C- Structurally complex organisms are necessarily derived from structurally simpler ancestors.
D- Evolution can only modify or build on what already exists
A trend in animal evolution has been towards increasing structural complexity. Evolution is a process that does not works from the scratch. This means that takes on account some basic characters that are already present and builds upon them. So it can either form something new from the present source or can build a complex structural unit as well. This is the case of animal evolution over the years. If we see the evolutionary history, single celled organisms ( prokaryotes ) have much simpler machinery and as the time passed by, they have build upon something which become complex step by step. From single celled animals, the complexity doesnot arise suddenly , instead it slowly moved along increasing minimum characteristics as we move along the evolutionary course of animal life from unicellular to multicellular, from development of first nervous net to whole nervous system. So structurally complex organisms could necessarily derived from simpler ancestors.
Natural selection does not specifically favours complexity rather chooses the individual on the basis of the fitness according to the environment. If there would have been a evolutionary drive towards greater complexity , than presence of such simple bacteria alongside humans would not have been possible.
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Question: A very general trend in animal evolution has been toward increasing structural complexity. What are...
Question: A very general trend in animal evolution has been toward increasing structural complexity. What are two reasons behind this? Select the two that apply. Options: A. There is an evolutionary 'drive' toward greater structural complexity. B. Natural selection tends to favor more structurally complex organisms over less structurally complex ones. C. Structurally complex organisms are necessarily derived from structurally simpler ancestors. D. Evolution can only modify or build on what already exists.
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