EVOLUTION AND DEVELOPMENT II

EVOLUTION AND DEVELOPMENT II - Consider the comparison...

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EVOLUTION AND DEVELOPMENT II: GENES AND MORPHOLOGY Documenting allometry and patterns of size and shape changes in evolution are helpful as descriptive approaches to the evolution of development. But these phenomena are themselves the result of developmental mechanisms at the molecular and cellular level. We can often say without reservation that there has been a change in development during evolution, but how that change in development was achieved is yet another question. We improve the description somewhat by saying that changes in development result from changes in the: 1) spatial organization of cells, 2) timing of gene action and tissue differentiation and 3) geometry of tissues and organs. But how are these changes mediated?
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Unformatted text preview: Consider the comparison between humans and chimps: the adult morphology is obviously distinct, but at the genetic level we are extremely close to chimps: > 99% similar at the genetic level . This is less genetic divergence that seen between sibling species (can't tell them apart) of Drosophila and some mammals These observations indicate that morphological evolution has proceeded faster than molecular evolution suggesting that regulatory evolution has proceeded faster than DNA sequence evolution. Where are the important mutations (short arrows)? in the coding sequences of genes or in the regulatory sequences upstream from them? May depend on how the product of a gene interacts with other genes (longer arrows)....
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