Biology unit 2 mod. 3 definitions

The number and variety of living things to be found in the world, in an ecosystem or in a habitat.

A group of organisms that can breed freely with one another to produce fertile offspring. 

note: they have anatomical, physiological, morphological, embryonic similarites

The organisation of living organisms into groups according to their shared similarities.

The study of the principles behind classification.

The evolutionary relationships between organisms.