Essential Knowledge 4.C.3

The level of variation in a population affects population dynamics.

Population ability to respond to changes in the environment is affected by genetic diversity. Species and populations with little genetic diversity are at risk for extinction. Examples include:

• California condors
• Black-footed ferrets
• Prairie chickens
• Potato blight causing the potato famine
• Corn rust affects on agricultural crops
• Tasmanian devils and infectious cancer

Genetic diversity allows individuals in a population to respond differently to the same changes in environmental conditions. Examples include:

• Not all animals in a population stampede.
• Not all individuals in a population in a disease outbreak are equally affected; some may not show symptoms, some may have mild symptoms, or some may be naturally immune and resistant to the disease.

Allelic variation within a population can be modeled by the Hardy-Weinberg equation(s).

Students should be able to:

LO 4.25 use evidence to justify a claim that a variety of phenotypic responses to a single environmental factor can result from different genotypes within the population.

LO 4.26 use theories and models to make scientific claims and/or predictions about the effects of variation within populations on survival and fitness.