Under Most Models for the Preservation of Duplicated Genes That

question 1

Multiple Choice

Under most models for the preservation of duplicated genes that eventually perform new functions,what is the proposed order of events and evolutionary reasoning behind them?

• A) After a gene is duplicated, it must rise to high frequency in a population due to drift; only after it has risen to high frequency will it then be likely to evolve to perform a new function favored by natural selection.
• B) After a gene is duplicated, one of the copies must evolve to perform a new function that increases an organism's fitness; only after the new function evolves will the duplicated gene rise in frequency within the population due to natural selection.
• C) After a gene is duplicated, it will typically be favored by natural selection even before it evolves to perform a new function, because having duplicate gene copies provides beneficial redundancy within genomes. Therefore, duplicate copies rise to high frequency in a population due to natural selection, and later a new function can evolve that is also favored by natural selection.
• D) Duplicated genes usually differ in function immediately after duplication, because gene duplication is an imperfect process and mutations are typically introduced during duplication. If the duplicate copy happens to perform a new function that benefits an organism, it rises in frequency in the population due to natural selection.

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