Biology (11th Edition)

Published by McGraw-Hill Education
ISBN 10: 1-25918-813-2
ISBN 13: 978-1-25918-813-8

Chapter 25 - Evolution of Development - Review Questions - Synthesize: 3

Answer

It now seems like a small set (100ish) of genes is responsible for many or most large scale developmental changes, the second view listed in the question. This is easier to see happening/more obviously probable rather than the accumulation of many needed changes in a large number of genes.

Work Step by Step

It takes time, a long time, to accumulate a number of evolutionary changes needed for a particular phenomenon. It is much more likely for this to happen in a relatively small set of control/regulatory genes than in many, many genes needed to explain phenomena.
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