The core concept is the sentence. The start. It's the biggest thought on the subject. There was a mistake. The author will find the principal idea in a paragraph in various ways. The principal concept is normally a phrase, and usually is the first phrase.
Organisms’ characteristics can be used to determine the evolutionary relationships among them. The more closely related two organisms, the more characteristics they have in common. These shared characteristics, along with the fossil record, indicate that organisms have evolved over time from a common ancestor.