Fitness and Selection

Fitness and Selection

Absolute fitness is the amount of offspring an organism produces over its entire lifetime. Whereas, relative fitness pertains to fitness of the other members of the population and compares an organism proportionately to the "most fit" organism in the population. Recall: fitness is one's reproductive success so the higher one's fitness is, the higher the amount of offspring they reproduce is. For example, the absolute fitness of a specific peacock (this fictional species has plumage and elaborate feathers in both sexes) named Jenny is 6 because she reproductively produced 4 peacocks in her lifetime. However, the relative fitness of Jenny is lower when compared to her sister Jenna who produced 5 peacocks in her lifetime.


Positive selection is when an allele is favored by natural selection, which is any consistent difference in fitness among different classes of biological entities. For example, Jenna has a biological trait that affects her dermal cells and enables her feathers to gleam brighter in direct sunlight. This increases her ability for male peacocks to see her so they can perform their mating ritual together. Due to this, Jenna is able to have a higher relative fitness compared to Jenny who is less noticeable. Overtime, this biological trait of increased gleaming may be more abundant in these specific peacocks due to Jenna being able to reproduce more than others like Jenny because she is easier to locate for mating.

Thank you for reading!

Comments

  1. Maddie MeinerOctober 3, 2024 at 10:01 AM

    Hello! I loved your drawings of the peacocks they are so cute! I think that you gave a very good example of what positive selection is and how it affects this specific population. The drawings with the clear explanation made this post easy to read and understand, great job!

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