Telemeco Rory S, Warner Daniel A, Reida Molly K, Janzen Fredric J
Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, Iowa 50011 , USA.
Integr Zool. 2013 Jun;8(2):197-208. doi: 10.1111/1749-4877.12019.
Increases in extreme environmental events are predicted to be major results of ongoing global climate change and may impact the persistence of species. We examined the effects of heat and cold waves during embryonic development of painted turtles (Chrysemys picta) in natural nests on the occurrence of abnormal shell morphologies in hatchlings. We found that nests exposed to extreme hot temperatures for >60 h produced more hatchlings with abnormalities than nests exposed to extreme hot temperatures for shorter periods, regardless of whether or not nesting females displayed abnormal morphologies. We observed no effect of extreme cold nest temperatures on the occurrence of hatchlings with abnormalities. Moreover, the frequency of nesting females with abnormal shell morphologies was approximately 2-fold lower than that of their offspring, suggesting that such abnormalities are negatively correlated with survival and fitness. Female turtles could potentially buffer their offspring from extreme heat by altering aspects of nesting behavior, such as choosing shadier nesting sites. We addressed this hypothesis by examining the effects of shade cover on extreme nest temperatures and the occurrence of hatchling abnormalities. While shade cover was negatively correlated with the occurrence of extreme hot nest temperatures, it was not significantly correlated with abnormalities. Therefore, female choice of shade cover does not appear to be a viable target for selection to reduce hatchling abnormalities. Our results suggest that increases in the frequency and intensity of heat waves associated with climate change might perturb developmental programs and thereby reduce the fitness of entire cohorts of turtles.
预计极端环境事件的增加是当前全球气候变化的主要结果，可能会影响物种的存续。我们研究了自然巢穴中华锦龟（Chrysemys picta）胚胎发育期间热浪和寒潮对幼龟异常壳形态发生的影响。我们发现，暴露于极端高温超过60小时的巢穴比暴露于极端高温较短时间的巢穴产生更多有异常的幼龟，无论筑巢雌龟是否表现出异常形态。我们观察到极端寒冷的巢穴温度对有异常的幼龟的出现没有影响。此外，壳形态异常的筑巢雌龟的频率比其后代低约2倍，这表明此类异常与生存和适应性呈负相关。雌龟可能通过改变筑巢行为的某些方面，如选择更阴凉的筑巢地点，来保护其后代免受极端高温影响。我们通过研究遮荫对极端巢穴温度和幼龟异常发生的影响来验证这一假设。虽然遮荫与极端高温巢穴温度的发生呈负相关，但与异常情况没有显著相关性。因此，雌龟对遮荫的选择似乎不是减少幼龟异常的可行选择目标。我们的结果表明，与气候变化相关的热浪频率和强度增加可能会扰乱发育程序，从而降低整个龟群的适应性。
