Some trees are very long-lived, such as the Great Basin Bristlecone Pine and the Giant Sequoia (up to 4,800 years old).

How does natural selection and evolution affect such long-lived organisms? Their DNA has remained unchanged for thousands of years. Mutation can't hope to change the DNA of the entire tree.

I don't understand how they can hope to be able to adapt to a changing environment. And yet the Sequoioideae subfamily has existed since at least the Jurassic, so they must have a winning strategy for survival.

Please help me understand how a species such as this can adapt. And what natural pressure would select for such longevity?

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    $\begingroup$ For some clarification, evolution isn't observed within individuals; it's observed in populations, and over multiple generations. $\endgroup$
    – Harris
    Jan 6, 2021 at 5:13
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    $\begingroup$ @Harris has correctly noted that evolutionary time is better measured in generations, rather than absolute years. You also have mentioned the Jurassic period - that is 200 million years ago - this is still hundreds of thousands of times longer that the lifetime of Sequoia given in your question (could you provdie a reference for this number?) $\endgroup$
    – Roger V.
    Jan 6, 2021 at 9:47
  • $\begingroup$ @Harris I am not quite sure what you mean by 'evolution isn't observed within individuals; it's observed within populations' - could you clarify that? $\endgroup$
    – user438383
    Jan 6, 2021 at 10:54
  • $\begingroup$ @user438383 The question seems to frame this as individual trees' DNA changing to adapt, which is not a typical context to consider evolution in. $\endgroup$
    – Harris
    Jan 6, 2021 at 18:01
  • $\begingroup$ Consider that a long-lived individual can produce offspring - in this case, seeds - over many years. In the case of the Giant Sequoia, seed production can begin as early as 10 years, and is heavy from about 150 years, which means about 2000 years or more of producing genetically diverse seeds, of which only a few individuals will survive. srs.fs.usda.gov/pubs/misc/ag_654/volume_1/sequoiadendron/… $\endgroup$
    – jamesqf
    Jan 6, 2021 at 18:02