Natural Selection and Fitness Concepts

The video tutorial explains the concept of natural selection and Darwinian fitness, focusing on absolute and relative fitness. It uses examples of blue-eyed and green-eyed cats to illustrate how fitness is measured by the number of offspring produced. Absolute fitness is defined as the average number of offspring per individual, while relative fitness compares the fitness of different genotypes. The tutorial also discusses the challenges in measuring fitness due to population size variations and allele frequency changes. Overall, fitness is a measure of natural selection, with higher fitness indicating a trait favored by natural selection.

What does Darwinian fitness measure in the context of natural selection?

• The lifespan of an organism

• The number of offspring produced by a genotype

• The speed of an organism

• The size of an organism

In the example of blue-eyed and green-eyed cats, what is the absolute fitness of the blue-eyed cats?

• Five

• Two

• Four

• Three

How is relative fitness determined between two groups?

• By measuring their speed

• By setting one group's fitness to one and adjusting the other

• By comparing their sizes

• By counting their total population

What is the relationship between absolute and relative fitness?

• Relative fitness is a comparison of absolute fitnesses

• They are unrelated

• Absolute fitness is always higher

• Relative fitness is always lower

Why is it often easier to calculate relative fitness rather than absolute fitness?

• Relative fitness is based on speed

• Absolute fitness is more accurate

• Relative fitness does not require population size data

• Populations are always increasing in size

What happens to an allele with lower relative fitness over generations?

• Its frequency increases

• Its frequency remains constant

• Its frequency decreases

• It becomes dominant

What does a gradual decline in allele frequency indicate about its relative fitness?

• It has higher relative fitness

• It has lower relative fitness

• It is neutral

• It is increasing in frequency

What does a higher fitness indicate in terms of natural selection?

• The organism is neutral

• The organism is extinct

• The organism is more favored

• The organism is less favored

What is the result of natural selection on organisms with lower fitness?

• They become dominant

• They remain unchanged

• They are removed faster

• They are favored

In the context of fitness, what does natural selection do to organisms with higher fitness?

• Ignores them

• Favors them

• Removes them from the population

• Decreases their numbers