1. Traits within a population vary from individual to individual
2. Variation must be heritable in some specific manner, not totally controlled by the environment
3. Both survival and reproduction differ among individuals
4. Individuals with a bigger amount of favorable traits are better adapted to the environment, with this said, they pass more genetic information to the next generation
(All of these postulates can be clearly established with the fire-mouth cichlid population.)
Expanding on each of the four postulates:
1. For Darwin, variation is a really important factor in order for evolution to occur. When connecting this specific postulate to the example of the cichlid population (mentioned before) the cichlids do have variation in their color. It is valid to say that variation can occur in both color and shape of a specific organism.
2. The second postulate consists of the fact that variation is heritable. This in a way can be proved by the fact that there is a big increase of dominant traits over successive generations. Referring to the example of the cichlid population, this occurs because of competition between sexual selection of females and between males.
3. This postulate consists of explaining the fact that there are different survival and reproductive rates in each of the individuals that make up the population, again, referring to the example of the cichlid population, it has been established by long-term studies that focus on change in coloration because of natural and sexual selection.
4. This postulate in general is a confirmation or a proof of the effects of the past postulates. With the mentioned postulates scientists and people interested in these topics are able to document heritable variation in a population and differential mating success and survival. Evolutionary change of the cichlid population can clearly be distinguished with the past observations and information.
Elijah, T. (2014). Darwin’s Postulates & Firemouth Cichlids. From
Necsi. (n.d.). Evolution. From
Science Clarified. (n.d.). Evolution - How it works. From
Science on the Half Shell. (n.d.). Natural Selection. From http://bivalves.teacherfriendlyguide.org/index.php?option=com_content