带状动物特征的非随机衰变导致化石解释中的偏见
Robert S Sansom1, Sarah E Gabbott, Mark A Purnell
1Department of Geology, University of Leicester, Leicester LE1 7RH, UK.
Nature
|February 2, 2010
概括
由于非随机的衰变,早期的带动物化石很难解释. 遗传学上有信息的特征首先丢失,对早期脊椎动物进化的解释产生偏见.
科学领域:
- 古生物学的古生物学
- 进化生物学 进化生物学
- 这是一种塔法诺米 (taphonomy).
背景情况:
- 软体的坎布里亚带动物的特殊保存提供了关于脊椎动物起源的见解.
- 解释这些早期的化石是具有挑战性的,因为分音学过程和缺乏衰变数据.
- 区分真正的缺失的特征从衰变诱导的损失是关键的族系学准确性.
研究的目的:
- 为了研究在状动物化石的分解过程中特征损失的非随机性质.
- 为了了解语音学过程如何对早期带状动物和脊椎动物进化产生偏见的解释.
- 评估衰变对坎布里亚化石的遗传学位置的影响.
主要方法:
- 两虫和弹虫 (早期的带动物) 的实验性衰变.
- 在分解过程中分析特性可变性和保存潜力.
- 腐烂数据的应用,以解释有问题的坎布里亚化石,如Cathaymyrus和Metaspriggina.
主要成果:
- 在衰变过程中,状动物的特征丧失是非随机的;在遗传学上,信息性特征是最不稳定的.
- plesiomorphic (祖先) 字符表现出更高的抗衰变能力.
- 这种差异性衰变会产生偏差,可能会将化石错误地放置在带血统的茎上.
结论:
- 被称为"向茎滑动"的taphonomic偏差挑战了早期状动物化石的可靠的原始遗传定位.
- 抗衰变的plesiomorphies和衰变的labile synapomorphies可以导致对早期动物进化的误解.
- 这种衰变过器可能是一个广泛的,未被识别的因素,影响了对早期类型进化的理解.
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