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Warmer Temperatures (warmer + temperature)

Distribution by Scientific Domains

Life Sciences	66%
Earth and Environmental Science	26%

Selected Abstracts

Temperature-dependent ovariole and testis maturation in the yellow dung fly

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2005
Wolf U. Blanckenhorn
Abstract Temperature is one of the abiotic environmental factors most strongly affecting animal behaviour, physiology, and life history. In insects, lower temperatures generally slow down most physiological processes, reducing growth rate and prolonging the juvenile period. Here, we investigate temperature-dependent ovariole and testis maturation in the anautogenous yellow dung fly, Scathophaga stercoraria L. (Diptera: Scathophagidae), and relate it to corresponding temperature effects on pre-adult development time and the adult pre-reproductive period. Flies were reared in the laboratory at three constant temperatures (18, 22, and 26 °C), and the size of the developing ovarioles and testes (reflecting sperm production) was measured over time (i.e., age). Ovariole size increased asymptotically over the first 12 days of adult life, while the testes continued to fill after day 10. In accordance with the temperature-size rule, warmer temperatures resulted in smaller ovarioles (eggs) and smaller testes, independent of body size. Warmer temperatures also greatly reduced pre-adult development time by more than half, from 12 to 25 °C, the larger males always taking 1,3 days longer than the females. Corresponding temperature effects on the adult pre-reproductive period were small (<1 day between 15 and 25 °C), with males taking 5,6 days and females 10,13 days to first reproduction. Time lost by males during the pre-adult stage, when ovaries and testes are produced, can thus be more than compensated-for by time gained during the pre-reproductive period, when eggs and sperm are produced, so males can nevertheless start reproducing sooner than females. [source]

Modeling past and future alpine permafrost distribution in the Colorado Front Range

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 12 2005
Jason R. Janke
Abstract Rock glaciers, a feature associated with at least discontinuous permafrost, provide important topoclimatic information. Active and inactive rock glaciers can be used to model current permafrost distribution. Relict rock glacier locations provide paleoclimatic information to infer past conditions. Future warmer climates could cause permafrost zones to shrink and initiate slope instability hazards such as debris flows or rockslides, thus modeling change remains imperative. This research examines potential past and future permafrost distribution in the Colorado Front Range by calibrating an existing permafrost model using a standard adiabatic rate for mountains (0·5 °C per 100 m) for a 4 °C range of cooler and warmer temperatures. According to the model, permafrost currently covers about 12 per cent (326·1 km2) of the entire study area (2721·5 km2). In a 4 °C cooler climate 73·7 per cent (2004·4 km2) of the study area could be covered by permafrost, whereas in a 4°C warmer climate almost no permafrost would be found. Permafrost would be reduced severely by 93·9 per cent (a loss of 306·2 km2) in a 2·0 °C warmer climate; however, permafrost will likely respond slowly to change. Relict rock glacier distribution indicates that mean annual air temperature (MAAT) was once at least some 3·0 to 4·0 °C cooler during the Pleistocene, with permafrost extending some 600,700 m lower than today. The model is effective at identifying temperature sensitive areas for future monitoring; however, other feedback mechanisms such as precipitation are neglected. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Temperature-dependent ovariole and testis maturation in the yellow dung fly

Groundfish species diversity and assemblage structure in Icelandic waters during recent years of warming

FISHERIES OCEANOGRAPHY, Issue 1 2010
LILJA STEFANSDOTTIR
Abstract Elevated ocean temperatures have been predicted to lead to a poleward shift in the latitudinal distribution ranges of fish species. Different responses of fish species to increased temperatures might lead to changes in assemblage structure and local species richness. In this study, the assemblage structure and diversity of groundfish in Icelandic waters were examined using data from a standardized groundfish survey conducted annually in 1996,2007. We used hierarchical cluster analysis to define assemblages in two time periods and canonical correspondence analysis to explore the relationships between the assemblages and temperature, depth, latitude, longitude and year. We further used two estimates of diversity, species richness and the Shannon index. Four major species assemblages were identified. Assemblages in the hydrographically stable deep waters north of the country were consistent during the study, while assemblage structure in the more variable shallow waters underwent some changes. For this period of generally increasing sea temperature, the canonical correspondence analysis also revealed a shift towards species representative of warmer temperatures. Diversity was shown to be highly variable both temporally and spatially, and also to vary with depth and temperature. Species richness increased with temperature and time southwest of the country, but decreased northeast of the country. The different trends detected between the northern and southern areas illustrate the importance of performing analyses at the most appropriate scale. [source]

Vertical distribution and behaviour of shrimp Pandalus borealis larval stages in thermally stratified water columns: laboratory experiment and field observations

FISHERIES OCEANOGRAPHY, Issue 5 2006
PATRICK OUELLET
Abstract By combining field data and laboratory observations of larvae in a simulated thermal gradient, we described the ontogenetic changes in vertical distribution and behaviour of early stages of shrimp Pandalus borealis in thermally stratified water columns. Both in the laboratory and at stations in the north-western Gulf of St Lawrence, the first two larval stages appear to actively select and maintain a position in the upper layer of warmer temperatures, within the thermocline and above the cold (<1°C) intermediate layer. Stage III larvae were distributed deeper in the water column and in colder waters than the previous two stages. Stage IV and V larvae showed the highest degree of swimming activity in the laboratory and a much wider range (from surface to ,200 m) in vertical distribution in the field. The shift to deeper waters and settlement to the bottom habitat appears to happen after the fifth moult, at stage VI. We propose that the pattern of vertical distribution in the field reflects the adjustment of the different developmental stages to the distribution of preferred prey. The description of the ontogenetic change in the vertical distributions and movements of early stages of P. borealis should be valuable information for future attempts to model larval transport and dispersion, and for detecting settlement/recruitment areas using 3D ocean circulation models. The identification of the thermal habitat of the different larval stages and the timing for settlement at the bottom also provides important information for the development of temperature-dependent growth models up to the first juvenile stages. [source]

Length and sex-specific associations between spiny dogfish (Squalus acanthias) and hydrographic variables in the Bay of Fundy and Scotian Shelf

FISHERIES OCEANOGRAPHY, Issue 2 2002
Travis Shepherd
The associations between spiny dogfish (Squalus acanthias) and hydrographic variables (temperature, salinity and depth) were examined in the Bay of Fundy and Scotian Shelf from 1970 to 1998. Data were obtained from standard groundfish bottom trawl surveys. Dogfish sex affected habitat associations. Males were found to occupy bottom water of significantly higher salinities and depths than that occupied by females. Length also significantly affected habitat associations. Smaller dogfish occupied relatively deep, high salinity bottom water compared with larger dogfish. Overall, the occupied temperatures, salinities and depths were significantly different from those which were available. Dogfish occupied warmer temperatures along a narrow range (6.62,9.19°C) compared with those which were available (1.57,9.35°C). Occupied salinity (32.70,34.43 ppt) and occupied depth (88.62,184.66 m) were also distributed along a narrower range than available salinity (32.16,34.79 ppt) and available depth (55.00,218.10 m). Sex-specific, length-specific and overall environmental preference by dogfish may bias traditional `offshore' groundfish surveys while large scale changes in hydrographic parameters may alter dogfish distribution and their interactions with other marine fauna. [source]

Metabolic cold adaptation and developmental plasticity in metabolic rates among species in the Fundulus notatus species complex

FUNCTIONAL ECOLOGY, Issue 5 2010
Jacob Schaefer
Summary 1.,In ectotherms, temperature and body size are the most influential and well studied variables affecting metabolic rate. Understanding mechanisms driving the evolution of metabolic rates is crucial to broader ecological theory. The metabolic cold adaptation hypothesis (MCA) makes predictions about the evolution of ectotherm metabolic rates and temperature-metabolic rate reaction norms. 2.,We examined intra and interspecific patterns in metabolic rate among populations in the Fundulus notatus species group (F. notatus, F. olivaceus and F. euryzonus). We ask if patterns of intra and interspecific variability in metabolic rate are consistent with the MCA and if metabolic rates in general are developmentally plastic. 3.,Support for the MCA was mixed among intra and interspecific tests. The northern population of F. olivaceus had increased metabolic rate and no difference in temperature sensitivity (slope of temperature-metabolic rate reaction norm). Northern populations of F. notatus had lower temperature sensitivity and no difference in overall metabolic rate. The southern coastal drainage endemic (F. euryzonus) had intermediate metabolic rates compared to southern populations of the other two more broadly distributed species. Metabolic rates were also developmentally plastic. Adults reared at warmer temperatures had lower metabolic rates after accounting for body size and temperature. 4.,Differences in thermal regimes explain some variability in metabolic rates among populations consistent with MCA. However, interspecific comparisons are not consistent with MCA and are likely influenced by species differences in ecology and life history strategies. [source]

Growth and physiological acclimation to temperature and inorganic carbon availability by two submerged aquatic macrophyte species, Callitriche cophocarpa and Elodea canadensis

FUNCTIONAL ECOLOGY, Issue 2 2000
B. Olesen
Abstract 1.,Interactive effects of temperature and inorganic carbon availability on photosynthetic acclimation and growth of two submerged macrophyte species, Elodea canadensis and Callitriche cophocarpa, were examined to test the hypotheses that: (1) effects of temperature on growth rate and photosynthetic acclimation are suppressed under low inorganic carbon availability; (2) the plants compensate for the reduction in activity of individual enzymes at lower temperatures by increasing the activity per unit plant mass, here exemplified by Rubisco. The experiments were performed in the laboratory where plants were grown in a factorial combination of three temperatures (7,25 °C) and three inorganic carbon regimes. 2.,The relative growth rate of both species was strongly affected by growth conditions and increased by up to 4·5 times with increased temperature and inorganic carbon availability. The sensitivity to inorganic carbon was greatest at high temperature and the sensitivity to temperature greatest at high carbon concentrations. 3.,Photosynthetic acclimation occurred in response to growth conditions for both species. The affinity for inorganic carbon and the photosynthetic capacity, both measured at 15 °C, increased with reduced inorganic carbon availability during growth and were greater at warmer than at cooler growth temperature. The acclimative change in photosynthesis was related to the extent of temperature and inorganic carbon stress. Using data for Elodea, a negative relationship between degree of temperature stress and photosynthetic performance was found. In relation to inorganic carbon, a linear increase in CO2 affinity and photosynthetic capacity was found with increased inorganic carbon stress during growth. 4.,The total Rubisco activity declined with increased inorganic carbon availability during growth and with enhanced growth temperature. In addition, the activation state of Rubisco was higher at cooler than at warmer temperatures for Callitriche. This suggests that low-temperature grown plants compensate for the temperature-dependent reduction in activity of the individual Rubisco molecules by enhancing resource allocations towards Rubisco. [source]

Hydrogeologic controls on streamflow sensitivity to climate variation

HYDROLOGICAL PROCESSES, Issue 22 2008
Anne Jefferson
Abstract Climate models project warmer temperatures for the north-west USA, which will result in reduced snowpacks and decreased summer streamflow. This paper examines how groundwater, snowmelt, and regional climate patterns control discharge at multiple time scales, using historical records from two watersheds with contrasting geological properties and drainage efficiencies. In the groundwater-dominated watershed, aquifer storage and the associated slow summer recession are responsible for sustaining discharge even when the seasonal or annual water balance is negative, while in the runoff-dominated watershed subsurface storage is exhausted every summer. There is a significant 1 year cross-correlation between precipitation and discharge in the groundwater-dominated watershed (r = 0·52), but climatic factors override geology in controlling the inter-annual variability of streamflow. Warmer winters and earlier snowmelt over the past 60 years have shifted the hydrograph, resulting in summer recessions lasting 17 days longer, August discharges declining 15%, and autumn minimum discharges declining 11%. The slow recession of groundwater-dominated streams makes them more sensitive than runoff-dominated streams to changes in snowmelt amount and timing. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Role of larval host plants in the climate-driven range expansion of the butterfly Polygonia c-album

JOURNAL OF ANIMAL ECOLOGY, Issue 3 2007
BRIGITTE BRASCHLER
Summary 1Some species have expanded their ranges during recent climate warming and the availability of breeding habitat and species' dispersal ability are two important factors determining expansions. The exploitation of a wide range of larval host plants should increase an herbivorous insect species' ability to track climate by increasing habitat availability. Therefore we investigated whether the performance of a species on different host plants changed towards its range boundary, and under warmer temperatures. 2We studied the polyphagous butterfly Polygonia c-album, which is currently expanding its range in Britain and apparently has altered its host plant preference from Humulus lupulus to include other hosts (particularly Ulmus glabra and Urtica dioica). We investigated insect performance (development time, larval growth rate, adult size, survival) and adult flight morphology on these host plants under four rearing temperatures (18,28·5 °C) in populations from core and range margin sites. 3In general, differences between core and margin populations were small compared with effects of rearing temperature and host plant. In terms of insect performance, host plants were generally ranked U. glabra U. dioica > H. lupulus at all temperatures. Adult P. c-album can either enter diapause or develop directly and higher temperatures resulted in more directly developing adults, but lower survival rates (particularly on the original host H. lupulus) and smaller adult size. 4Adult flight morphology of wild-caught individuals from range margin populations appeared to be related to increased dispersal potential relative to core populations. However, there was no difference in laboratory reared individuals, and conflicting results were obtained for different measures of flight morphology in relation to larval host plant and temperature effects, making conclusions about dispersal potential difficult. 5Current range expansion of P. c-album is associated with the exploitation of more widespread host plants on which performance is improved. This study demonstrates how polyphagy may enhance the ability of species to track climate change. Our findings suggest that observed differences in climate-driven range shifts of generalist vs. specialist species may increase in the future and are likely to lead to greatly altered community composition. [source]

Snake activity affects seasonal variation in nest predation risk for birds

JOURNAL OF AVIAN BIOLOGY, Issue 4 2008
Jinelle H. Sperry
Variation in predator behavior has been proposed, but not tested, as a mechanism producing seasonal declines in avian nest success. We test this hypothesis by documenting seasonal activity of Texas ratsnakes Elaphe obsoleta and nest failure of endangered black-capped vireos Vireo atricapilla and golden-cheeked warblers Dendroica chrysoparia on which the snakes prey. Nest survival analysis was based on 880 vireo and 228 warbler nests and 3,060 snake locations from 62 radio-tracked snakes. Although nest success varied with snake activity for both birds, specific patterns differed substantially. Vireo daily nest survival was negatively correlated with snake activity over the three-year study, despite substantial variation among years in weather, and the fact that these birds are almost certainly a minor prey species of the ratsnakes. Warblers exhibited less clear-cut seasonal variation in nest success, and the association between nest success and snake activity was less pronounced than for vireos. Increased activity at warmer temperatures explained some of the seasonal change in snake movements, although mating may have accounted for a mid-season peak in activity. These results indicate that variation in predator behavior can be associated with and potentially cause seasonal changes in nest success, but also that these relationships are species specific even within the same community and may depend on aspects of the nesting ecology of the prey such as nest site selection. [source]

Plant functional types do not predict biomass responses to removal and fertilization in Alaskan tussock tundra

JOURNAL OF ECOLOGY, Issue 4 2008
M. Syndonia Bret-Harte
Summary 1Plant communities in natural ecosystems are changing and species are being lost due to anthropogenic impacts including global warming and increasing nitrogen (N) deposition. We removed dominant species, combinations of species and entire functional types from Alaskan tussock tundra, in the presence and absence of fertilization, to examine the effects of non-random species loss on plant interactions and ecosystem functioning. 2After 6 years, growth of remaining species had compensated for biomass loss due to removal in all treatments except the combined removal of moss, Betula nana and Ledum palustre (MBL), which removed the most biomass. Total vascular plant production returned to control levels in all removal treatments, including MBL. Inorganic soil nutrient availability, as indexed by resins, returned to control levels in all unfertilized removal treatments, except MBL. 3Although biomass compensation occurred, the species that provided most of the compensating biomass in any given treatment were not from the same functional type (growth form) as the removed species. This provides empirical evidence that functional types based on effect traits are not the same as functional types based on response to perturbation. Calculations based on redistributing N from the removed species to the remaining species suggested that dominant species from other functional types contributed most of the compensatory biomass. 4Fertilization did not increase total plant community biomass, because increases in graminoid and deciduous shrub biomass were offset by decreases in evergreen shrub, moss and lichen biomass. Fertilization greatly increased inorganic soil nutrient availability. 5In fertilized removal treatments, deciduous shrubs and graminoids grew more than expected based on their performance in the fertilized intact community, while evergreen shrubs, mosses and lichens all grew less than expected. Deciduous shrubs performed better than graminoids when B. nana was present, but not when it had been removed. 6Synthesis. Terrestrial ecosystem response to warmer temperatures and greater nutrient availability in the Arctic may result in vegetative stable-states dominated by either deciduous shrubs or graminoids. The current relative abundance of these dominant growth forms may serve as a predictor for future vegetation composition. [source]

Vectors and alternative hosts of Tobacco yellow dwarf virus in southeastern Australia

ANNALS OF APPLIED BIOLOGY, Issue 1 2010
P. Tr, bicki
Factors that determine the epidemiology of Tobacco yellow dwarf virus (TbYDV), including alternative host plants and insect vector(s), were assessed over three consecutive growing seasons at four field sites in Northeastern Victoria in commercial tobacco growing properties. In addition, these factors were assessed for one growing season at three bean growing properties. Overall, 23 leafhopper species were identified at the 7 sites, with Orosius orientalis as the predominant leafhopper. Of the leafhoppers collected, only O. orientalis and Anzygina zealandica tested positive for TbYDV by polymerase chain reaction (PCR). The population dynamics of O. orientalis was assessed using sweep net sampling over three growing seasons and a trimodal distribution was observed. Despite large numbers of O. orientalis occurring early in the growing season (September,October), TbYDV was only detected in these leafhoppers between late November and end of January. The peaks in the detection of TbYDV in O. orientalis correlated with the observation of disease symptoms in tobacco and bean and were associated with warmer temperatures and lower rainfall. Spatial and temporal distribution of vegetation at selected sites was determined using quadrat sampling. Of the 40 plant species identified, TbYDV was detected only in four dicotyledonous species, Amaranthus retroflexus, Phaseolus vulgaris, Nicotiana tabacum and Raphanus raphanistrum. The proportion of host and non-host availability for leafhoppers was associated with climatic conditions. [source]

Combined effect of incubation and ambient temperature on the feeding performance of a small ectotherm

AUSTRAL ECOLOGY, Issue 8 2006
JOKE BILCKE
Abstract Many ectothermic animals are subject to fluctuating environmental temperatures during incubation as well as post-birth. Numerous studies examined the effects of incubation temperature or ambient temperature on various aspects of offspring phenotype. We investigated whether incubation temperature and ambient temperature have an interactive effect on offspring performance. Our study animal, the ectothermic vertebrate Lampropholis delicata (common garden skink; De Vis 1888), experiences fluctuating environmental temperatures caused by differential invasion of an exotic plant Vinca major (blue periwinkle). In the laboratory, eggs from wild-caught females were assigned to different incubation temperatures that mimicked variation in natural nests. The feeding performance and digestion time of each hatchling was tested at ambient temperatures that represented environments invaded to different degrees by periwinkle. Incubation and ambient temperature interacted to affect a lizard's mobility, the time that it took to capture, subdue and handle a prey, and the number of handling ,errors' that it made while foraging. For a number of these characteristics, incubation-induced changes to a lizard's mass significantly affected this relationship. Irrespective of size, no interaction effect was found for digestion time: lizards digested food faster at warmer temperatures, regardless of incubation temperature. Thus, temperatures experienced during incubation may alter an animal's phenotype so that the surrounding thermal environment differentially affects aspects of feeding performance. Our results also demonstrate that incubation environment can induce changes to morphology and behaviour that carry over into a lizard's early life, and that in some cases these differences in phenotype interact to affect performance. We suggest that the immediate removal of exotic plants as part of a weed control strategy could have important implications for the foraging performance, and presumably fitness, of ectothermic animals. [source]

Population Ecology of the Riparian Frog Eleutherodactylus cuneatus in Cuba

BIOTROPICA, Issue 3 2010
Ansel Fong G.
ABSTRACT A population of the poorly known riparian frog Eleutherodactylus cuneatus was studied for 1 yr along a mountain stream in eastern Cuba. We examined population structure, seasonal and daily activity, growth, and habitat use using mark-recapture and call-point counts. Juveniles were observed during all survey periods with a spike in March. Higher numbers of adults were present in May,July, associated with longer day length, warmer temperatures, and the onset of the rainy season. This was coincident with higher calling activity away from the stream, suggesting an increase in both reproductive and nonreproductive activity in the warmer months between May and September. The number of individuals peaked at 2000,2200 h, but high numbers of individuals were visible throughout the night. Lower activity levels were observed throughout the day. Population size estimates were 84,131 adults and 124,304 juveniles, with averages of 110 and 236 individuals, survival rates were high but capture probabilities were low for a 5-d period in March 2004. Growth rate was negatively related to the size of recaptured individuals, although decreases in growth rate were slight. Frogs were found either in the water (49.7%), or in the banks and on the ground adjacent to the stream where most individuals were found on the ground under the cover of rocks, leaf litter, or large palm fronds. These results provide baseline knowledge of E. cuneatus population dynamics and ecology needed for a rapid detection of any decline this population may undergo in the future. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source]