Question

One hypothesis for why the tropics have far greater species richness than higher latitudes is that the tropics are relatively aseasonal. Low seasonality can encourage high species richness through which one or more of the following mechanisms?

• A. Numerous resources are consistently available throughout the year, allowing different species to specialize on different resources, thereby minimizing competition and allowing co-existence.
• B. Low seasonality is associated with lower rates of predation, allowing large populations to thrive.
• C. Low seasonality is associated with more stable populations that are less vulnerable to demographic stochasticity and extinction.
• D. Low seasonality is associated with longer generation times, which enhances species richness.

Hint:

In ecology questions on tropical diversity, look for mechanisms related to {environmental stability, niche specialization, and reduced extinction risk}. These are key drivers of high species richness in the tropics.

Answer 1

The Correct Option is A

Step 1: Understand the ecological hypothesis.
Tropical regions experience relatively low seasonal variation in temperature and resource availability. This environmental stability is hypothesized to promote higher species richness compared to highly seasonal temperate regions.
Step 2: Analyze option (A).
Low seasonality leads to consistent availability of resources throughout the year.
This allows species to specialize on different niches and resources, reducing direct competition and enabling long-term coexistence.
This mechanism is a well-accepted explanation for high tropical biodiversity.
Hence, (A) is correct.
Step 3: Analyze option (B).
There is no strong ecological evidence that low seasonality necessarily results in lower predation rates.
In fact, predation pressure in the tropics is often high.
Hence, (B) is incorrect.
Step 4: Analyze option (C).
Low seasonality promotes stable environmental conditions, leading to more stable population sizes.
Such populations are less affected by demographic stochasticity and have lower extinction risks.
This stability allows more species to persist over evolutionary timescales.
Hence, (C) is correct.
Step 5: Analyze option (D).
Low seasonality is not generally associated with longer generation times.
Moreover, longer generation times do not directly enhance species richness.
Hence, (D) is incorrect.
Step 6: Conclusion.
Low seasonality can enhance species richness by promoting resource specialization and population stability.
Therefore, the correct mechanisms are: \[ \boxed{(A) \text{ and } (C)} \]