How does the number of generations per year influence the likelihood of seeing a response to natural selection once a new host plant has been colonized?

As the generations are increasing or gets much over time, we have a more likelihood of seeing a response to natural selections as the favourable alleles are going to be moved from one generation to the next while those that are not favourable would be eliminated over generations.

If the new host gives allowance for early reproduction and ease of access then the generations each year would rise.

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