On the Volcanic, Equatorial West African Island of Sao Tomé

question 2

Multiple Choice

On the volcanic, equatorial West African island of Sao Tomé, two species of fruit fly exist. Drosophila yakuba inhabits the island's lowlands and is also found on the African mainland, located about 320 kilometres away. At higher elevations, and only on Sao Tomé, is found the very closely-related Drosophila santomea. The two species can hybridise, though male hybrids are sterile. A hybrid zone exists at middle elevations, though hybrids there are greatly outnumbered by D. santomea. Studies of the two species' nuclear genomes reveal that D. yakuba on the island is more closely related to mainland D. yakuba than to D. santomea (2n = 4 in both species) . Sao Tomé rose from the Atlantic Ocean about 14 million years ago.
Using only the information provided in the paragraph, which of the following is the best initial hypothesis for how D. santomea descended from D. yakuba?

• A) allopolyploidy
• B) autopolyploidy
• C) habitat differentiation
• D) sexual selection

---

Definitions:

Major Depressive Disorder

A mood disorder marked by feelings of great sadness, despair, and hopelessness as well as the loss of the ability to experience pleasure.

Schizophrenia

A mental disorder characterized by disturbances in thought, perception, and behavior, including delusions, hallucinations, and disorganized speech.

Panic Disorder

A type of anxiety disorder characterized by sudden and recurrent panic attacks that involve overwhelming fear and physical symptoms.

Social Phobia

A chronic mental health condition characterized by an intense fear of social situations, leading to avoidance and distress.