Fitness and Selection

 Absolute fitness and relative fitness are evolutionary terms used to describe an organism's ability to survive and reproduce. However, there are key details to these terms that make them different and can make a huge difference in an organism's fitness rating. Absolute fitness is the number of offspring an organism can reproduce that reach reproductive age. These offspring will contribute to the next gene pool, resulting in a continuation of the parent's genetics and increasing their fitness. However, relative fitness compares the absolute fitness of different organisms in a population, comparing the reproductive success of different genotypes. 

The organisms in this example are dogs, but I am going to use names, so this example is easier to follow. For example, if Betty produces 10 offspring and 9 survive to reproductive age, she would be considered to have a high absolute fitness. However, if you compare Betty to Shanna, who is producing 20 offspring with 17 making it to reproductive age, Betty is considered not very relatively fit. 

After about 30 years, you start to realize that a lot of the dogs in the area have similar features as Shanna... big ears! The big ears helped Shanna listen for prey and detect predators, helping her live an easier life and allowing her more time to reproduce compared to Betty, the dog with small ears. At this point in time, Shanna's 17 kids who made it to reproduction are having kids, and those kids are starting to have kids, so Shanna's genetics are very frequent in the population. Especially compared to Betty, who has only had 9 kids, and those kids are struggling to have at least 9 more kids like their mom because the population is starting to only like dogs with big ears because of their easier lifestyle. 

Comments

  1. Keli P.September 28, 2024 at 11:55 PM

    Hi Abby, I think you did a great job explaining the difference between absolute and relative fitness in terms of an organisms ability to pass genes onto there offspring and how the number of offspring is key to both concepts. I really liked your dog example, I think it was easy to understand by you giving each dog a name and helped make the concepts more clear.

    ReplyDelete
  2. AsheSeptember 29, 2024 at 12:50 PM

    I love big dogs and reading your dog explanation made it really cute in my mind. I was smiling while learning, so thanks for that!

    ReplyDelete
  3. Jasmine Plata's Evolution BlogSeptember 29, 2024 at 5:07 PM

    Haha Shannan really took over the neighborhood. Really great job in breaking down the difference between absolute and relative fitness.

    ReplyDelete

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