Evolution is ___ over ____.
Change over Time
Evolution is ___ with ____
Decent with modification
2 categories of evolution:
Microevolution & Macroevolution
Microevolution is:
- Samller-scale changes within a population
- Usually occurs over short time fame
Macroevolution is:
- Largescale changes in a ____ or ____.
- Can result in _____, or the formation of new species.
- Typically occures over a ___ time fame.
- Population or Species
- Speciation
- Long
Define Microevolution:
Change in the frequency of alleles within a population over multiple generations.
______ _______ causes no change in allele frequencies.
Random mating
Mechanisms One and Two are:
Mutations & Gene Flow
Changes in the DNA code. Ex- allele “B” changes to allele “b”
Mutation
Gene Flow:
Individuals may move into or out of the population, taking out (or bringing in) their alleles with them.
2 examples of gene flow.
Immigration and Emigration
Mechanisms Three and Four are:
Non-random mating & Genetic Drift
100 Locusts fly across the road when you come zooming over a hill, smooshing 60 of the poor insects. the dead ones are NOT killed because they happened to be “less good” than the surviving locusts: no they just happened to be in the wrong place at the wrong time. This is an example of what?
Genetic Drift
One example of genetic drift is the _____ effect.
Bottle-neck
Mechanism Five:
Natural Selection
Natural Selection is:
Differences in survival and/or reproduction due to differences in traits among individuals.
Natural Selection is the most important process leading to Microevolution, primarily because….
It always leads to ADAPTIVE changes in populations.
Who were the co-discoverers of evolution via natural selection?
Charles Darwin & Alfred Russel Wallace
Darwin based his ideas about natural selection on what 3 major observations:
- All organisms produce more offspring than is needed
- Limited supply of food, water, space, and other recources
- All organisms varied. That variation was passed along from parent to offspring
Darwins 3 major Hypothesis on top of his natural selection ideas:
- Individuals will compete among themselves to get resources
- Individuals with better traits will survive and reproduce better
- The strong will thrive, and the weak will be weeded out
Biologists define “fitness” as:
The RELATIVE success of a trait compared to other traits.
How to measure “fitness”
of offspring
Probability of each offspring reproducing
Growth rate of a population will all individuals having a single allele.
Fitness is generally symbolized by the letter __.
w
The fitness of a trait is _____ dependent on what other traith you compare it to, and the circumstances under which the comparison is made.
always
