The answer is descent with modification.
Descent with modification practically means that a species have changed appearance wise over long periods of time to adapt to their environments better.
<span>The most likely means by which the zoospores spread from one free-living amphibian to another is via the flagella. The flagella is a tail-like structure on zoospores that helps them to move.</span>
In ecology<span>, a </span>niche<span> is a term describing the relational position of a </span>species<span> or population in an </span>ecosystem<span>. ... According to the competitive exclusion principle, no two </span>species can<span> occupy the same </span>niche<span> in the same environment for a long time.</span>
