Evolution Flashcards
Species
Grouping of animals that are able to procreate.
Population
Amount of animals living in the same area.
What are the factors required for evolution?
Variation (mutation): A mutation must occur to change a certain trait (create a variation).
Heredity: This trait can then be passed down through generations.
Natural Selection: The animals with traits that are most well-adapted to their environment have the easiest time surviving and therefore more chance to procreate and pass on their genes.
Time: Evolution does not happen over night. The traits must be passed on through generations and the most favourable ones will gradually become more prominent on the animals.
“Survival of The Fittest”
It is not always the strongest or most intelligent animal that survives, but the one most adapted (fitted) to the environment.
Mutation
An accidental change in the DNA which results in a variation of traits.
Proof for evolution: Comparative Anatomy
Comparing the body structure (bones, muscles, etc.) of different species to show that we all have similarities (could have come from a common ancestor, e.g. a fish with leg-bones, a remainder from their evolutionary history because they evolved from a land animal).
Proof for evolution: Embryos & Development
Comparing embryos of different species shows most early babies are the same and grow to be different.
Proof for evolution: Fossil Record, Intermediate Species
Many extinct species can be observed as “intermediate species”, the awkward stage between evolutions that we know of.
Proof for evolution: DNA comparison
By looking at DNA, we can see what percentage organisms share, which helps us see how they are related, which order they appeared in and what they evolved from.
How do we know that humans, whales and bats have a common ancestor?
Despite whales, bats and humans being obviously different, there are still many similarities that indicate that they are relatives.
We can take a simple look at DNA to see how much DNA we share.
The bat may have developed wings over time to be able to fly and the whale may have huge fins to be able to swim, but by performing comparative anatomy, we can see the similarities in the bone structure of these animals.
Humans, bats and whales all have wrist, hand and finger-bones, despite the last animal not really needing it. This is most likely a left-over from the whale’s evolutionary history, because it evolved from a land mammal that had those traits. Through mutations and natural selections, the animals gradually evolved and adapted to their own environment. Wrists and fingers are beneficial bats and humans, so we have kept those traits, unlike the whale.
Evolution is a slow and gradual process, so traits don’t just disappear overnight, even though they aren’t beneficial to a species.
