Fitness in Evolution
If you were to ask me before this class how to define
fitness in biology a few thoughts would come to mind. The first thought that I
would immediately think of is the phrase “Survival of the fittest” which is
something that has been hammered into my brain since my first biology class.
Another thought that comes to mind is the meme above that I absolutely love and
no matter how many times I see it, it always takes me approximately 2 minutes
to stop laughing/giggling. The third thought that would come to mind is a muscular
kangaroo squaring up and ready to fight (I credit this thought to the awesome
childhood movie, Kangaroo Jack).
Now that I am in an actual evolution class, I think I would
define it as ultimately a description of how successful a species is at reproducing.
I believe this is a very basic definition of fitness in evolution but really
describes the gist of what we discussed in class. It represents sexual and
natural selection and concerns specific genotypes/phenotypes that are
completely dependent on the environment. A slide in the class described fitness as
having an average contribution to a gene pool in future generations that are
made by individual organisms of a specific genotype or phenotype. Fitness can be
measured by the number of offspring that are produced from the individual organisms
that have a certain genotype/phenotype that is then seen in future generations with
a certain extent of reproductive success.
A specific example of fitness playing out is comparing brown beetles and green beetles. Brown beetles have a consistently higher survival rate compared to green beetles. Because fitness is a relative concept, the theory is that the color of the beetles is a key factor in the survival and better reproductive success. Brown beetles have an easier time blending in with their surroundings than with green beetles, depending on the environment. According to a study, done to determine the survival rate of the two beetles, 95% of brown beetles survive and reproduce compared to the 33% of green beetles.
I think I have gotten into the habit of immediately thinking
of what humans consider ‘fit’ compared to what the actual definition of
evolutionary fitness is. Hopefully, by the end of this class, I will be able to
immediately think of the right definition of ‘fitness’ in terms of biology; though one of the thoughts that will always come to mind is the meme of the beautiful
dog with a giant pizza in front of him <3
What about fitness? (berkeley.edu)
I really like how your example is a phenotypic expression! Oftentimes it really is something like behavior or coat color that makes such a huge difference. I don't remember the species, but I know there's a type of bird that is massively endangered just because there's so few adult males, so all the new baby boys don't know how to sing the mating song properly and can't get laid. Love that honestly.
ReplyDeleteI literally love this meme so much, and that it's always the first thing that comes to mind when talking about fitness! I mentioned in my post I think it's funny how some people really seem to think "survival of the fittest" means that the bodybuilders are going to be the last people on earth, saved from extinction. Gotta love the English language and how we use the same words to talk about completely different things!
ReplyDeleteOh, interesting! Let's talk about fitness as defined by reproductive success. Does "most offspring" always equal "most fit"? Rabbits can produce hundreds of offspring in their lifetime, and whales are lucky to average one a year - are rabbits, therefore, more fit than whales? Why might this not be the case? What might you measure, instead, to get that fitness?
ReplyDeleteHow does the unequal contribution of sexes to reproduction impact this concept? What other natural phenomenon might this drive?
I love how you go through all the ways fitness first pops into your head. Just like you, I have about 5 ideas about other types of fitness pop into my head before the evolution/biology kind. Your example of the brown vs green beetles was also very good and well thought out!
ReplyDelete