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平鱼不对称性的进化起源
1Committee on Evolutionary Biology, University of Chicago, 1025 East 57th Street, Chicago, Illinois 60637, USA. mattf@uchicago.edu
Nature
|July 11, 2008
概括
化石鱼的发现揭示了平鱼不对称性的逐渐演变. 原始的平鱼祖先,Amphistium和Heteronectes,显示眼睛的中间迁移,支持渐进的进化变化.
科学领域:
- 古生物学的古生物学
- 进化生物学 进化生物学
- 鱼类学 鱼类学 鱼类学
背景情况:
- 平鱼 (Pleuronectiformes) 表现出极端的头骨不对称性,两只眼睛都在一边,这是脊椎动物中独特的特征.
- 这种不对称性通过幼虫阶段的眼睛迁移而发展,但由于缺乏过渡性化石,进化途径仍然不清楚.
- 之前的辩论质疑了自然选择在平鱼进化中的作用,暗示了性 (突然) 变化.
研究的目的:
- 为了研究平鱼头骨不对称的进化起源.
- 为了识别和描述已知的最原始的状鱼类.
- 为平鱼眼睛迁移和骨不对称的渐进性提供证据.
主要方法:
- 考古学分析了来自欧世时代的化石刺鱼.
- 在已灭绝和现存的平鱼中对头骨形态的比较解剖学研究.
- 在化石标本中检查轨道区域和眼睛的位置.
主要成果:
- 发现和描述Amphistium和Heteronectes,这是已知的最原始的状状体.
- 这些化石种群表现出强烈的头骨不对称性,类似于现代的平鱼.
- 关键的是,在Amphistium和Heteronectes中,轨道迁移是不完整的,在变形后的眼睛在相反的侧面,代表了一个中间阶段.
结论:
- 安菲斯和异构体为平鱼进化提供了关键的过渡证据.
- 平鱼的深层头骨不对称性是逐渐进化的,而不是通过变化.
- 这些发现解决了长期以来关于状状不对称性演变的争论.
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