Darwin's Theories
STRUGGLE FOR EXISTENCE Darwin’s central theme Based on Malthus’s work on population growth
FITNESS A Key factor in the struggle for existence The result of adaptations Central to natural selection
NATURAL SELECTION Only certain individuals produce new individuals Over time, it will result in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment.
DESCENT WITH MODIFICATION Each living species has descended, with changes, from other species over time.