Question

define species provide a suitable explanation to prove that geographical isolation of individuals of the species lead to formation of new species.

Answer 1

Species are the fundamental unit of the taxonomic classification. A species is defined as the group of organisms which have some common characteristics and are capable of breeding.
Geographical isolation that leads to the formation of new species. This happens because the two subpopulation get reproductively isolated due to the geographical barrier. They will interbreed among themselves. Apart from this, there are changes in the environmental conditions that leads to the character displacement. There will be some changes in the subpopulations in order to become more fit for their habitat (to adapt to the environmental changes). Due to long term isolation, the two subpopulations would no longer be breed; thus, they get diverged into different species.