Understanding Flashcards
(37 cards)
What are the three requirements for adaptation
They must have a genetic basis, they must increase fitness in the given environment, and they must have evolved for the purpose they are being used now
An example of adaptation must have a genetic basis
The fact that you know how to drive CANNOT be an adaptation because that is a phenotype you got from your environment. You didn’t have it in your DNA when you were born
What are the three components of fitness?
How good you are at surviving, finding a mate and having offspring
Adaptations must have evolved for the purpose it is currently serving example:
Bird feathers are thought to have originally evolved to keep birds warm but now they are used to help birds fly
Adaptation evolve due to natural and sexual selection
Natural selection leads to adaptations
Ex: mice that live on the lava rocks have dark fur because it’s an adaptation to their environment
Adaptation examples
Some fish have antifreeze proteins that are an adaptation that allow them to survive in very cold water
Some of the best evidence for adaptation comes from convergent evolution
This is because species experienced similar environments. So they evolved independently similar traits to handle their environments
Convergent evolution is almost an opposite to homólogy
In homology species have the same trait due to a common ancestor but in convergent evolution species have similar traits because they evolved independently
Examples of convergent evolution
Two plants can look similar due to adapting to similar environments
What are examples of traits that aren’t adaptations
- Traits that evolved as side effects (pleiotropy)
- An outdated adaptation
- An exaptation
- Traits that evolved due to genetic drift
- Traits that no longer serve a function
- Traits that evolved as aide effects example
We give birth to small babies because when we started walking in two legs. Our pelvis got smaller. So we started to give birth early in pregnancy so the baby can still fit through the pelvis.
- Trait that are outdated adaptations
Example the calabash tree has large hard shelled fruits. It was thought because of gomphothere that could easily move the fruit. But then they went extinct and the fruits kept the hard shell.
- Traits that are an exaptation
Birds used to use feather to keep warm but now they use them to help fly
- Traits that evolved due to genetic drift and non random mating (inbreeding) example
Royal families with big jaws evolved due to inbreeding
- Traits that no longer serve a function example
Vestigial traits
Wisdom teeth or human tail bone
Why don’t all adaptations evolve?
- Physical constraints
- Pleiotropy
- No variation
- Trade offs
- Physical constraints examples
Plants can’t have skinny stems and big leaves or else they will fall over
- Pleiotropy examples
Sometimes the pleiotropic effects of an adaptation trait are so bad that the trait cannot evolve
Ex: human babies can’t be born earlier unless we go back to walking on 4 limbs
- No variation
Remember the three conditions for natural selection
Variation in population, variation is heredity, and variation leads to higher fitness
- No variation
In order to see evolution you have to have variation in the trait
Ex: humans can’t have wings until a mutation arises that leads to wings on our back
- Tradeoffs
Organisms have a limited amount of energy
Ex: if you spend more energy on reproduction (making babies) you will have less energy to spend on surviving.
Tradeoffs prevent some adaptations from evolving
An adaptation does not lead to a perfect fit in the environment
Sometimes the environment changes and the population doesn’t evolve fast enough to adapt to it
Examples of evolutionary mismatch
Snowshoe hares (bunnies) change colors eight the seasons so they camouflage better. With climate change and changing seasons, they are sometimes color mismatch, leading to easy pickings
What is the difference between adaptation and phenotypic plasticity?
The key is the environment
Adaptation is passed down while phenotypic is when an individuals phenotype changes because of the environment