Species

analogy

The external similarity between two structures, which have the same function but do not have an identical embryonic origin.

Sympatric speciation

Sympatric speciation: The formation of new species in the same environment without being geographically isolated.

Homology

The internal similarity between two structures that have the same embryonic origin.

Allopatric species

Allopatric species live in different environments.

Allopatric speciation

Allopatric speciation: The formation of new species in different environments; this process starts with geographic isolation.

Sympatric species

Sympatric species live in the same environment; they, therefore, belong to the same biological community.