Question

Species that co-occur in space and time tend to be similar to each other in traits such as tolerance to heat or to drought. This is most likely because of _________.

• A. Limiting similarity
• B. Divergent evolution
• C. Environmental filtering
• D. Competitive exclusion

Hint:

Ask whether the pattern is driven by the physical habitat screening out unsuited species, or by competition between species; a shared abiotic stress producing shared traits points to filtering, not competition.

Answer 1

The Correct Option is C

Step 1: Understanding the Question.
The question describes a pattern seen in nature: species living together in the same place and time often share similar trait values, such as how much heat or drought they can handle. We need to find the process that produces this kind of trait similarity among co-occurring species.

Step 2: Key Concept or Approach.
Environmental filtering (also called habitat filtering) says that the local abiotic conditions of a site, things like heat, drought, soil salinity or cold, act as a filter. Only species whose traits let them survive under that specific stress get through the filter and persist there. Since the filter is the same for everyone at that site, the species that pass through end up sharing similar trait values.

Step 3: Detailed Explanation.
Think of a dry, hot habitat. Any species living there must already tolerate heat and drought, or it would not survive at that site at all. So when we look at the species that actually co-occur there, we find them clustered around similar tolerance traits, not because they copied each other, but because the environment only let similar-trait species in.
This is different from limiting similarity, which is a competition based idea. Limiting similarity predicts that species coexisting at a site should differ enough in their traits (such as resource use) so that competition between them is reduced. That theory expects trait divergence among co-occurring species, the opposite pattern from what the question describes.
Divergent evolution refers to two or more related lineages evolving away from a common ancestor over long time scales, becoming more different from each other. It is a statement about evolutionary history, not about which species end up living together at a site today, so it does not explain the observed trait similarity.
Competitive exclusion states that two species competing for exactly the same limiting resource cannot stably coexist forever, one will outcompete and displace the other. This idea again pushes toward less similarity among coexisting species, or exclusion of one of them, not toward the shared trait pattern seen here.

Step 4: Final Answer.
Trait similarity among species that co-occur in space and time, driven by the local abiotic stress acting as a common filter, is the mark of environmental filtering.
\[ \boxed{\text{Environmental filtering}} \]