取而代之并渐为人知的是一种更乏味的观点:斑点产生于反应-扩散的图案形成过程,其中,胚胎细胞分化由化学反应引发,各类化学反应之间又发生作用,其作用模式最后在表皮细胞的发育中表现出来。
But that, too, has its difficulties. Just how much a process like this can be shaped by naturalselection is unclear.
但这一说也有其困难,它在多大程度上收到自然选择的影响,目前尚不清楚。
Reaction-diffusion patterns which can be created in a laboratory using standard reagents aresimple and deterministic.
反应-扩散模式可在实验室用标准试剂产生简洁而又有说服力。
That simple reactions of this sort sometimes result in cryptic patterns could be acoincidence.
这类偶尔引发神奇图案的简单反应纯粹是巧合。
Nevertheless, the details of the patterns produced vary, according to things like how rapidlythe chemicals diffuse.
不过,图案产生的细节各各不同,依据诸如扩散速度等情形而有差别。
That could be selected. Different cats do, indeed, have different patterns.
这就可加以选择。确实,不同的猫科动物有不同图案。
So researchers at the University of Bristol, led by William Allen, have been deconstructingthese patterns, trying to match the elements to cats habits and habitats, and thus showwhether the patterns are evolving.
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