Physiological zoology最新文献

{"title":"Energy requirements for growth in relation to sexual size dimorphism in marsh harrier Circus aeruginosus nestlings.","authors":"K L Krijgsveld,&nbsp;C Dijkstra,&nbsp;G H Visser,&nbsp;S Daan","doi":"10.1086/515983","DOIUrl":"https://doi.org/10.1086/515983","url":null,"abstract":"<p><p>Food consumption was measured in six female and seven male hand-raised marsh harrier (Circus aeruginosus) nestlings. Females consumed on average 4,321 g and males consumed 3,571 g of food during the nestling stage from 0 to 36 d. Total consumption until 56 d was 6,960 g and 5,822 g for females and males, respectively. On the basis of Fisher's sex ratio theory, this food intake ratio of 0.46 (intake male/[intake male + female]) would explain the observed male-biased fledging sex ratio of 55% males in marsh harrier broods. Growth, gross energy intake, and metabolizable energy intake were measured, along with metabolism of the nestlings, enabling us to determine energy allocation. The assimilation quotient (Q = 0.72) did not differ systematically between the sexes. Differences in metabolic rates between males and females at 15 and 30 d of age were fully attributable to the difference in body mass. Sexual size dimorphism in marsh harriers (female body mass around 60 d of age is 1.28 times greater than male mass) did not fully explain the difference in food intake between male and female nestlings: an analysis of energy requirements for growth and body mass in 16 avian species shows that energy intake was less than proportional to the average body mass at release. The data presented in this study are in agreement with Fisher's theory of inverse proportionality between the sex-specific ratios of energy requirements for growth and of offspring numbers in the marsh harrier population.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"693-702"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515983","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20710075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in pattern of heat loss at high ambient temperature caused by water deprivation in a large flightless bird, the emu.","authors":"S K Maloney,&nbsp;T J Dawson","doi":"10.1086/515997","DOIUrl":"https://doi.org/10.1086/515997","url":null,"abstract":"<p><p>When exposed to high ambient temperatures, birds defend body temperature by increasing evaporative water loss, via either respiratory or cutaneous water loss. Water deprivation can lead to changes in thermal responses and lower levels of water use for thermoregulation. We have studied the effect of 2-3 wk of water deprivation on the physiological responses of emus during exposure to an ambient temperature of 45 degrees C. Water deprivation led to a delay in the onset of panting (54 vs. 24 min after start of exposure) and to higher body temperatures (38.7 degrees vs. 38.3 degrees C) at the end of exposure to 45 degrees C. After panting was initiated and body temperature stabilised, the water-deprived emus had a lower total evaporative water loss (77 vs. 101 g/h), the same respiratory water loss (70 vs. 72 g/h), and a lower cutaneous water loss (7 vs. 29 g/h) than they did when hydrated. The factor contributing most to the lower total evaporative water loss in the dehydrated emus was a 47% reduction in dry thermal conductance, which led to a decrease in the exogenous environmental heat load and therefore the level of evaporation needed to defend body temperature. We suggest that the decrease in dry thermal conductance follows from the lower level of cutaneous water loss.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"712-9"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515997","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20710078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Changes in gut capacity with lactation and cold exposure in a species with low rates of energy use, the pine vole (Microtus pinetorum).","authors":"T L Derting,&nbsp;M W Austin","doi":"10.1086/515981","DOIUrl":"https://doi.org/10.1086/515981","url":null,"abstract":"<p><p>Interspecific differences in the adaptive capacity of the gut may contribute to interspecific differences in rate of energy use and life-history traits. We tested the hypothesis that changes in gut capacity when energy demands are elevated are similar in species with low average rates of energy use compared with a species with higher average rates of energy use. We measured changes in gut capacity in Microtus pinetorum, a species with low average rates of energy use, and compared these with published data of changes in gut capacity of other rodent species with higher average rates of energy use. We quantified food ingestion, daily metabolic rate, resting metabolic rate, and gut organ masses, lengths, and functional volumes in nonreproducing, lactating, and cold-exposed females. Cold-exposed females had significantly higher, and lactating females moderately higher, mass-independent daily metabolic rates than control females. No significant changes in the mass or length of the intestinal organs occurred with cold exposure. Length, but not mass, of the gut was significantly greater in lactating females and functional volume was greater in cold-exposed females, compared with control females, independent of body mass. These changes in gut capacity were much less extensive than those reported for other rodent species. Interspecific differences in gut capacity were not attributable to differences in rates of ingestion and energy need among species. A large adaptive capacity of the gut or maintenance of a large reserve capacity may be a requirement for high rates of energy use and may contribute to the positive interspecific correlations that exist between rates of growth and reproduction and energy use for maintenance metabolism.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"611-23"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515981","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20709514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Body cooling and its energetic implications for feeding and diving of tufted ducks.","authors":"J J de Leeuw,&nbsp;P J Butler,&nbsp;A J Woakes,&nbsp;F Zegwaard","doi":"10.1086/516003","DOIUrl":"https://doi.org/10.1086/516003","url":null,"abstract":"<p><p>Wintering in a temperate climate with low water temperatures is energetically expensive for diving ducks. The energy costs associated with body cooling due to diving and ingesting large amounts of cold food were measured in tufted ducks (Aythya fuligula) feeding on zebra mussels (Dreissena polymorpha), using implanted heart rate and body temperature transmitters. The effects of diving depth and food ingestion were measured in two sets of experiments: we measured body cooling and energy costs of six tufted ducks diving to different depths in a 6-m-deep indoor tank; the costs for food ingestion and crushing mussel shells were assessed under seminatural winter conditions with the same ducks feeding on mussels in a 1.5-m-deep outdoor pond. Body temperature dropped during feeding bouts and increased gradually during intermittent resting periods. The temperature drop increased linearly with dive duration. The rate of body cooling increased with feeding depth, but it was lower again at depths below 4 m. Half of the increment in energy costs of diving can be attributed to thermoregulatory heat production, of which approximately 50% is generated after diving to warm up the body. The excess costs for ducks feeding on large-sized mussels could be entirely explained by the estimated energy cost necessary to compensate the heat loss following food ingestion, suggesting that the heat production from shell crushing substituted for thermoregulation. Recovery from heat loss is probably a major component of the activity budget of wintering diving ducks.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"720-30"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/516003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20709938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of the herbicide atrazine on Ambystoma tigrinum metamorphosis: duration, larval growth, and hormonal response.","authors":"D L Larson,&nbsp;S McDonald,&nbsp;A J Fivizzani,&nbsp;W E Newton,&nbsp;S J Hamilton","doi":"10.1086/515999","DOIUrl":"https://doi.org/10.1086/515999","url":null,"abstract":"<p><p>We exposed larval tiger salamanders (Ambystoma tigrinum) reared in the laboratory from eggs collected from a prairie wetland in North Dakota to three concentrations of atrazine (0, 75, and 250 micrograms/L) in a static renewal test to determine the pesticide's effect on (1) plasma corticosterone and thyroxine concentrations, (2) larval size, and (3) days-to-stage at stages 2 and 4 of metamorphic climax. We found significant effects of atrazine on each of these response variables. Plasma thyroxine was elevated in both atrazine-exposed groups compared with the control group; plasma corticosterone was depressed in the 75 micrograms/L treatment compared with both the control and 250 micrograms/L treatment. Larvae exposed to 75 micrograms/L atrazine reached stage 4 later but at a size and weight comparable to the control group. By contrast, larvae in the 250 micrograms/L treatment progressed to stage 4 at the same time but at a smaller size and lower weight than larvae in the control group. These results indicate that the herbicide has the potential to influence tiger salamander life history. We present a model consistent with our results, whereby corticosterone and thyroxine interact to regulate metamorphosis of tiger salamanders based on nutrient assimilation and adult fitness.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"671-9"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515999","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20710073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermoregulation by a nocturnal elapid snake (Hoplocephalus bungaroides) in southeastern Australia.","authors":"J K Webb,&nbsp;R Shine","doi":"10.1086/515979","DOIUrl":"https://doi.org/10.1086/515979","url":null,"abstract":"<p><p>Studies of reptilian thermoregulation have tended to focus on diurnal heliothermic taxa that display overt thermoregulatory behavior, with nocturnal reptiles attracting less attention. We studied thermoregulation by the broad-headed snake (Hoplocephalus bungaroides), a small (mean snout-vent length = 57 cm) nocturnal elapid that spends long periods sequestered in diurnal retreat sites. The snakes selected body temperatures of 28.1 degrees-31.1 degrees C in laboratory thermal gradients. Prey-capture ability (strike speed and accuracy) increased at higher body temperatures over the range 20 degrees-30 degrees C. Using temperature-sensitive radio transmitters, we obtained 7,801 body-temperature measurements of 19 free-ranging snakes. Information on operative environmental temperatures was obtained at the same time. From these data, we quantified the degree to which the snakes exploit the environmental thermal heterogeneity available to them (i.e., the time they spent within their set-point range, relative to the total time that these body temperatures were available to them). Mean body temperatures (both diurnally and nocturnally) differed among seasons but not among different types of retreat sites. Inclement weather prevented snakes from attaining \"preferred\" body temperatures on 30% of days. However, even when preferred temperatures were available, the snakes exploited this opportunity for only 26% of the time: they remained within retreat sites and rarely emerged to bask. Nonetheless, judicious retreat-site selection resulted in snakes being within their set-point range for 60% of the time at the most crucial time of day (i.e., the 2-h period around dusk, when the opportunity to capture prey is highest). Basking may be rare not only because of its high potential costs (e.g., risk of avian predation) but also because high body temperatures enhance snake fitness for only a short time each day and can be attained over that short period without the \"expense\" of heliothermy. Our results suggest that precise thermoregulation may not be widespread among snakes, particularly small nocturnal species that spend long periods sequestered in retreat sites.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"680-92"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515979","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20710074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of salinity on the swimming velocity of the water flea Daphnia magna.","authors":"M Baillieul,&nbsp;B De Wachter,&nbsp;R Blust","doi":"10.1086/515985","DOIUrl":"https://doi.org/10.1086/515985","url":null,"abstract":"<p><p>The swimming velocity of the water flea Daphnia magna is dependent on its body size. Therefore, environmental factors that influence growth also influence swimming velocity. This study examined whether exposure to increased salinity reduces swimming velocity only through its effect on body size or whether it also reduces size-specific swimming velocity. Initially, size-specific swimming velocity decreased in a salinity-dependent way. Thereafter, swimming velocities gradually returned to their expected values in all treatments. This acclimation coincided with considerable mortality in the highest-salinity treatment, indicating that daphnids in this treatment either acclimated or died. The initial decrease in size-specific swimming velocity could not be explained by decreased uptake of food. Thus, the results indicate that salinity temporarily impaired physiology. The experiment illustrates how size effects can be accounted for in swimming-velocity analysis and how size-specific swimming-velocity analysis can be used as a non-invasive method to detect stress-induced deviations from normal physiology.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 6","pages":"703-7"},"PeriodicalIF":0.0,"publicationDate":"1998-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515985","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20710076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New directions in comparative physiology and biochemistry: mechanisms, adaptations, and evolution.","authors":"C P Mangum,&nbsp;P W Hochachka","doi":"10.1086/515953","DOIUrl":"https://doi.org/10.1086/515953","url":null,"abstract":"<p><p>Historically, the discipline of comparative physiology and biochemistry has had two major goals: (1) elucidation of mechanisms and their adaptative significance, and (2) understanding of the evolution of mechanisms and adaptations. In general, the first goal has dominated the field. In a mechanistic/adaptational approach, the diversity of organisms is an experimental parameter in the investigation. Lineage-specific characteristics reveal both how physiological systems work and how different kinds of animals are adapted to different kinds of environments. We believe that this approach is far from outdated, in part because many animal groups have been investigated superficially if at all, and in part because the incorporation of fundamentally new technologies into our discipline permits us to address previously intractable questions about even intensively studied animal groups. In evolutionary physiology and biochemistry, the diversity of lineage-specific physiological systems and how they came to be is the subject of investigation. Early attempts to employ the evolutionary approach were not only few in number, they were unsatisfying in outcome because neither phylogenetic nor mechanistic/adaptational knowledge was adequate to serve as a firm foundation. We agree with earlier authors that new and more sophisticated applications of this approach, together with progress in understanding both animal phylogeny and mechanisms/adaptations, all promise to allow us at last to fulfill our second historic goal. In our view, an integration of the two approaches seems to present the most productive trajectory into the next century.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 5","pages":"471-84"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515953","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20667791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glyconeogenesis and Urea Synthesis in the Toad Bufo viridis during Acclimation to Water Restriction","authors":"J. Hoffman, U. Katz,","doi":"10.1086/515945","DOIUrl":"https://doi.org/10.1086/515945","url":null,"abstract":"","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 1","pages":"595 - 595"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515945","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60422935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrogen excretion and the cardiorespiratory physiology of the gulf toadfish, Opsanus beta.","authors":"K M Gilmour,&nbsp;S F Perry,&nbsp;C M Wood,&nbsp;R P Henry,&nbsp;P Laurent,&nbsp;P Pärt,&nbsp;P J Walsh","doi":"10.1086/515969","DOIUrl":"https://doi.org/10.1086/515969","url":null,"abstract":"<p><p>Gulf toadfish, Opsanus beta, are facultatively ureotelic and can excrete the majority of their nitrogenous waste as urea. Urea excretion occurs in \"pulses.\" The hypothesis that pulsatile urea excretion reflects sudden, transient, generalized increases in the branchial conductance was investigated by the simultaneous monitoring of cardiorespiratory variables, oxygen uptake, and whole-body urea, ammonia, and/or 3H2O effluxes. The direct monitoring of both expired branchial water and water exiting a respirometer demonstrated that urea pulses were derived from the gills. No significant changes in ventilation or cardiac frequency, oxygen uptake, or ammonia efflux were observed during natural urea pulses, refuting the hypothesis that pulsatile urea excretion reflects pulsatile increases in the generalized diffusive properties of the gill for solute transfer. An alternative model for pulsatile urea excretion postulates that the gill urea permeability is increased periodically by the insertion and/or activation of specific urea transporters into gill cell membranes. Pulsatile urea excretion was abolished by pretreatment with the cytoskeletal-disrupting agent colchicine; colchicine may block trafficking of urea transporter-containing vesicles. Exocytosis of water following the fusion of vesicles with gill cell membranes could explain the significantly elevated 3H2O efflux observed during urea pulses.</p>","PeriodicalId":79527,"journal":{"name":"Physiological zoology","volume":"71 5","pages":"492-505"},"PeriodicalIF":0.0,"publicationDate":"1998-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1086/515969","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20667793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}