1. form and structure of an organism or any of its parts morphology

2. the splitting of a lineage into separate and distinct species speciation

3. group of related organisms that share features and characteristics species

4. small or underdeveloped vestigial

1) morphology

2) speciation

3) species

4) vestigal

Explanation:

Morphology is the study of forms or the physical appearance of organisms.

Speciation is the splitting of lineage into distinct species capable of interbreeding and producing fertile offspring.

Species is a group of organisms that are genetically related and share features and characteristics. They are capable of interbreeding and produce live offsprings.

Vestigal organs are organs that have lost their function over time, they are usually small and underdeveloped. Example is the human tail bone.