Lec32_Protostomes_handout - BioG1780 Evolution and...

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BioG1780 Fall 2010 Evolution and Biodiversity Today’s lecturer: Harry Greene Lectures 32: November 15, 2010 1. Animals—bilateral symmetry and the hole that matters. With this and the remaining biodiversity lectures we continue exploring the remarkable adaptive radiation of animals, with today’s emphasis on first, the early diversification of bilaterians into Protostomes and Deuterostomes on the basis of developmental patterns, and second, diversification of the first of two main subgroups in Protostomes. You should thoroughly review Ch. 32 in Sadava et al. 2. What are Protostomes and Deuterostomes? A key distinction between the two basal lineages of living bilaterians involves embryonic development. Recall that cleavage results in a zygote forming successively larger balls of 2, 4, 8, 16, 32 and so forth cells, such that earlyon the embryo is a berry-like cluster (blastula). The process of gastrulation starts when an inverting patch of cells forms a pore (blastopore) and then a tube that eventually opens to the opposite side. During gastrulation cells that
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This note was uploaded on 12/29/2010 for the course BIOEE 1780 at Cornell University (Engineering School).

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Lec32_Protostomes_handout - BioG1780 Evolution and...

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