Scientists studying a group of related bird species on an island archipelago discover that these species are always more closely related to each other within an island than they are between any two islands.The most likely explanation for this result is that
A)each bird species evolved different adaptations in allopatry and then colonized the other islands.
B)one bird species colonized each island and then evolved into distinct species on that island through character displacement.
C)each bird species became reproductively isolated by living on a different island,then later colonized the other islands and acquired new adaptations.
D)many ancestral bird species colonized each island.

Question

Quizplus · Accepted Answer

The pattern suggests that one original species colonized each island and then evolved into distinct species on that island through character displacement. This would lead to the relatedness between species being highest within an island and decreasing as you compare species between islands. Option A suggests that each species evolved independently on each island, which would not explain the consistent pattern observed. Option C suggests that each species became reproductively isolated on different islands, but this does not explain why they are more closely related within an island. Option D suggests that many ancestral species colonized each island, which may be a possibility, but the pattern observed suggests a single colonizing species.

Scientists Studying a Group of Related Bird Species on an Island