Lets consider - determined by careful 1 observation 2...

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Lets consider plants and insects : there is little evidence to determine whether plants' secondary compounds arose for the purpose of preventing herbivores from eating plant tissue. Certain plants may have produced certain compounds as waste products and herbivores attacked those plants that they could digest. Parasites and hosts : when a parasite invades a host, it will successfully invade those hosts whose defense traits it can circumvent because of the abilities it caries at that time . Thus presence of a parasite on a host does not constitute evidence for coevolution. These criticisms are quite distinct from the opportunity for coevolution once a parasite has established itself on a host. The main point is that any old interaction, symbiosis, mutualism, etc. is not synonymous with coevolution. In one sense there has definitely been "evolution together" but whether this fits our strict definition of coevolution needs to be
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Unformatted text preview: determined by careful 1) observation , 2) experimentation and 3) phylogenetic analysis . The classic analogy is the coevolutionary arms race : a plant has chemical defenses, an insect evolves the biochemistry to detoxify these compounds, the plant in turn evolves new defenses that the insect in turn "needs" to further detoxify. At present the evidence for these types of reciprocal adaptations is limited, but the suggestive evidence of plant animal interactions is widespread. An important point is the relative timing of the evolution of the various traits that appear to be part of the coevolution. If the presumed reciprocally induced, sequential traits actually evolved in the plant (host) before the insect (parasite) became associated with it, we should not call it coevolution....
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