Question

Observations of algal species showed that their diversity was higher in pools where there were grazing snails compared to pools without snails. Which one of the following statements best explains this result?

• A. Snails feed preferentially on the more abundant algal species.
• B. Snails avoid feeding on algal species.
• C. Snails feed only on the less abundant algal species.
• D. Snails feed equally on all the algal species irrespective of algal abundance.

Hint:

To understand ecological interactions: 1. Grazers can promote diversity by reducing the dominance of abundant species.
2. Selective feeding creates ecological niches for less common species.
3. Avoidance or equal feeding typically does not enhance diversity.

Answer 1

The Correct Option is A

Step 1: Understand the ecological relationship. The presence of grazing snails leads to higher diversity of algal species. This suggests that snails reduce the dominance of the most abundant algal species, creating opportunities for less common species to coexist. Step 2: Analyze the options. Option (A): Correct. If snails preferentially feed on the more abundant algal species, this reduces competition and allows less abundant species to thrive, increasing diversity. Option (B): Incorrect. If snails avoided feeding on algal species, their presence would not influence algal diversity. Option (C): Incorrect. Feeding only on less abundant species would reduce their numbers further, decreasing diversity rather than increasing it. Option (D): Incorrect. Feeding equally on all algal species would not create a selective pressure to increase diversity, as it would impact all species uniformly.