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.
Então, como voces todos sabem, as espécies viviam em nichos ecológicos particulares e ambientes específicos, e as pressões desses ambientes selecionavam quais mudanças, através de mutações aleatórias nas espécies, seriam preservadas.