, and neurotransmitters that regulate aggression. AGGRESSION IN DROSOPHILA Aggression is an evolutionarily conserved behavior, essential for survival and genetic success, as gaining access to mates, access to resources and defending progeny are key favorable outcomes (Lorenz and

Aggression is an innate behavior that likely evolved in the framework of defending or obtaining resources. This complex social behavior is influenced by genetic, environmental, and internal factors.Drosophila melanogasterremains an effective and exciting model organism with which to unravel the mechanistic basis of aggression due to its small but sophisticated brain, an impressive array of neurogenetic tools, and robust stereotypical behavioral patterns. The investigations of many laboratories have led to the identification of external and internal state factors that promote aggression, sex differences in the patterns and outcome of aggression, and neurotransmitters that regulate aggression.

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…

Understanding the evolution of microbial diversity is an important and current problem in evolutionary ecology. In this paper, we investigated the role of two established biochemical trade-offs in microbial diversification using a model that connects ecological and evolutionary processes with fundamental aspects of biochemistry. The trade-offs that we investigated are as follows:(1) a tradeoff between the rate and affinity of substrate transport; and (2) a trade-off between the rate and yield of ATP production. Our model shows that these biochemical trade-offs can drive evolutionary diversification under the simplest possible ecological conditions: a homogeneous environment containing a single limiting resource. We argue that the results of a number of microbial selection experiments are consistent with the predictions of our model.

Although a species' locomotor capacity is suggestive of its ability to escape global climate change, such a suggestion is not necessarily straightforward. Species vary substantially in locomotor capacity, both ontogenetically and within/among populations, and much of this variation has a genetic basis. Accordingly, locomotor capacity can and does evolve rapidly, as selection experiments demonstrate. Importantly, even though this evolution of locomotor capacity may be rapid enough to escape changing climate, genetic correlations among traits (often due to pleiotropy) are such that successful or rapid dispersers are often limited in colonization or reproductive ability, which may be viewed as a tradeoff. The nuanced assessment of this variation and evolution is reviewed for well-studied models: salmon, flying versus flightless insects, rodents undergoing experimental evolution, and metapopulations of butterflies. This work reveals how integration of physiology with population biology and functional genomics can be especially informative.

A high-yield procedure based on hypotonic lysis and isotonic resealing of erythrocytes was used in order to achieve entrapment of homogeneous human glucose g-phosphate dehydrogenase and of other metabolically related enzyme proteins (hexokinase and 6-phosphogluconate dehydrogenase). Erythrocytes from normal subjects and from individuals affected by glucose 6-phosphate dehydrogenase deficiency (glucose 6-phosphate dehydrogenase Mediterranean) were used for such studies. The following properties of the variously loaded erythrocyte suspensions were investigated: (a) hexose monophosphate shunt activity, (b) glycolytic activity, (c) intracellular concentrations of glucose 6-phosphate, 6phosphogluconate, NADP, and NADPH. These parameters were evaluated on the erythrocyte suspensions both in the resting state and under oxidative stimulation by methylene blue. In the glucose g-phosphate dehydrogenase-deficient cells, complete normalization of hexose monophosphate shunt activity and of the other metabolic properties under study was achieved by restoring the intracellular glucose 6-phosphate dehydrogenase activity up to the levels of normal erythrocytes. Specifically, hexokinase became the rate-limiting step of the overall glucose oxidation pathway under methylene blue stimulation, this reproducing the situation found in normal erythrocytes. The extent of Heinz bodies formation upon incubation with acetylphenylhydrazine confirmed the full metabolic competence of the glucose 6-phosphate dehydrogenase-reconstituted Mediterranean erythrocytes compared with the unloaded ones. 543

Through functional analyses, integrative physiology is able to link molecular biology with ecology as well as evolutionary biology and is thereby expected to provide access to the evolution of molecular, cellular, and organismic functions; the genetic basis of adaptability; and the shaping of ecological patterns. This paper compiles several exemplary studies of thermal physiology and ecology, carried out at various levels of biological organization from single genes (proteins) to ecosystems.

Temperature is the most important abiotic factor affecting physiology, ecology and evolution in ectotherms. Do organisms broadly distributed along a latitudinal gradient adapt to local differences in temperature? In ectotherms this question has played a central role in evolutionary physiology. By means of an extensive field study and laboratory experiments, we tested the existence of local adaptations in thermal traits along 10Њ of latitude in northern-central Chile. We studied behavioural and thermal traits that have been directly connected with the thermal physiology of ectotherms, along the latitudinal gradient. Using three populations of the common woodlouse (terrestrial isopod), Porcellio laevis, we examined changes in thermal physiology traits (i.e. thermal tolerance, thermal performance) and behavioural traits (i.e. thermoregulation in the field and the laboratory). Performance (i.e. righting response speed) reached a maximum value at intermediate temperatures, and was highest for the northern population. Chill-coma temperature showed an increase towards high latitude, while heat-coma temperature did not vary between populations. On the other hand, optimum temperature was negatively correlated with latitude. Thus, southern woodlice appear to have evolved towards becoming low-temperature specialists, whereas woodlice from warm regions demonstrate low cold tolerance as well as a higher optimum temperature. Our results demonstrate that P. laevis woodlice from different parts of the distribution range show patterns in thermal physiology that covary with the thermal environment (i.e. latitude); thus, P. laevis adapts to local environments to increase its performance.

Sex differences have been identified in various biological processes, including hypertension. The mineralocorticoid signaling pathway is an important contributor to early arterial hypertension, however its sex-specific expression has been scarcely studied, particularly with respect to the kidney. Basal systolic blood pressure (SBP) and heart rate (HR) were measured in adult male and female mice. Renal gene expression studies of major players of mineralocorticoid signaling were performed at different developmental stages in male and female mice using reverse transcription quantitative PCR (RT-qPCR), and were compared to those of the same genes in the lung, another mineralocorticoid epithelial target tissue that regulates ion exchange and electrolyte balance. The role of sex hormones in the regulation of these genes was also investigated in differentiated KC3AC1 renal cells. Additionally, renal expression of the 11 β-hydroxysteroid dehydrogenase type 2 (11βHSD2) protein, a regulator of mineralocorticoid specificity, was measured by immunoblotting and its activity was indirectly assessed in the plasma using liquid-chromatography coupled to mass spectrometry in tandem (LC-MSMS) method. SBP and HR were found to be significantly lower in females compared to males. This was accompanied by a sex-and tissue-specific expression profile throughout renal development of the mineralocorticoid target genes serum and glucocorticoid-regulated kinase 1 (Sgk1) and glucocorticoid-induced leucine zipper protein (Gilz), together with Hsd11b2, Finally, the implication of sex hormones in this sex-specific expression profile was demonstrated in vitro, most notably for Gilz mRNA expression. We demonstrate a tissue-specific, sex-dependent and developmentally-regulated pattern of expression of the mineralocorticoid pathway that could have important implications in physiology and pathology.

Glucocorticoids are amongst the most used drugs to treat retinal diseases of various origins. Yet, the transcriptional regulations induced by glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) activation in retinal pigment epithelium cells (RPE) that form the outer blood–retina barrier are unknown. Levels of endogenous corticoids, ligands for MR and GR, were measured in human ocular media. Human RPE cells derived from induced pluripotent stem cells (iRPE) were used to analyze the pan-transcriptional regulations induced by aldosterone—an MR-specific agonist, or cortisol or cortisol + RU486—a GR antagonist. The retinal phenotype of transgenic mice that overexpress the human MR (P1.hMR) was analyzed. In the human eye, the main ligand for GR and MR is cortisol. The iRPE cells express functional GR and MR. The subset of genes regulated by aldosterone and by cortisol + RU-486, and not by cortisol alone, mimics an imbalance toward MR activation. They are involved in extracell...

The catalase within normal, intact human erythrocytes was completely inactivated with amino triazole. The rate of 14CO2 evolution, when the cells were subsequently incubated with 14C-labeled glucose, provided a measure of the rate at which NADPH was being oxidized by the glutathione peroxidase/reductase system for the disposal of H2O2. This rate was determined in control cells and in catalase-inactivated cells while the cells were exposed to H2O2, which was generated at various constant and predetermined rates by glucose oxidase. The results indicated that catalase handles approximately half of the generated H2O2. The glutathione peroxidase/reductase mechanism accounted for the other half. These results are in agreement with our earlier findings on erythrocytes of a subject with a genetic deficiency of catalase. However, an unexpected result with the present approach was the finding that the increased dependence on the glutathione peroxidase/reductase mechanism did not occur until g...

Background: Several hypotheses have been proposed to explain invasive species success. Much of the research in this field has been conducted at the ecosystem or community level. Physiological traits are usually ignored, although they may play a role. As invasiveness has been correlated with species range expansion, it has been assumed – but scarcely tested – that species with greater physiological thermotolerances could be more invasive and colonize more habitats. Aims: We assessed the responses of native (Eriopis chilensis) and invasive (Harmonia axyridis, Hippodamia variegata) coccinellids to thermal stress in central Chile after a period of acclimation. We tested and compared their thermal tolerances, their acclimation responses, and the consequences of these on fitness. Results: Upper and lower lethal temperatures were not significantly different among species and no species was able to increase its lethal limits following acclimation. Our results suggest a trade-off between the...

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…

The catalase within normal, intact human erythrocytes was completely inactivated with amino triazole. The rate of 14CO2 evolution, when the cells were subsequently incubated with 14C-labeled glucose, provided a measure of the rate at which NADPH was being oxidized by the glutathione peroxidase/reductase system for the disposal of H2O2. This rate was determined in control cells and in catalase-inactivated cells while the cells were exposed to H2O2, which was generated at various constant and predetermined rates by glucose oxidase. The results indicated that catalase handles approximately half of the generated H2O2. The glutathione peroxidase/reductase mechanism accounted for the other half. These results are in agreement with our earlier findings on erythrocytes of a subject with a genetic deficiency of catalase. However, an unexpected result with the present approach was the finding that the increased dependence on the glutathione peroxidase/reductase mechanism did not occur until g...

Predicting species responses to global warming is the holy grail of climate change science. As temperature directly affects physiological rates, it is clear that a mechanistic understanding of species vulnerability should be grounded in organismal physiology. Here, we review what respiratory physiology can offer the field of thermal ecology, showcasing different perspectives on how respiratory physiology can help explain thermal niches. In water, maintaining adequate oxygen delivery to fuel the higher metabolic rates under warming conditions can become the weakest link, setting thermal tolerance limits. This has repercussions for growth and scaling of metabolic rate. On land, water loss is more likely to become problematic as long as O2 delivery and pH balance can be maintained, potentially constraining species in their normal activity. Therefore, high temperatures need not be lethal, but can still affect the energy intake of an animal, with concomitant consequences for long-term fi...

The ability of an animal to shed its tail is a widespread antipredator strategy among lizards. The degree of expression of this defense is expected to be shaped by prevailing environmental conditions including local predation pressure. We test these hypotheses by comparing several aspects of caudal autotomy in 15 Mediterranean lizard taxa existing across a swath of mainland and island localities that differ in the number and identity of predator species present. Autotomic ease varied substantially among the study populations, in a pattern that is best explained by the presence of vipers. Neither insularity nor the presence of other types of predators explain the observed autotomy rates. Final concentration of accumulated tail muscle lactate and duration of movement of a shed tail, two traits that were previously thought to relate to predation pressure, are in general not shaped by either predator diversity or insularity. Under conditions of relaxed predation selection, an uncoupling of different aspects of caudal autotomy exists, with some elements (ease of autotomy) declining faster than others (duration of movement, lactate concentration). We compared rates of shed tails in the field against rates of laboratory autotomies conducted under standardized conditions and found very high correlation values (r > 0.96). This suggests that field autotomy rates, rather than being a metric of predatory attacks, merely reflect the innate predisposition of a taxon to shed its tail.

Benefits of physical exercise for brain functions are well documented in mammals, including humans. In this review, we will summarize recent research on the effects of species-specific intense locomotion on behavior and brain functions of different invertebrates. Special emphasis is made on understanding the biological significance of these effects as well as underlying cellular and molecular mechanisms. The results obtained in three distantly related clades of protostomes, Nematodes, Molluscs and Artropods, suggest that influence of intense locomotion on the brain could have deep roots in evolution and wide adaptive significance. In C. elegans, improved learning, nerve regeneration, resistance to neurodegenerative processes were detected after physical activity; in L. stagnalis—facilitation of decision making in the novel environment, in Drosophila—increased endurance, improved sleep and feeding behavior, in G. bimaculatus—improved orientation in conspecific phonotaxis, enhanced ag...

Salinity is the primary driver of osmoregulatory evolution in decapods, and may have influenced their diversification into different osmotic niches. In semi-terrestrial crabs, hyper-osmoregulatory ability favors sojourns into burrows and dilute media, and provides a safeguard against hemolymph dilution; hypo-osmoregulatory ability underlies emersion capability and a life more removed from water sources. However, most comparative studies have neglected the roles of the phylogenetic and environmental components of inter-specific physiological variation, hindering evaluation of phylogenetic patterns and the adaptive nature of osmoregulatory evolution. Semi-terrestrial fiddler crabs (Uca) inhabit fresh to hyper-saline waters, with species from the Americas occupying higher intertidal habitats than Indo-west Pacific species mainly found in the low intertidal zone. Here, we characterize numerous osmoregulatory traits in all ten fiddler crabs found along the Atlantic coast of Brazil, and w...

The reproductive state of Ceramium tenuicorne (Kütz.) Waern was studied in a salinity and latitudinal gradient near its inner distribution limit in the brackish Baltic Sea, and in laboratory growth experiments on the gametophytes and tetrasporophytes. Along the gradient, a strong reduction in sexual reproduction and an increased tetrasporophyte dominance were observed. The observed changes may not only be explained by salinity constraints. Growth occurred between 1 and 24 PSU and the optimum range for growth corresponded well to the salinity regime of the area studied. Field observations showed that sexual reproduction is at least occasionally possible in salinities around 4 PSU. It is likely that severed climatic conditions constrain sexual reproduction towards the north, but C. tenuicorne remains an ecologically dominant species in large parts of its distributional area. Viable populations are maintained essentially by vegetative reproduction, such as fragmentation and rhizoidal re-attachment. Observations on vegetative propagules were sparse, but these may serve as an important physical escape from temporarily unfavourable conditions in areas where sexual reproduction is unreliable.

Sweating is a basic skin function in body temperature control. In sweat glands, salt excretion and reabsorption are regulated to avoid electrolyte imbalance. To date, the mechanism underlying such regulation is not fully understood. Corin is a transmembrane protease that activates atrial natriuretic peptide (ANP), a cardiac hormone essential for normal blood volume and pressure. Here, we report an unexpected role of corin in sweat glands to promote sweat and salt excretion in regulating electrolyte homeostasis. In human and mouse eccrine sweat glands, corin and ANP are expressed in the luminal epithelial cells. In corin-deficient mice on normal- and high-salt diets, sweat and salt excretion is reduced. This phenotype is associated with enhanced epithelial sodium channel (ENaC) activity that mediates Na+ and water reabsorption. Treatment of amiloride, an ENaC inhibitor, normalizes sweat and salt excretion in corin-deficient mice. Moreover, treatment of aldosterone decreases sweat and...

SYNOPSIS. An understanding of interactions between the thermal physiology and ecology of ectotherms remains elusive, partly because information on the relative performance of whole-animal physiological systems at ecologically relevant body temperatures is limited. After discussing physiological systems that have direct links to ecology (e.g., growth, locomotor ability), we review analytical methods of describing and comparing certain aspects of performance (including optimal temperature range, thermal performance breadth), apply these techniques in an example on the thermal sensitivity of locomotion in frogs, and evaluate potential applications.

Thermal and water balance are coupled in anurans, and species with particularly permeable skin avoid overheating more effectively than minimizing variance of body temperature. In turn, temperature affects muscle performance in several ways, so documenting the mean and variance of body temperature of active frogs can help explain variation in behavioral performance. The two types of activities studied in most detail, jumping and calling, differ markedly in duration and intensity, and there are distinct differences in the metabolic profile and fiber type of the supporting muscles. Characteristics of jumping and calling also vary significantly among species, and these differences have a number of implications that we discuss in some detail throughout this paper. One question that emerges from this topic is whether anuran species exhibit activity temperatures that match the temperature range over which they perform best. Although this seems the case, thermal preferences are variable and may not necessarily reflect typical activity temperatures. The performance versus temperature curves and the thermal limits for anuran activity reflect the thermal ecology of species more than their systematic position. Anuran thermal physiology, therefore, seems to be phenotypically plastic and susceptible to adaptive evolution. Although generalizations regarding the mechanistic basis of such adjustments are not yet possible, recent attempts have been made to reveal the mechanistic basis of acclimation and acclimatization.

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.

1. Many studies have been performed in an attempt to explain physiological, ecological and evolutionary factors behind inter-and intraspecific variation in basal metabolic rate (BMR) and maximum aerobic metabolic rate (VO 2max). However, very little is known about the association between the traits and fitness components in populations of free-living animals. 2. We studied the association between body size and the metabolic rates of bank voles Myodes (= Clethrionomys) glareolus and their survival, measured by repeated trappings across 2 years in an isolated, island population. All measured traits (body mass, BM; head width, HW; VO 2max and BMR) were significantly repeatable over short (mean 5•4 days) and long (mean 56•4 days) intervals. 3. Logistic regression analyses showed no consistent relationship between the measured traits and survival until the next trapping session. The correlations, if present, differed in direction between sessions and sexes. Survival over winters was negatively correlated with BM in males (P = 0•001) but not in females (P = 0•43). The logistic regression with quadratic effects revealed stabilizing selection on VO 2max in males (across all sessions: P = 0•010; in breeding seasons only: P = 0•001). 4. Both the presence of stabilizing selection and the opposite direction of the selection between sexes and/or seasons could contribute to the relatively high additive genetic variance of metabolic rates, reported earlier in the bank voles. 5. The results indicate that the maximum rather than the basal rate of metabolism is important to individual fitness of the voles. However, lack of consistency in the association between survival and the metabolic traits casts doubt on previous assumptions regarding the importance of the level of metabolism to an individual's fitness.

According to the aerobic capacity model, endothermy in birds and mammals evolved as a correlated response to selection for an ability of sustained locomotor activity, rather than in a response to direct selection for thermoregulatory capabilities. A key assumption of the model is that aerobic capacity is functionally linked to basal metabolic rate (BMR). The assumption has been tested in several studies at the level of phenotypic variation among individuals or species, but none has provided a clear answer whether the traits are genetically correlated. Here we present results of a genetic analysis based on measurements of the basal and the maximum swim-and cold-induced oxygen consumption in about 1000 bank voles from six generations of a laboratory colony, reared from animals captured in the field. Narrow sense heritability (h 2) was about 0.5 for body mass, about 0.4 for mass-independent basal and maximum metabolic rates, and about 0.3 for factorial aerobic scopes. Dominance genetic and common environmental (ϭ maternal) effects were not significant. Additive genetic correlation between BMR and the swim-induced aerobic capacity was high and positive, whereas correlation resulting from specific-environmental effects was negative. However, BMR was not genetically correlated with the cold-induced aerobic capacity. The results are consistent with the aerobic capacity model of the evolution of endothermy in birds and mammals.

Like most animal species, fruit flies fight to obtain and defend resources essential to survival and reproduction. Aggressive behavior in Drosophila is genetically specified and also strongly influenced by the fly's social context, past experiences and internal states, making it an excellent framework for investigating the neural mechanisms that regulate complex social behaviors. Here, I summarize our current knowledge of the neural control of aggression in Drosophila and discuss recent advances in understanding the sensory pathways that influence the decision to fight or court, the neuromodulatory control of aggression, the neural basis by which internal states can influence both fighting and courtship, and how social experience modifies aggressive behavior.

Males of most species are more aggressive than females, but the neural mechanisms underlying this dimorphism are not clear. Here, we identify a neuron and a gene that control the higher level of aggression characteristic of Drosophila melanogaster males. Males, but not females, contain a small cluster of FruM + neurons that express the neuropeptide tachykinin (Tk). Activation and silencing of these neurons increased and decreased, respectively, intermale aggression without affecting male-female courtship behavior. Mutations in both Tk and a candidate receptor, Takr86C, suppressed the effect of neuronal activation, whereas overexpression of Tk potentiated it. Tk neuron activation overcame reduced aggressiveness caused by eliminating a variety of sensory or contextual cues, suggesting that it promotes aggressive arousal or motivation. Tachykinin/ Substance P has been implicated in aggression in mammals, including humans. Thus, the higher aggressiveness of Drosophila males reflects the sexually dimorphic expression of a neuropeptide that controls agonistic behaviors across phylogeny.