Human activities are causing the fragmentation of the Brazilian Atlantic rain forest. One result is that toucans have become extinct or nearly extinct in some of the forest fragments. Does the absence of toucans affect the forest? Toucans disperse seeds of key forest species such as juçara palms by eating the fruit and defecating the seeds in new locations, sometimes more than a kilometer away. If there are no toucans, is the genetic diversity of palms likely to increase or decrease within forest fragments? Why? a. increase (due to increased genetic drift) b. decrease (due to decreased gene flow) c. decrease (due to decreased mutation rate) d. decrease (due to decreased natural selection)

Verified step by step guidance

1. Understand the role of toucans in the ecosystem: Toucans help in dispersing seeds of key forest species like juçara palms by eating the fruit and defecating the seeds in new locations. This process is crucial for maintaining genetic diversity across the forest.
2. Analyze the impact of toucans' absence: With no toucans to disperse the seeds, the seeds of juçara palms are likely to be less widely distributed, leading to more localized growth of these plants.
3. Consider the concept of gene flow: Gene flow involves the transfer of genetic material within and between populations. High gene flow increases genetic diversity, while low gene flow can lead to decreased genetic diversity due to inbreeding and genetic drift.
4. Link the absence of toucans to gene flow: The absence of toucans likely results in decreased gene flow, as the seeds are not being spread over larger distances. This decreased gene flow can lead to reduced genetic diversity within the forest fragments.
5. Choose the correct answer: Given that the absence of toucans leads to decreased gene flow, the genetic diversity of palms within forest fragments is likely to decrease. Therefore, the correct answer is 'b. decrease (due to decreased gene flow)'.