绒毡层的演化
Evolution of the tapetum.
作者信息
Schwab Ivan R, Yuen Carlton K, Buyukmihci Nedim C, Blankenship Thomas N, Fitzgerald Paul G
机构信息
Department of Ophthalmology, University of California, Davis, Medical Center, USA.
出版信息
Trans Am Ophthalmol Soc. 2002;100:187-99; discussion 199-200.
PURPOSE
To review, contrast, and compare current known tapetal mechanisms and review the implications for the evolution of the tapetum.
METHODS
Ocular specimens of representative fish in key piscine families, including Acipenseridae, Cyprinidae, Chacidae; the reptilian family Crocodylidae; the mammalian family Felidae; and the Lepidopteran family Sphingidae were reviewed and compared histologically. All known varieties of tapeta were examined and classified and compared to the known cladogram representing the evolution of each specific family.
RESULTS
Types of tapeta include tapetum cellulosum, tapetum fibrosum, retinal tapetum, invertebrate pigmented tapetum, and invertebrate thin-film tapetum. All but the invertebrate pigmented tapetum were examined histologically. Review of the evolutionary cladogram and comparison with known tapeta suggest that the tapetum evolved in the Devonian period 345 to 395 million years ago. Tapeta developed independently in at least three separate orders in invertebrates and vertebrates, and yet all have surprisingly similar mechanisms of light reflection, including thin-film interference, diffusely reflecting tapeta, Mie scattering, Rayleigh scattering, and perhaps orthogonal retroreflection.
CONCLUSION
Tapeta are found in invertebrates and vertebrates and display different physical mechanisms of reflection. Each tapetum reflects the wavelengths most relevant to the species' ecological niche. With this work, we have hypothesized that the tapetum evolved independently in both invertebrates and vertebrates as early as the Devonian period and coincided with an explosion of life forms.
目的
回顾、对比和比较当前已知的绒毡层机制，并探讨绒毡层进化的意义。
方法
对关键鱼类家族（包括鲟科、鲤科、蟾鱼科）、爬行类家族鳄科、哺乳类家族猫科以及鳞翅目家族天蛾科中有代表性鱼类的眼部标本进行组织学检查和比较。对所有已知类型的反光层进行检查、分类，并与代表每个特定家族进化的已知系统发育树进行比较。
结果
反光层类型包括纤维性反光层、细胞性反光层、视网膜反光层、无脊椎动物色素性反光层和无脊椎动物薄膜反光层。除无脊椎动物色素性反光层外，对其他所有反光层都进行了组织学检查。对进化系统发育树的回顾以及与已知反光层的比较表明，反光层在3.45亿至3.95亿年前的泥盆纪时期进化而来。反光层在无脊椎动物和脊椎动物中至少在三个不同的目里独立进化，然而它们都具有惊人相似的光反射机制，包括薄膜干涉、漫反射反光层、米氏散射、瑞利散射，或许还有正交后向反射。
结论
无脊椎动物和脊椎动物中都存在反光层，且表现出不同的物理反射机制。每个反光层反射与该物种生态位最相关的波长。通过这项研究，我们推测反光层早在泥盆纪时期就在无脊椎动物和脊椎动物中独立进化，并且与生命形式的爆发同时发生。
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