Fitness Review of H.Aa Orr 2009

Define fitness

in its crudest terms, involves the ability of organisms or more rarely populations of species to survive and reproduce in the environment in which they find themselves

Individual fitness is also referred as

viability

Individual fitness is ____

binary

Individual fitness is binary meaning what

either an individual survives or it does not

If an individual survives the fitness value is what

1

If an individual does not survive the fitness value is what

0

Absolute fitness is a statistics that is usually assigned to what

a genotype

Absolute fitness usually refers to….

the genotypes total expected fitness

These factors play a role in the degree to which alleles comprise this genotype which is represented in subsequent generations

totality of viability, fecundity, mating success and others

this fitness is the summary statistic most often used by evolutionary geneticists

relative fitness

relative fitness is represented by which variable

w

the relative fitness of a genotype is equal to what?

its absolute fitness divided by the absolute fitness of the fittest genotype

This normalization is generally achieved how?

by setting the fitness of the fittest genotypes to a value of 1

This process allows us to do what?

define an additional variable we refer to as the selection coefficient

This variable is represented by what letter?

s

S is the measure of

how much worse one allele (A₂) is than another allele (A₁) that is more fit

mathematically, the fitness of the LESS fit allele is calculated by what equation?

w₂ = 1 - s

The following all follow the Quantitative Genetic View

okkk

T/F: 1. fitness is a trait

true

T/F: 2. It is a special trait however in that it is the only trait of an organism that allows us to predict how much any other trait will change from one generation to the next under natural selection.

true

T/F: 3. The amount by which A SPECIFIC trait changes from one generation to the next is given by the genetic covariance between the trait itself and relative fitness

false: The amount by which ANY trait changes from one generation to the next is given by the genetic covariance between the trait itself and relative fitness.

T/F: 4. If a trait strongly covaries with relative fitness, it will NOT change a lot from one generation to the next. If it does not strongly covary with relative fitness, it WILL change a lot.

false: If a trait strongly covaries with relative fitness, it WILL change a lot from one generation to the next. If it does not strongly covary with relative fitness, it will NOT change a lot.

T/F: 5. The point 4 above is known as the Secondary Theorem of Natural Selection

true

T/F: If the trait under consideration is relative fitness 1 we can predict how much the average relative fitness of a population will change from one generation to the next
under natural selection. (This essentially amounts to the additive genetic variance in relative fitness-you don't need to grasp this particular idea other than to understand that you cannot have a negative variance).

true

T/F: Because a variance CAN be POSITIVE, the mean relative fitness of a population either increases or doe snot change under natural selection

false: Because a variance CANNOT be NEGATIVE, the mean relative fitness of a population either increases or does not change under natural selection

T/F: Point 7 above is referred to as the Objective Theorem of Natural Selection

false: Point 7 above is referred to as the Fundamental Theorem of Natural Slection

The Fundamental Theorem of Natural Selection was first derived by who?

R.A. Fisher

T/F: 9. According to Orr (and others) the Fundamental Theorem is actually a special case of the Secondary Theorem. The Secondary Theorem is in reality more fundamental

true

T/F: The Secondary Theorem is loosely associated with a particular way of thinking about fitness and natural selection." "According to this view, the "character" that natural selection selects for is fitness. Fitness 1 in other words is the trait that natural selection "sees" and other traits change only because they are genetically associated with fitness and so get dragged along with the response to selection on fitness
itself.

true

What does the fundamental theorem of natural selection imply

(under selection) the mean relative fitness of a population generally increases through time and specifies the amount by which it will increase per small unit of time

Given this: Natural Selection is a process that increase or decreases mean relative fitness

increases