Explanation

All of the above. [image:7_image36.emf] Darwin’s theory of natural selection states that the species tend to overproduce due to limiting resources. This sets up competition or struggle for existence. Those most fit in that environment are likely to survive, passing those favourable genes on to the offspring. In time, a new species evolves from the accumulation of favourable genes. Punctuated equilibrium is a theory that was formulated after Darwin’s theory and it states that the species remains relatively stable for long period of time and then, due to some natural catastrophe, change rapidly in a short period of time Darwin’s evidence for evolution: Biogeographic distributions (i) Environment cannot account for either similarity for dissimilarity, since similar environments can harbor entirely different species groups (ii) Affinity (similarity) of groups on the same continent (or sea) is closer than between continents (or sea) (iii) Geographical barriers usually divide these different groups, and there is a correlation between degree of difference and rate of migration of ability to disperse across the barriers