Answer:
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Phylogenetic species concept (PSC) The concept of a species as an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining, or derived, traits (see apomorphy). ... "phylogenetic species concept." A Dictionary of Biology. .
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The biological species concept has its limitations (although it works well for many organisms and has been very influential in the growth ofevolutionary theory). ... In thisexample, Ensatina salamander lineages A and B are separate species.Each has a common ancestor that individuals of other species do not.
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Explanation:
Radioactive dating works on the principle that a radioactive isotope can decay into the stable daughter nuclei at a constant rate. Geologist generally use the principle for half life. Half life is the time required for half of the radioactive substance to decay. This is constant for a particular element.