Complex sentence: This time is not evolutionarily significant because individuals that were at one point capable of reproducing have most likely already done so, and their ability to survive beyond this point, therefore, has no effect on the gene pool of the next generation.
Split into simpler sentences: This time is not evolutionarily significant because individuals that were at one point capable of reproducing have most likely already done so. These individuals abilities to survive beyond this point, therefore, have no effect on the gene pool of the next generation.