Algal Diversity Explanation: Snail Grazing Effects
The observation that algal species diversity is higher in pools with grazing snails compared to pools without snails can be explained by the feeding behavior of the snails. Snails act as herbivores that can significantly influence the structure of the algal community.
Mechanism of Increased Diversity
When snails feed selectively, they can prevent dominant algal species from monopolizing resources and outcompeting less dominant species. By keeping the most abundant species in check, snails create opportunities for rarer species to persist, leading to higher overall species richness.
Analysis of Options
- Option A: Snails feed preferentially on the more abundant algal species. This statement provides the best explanation. Selective grazing on abundant species reduces their competitive advantage, allowing less abundant species to survive and thrive, thereby increasing overall diversity.
- Option B: Snails avoid feeding on algal species. This contradicts the role of grazing snails and does not explain the observed increase in diversity.
- Option C: Snails feed only on the less abundant algal species. This feeding strategy would lead to a decrease in diversity by eliminating rarer species.
- Option D: Snails feed equally on all the algal species irrespective of algal abundance. While grazing occurs, feeding equally on all species does not inherently explain why diversity would be *higher* than in the absence of snails. Preferential grazing on dominant species is a more direct mechanism for increasing diversity.
Important Questions from Community interactions
- Certain species of ibex and weevils depend on the same food source. A study finds that the removal of ibex results in an increase in the number of weevils, but the removal of weevils does not affect the ibex. Which one of the following options best describes this interaction?
- Fungus S infects elm trees and fungus T infects chestnut trees, and both kill their hosts within a year of infection. A forest with equal density of elm and chestnut trees is colonized by both pathogenic fungi. A 100 years later, the elm tree population has declined and the chestnut trees have become extinct. Which one of the following mechanisms would NOT contribute to this outcome?
- Which one of the following is a result of antagonistic coevolution?
- Which one of the following ecological processes best explains the observation thatseedling establishment increases with distance from the parent tree in a forest?
- Depending on soil nutrient availability, which one or more of the following interaction(s) can occur between soil mycorrhizal fungi and plants?
