Darwin's 4 Postulates

Julia Llaguno


Organisms (within populations) show individual variation in appearance and behavior. These variations may involve body size, hair color, facial markings, voice properties, or number of offspring. On the other hand, some traits show little to no variation among individuals. For example, number of eyes in vertebrates.
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Some traits are consistently passed on from parent to offspring. Such traits are heritable, other traits are strongly influenced by environmental conditions and show weak heritability. This can be seen as physical characteristics that have unique genetic codes and cellular structures. In organisms that reproduce sexually, traits from both parents are combined and passed along to unborn babies. Normally, these traits contain unique attributes of the mother and father, but also contain some quite similar components, which explains why children look so alike to their parents and at the same time have some cellular and physical differences too.
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Differential Survival

Simply known as Natural Selection, differential survival is when individuals who have traits well suited for the struggle of their everyday lives will more likely survive and reproduce more than others. Because their traits are advantageous, they are more likely to reproduce and contribute more offspring to the next generation.
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Some traits are not suited for survival and those with them will die out. Also, because of a high rate of population growth certain individuals have a struggle for existence. Most populations have more offspring each year than local resources can support. Each generation experiences solid mortality rate therefor creating an extinction in certain species.
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