CALIBRATION OF TEST DIAMETER AND AREA AS PROXIES FOR BODY SIZE IN THE PLANKTONIC FORAMINIFER GLOBOCONELLA PUNCTICULATA
CALIBRATION OF TEST DIAMETER AND AREA AS PROXIES FOR BODY SIZE IN THE PLANKTONIC FORAMINIFER GLOBOCONELLA PUNCTICULATA
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DOI：
10.2113/gsjfr.48.3.241
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发表时间：
2018-07-01
影响因子：
1.1
通讯作者：
Ezard, Thomas H. G.
中科院分区：
文献类型：
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作者：
Brombacher, Anieke;Elder, Leanne E.;Ezard, Thomas H. G.
身体大小是生态学和进化中最常测量的特征之一，因为它与环境（例如，温度、纬度、种群隔离程度）和生活史（例如，代谢率、世代时间）性状。然而，在遥远的地质过去的身体大小变化的驱动机制知之甚少，复杂的部分标本恢复，有限的人口水平的采样，并使用线性测量作为代理的三维体积大小的数据。我们使用近似的身体尺寸度量标准遗漏了多少信息？在这里，我们研究这个问题在一个不断发展的谱系的南极有孔虫。我们测量测试直径和表面积超过500个个体的物种Globoconella puncticulata使用二维图像。这些结果进行了比较与测量的测试体积的相同的个人作为测量的一个最近开发的高通量的方法，用于分析三维形态度量以及高分辨率的三维计算机断层扫描。我们的研究结果表明，即使在一个谱系显示大量的形态变化，横截面测试面积可以提供一个一致的代理身体体积。用一维（线性）尺寸测量来近似身体体积更有问题，因为它分别系统地高估和低估了最小和最大的测试。在我们的研究中，形状（这里测量为壳的长宽比）在回归中仅解释了略微更多的变化。3D光学显微镜的使用在数据中引入了小程度的分散，但是以足够的统计功效检测身体大小趋势所需的个体数量与其他性状所需的样本量相当。这些结果意味着，即使在一个不断发展的谱系经历了实质性的形态变化，横截面积可以提供一个一致的代理身体大小。
Body size is one of the most commonly measured traits in ecology and evolution because it covaries with environmental (e.g., temperature, latitude, degree of population isolation) and life-history (e.g., metabolic rate, generation time) traits. However, the driving mechanisms of body size variation in the distant geological past are poorly known and complicated by partial specimen recovery, limited population-level sampling, and the use of linear measurements as proxies for three-dimensional volumetric-size data. How much information are we missing by using approximate metrics of body size? Here we examine this question in an evolving lineage of planktonic foraminifera. We measure test diameter and surface area of over 500 individuals of the species Globoconella puncticulata using two-dimensional images. These results are compared with measurements of test volume of the same individuals as measured by a recently developed high-throughput method for analysing three-dimensional morpho-metrics as well as high-resolution three-dimensional computed tomography scanning. Our results show that even in a lineage showing substantial morphological change, a cross-sectional test area can provide a consistent proxy for body volume. Approximating body volume with one-dimensional (linear) size measurements is more problematic as it systematically over and underestimates the smallest and largest tests, respectively. In our study, shape (here measured as shell-aspect ratio) only explained marginally more variation when included in the regressions. The use of 3D light microscopy introduces a small degree of scatter in the data, but the number of individuals necessary to detect trends in body size with sufficient statistical power is comparable to the sample size required for other traits. These results imply that even in an evolving lineage undergoing substantial morphological change, cross-sectional area can provide a consistent proxy for body size.