Two bands of a population come together after a period of isolation. Speciation will have taken place if the two groups

Options

A. No longer mate
B. Cannot interbreed or produce fertile offspring
C. Compete for the same food supply
D. No longer intermingle

Answer

**Step-by-Step Solution:**

1. **Understanding Speciation**: Speciation is the process through which new species arise. It often occurs when populations of a species become isolated from each other due to geographical barriers, leading to evolutionary changes over time.

2. **Isolation of Populations**: In this scenario, two bands of a population (let's call them Band A and Band B) have been separated by a geographical barrier. During this period of isolation, each band may undergo genetic changes due to natural selection, mutation, and genetic drift.

3. **Reunion of Populations**: After some time, the geographical barrier is removed, and Band A and Band B come into contact again.

4. **Mating and Hybrid Offspring**: When individuals from Band A and Band B mate, they produce hybrid offspring. The success of these hybrids is crucial in determining whether speciation has occurred.

5. **Survivorship and Fertility of Hybrids**: For speciation to be confirmed, the hybrids must exhibit lower survivorship and reduced fertility. This means that:
- The hybrids may not survive as well as the parent species.
- If they do survive, they may be less fertile, leading to difficulties in producing viable offspring.

6. **Conclusion on Speciation**: If the hybrids produced from the mating of Band A and Band B are unable to integrate back into the populations (i.e., they cannot produce fertile offspring), it indicates that speciation has taken place. This is because reproductive isolation has been established, preventing gene flow between the two groups.

**Final Answer**: Speciation will have taken place if the two groups cannot integrate and produce fertile offspring.

---