IB 150 U3: Natural selction and fitness
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6 Terms
The outcome of natural selection is highly______
Why?
Predictable.
Selection pressures can determine which phenotype is best suited for the environment.
Natural selection operates directly on the ____ and indirectly on the ____.
Because…
Phenotype, genotype
this is because a trait is what is actively being favored or unfavored in the environment. The alleles conveying those traits that are favored thus increase in frequency.
What are the three parameters for natural selection
population has to have phenotypic variation
Phenotypic variation has to be heritable
Phenotypic variation has to cause different reproductive success
Relative fitness
absolute fitness divided by average fitness of the entire population.
Fitness (absolute)
How many offspring an individual produce during its lifetime.
Three components of fitness
length of survival beyond reproductive age: more care to offspring
Ability to acquire a mate: sexual selection
Being fertile: being able to produce viable offspring