[Campbell Biology P.593] Which statement best defines heterochrony and provides a correct ex... | Practice Question
Which statement best defines heterochrony and provides a correct example of its evolutionary effect?
A: Heterochrony is an evolutionary change in the *number* of developmental genes, leading to new body forms, such as the increased number of fingers in bats.
B: Heterochrony is an evolutionary change in the *rate or timing* of developmental events, exemplified by the increased growth rate of finger bones in bats leading to wings.
C: Heterochrony is the process by which sexually mature organisms retain *adult* body features of their ancestral species due to accelerated reproductive development.
D: Heterochrony is a sudden, large-scale genetic mutation causing immediate changes in body plan, such as the development of human upright posture.
Explanation
The text explicitly defines heterochrony as 'an evolutionary change in the rate or timing of developmental events.' It then provides the example: 'increased growth rates of finger bones yielded the skeletal structure of wings in bats.'