When studying the genetic diversity of a bird species on an island compared to that on the mainland, what best describes the relationship between the two populations of birds on the mainland and the island? a) the mainland population will have increased genetic diversity due to a reduction in competition from the birds that flew to the island. b) the island population will have reduced genetic variability due to a smaller gene pool present in the founding members of the island population. c) the island population will have increased genetic variability since the birds have access to increased food supplies that are not present on the mainland. d) the mainland population will have decreased genetic diversity because the founding members of the island population were those with the greatest evolutionary fitness.