Which things do we need to remember in an exercise of tracing the family trees of species ?

Explanation

In an exercise of tracing the family trees of species, we need to remember following things :
`rarr` There are multiple branches possible at each and every stage of this process.
`rarr` Evolution is not as if one species is eliminated to give rise to a new one.
`rarr` A new species has emerged does not mean that the old species will disappear. It depends on the interactions with the environment.
`rarr` It is not necessary that the newly generated species are in any way better than the older one.
`rarr` Natural selection and genetic drift have together led to formation of a population that cannot reproduce with the original one. This creates isolation, which further lead to speciation.