Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades, or even millions of years after a mass extinction
The best answer would be "research reasons why species change over long periods of time"
if not i apologize but this is my best guess<span />
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<h3>1. Hepatitis B </h3><h3>2. Levels of circulating antibodies against a certain antigen.</h3>
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Explanation:</h2>
<h3>Hope its help</h3>
