A trait that is morphologically and functionally similar to another, but which
arose from a different ancestral condition.
Evolution that results from the relationships between animals. For example, one
animal might prey on another, meaning that only the fastest of the second animal
survive, creating a selection pressure. As the second animal gets extremely
fast, only the fastest of the first predatory animal can catch enough food to
survive, creating selection pressure on the predator to become faster.
Coevolutionary arms race
The back-and-forth evolution of defense and offense between predator or parasite
and prey that often a can often result in a rapid burst of evolutionary change
in both species.
Pattern of evolution in which two unrelated species gradually become similar to
each other through adaptation to a common environment, often resulting in
analogous structures. Compare with divergent evolution and parallel
Pattern of evolution in which two closely related species gradually become more
and more dissimilar. Compare with convergent evolution and parallel
Pattern of evolution in which two species maintain the same degree of similarity
while each undergoes change along an independent path. Compare with
convergent evolution and divergent evolution.
The most specific categorization for organisms. The term "species" refers to a
group of organisms that shares the same gene pool and can successfully mate. A
bulldog and a greyhound are of the same species because they can produce young.
A cat and a bulldog, which experience reproductive
isolation from each other and
therefore cannot produce young, are separate species.