An example of variation in a species
Open ended
Evolution
Change in a population over time
What trait is being selected for?
Dark color in moths
Are the weeds evolving? How do you know?
Yes, a greater percentage of the population has adapted herbicide resistance.
How rock pocket mice varied
color: light/dark
Fitness
An organism's ability to survive to reproduce
What is driving selection for different beak shapes?
Terrain/environmental differences (sand/water depth)
Is eevee evolving? Why?
No. Individuals do not evolve.
An environmental factor that has lead to variation in humans.
UV/the tilt of Earth's axis
Adaptation
A physical or behavioral trait that increases an organisms fitness
Short legged cheetahs have stronger bones resistant to breaking. Long legged cheetahs have increased speed but more fragile bones. Over time, what will most cheetahs look like?
In which population is the recessive phenotype most likely increasing?
Population D
Why is variation important for natural selection?
It allows for a range of traits for selection to act on.
Selective Pressure
An environmental factor that causes some phenotypes to be favored over others
In salmon, large males are better able to fight off competing males for breeding. Small males are able to "sneak by" larger males to find mates.
What will salmon look like over time.
Compare the selective pressures acting on population A and B
They are both selecting for allele A over allele B
What determines whether a mutation is good, bad, or neutral?
The environment
Artificial Selection
When humans, not nature, determine what traits are valuable/passed on.
Desert frogs are capable of producing cocoons of mucus and dead skin cells. What could have selected for this adaptation and why?
Dryness of the desert/water retention
Huntington's Disease is an inherited neurologic disease that onsets in a person's 30s-40s. It has severe impacts including loss of motor function, cognitive decline, and behavioral changes.
Why has HD persisted in the human population?
It doesn't onset until after many people have already had children.