Effect of age and body size on selected temperature by juvenile wood turtles (Glyptemys insculpta)

In an aquatic thermal gradient of 15–30 °C, 3-, 6-, and 12-month-old juvenile wood turtles (Glyptemys insculpta) acclimated to 20 °C selected the warmest temperature available (30 °C) and avoided the coldest temperatures available (15 and 18 °C). Mean selection of chambers differed between control and gradient tests across all temperatures except 27 °C. Turtles of all age classes relocated between chambers less often when the gradient was present than during control tests. Six- and 12-month-old turtles selected 30 °C more frequently, and selected colder temperatures less frequently, than 3-month-old turtles, suggesting that the ability to select preferred temperatures is better developed in older hatchlings.     

Response of hatchling wood turtles (Glyptemys insculpta) to an aquatic thermal gradient

Effective thermoregulation and the ability to select preferred temperature is an important factor influencing fitness in hatchling and juvenile turtles. Six-month-old Glyptemys insculpta acclimated to 20 °C selected the warmest temperature available and avoided the coldest temperature available in a gradient of 12–27 °C. Turtles visited fewer chambers and switched chambers in the gradient tank less frequently when the gradient was present than during control tests. Mean selection of chambers differed between control and gradient tests across all temperatures except at 21 °C, the temperature closest to the acclimation and control temperature (20 °C).     

Response of juvenile diamond-backed terrapins (Malaclemys terrapin) to an aquatic thermal gradient

In many ectotherms, selection of environmental thermal niches may positively affect growth, nutrient assimilation rates, immune system function, and ultimately survival. Temperature preference in some turtle species may be influenced by environmental conditions, including acclimation temperature. We tested for effects of acclimation temperature (22 °C, 27 °C) on the selected temperature and movement patterns of 14 juvenile Malaclemys terrapin (Reptilia: Emydidae) in an aquatic thermal gradient of 14–34 °C and in single-temperature (22 °C, 27 °C) control tests. Among 8–10 month old terrapins, acclimation temperature influenced activity and movement patterns but did not affect temperature selection. In thermal gradient and single-temperature control tests, turtles acclimated to 27 °C used more tank chambers and relocated between chambers significantly more frequently than individuals acclimated to 22 °C. However, acclimation temperature did not affect temperature selection: both 22- and 27 °C-acclimated turtles selected the warmest temperature (34 °C), and avoided the other temperatures available, during thermal gradient tests. These results suggest that young M. terrapin are capable of detecting small temperature increments and prefer warm temperatures that may positively influence growth and metabolism.     

Effect of acclimation temperature and substrate type on selected temperature,movement and activity of juvenile spiny softshell turtles (Apalone spinifera) in an aquatic thermal gradient

In some turtle species, temperature selection may be influenced by environmental conditions, including acclimation temperature and substrate quality. These factors may be particularly important for softshell turtles that are highly aquatic and often thermoregulate by burying in the substrate in shallow water microhabitats. We tested for effects of acclimation temperature (22 °C or 27 °C) and substrate type (sand or gravel) on the selected temperature and movement patterns of 20 juvenile spiny softhshell turtles (Apalone spinifera; Reptilia: Trionychidae) in an aquatic thermal gradient of 14–34 °C. Among 7–11 month old juvenile softshell turtles, acclimation temperature and substrate type did not influence temperature selection, nor alter activity and movement patterns. During thermal gradient tests, both 22- and 27 °C-acclimated turtles selected the warmest temperature (34 °C) available most frequently, regardless of substrate type (sand or gravel). Similarly, acclimation temperature and substrate type did not influence movement patterns of turtles, nor the number of chambers used in the gradient tests. These results suggest that juvenile Apalone spinifera are capable of detecting small temperature increments and prefer warm temperatures that may positively influence growth and metabolism, and that thermal factors more significantly influence aquatic thermoregulation in this species than does substrate type.     

Effects of summer- and winter-like acclimation on the thermoregulatory behavior of fed and fasted desert hamsters, Phodopus roborovskii

1.

Thermoregulatory behavior of fed and fasted desert hamsters (Phodopus roborovskii) acclimated to summer- [16 light (L):8 dark (D), ambient temperature (T_a)=26.5 °C] and winter-like (8L:16D, T_a=10 °C) conditions was studied. Body temperature (T_b), selected temperature and activity were measured in hamsters placed in a thermal gradient system for 48 h.     

Embryonic development rate and hatchling phenotypes in the Chinese three-keeled pond turtle (Chinemys reevesii): The influence of fluctuating temperature versus constant temperature

Although the effects of constant temperatures on hatchling traits have been extensively studied in reptiles, the effects of fluctuating temperatures remain poorly understood. Eggs of the Chinese three-keeled pond turtle (Chinemys reevesii) were incubated at a constant temperatures (28 °C) and two fluctuating temperatures (28±3 °C and 28±6 °C) to test for the influence of thermal environment on incubation duration, hatchling traits, and post-hatching growth. Incubation duration was shorter at constant temperature than at fluctuating temperatures. The sex ratio of hatchlings varied among temperature treatments, with more females from 28±6 °C than from 28 °C. The size and mass were greater for hatchlings from a constant temperature than from fluctuating ones, but this difference in body size disappeared when the hatchlings were 3 months old. In addition, the swimming ability, survival, and growth of hatchlings from fluctuating temperatures did not differ from those of hatchlings from constant temperature, when they were kept at an artificial environment without food scarcity or predation. Therefore, the thermal environments with various temperature fluctuations used in this study do not significantly affect fitness-related hatchling traits in this species.     

Daily and annual patterns of thermoregulation in painted turtles (Chrysemys picta marginata) living in a thermally variable marsh in Northern Michigan

The capacity for an ectothermic reptile to thermoregulate has implications for many components of its life history. Over two years, we studied thermoregulation in a population of Midland painted turtles (Chrysemys picta marginata) in a shallow, thermally variable wetland during summer in Northern Michigan. Mean body temperature (T_b) of free-ranging turtles was greater in 2008 (25.8 °C) than in 2010 (19.7 °C). Laboratory determined thermoregulatory set point (T_set) ranged from 25 °C (T_set-min) to 31 °C (T_set-max) and was lower during the fall (17–26 °C). Deviations of T_b distributions from field measured operative temperatures (T_e) and indices of thermoregulation indicated that C. picta marginata were capable of a limited degree of thermoregulation. Operative temperatures and thermal quality (d_e=|T_set-min−T_e| and |T_e−T_set-max|) cycled daily with maximal thermal quality occurring during late morning and late afternoon. The accuracy of thermoregulation (d_b=|T_set-min−T_b| and |T_b−T_set-max|) was maximal (d_b values were minimal) as T_b declined and traversed T_set during the late afternoon–early evening hours and was higher on cloudy days than on sunny days because relatively low T_e values decreased the number of T_b values that were above T_set. Our index of thermal exploitation (E_x=frequency of T_b observations within T_set) was 36%, slightly lower than that reported for an Ontario population of C. picta marginata. Regression of d_b (thermal accuracy) on d_e (thermal quality) indicated that turtles invested more in thermoregulation when thermal quality was low and when water levels were high than when they were low. There were no intersexual differences in mean T_b throughout the year but females had relatively high laboratory determined T_b values in the fall, perhaps reflecting the importance of maintaining ovarian development prior to winter.     

驯化温度与急性变温对南方鲇幼鱼皮肤呼吸代谢的影响

为了考查鱼类皮肤呼吸代谢的温度反应特征,在不同驯化温度(10、20、30℃)及双向急性变温(10→20℃、20→30℃、10→30℃;20→10 ℃、30→20℃、30→10℃)条件下采用自行设计的皮肤呼吸代谢装置测定麻醉后南方鲇(Silurus meridionalis)幼鱼的皮肤耗氧率(MO2skin)及鳃部耗氧率(MO2gill),并计算整体耗氧率(MO2total).研究显示:南方鲇幼鱼的MO2skin占MO2total 的16.4％-19.0％,随着驯化温度的升高,MO2skin上升的幅度显著低于MO2total(P＜0.05),MO2skin占MO2total的比例则呈下降趋势;急性升(降)温组的MO2skin与升(降)温前驯化温度组相比显著升高(降低)(P＜0.05),却与相应温度驯化组的MO2skin无显著性差异(P＞0.05);急性变温组MO2skin的Q10值与驯化温度组的差异不显著(P＞0.05),却显著低于MO2total的Q10值(P＜0.05).通过相关资料比较发现,南方鲇幼鱼MO2skin占MO2total的比例处于中上水平.研究表明,在驯化温度和急性变温条件下,实验鱼的MO2total分别存在代谢补偿反应和急性胁迫反应;MO2skin与MO2total的温度反应不同,它既不是一个完全的化学反应过程,也不是生物反应过程,而更倾向于是一个物理的扩散过程.     

Effects of crowding and temperature on Wolbachia infection density among life cycle stages of Aedes albopictus

Species of the genus Wolbachia are a group of Rickettsia-like, maternally-inherited bacteria (gram negative), which cause various reproductive alterations in their arthropod and nematode hosts including cytoplasmic incompatibility (CI), male-killing, parthenogenesis and feminization. They can be divided into supergroups such as A and B based on phylogenetic analysis of 16S rDNA sequences. In this study, we examined the relative infection densities of Wolbachia strains among life cycle stages in the mosquito, Aedes albopictus in terms of crowding effect and temperature effect. A. albopictus is known to be superinfected with both A- and B-supergroup Wolbachia which cause CI. The relative Wolbachia densities within each individual mosquito were determined and quantified by using real-time quantitative PCR assay based on the wsp gene. We found that B-supergroup Wolbachia strain densities in this host species were consistently and significantly higher than in the A-supergroup. Larval crowding also reduced adult size of mosquitoes. Our results show clearly that the higher densities of mosquito larvae cause lower densities of Wolbachia strains. Examination of the effect of temperature on Wolbachia density in each stage of the mosquito clearly revealed a significant decrease in bacterial density following exposure to elevated temperature (37 °C) in both males and females.     

孵化温度对黄喉拟水龟胚胎发育和幼体特征的影响

用3个恒定温度(24、26和28℃)孵化黄喉拟水龟南方种群卵,检测孵化温度对孵化期、孵化成功率和孵出幼体特征的影响。孵化温度显著影响孵化期和孵化成功率、以及幼体的性别、大小和早期生长。黄喉拟水龟幼体的性别取决于孵化温度(属TSDⅠa型),26℃和28℃孵出幼体偏雄性,30℃孵出幼体都是雌性。随着孵化温度的升高,孵化期呈非线性缩短,而孵化成功率略微增加。较高温度下孵出的幼体较大且具有较好的功能表现,但生长较慢。低温孵出幼体较小,但胚后生长速率较快。低温孵出幼体较小可能与胚胎发育期长、总代谢消耗大有关;而生长速率快则可能是因为低温产生的雄性幼体生长快于高温产生的雌性幼体。与已报道的黄喉拟水龟北方种群卵孵化结果相比较,26℃和28℃条件下南方种群卵的孵化期和产生1∶1性比的关键温度较大。这种地理上的变异可能反映不同种群对当地热环境适应性上的差异。     

Fuel use and corticosterone dynamics in hatchling green sea turtles (Chelonia mydas) during natal dispersal

During their natal dispersal hatchling sea turtles depart their nest, beach and inshore areas quickly to move into offshore developmental habitat using their finite energy stores. Patterns of fuel use and endocrine responses that could facilitate hatchling sea turtle dispersal activity are poorly understood. This study, examined aspects of intermediary metabolism by measuring plasma fuel use and an endocrine response of hatchling green turtles (Chelonia mydas) during terrestrial and aquatic activity coinciding with natal dispersal. Specifically, we measured plasma concentrations of glucose, non-esterised free fatty acids and protein to gauge the contributions of carbohydrate, lipid and protein metabolism for fuelling natal dispersal. In addition, we measured plasma levels of the steroid hormone corticosterone (CORT) a hormone implicated in regulating a number of metabolic events associated with migration and energy use in vertebrates. During terrestrial activity, hatchlings ascended through the sand from their nests and exhibited significant increases in plasma CORT and lactate indicating intense periods of anaerobic activity. During swimming, all plasma metabolites, with the exception of plasma protein, peaked between 1 and 4 h post-beginning swimming activity. Plasma CORT peaked at between 3 and 5 h of swimming activity. These plasma concentrations are consistent with intensive activity inducing catabolism of carbohydrate, lipid and protein stores to support prolonged activity. These results are similar to other vertebrates and suggest a relatively uniform cascade of physiological processes during such arduous migratory events.     

Thermoregulation in mixed-species colonies of honeybees (Apis cerana and Apis mellifera)

Apis cerana and Apis mellifera normally display different strategies in cooling hive temperature, raising the question whether they would coordinate their efforts in to achieve stable thermoregulation in mixed colonies. The results show that the normal temperatures in the brood area in mixed colonies are more similar to those of pure A. cerana colonies than pure A. mellifera colonies. Under heat stress, A. cerana workers are more sensitive, and initiate fanning earlier than A. mellifera workers. In mixed colonies, the former become the main force for thermoregulation. When worker bees of both species were fanning together at the entrance, their own species-specific postures were adopted, but due to a significantly smaller number of A. mellifera workers engaged in fanning, the cooling efficiency of mixed colonies were closest to that of pure A. cerana colonies.     

Food consumption does not affect the preferred body temperature of Yarrow's spiny lizard (Sceloporus jarrovi)

When animals consume less food, they must reduce their body temperature to maximize growth. However, high temperatures enhance locomotion and other performances that determine survival and reproduction. Therefore, thermoregulatory behaviors during different metabolic states reveal the relative importance of conserving energy and sustaining performance. Using artificial thermal gradients, we measured preferred body temperatures of male spiny lizards (Sceloporus jarrovi) in fed and fasted states. Both the mean and maximal body temperatures (33° and 35 °C, respectively) were unaffected by metabolic state. This finding suggests that the benefits of foraging effectively, evading predators, and defending territory outweigh the energetic cost of a high body temperature during fasting.     

Phenotypic variation in hatchling Chinese ratsnakes (Zaocys dhumnades) from eggs incubated at constant temperatures

We incubated eggs of the Chinese ratsnake Zaocys dhumnades at four constant temperatures (24, 27, 30 and 30 °C) to examine the effects of incubation temperature on hatching success and hatchling phenotypes. Incubation length increased nonlinearly as temperature decreased, with the mean incubation length being 76.7 d at 24 °C, 57.4 d at 27 °C, 47.3 d at 30 °C, and 44.1 d at 33 °C. Hatching successes were lower at the two extreme temperatures (69% at 24 °C, and 44% at 33 °C) than at the other two moderate temperatures (96% at 27 °C, and 93% at 30 °C). Incubation temperature affected nearly all hatchling traits examined in this study. Incubation of Z. dhumnades eggs at 33 °C resulted in production of smaller hatchlings that characteristically had less-developed carcasses but contained more unutilized yolks. Hatchlings from eggs incubated at 27 and 30 °C did not differ in any examined traits. Taking the rate of embryonic development, hatching success and hatchling phenotypes into account, we conclude that the temperature range optimal for incubation of Z. dhumnades eggs is narrower than the range of 24−33 °C but should be wider than the range of 27−30 °C.     

Effects of water temperature change on immune function in surf clams, Mactra veneriformis (Bivalvia: Mactridae)

Surf clam, Mactra veneriformis is one of the crucial fishery resources in Korea. This study was performed to examine the immune functions of the surf clam under the stress of water temperature changes at 10 °C, 20 °C or 30 °C for 24 h. Viable bacterial counts (VBC), total haemocyte count (THC), phagocytic activity, lysozyme activity, NRR times and SOD activity were assessed in three different water temperature groups. Clams held at 10 °C decreased in THC, lysozyme activity and NRR times, but phagocytic activity was increased. The highest temperature (30 °C) significantly increased in THC, whereas it decreased in phagocytic activity, lysozyme activity and NRR times. In clams maintained at 20 °C, phagocytic activity, lysozyme activity and NRR times were increased whereas THC was somewhat decreased with respect to clams held at 30 °C. However, water temperature changes did not elicit any alteration of VBC and SOD activity. The present study demonstrates that acute water temperature change affects the haemocytic and haemolymphatic functions, reducing immunosurveillance in stressed surf clam, M. veneriformis.     

温度对麦长管蚜体色变化的影响

研究了温度对麦长管蚜体色变化的影响及不同温度下麦长管蚜种群数量变动的规律.结果表明:在21(CK)、23、26、29、31℃5个温度处理下,随着温度的升高,红色型麦长管蚜在实验种群中所占比例逐渐升高;绿色型麦长管蚜的种群增长的高峰先缩短后延长,而红色型麦长管蚜的种群增长的高峰逐渐延长;绿色型蚜虫的平均世代时间呈先缩短再延长的趋势,红色型蚜虫的平均世代时间仅仅呈延长的趋势.结论:麦长管蚜体色变化受温度影响,红色型蚜虫为高温诱导所产生的生物型.当温度为25.91℃时(T50 =25.91℃),麦长管蚜的后代中有50％的个体是红色型蚜虫.该结论为蚜虫生态遗传与进化提供理论依据.     

Influence of acclimation temperature on GDP-mannose: Dolicholphosphate mannosyltransferase of trout liver (Salmo Gairdneri)

Mannosyltransferase activity has been studied in trout liver microsomes prepared from fish adapted during 1 month at three different temperatures: 7, 15 and 21°C; the purpose of the study was to try and answer this question: is the enzyme sensitive to temperature variations and if so, do optimum pH variations reflect an adaptation to temperature changes? The following effects were observed: 1. Optimum pH values do not vary significantly with incubation temperature; only a discrete shift towards more acidic pH has been observed for trouts raised at 21°C. 2. For trouts raised at 7 and 15°C, the enzymic activity increases slightly with incubation temperature while it remains constant for the trouts acclimated at 21°C. This observation could be explained by a lower level of endogenous dolicholphosphate. 3. At any incubation temperature, the higher the acclimation temperature, the lower the enzymic activity.