Direct and indirect effects of biological factors on extinction risk in fossil bivalves
Direct and indirect effects of biological factors on extinction risk in fossil bivalves
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DOI：
10.1073/pnas.1100572108
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发表时间：
2011-08-16
影响因子：
11.1
通讯作者：
Harnik, Paul G.
中科院分区：
文献类型：
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作者：
Harnik, Paul G.
生物因素，如丰度和身体大小，可能直接导致灭绝风险，并通过其对其他生物特征，如地理范围大小的影响间接。古生物学数据可以用来明确地测试这些假设的关系中的许多，通过分析化石记录揭示的一般模式可以帮助完善现存物种灭绝风险的预测模型。在这里，我使用结构方程模型梳理除了三个典型的预测的贡献，丰度，身体大小，地理范围大小的双壳类物种的持续时间在美国东部的新生代早期海洋化石记录。我发现，地理范围的大小有很强的直接影响灭绝的风险和丰富的明显的直接影响可以完全解释其与地理范围的协变。地理范围对灭绝风险的影响在三个生态上不同的双壳类分支中表现出来。身体大小对灭绝风险也有很强的直接影响，但在不同的分支中以相反的方向运作，因此，它似乎与整个双壳类的灭绝风险脱钩。虽然丰度并不直接预测灭绝的风险，我揭示了弱间接影响的丰度和身体大小，通过它们的积极影响的地理范围大小。解释生物因素和灭绝之间普遍存在的协变的多变量模型对于评估进化过程中的因果关系和在应用保护工作中做出明智的预测是必要的。
Biological factors, such as abundance and body size, may contribute directly to extinction risk and indirectly through their influence on other biological characteristics, such as geographic range size. Paleontological data can be used to explicitly test many of these hypothesized relationships, and general patterns revealed through analysis of the fossil record can help refine predictive models of extinction risk developed for extant species. Here, I use structural equation modeling to tease apart the contributions of three canonical predictors of extinction-abundance, body size, and geographic range size-to the duration of bivalve species in the early Cenozoic marine fossil record of the eastern United States. I find that geographic range size has a strong direct effect on extinction risk and that an apparent direct effect of abundance can be explained entirely by its covariation with geographic range. The influence of geographic range on extinction risk is manifest across three ecologically disparate bivalve clades. Body size also has strong direct effects on extinction risk but operates in opposing directions in different clades, and thus, it seems to be decoupled from extinction risk in bivalves as a whole. Although abundance does not directly predict extinction risk, I reveal weak indirect effects of both abundance and body size through their positive influence on geographic range size. Multivariate models that account for the pervasive covariation between biological factors and extinction are necessary for assessing causality in evolutionary processes and making informed predictions in applied conservation efforts.