Do temperature fluctuations during incubation always play an important role in shaping the phenotype of hatchling reptiles
Do temperature fluctuations during incubation always play an important role in shaping the phenotype of hatchling reptiles
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DOI：
10.1016/j.jtherbio.2007.12.003
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发表时间：
2008-04
影响因子：
2.7
通讯作者：
Longhui Lin;Hong Li;H. An;X. Ji
中科院分区：
文献类型：
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作者：
Longhui Lin;Hong Li;H. An;X. Ji
在一些爬行动物中，波动温度(FT)对幼体表型的影响不同于恒温(CT)，但在其他爬行动物中则不同。这种不一致提出了一个问题，即孵化过程中的温度波动是否总是在塑造孵化幼体的表型方面发挥重要作用。为了回答这个问题，我们在一个CT(28°C，CT)、两个温度变化(先冷(CF)和先热(HF)，其中卵首先在24或32°C下孵化，然后在另一个温度下孵化20天，最后在28°C下孵化直到孵化)和一个FT温度条件下孵化眼镜蛇的卵。雌性孵化出的卵比同大小的卵孵化出的雄性幼体口鼻长，尾长小，头部大，腹侧鳞片较多。FT和HF处理的孵化时间较短。尾长以CT处理最大，FT处理最小，CF和HF处理介于两者之间；头宽CT处理大于其他三个处理。其他被检测的孵化性状在不同处理之间没有差异。观察到的形态变化不能归因于温度波动的影响，而是接近物种生存上限和下限的温度的影响。因此，我们的结果支持这样的假设，即在某些阈值范围内，孵化温度没有表型反应的物种的孵化表型不受温度波动的影响。
Fluctuating temperatures (FTs) influence hatchling phenotypes differently from constant temperatures (CTs) in some reptiles, but not in others. This inconsistency raises a question of whether thermal fluctuations during incubation always play an important role in shaping the phenotype of hatchlings. To answer this question, we incubated eggs of Naja atra under one CT (28°C, CT), two temperature-shift [cold first (CF) and hot first (HF) in which eggs were first incubated at 24 or 32°C and then at the other, each for 20 days, and finally at 28°C until hatching], and one FT thermal regimes. Female hatchlings were larger in snout–vent length but smaller in tail length, head size than male hatchlings from the same-sized egg; female hatchlings had more ventral scales than did male hatchlings. The FT and HF treatments resulted in shorter incubation lengths. Tail length was greatest in the CT treatment and smallest in the FT treatment, with the CF and HF treatments in between; head width was greater in the CT treatment than in the other three treatments. Other examined hatchling traits did not differ among treatments. The observed morphological modifications cannot be attributed to the effect of thermal fluctuations but to the effect of temperatures close to the upper and lower viable limits for the species. Our results therefore support the hypothesis that hatchling phenotype is not altered by thermal fluctuation in species with no phenotypic response to incubation temperature within some thresholds.