Environmental Filtering Explains Species Similarity

When species live together in the same place and at the same time (co-occur), they often share similar characteristics, like how well they tolerate heat or drought. This happens because the environment acts as a filter.

Environmental filtering means that only species whose traits allow them to survive and reproduce under the specific environmental conditions (like temperature, water availability, etc.) can persist in that habitat. Species that are not well-suited to these conditions are excluded.

Therefore, the species found together are likely those that have passed this environmental filter, leading to them being similar in their tolerances and other traits.

Analyzing Options Related to Species Co-occurrence

• Environmental filtering: This directly explains why co-occurring species are similar. Only individuals adapted to the local conditions (e.g., heat tolerance, drought tolerance) can survive and form a community.
• Limiting similarity: This concept suggests that species competing for the same resources tend to evolve differences to reduce competition, which is the opposite of the observed similarity in traits due to environmental tolerance.
• Divergent evolution: This process leads to species becoming more different over time, usually as they adapt to different environments or niches, not more similar.
• Competitive exclusion: This principle states that two species competing for the exact same limited resources cannot coexist indefinitely; one will eventually eliminate the other. It explains exclusion, not the similarity of coexisting species.

Based on the principle that the environment selects for species with specific suitable traits, environmental filtering is the most likely reason for the observed similarity among co-occurring species.