共查询到20条相似文献,搜索用时 0 毫秒
1.
H. Arthur Woods Amy L. Moran Claudia P. Arango Lindy Mullen Chris Shields 《Proceedings. Biological sciences / The Royal Society》2009,276(1659):1069-1075
Compared to temperate and tropical relatives, some high-latitude marine species are large-bodied, a phenomenon known as polar gigantism. A leading hypothesis on the physiological basis of gigantism posits that, in polar water, high oxygen availability coupled to low metabolic rates relieves constraints on oxygen transport and allows the evolution of large body size. Here, we test the oxygen hypothesis using Antarctic pycnogonids, which have been evolving in very cold conditions (−1.8–0°C) for several million years and contain spectacular examples of gigantism. Pycnogonids from 12 species, spanning three orders of magnitude in body mass, were collected from McMurdo Sound, Antarctica. Individual sea spiders were forced into activity and their performance was measured at different experimental levels of dissolved oxygen (DO). The oxygen hypothesis predicts that, all else being equal, large pycnogonids should perform disproportionately poorly in hypoxia, an outcome that would appear as a statistically significant interaction between body size and oxygen level. In fact, although we found large effects of DO on performance, and substantial interspecific variability in oxygen sensitivity, there was no evidence for size×DO interactions. These data do not support the oxygen hypothesis of Antarctic pycnogonid gigantism and suggest that explanations must be sought in other ecological or evolutionary processes. 相似文献
2.
3.
4.
Stephanie Brodie Matthew D. Taylor James A. Smith Iain M. Suthers Charles A. Gray Nicholas L. Payne 《Ecology and evolution》2016,6(8):2262-2274
Consumption is the basis of metabolic and trophic ecology and is used to assess an animal''s trophic impact. The contribution of activity to an animal''s energy budget is an important parameter when estimating consumption, yet activity is usually measured in captive animals. Developments in telemetry have allowed the energetic costs of activity to be measured for wild animals; however, wild activity is seldom incorporated into estimates of consumption rates. We calculated the consumption rate of a free‐ranging marine predator (yellowtail kingfish, Seriola lalandi) by integrating the energetic cost of free‐ranging activity into a bioenergetics model. Accelerometry transmitters were used in conjunction with laboratory respirometry trials to estimate kingfish active metabolic rate in the wild. These field‐derived consumption rate estimates were compared with those estimated by two traditional bioenergetics methods. The first method derived routine swimming speed from fish morphology as an index of activity (a “morphometric” method), and the second considered activity as a fixed proportion of standard metabolic rate (a “physiological” method). The mean consumption rate for free‐ranging kingfish measured by accelerometry was 152 J·g−1·day−1, which lay between the estimates from the morphometric method (μ = 134 J·g−1·day−1) and the physiological method (μ = 181 J·g−1·day−1). Incorporating field‐derived activity values resulted in the smallest variance in log‐normally distributed consumption rates (σ = 0.31), compared with the morphometric (σ = 0.57) and physiological (σ = 0.78) methods. Incorporating field‐derived activity into bioenergetics models probably provided more realistic estimates of consumption rate compared with the traditional methods, which may further our understanding of trophic interactions that underpin ecosystem‐based fisheries management. The general methods used to estimate active metabolic rates of free‐ranging fish could be extended to examine ecological energetics and trophic interactions across aquatic and terrestrial ecosystems. 相似文献
5.
大鸨繁殖期活动时间预算和日节律 总被引:18,自引:1,他引:18
2000和2001年的4~7月连续两年,在内蒙古自治区科尔沁右翼前旗东南部的草原上,采用野外直接观察法对野生大鸨的活动时间预算和日节律进行了研究。结果表明,大鸨繁殖期的各种行为活动具有一定的时间分配,其时间预算存在着性别间的差异,同时随活动空间大小、食物条件以及繁殖阶段的不同而变化,在繁殖前期,大鸨的时间预算以取食、休息、行走、观察为主要行为,雄鸨和雌鸨的这4种行为分别占全部行为的87%和93%;到繁殖后期,雌鸨各种行为的时间和强度发生较大变化。大鸨在取食、休息和炫耀等行为上都存在不同程度的日节律,取食和炫耀出现两次高峰,中午大部分时间大鸨处于静栖休息状态。 相似文献
6.
Mark Hebblewhite 《Population Ecology》2013,55(4):511-522
A growing number of studies suggest ratio-dependence may be common in many predator–prey systems, yet in large mammal systems, evidence is limited to wolves and their prey in Isle Royale and Yellowstone. More importantly, the consequences of ratio-dependent predation have not been empirically examined to understand the implications for prey. Wolves recolonized Banff National Park in the early 1980s, and recovery was correlated with significant elk declines. I used time-series data of wolf kill rates of elk, wolf and elk densities in winter from 1985–2007 to test for support for prey-, ratio-, or predator dependent functional and numeric responses of wolf killing rate to elk density. I then combined functional and numeric responses to estimate the total predation response to identify potential equilibrium states. Evidence suggests wolf predation on elk was best described by a type II ratio-dependent functional response and a type II numeric response that lead to inversely density-dependent predation rate on elk. Despite support for ratio-dependence, like other wolf-prey systems, there was considerable uncertainty amongst functional response models, especially at low prey densities. Consistent with predictions from ratio-dependent models, however, wolves contributed to elk population declines of over 80 % in our Banff system. Despite the statistical signature for ratio-dependence, the biological mechanism remains unknown and may be related to multi-prey dynamics in our system. Regardless, ratio-dependent models strike a parsimonious balance between theory and empiricism, and this study suggests that large mammal ecologists need to consider ratio-dependent models in predator–prey dynamics. 相似文献
7.
四川梅花鹿春季昼夜活动节律与时间分配 总被引:13,自引:3,他引:13
1997年4月,在四川铁布自然保护区用直接观察法对220头次四川梅花鹿群的昼夜活动节律和时间分配进行了观察。结果表明,鹿群春季昼夜活动的规律性较强。白昼,鹿群活动呈现明显的双峰型,2个高峰时段为08:30和19:30前后,活动频率分别为71.9%和94.13%,其他时间多处于休息状态;鹿群夜间活动强于昼间,活动频率均在6l%以上,仅在半夜01:30前后有一个相对不活跃期。同时发现,春季活动高峰期约90%的活动时间被四川梅花鹿用于采食和移动。这可能与光照、食物及人类活动的影响有关。 相似文献
8.
9.
M. Bonnefoy T. Kostka S. E. Berthouze J. -R. Lacour 《European journal of applied physiology and occupational physiology》1996,74(6):528-533
The purpose of this study was to validate a physical activity (PA) questionnaire, Questionnaire d'Activité Physique Saint-Etienne
(QAPSE), in an homogenous population of elderly subjects and to estimate its potential for application in routine PA assessments
in that age group. A group of 65 (31 men and 34 women) community dwelling, healthy people aged 65–84 years volunteered to
participate in a validation substudy comparing maximal oxygen uptake (
) and anthropometric data.
correlated positively with mean habitual daily energy expenditure (MHDEE) (r=0.56,P<0.0001), greater than 3MET (metabolic equivalent) daily energy expenditure (DEE) activity (r=0.371,P=0.002), leisure activity (r=0.368,P=0.003), sports activity (r=0.461,P<0.0001), basic daily activity (r=0.325,P=0.008) and moving DEE activity (r=0.273,P=0.028) in both sexes, with MHDEE (r=0.366,P=0.043) and moving DEE activity (r=0.388,P=0.031) in the men and with MHDEE (r=0.624;P<0.001), greater than 3MET DEE activity (r=0.513,P=0.002), leisure activity (r=0.388,P=0.024) and sports activity (r=0.683,P<0.001) in the women. The MHDEE was positively correlated with body mass (r=0.464) and with fat free mass (r=0.639) and negatively correlated with percentage body fat (r=−0.501). In a reproducibility substudy (n=44) a paired Student'st-test, based on mean differences between the two administrations of the questionnaire did not reach statistical significance
for any of the QAPSE activity scores studied. Test-retest correlation coefficients ranged from 0.648 for moving score to 0.967
for MHDEE with correlation coefficientP values being less than 0.001 for all of the QAPSE activity scores. We concluded that QAPSE demonstrated excellent repeatability
and good validity in relation to physical fitness and anthropometric data in the population of these healthy elderly volunteers. 相似文献
10.
11.
Enda Crossin Karli Verghese Simon Lockrey Hieu Ha Gordon Young 《Journal of Industrial Ecology》2020,24(4):791-803
We present a life cycle assessment (LCA) of the operation of Casey Station in Antarctica. The LCA included quantifying material and energy flows, modeling of elementary flows, and subsequent environmental impacts. Environmental impacts were dominated by emissions associated with freight operations and electricity cogeneration. A participatory design approach was used to identify options to reduce environmental impacts, which included improving freight efficiency, reducing the temperature setpoint of the living quarters, and installing alternative energy systems. These options were then assessed using LCA, and have the potential to reduce environmental impacts by between 2% and 19.1%, depending on the environmental indicator. 相似文献
12.
Studies of benthic Foraminifera typically rely on the morphological identification of dried specimens. This approach can introduce sampling bias against small, delicate, or morphologically ambiguous forms. To overcome this limitation, we extracted total DNA from sediment followed by PCR using group- and species-specific primers. Phylogenetic analyses revealed that approximately ninety percent of the PCR products represented previously undescribed sequence types that group with undersampled members of the allogromiid Foraminifera. We also used a modification of this technique to track individual species in sediment fractions too fine for normal morphological identification, and to confirm species placement of morphologically ambiguous foraminiferans. We were able to identify the DNA of several large foraminiferal species in fine fractions in a seasonally-dependent manner, indicating that in some seasons the majority of the standing stock of these species exists as gametes/juveniles. The approach outlined here represents a powerful strategy for exploring the total diversity of benthic foraminiferal communities. 相似文献
13.
Adaptations for the maintenance of water balance by three species of Antarctic mites 总被引:1,自引:0,他引:1
J. B. Benoit J. A. Yoder G. Lopez-Martinez M. A. Elnitsky R. E. Lee Jr. D. L. Denlinger 《Polar Biology》2008,31(5):539-547
Three species of Antarctic mites, Alaskozetes antarcticus, Hydrogamasellus antarcticus and Rhagidia gerlachei, are abundant in the vicinity of Palmer Station, Antarctica. No single mechanism for reducing water stress was shared by
all three species. A. antarcticus and R. gerlachei (both ca. 200 μg) are over twice as large as H. antarcticus (ca. 90 μg), but all had similar body water content (67%) and tolerated a loss of up to 35% of their body water before succumbing
to dehydration. All imbibed free water and had the capacity to reduce water loss behaviorally by forming clusters. Alaskozetes antarcticus was distinct in that it relied heavily on water conservation (xerophilic classification) that was largely achieved by its
thick cuticular armor, a feature shared by all members of this suborder (Oribatida), and abundant cuticular hydrocarbons.
In comparison to the other two species, A. antarcticus was coated with 2–3× the amount of cuticular hydrocarbons, had a 20-fold reduction in net transpiration rate, and had a critical
transition temperature (CTT) that indicates a pronounced suppression in activation energy (E
a) at temperatures below 25°C. In contrast, H. antarcticus and R. gerlachei lack a CTT, have lower amounts of cuticular hydrocarbons and have low E
as and high net transpiration rates, classifying them as hydrophilic. Only H. antarcticus was capable of utilizing water vapor to replenish its water stores, but it could do so only at relative humidities close
to saturation (95–98 %RH). Thus, H. antarcticus and R. gerlachei require wet habitats and low temperature to counter water loss, and replace lost water behaviorally through predation. Compared
to mites from the temperate zone, all three Antarctic species had a lower water content, a feature that commonly enhances
cold tolerance. 相似文献
14.
1. Marine Iguanas ( Amblyrhynchus cristatus ) inhabiting the rocky shores of the Galápagos Islands apply two foraging strategies, intertidal and subtidal foraging, in a seasonal climate. Effects of both foraging strategy and seasonality on the daily energy expenditure (DEE) were measured using doubly labelled water.
2. Difference in foraging mode did not result in significant differences in DEE.
3. On Santa Fé the DEE in the warm season was significantly higher than in the cool season (67·8 ± 21·8 kJ kg–0·8 day–1 vs 38·0 kJ kg–0·8 day–1 ). This difference can be explained by body temperature. A model estimate of the body temperature was used to predict monthly DEE figures, giving a year round budget. On average a 1-kg iguana would need only 47 kJ day–1 , or 17 mJ year –1 . This is lower than previous estimates in which body temperatures were not taken into account.
4. The water flux of the Marine Iguana increases with increasing foraging time. The linear rise per minute foraging is roughly two times as high for subtidally foraging animals as for intertidal foragers. 相似文献
2. Difference in foraging mode did not result in significant differences in DEE.
3. On Santa Fé the DEE in the warm season was significantly higher than in the cool season (67·8 ± 21·8 kJ kg
4. The water flux of the Marine Iguana increases with increasing foraging time. The linear rise per minute foraging is roughly two times as high for subtidally foraging animals as for intertidal foragers. 相似文献
15.
Gunnar Rehfeldt 《Oecologia》1992,89(4):550-556
Summary Predation by orb-weaving spiders and crab spiders on the damselfly Calopteryx haemorrhoidalis was studied at a small stream in Southern France. One species of orb-weaving spider, Larinioides folium, caught 76% of the damselflies which fell prey to spiders. Displacement experiments on spiders on sections of bank and the positioning of webs in male territories show that the density and distribution of damselflies is not influenced by orbweb density or by the position of webs. Predation rates corresponded to orb-web density, but neither for sex nor for stage was there a relationship with damselfly density. Mean daily predation rates ranged between 0.9% for females and 4.1% for adult males. Predation risk to adult damselflies by orb-weaving spiders was male biased, whereas among tenerals there was no bias. Males were captured more frequently at territories near the water. Captures show a maximum at noon when territorial disputes of adult males were most frequent. After orbwebs were placed within territories predation rate of males was strongly increased. Predation risk to adult females in the direct vicinity of the stream was less than in the bank vegetation where they perch close to orbwebs. The risk of predation by crab spiders, which catch damselflies at their perching sites, was not sex-biased. 相似文献
16.
圈养林麝春季活动节律及时间分配 总被引:2,自引:0,他引:2
2006 年春季,使用红外夜间观察记录仪,对崇明东平麝场12 只成年林麝(8 雌,4 雄)的行为进行了24 h昼夜连续观察。发现春季林麝的行为有37 种,可归并为休息、摄食、运动、社会、维持和排遗6 大行为类型,据此,建构了春季林麝的行为谱。根据各行为持续时间比率和频次分析表明,林麝的主要行为为休息;雌麝的摄食行为所占的比率高于雄麝,这是由于春季雌麝妊娠的能量需求较高所致。活动节律呈典型的晨昏双峰型,清晨(4:00 ~ 6:00)和傍晚(17:00 ~ 19:00)为活动高峰;夜间活动性显著高于白天。 相似文献
17.
18.
Gary K. Grunwald Edward L. Melanson Jeri E. Forster Helen M. Seagle Teresa A. Sharp James O. Hill 《Obesity (Silver Spring, Md.)》2003,11(6):752-759
Objective: To evaluate and compare methods for achieving 24‐hour energy balance in a whole‐room indirect calorimeter. Research Methods and Procedures: Twenty‐four‐hour energy expenditure (EE) for 34 healthy adults (16 women, 18 men) was measured in a calorimeter during a prestudy day and on a subsequent nonconsecutive assessment day (AD). Several methods for estimating EE on the AD using activity factors or regression equations with data available before the AD [anthropometrics, body composition, resting metabolic rate (RMR), sleeping metabolic rate (SMR) on prestudy day, 24‐hour EE on prestudy day] were compared for predictive accuracy. Results: Use of a 24‐hour calorimeter stay gave the smallest mean absolute error (119 ± 16 kcal/d) and smallest single maximum error (361 kcal/d). However, several other methods were only slightly, and not significantly, less accurate (e.g., mean absolute error = 131 ± 17, 140 ± 20, and 141 ± 22 kcal/d and greatest error = 384, 370, and 593 kcal/d for anthropometric, RMR, and SMR regression equations, respectively). Fat‐free mass alone and SMR with a simple activity factor were seen to be less accurate. Discussion: Our results indicate that there may be some improvement in achieving 24‐hour energy balance in a metabolic chamber by using a preceding 24‐hour calorimeter stay; that only slightly less accurate predictions can be obtained using a combination of anthropometric, body composition, and/or RMR measurements; and that there is little or no advantage in using SMR from a previous overnight calorimeter stay. 相似文献
19.
Schmid J Speakman JR 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2000,170(8):633-641
We aimed to investigate the pattern of utilisation of torpor and its impact on energy budgets in free-living grey mouse lemurs
(Microcebus murinus), a small nocturnal primate endemic to Madagascar. We measured daily energy expenditure (DEE) and water turnover using doubly
labelled water, and we used temperature-sensitive radio collars to measure skin temperature (T
sk) and home range. Our results showed that male and female mouse lemurs in the wild enter torpor spontaneously over a wide
range of ambient temperatures (T
a) during the dry season, but not during the rainy season. Mouse lemurs remained torpid between 1.7–8.9 h with a daily mean
of 3.4 h, and their T
sk s fell to a minimum of 18.8 °C. Mean home ranges of mouse lemurs which remained normothermic were similar in the rainy and
dry season. During the dry season, the mean home range of mouse lemurs showing daily torpor was significantly smaller than
that of animals remaining normothermic. The DEE of M. murinus remaining normothermic in the rainy season (122 ± 65.4 kJ day−1) was about the same of that of normothermic mouse lemurs in the dry season (115.5 ± 27.3 kJ day−1). During the dry season, the mean DEE of M. murinus that utilised daily torpor was 103.4 ± 32.7 kJ day−1 which is not significantly different from the mean DEE of animals remaining normothermic. We found that the DEE of mouse
lemurs using daily torpor was significantly correlated with the mean temperature difference between T
sk and T
a (r
2=0.37) and with torpor bout length (r
2
=0.46), while none of these factors explained significant amounts of variation in the DEE of the mouse lemurs remaining normothermic.
The mean water flux rate of mouse lemurs using daily torpor (13.0 ± 4.1 ml day−1) was significantly lower than that of mouse lemurs remaining normothermic (19.4 ± 3.8 ml day−1), suggesting the lemurs conserve water by entering torpor. Thus, this first study on the energy budget of free-ranging M. murinus demonstrates that torpor may not only reflect its impact on the daily energy demands, but involve wider adaptive implications
such as water requirements.
Accepted: 29 August 2000 相似文献
20.
Objective: This study examined the repeatability of measuring resting metabolic rate (RMR) in preschool children and the effect of different calculation protocols. Research Methods and Procedures: Eleven children (4 females and 7 males) participated in the project. They were recruited through advertisements in local schools and community centers. Resting metabolic rate was measured on 3 occasions over a 2‐week period, each after an overnight fast and each lasting ~20 to 25 minutes. Results were compared using repeated‐measures ANOVA to check for repeatability, and a number of methods of calculating RMR were assessed. Results: Repeatability of RMR measurements was good (coefficient of variation of replicates, 6.8%), with no significant difference between days of measurement. The lowest RMR measurement was obtained when the first 10 minutes were excluded and periods during which large activity was observed were excluded. This measurement was, on average, 4% lower than averaging the measurements after the first 5 minutes, including body movements. Discussion: This study suggests that RMR can be measured in preschool children and that the best method for calculating RMR in these subjects is to exclude periods when large body movements occur and the first 10 minutes of the measurement period. Only a single measurement of RMR is needed to obtain a reliable estimate. 相似文献