So, as you all know, species lived in particular ecological niches and particular environments, and the pressures of those environments selected which changes, through random mutation in species, were going to be preserved.
Quindi, come sapete, le specie vivevano in precise nicchie ecologiche e precisi ambienti e le pressioni di quegli ambienti selezionavano quali cambiamenti, attraverso mutazioni casuali delle specie, venivano preservati.