What's in a whisker? Disentangling ecological and physiological isotopic signals.
What's in a whisker? Disentangling ecological and physiological isotopic signals.
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胡须里有什么？
DOI：
10.1002/rcm.8312
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Costa,DanielP
中科院分区：
文献类型：
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作者：
McHuron,ElizabethA;Holser,RachelR;Costa,DanielP
角化组织的稳定同位素分析是量化觅食生态学的信息工具，可以解决与生态位专业化和行为的时间变化有关的问题。这种方法的应用依赖于对组织生长的理解，以及同位素比率与生理和生态过程的关系，许多物种缺乏这些数据。方法收集16只海象的成对须长数据，分析其生长和脱落规律。一组海豹（n= 5）携带卫星标签和时间深度记录仪，在每年的毛皮蜕皮后进行了7个多月的觅食之旅。在陆地上禁食6周以上和随后的觅食旅行中，对生长的须段进行了碳和氮的稳定同位素测量；将剖面与生长参数相结合，对每个片段进行时间戳，并研究与觅食行为的关系。结果毛须的丢失和新生主要发生在每年的被毛蜕皮过程中，而新生的毛须则在整个觅食过程中表现出活跃的非线性生长。δ 13c和δ 15n值在陆地生长段高于海洋生长段，并在离开栖息地后呈下降趋势。纬度、经度与δ 15n值之间存在一定的关系，对海上生长的个别须段进行正确的分类，准确率达81%。结论：温度对δ 13c和δ 15n值都有影响，考虑到与组织生长的时间重叠，从生态调查中排除这些值的能力至关重要。同位素比值在分离时的快速下降可以用来分离具有强烈生理信号的晶须部分，即使对于生长历史未知的晶须也是如此。在觅食过程中的主动生长与识别觅食行为差异的能力相结合，验证了这种方法在解决生态问题方面的实用性。
RationaleStable isotope analysis of keratinized tissues is an informative tool for quantifying foraging ecology that can address questions related to niche specialization and temporal variation in behavior. Application of this approach relies on an understanding of tissue growth and how isotope ratios relate to physiological and ecological processes, data that are lacking for many species.MethodsWe collected paired whisker length measurements from northern elephant seals to estimate growth and shedding patterns (n= 16). A subset of seals (n= 5) carried a satellite tag and time–depth recorder across the 7+ month foraging trip following the annual pelage molt. Stable isotopes of carbon and nitrogen were measured in whisker segments grown across the 6+ week fasting on land and the subsequent foraging trip; profiles were combined with growth parameters to timestamp each segment and investigate relationships with foraging behavior.ResultsWhisker loss and initial regrowth primarily occurred during the annual pelage molt, but newly grown whiskers exhibited active, nonlinear growth across the foraging trip. Theδ13C andδ15N values were higher in segments grown on land than at sea and exhibited a characteristic decline upon departure from the rookery. There was a relationship between latitude and longitude andδ15N values, and individual whisker segments grown at sea could be classified to the correct ecoregion with 81% accuracy.ConclusionsFasting affected bothδ13C andδ15N values and the ability to exclude these values from ecological investigations is crucial given the temporal overlap with tissue growth. The rapid decline in isotope ratios upon departure can be used to isolate portions of the whisker with a strong physiological signal, even for whiskers with unknown growth histories. The active growth across the foraging trip combined with the ability to identify differences in foraging behavior validates the utility of this approach for addressing ecological questions.