Question

Define the terms: A) apomorphy and B) plesiomorphy, with respect to mammals provide one example of an apomorphic and one example of a plesiomorphic character

Answer 1

In phylogenetics, apomorphy refers to derived characters of a clad whic refers to the characters or traits that are derived from ancestral characters over evolutionary history.

Example: In most groups of mammals, the vertebral column is highly conserved, with the same number of vertebrae found in the neck of a giraffe, for example, as in mammals with shorter necks. In the Afrotheria clade, which includes elephant shrews, golden moles and elephants, there is an increase in the number of thoracolumbar vertebrae. This is a synapomorphy of the clade: a shared feature considered to be derived from a common ancestor.

Plesiomorphy is an ancestral character which is not only shared by two or more taxa, but also with other taxa linked earlier in the clade.