虎纹蛙选择体温和热耐受性在个体发育过程中的变化

体温是影响变温动物表现的最重要生理学变量。检测了国家二级保护动物虎纹蛙的雌性亚成体、雄性亚成体、幼体和蝌蚪这4个发育阶段的选择体温和热耐受性。单因子方差分析表明,虎纹蛙选择体温、耐受低温、耐受高温和温度耐受范围的组间差异均显著,幼体的选择体温(24.13℃)显著低于雌性亚成体(28.06℃)、雄性亚成体(29.27℃)和蝌蚪(28.23℃),雌性亚成体、雄性亚成体和蝌蚪之间差异不显著;幼体的耐受低温(13.85℃)显著高于雌性亚成体(11.27℃)、雄性亚成体(10.84℃)和蝌蚪(10.74℃),雌性亚成体、雄性亚成体和蝌蚪之间差异不显著;幼体具有显著低的耐受高温(35.48℃)、蝌蚪具有显著高的耐受高温(43.31℃),雌性亚成体(39.55℃)和雄性亚成体(39.02℃)的耐受高温差异不显著;幼体(21.62℃)具有显著小的温度耐受范围、蝌蚪(32.58℃)具有显著大的温度耐受范围,雌性亚成体(28.28℃)和雄性亚成体(28.18℃)的温度耐受范围差异不显著。虎纹蛙幼体和亚成体体温和水温之间在降温速度和升温速度的相关关系均显著。用回归剩余值去除水温变化速度对体温变化的影响,双因子方差分析(降温和升温速度为重复检验设置)表明,幼体的体温变化速度显著大于亚成体,两性亚成体间差异不显著;温度变化类型(降温和升温)和两因子的交互作用对体温变化的影响不显著。基本热生态位分离和体温调节能力的发育限制是形成上述现象的最可能的原因。

Ontogenetic shifts in selected body temperature and thermal tolerance of the tiger frog, Hoplobatrachus chinensis

Body temperature is the most important physiological variable affecting the performance of ectothermic animals.In June and October of 2011,we collected female and male subadults(gonads have not yet matured),juveniles(tails have just been completely absorbed),and tadpoles(stages 28—38) of the tiger frog Hoplobatrachus chinensis,which is a national secondary grade protection animal,from the herpetological laboratory of Lishui University,Zhejiang,East China.The objectives of this study were to examine ontogenetic shifts in the selected body temperature(Tsel),critical thermal maximum(CTmax),and critical thermal minimum(CTmin) of the tiger frog.Tsel of tadpoles was measured by recording the water temperature of their selected location in a thermal gradient ranging from 10—42℃,while Tsel of juveniles and subadults was measured by recording cloacal temperature in a thermal gradient ranging from 20—45℃.We cooled(for CTmin determination) or heated(for CTmax determination) experimental animals from 25℃.Body temperatures associated with a transient loss of the righting response at lower and upper limits of thermal tolerance were considered to be the endpoints for CTmin and CTmax,respectively.Statistical analysis by ANOVA showed that there were significant differences in Tsel,CTmin,CTmax,and viable temperature range among the three age groups.The Tsel of juveniles(24.10℃) was significantly lower than that of female subadults(28.06℃),male subadults(29.17℃),and tadpoles(28.23℃),while there was no significant difference in Tsel among the latter three groups.The CTmin of juveniles(13.85℃) was significantly higher than that of female subadults(11.27℃),male subadults(10.84℃),and tadpoles(10.74℃),while there was no significant difference in CTmin among the latter three.Tadpoles had the highest CTmax,which was 43.31℃,followed by subadults(female: 39.55℃;male: 39.02℃) and juveniles in decreasing order.Similarly,tadpoles had the widest viable temperature range(32.58℃),followed by subadults(female: 28.28℃;male: 28.18℃),and juveniles(21.62℃) in decreasing order.There were no significant differences in Tsel,CTmin,CTmax,and viable temperature range between female and male subadults.Body temperature of juveniles and subadults of H.chinensis was significantly correlated with water temperature in both decreasing and increasing rates.After removing the effects of water temperature,changes in rates of body temperature variation were removed by using residuals from the regression.Two-way ANOVA(cooling and heating rate were measured repeatedly) indicated that the rates of change in the body temperature of juveniles were significantly greater than rates of change of subadults.Types of thermal changes(i.e.rates of cooling and heating) and the interaction of these factors had no effect on changes in the body temperature of H.chinensis.In conclusion,we suggest that in the tiger frog H.chinensis,fundamental thermal niche separation and development restrictions are the most probable explanations for our findings.