As a population declines in size, what would you predict? Check all that apply.

Question

_____  Loss of genetic variation.
_____  More individuals with heterozygote advantage.
_____  Deleterious alleles can become fixed due to chance.
_____  Homozygosity within individuals in the population will decline.
_____  The few remaining individuals will be tough, healthy and fertile.
_____  If the environment changes, the population will adapt quickly.

Additional:
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you already know about population size and genetic diversity?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

__X__  Loss of genetic variation.
_____  More individuals with heterozygote advantage.
__X__  Deleterious alleles can become fixed due to chance.
_____  Homozygosity within individuals in the population will decline.
_____  The few remaining individuals will be tough, healthy and fertile.
_____  If the environment changes, the population will adapt quickly.

Clarify Question

· What is the key concept addressed by the question?
        o This question addresses population size and genetic diversity.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
 
Gather Content

· What do you already know about population size and genetic diversity?
        o Small populations face a dilemma. They are prone to the loss of genetic variation as a result of genetic drift. Many small populations have little or no genetic variability.
        o Genetichomogeneity can be catastrophic. Variation is beneficial because of heterozygote advantage and because genetically variable individuals tend not to have two copies of deleterious recessive alleles. Populations lacking variation are often composed of sickly, unfit, or sterile individuals.
        o Studies of zoo and natural populations reveal that more genetically variable individuals have greater fitness. Furthermore, in the longer term, populations with low variation have less ability to adapt to changing environments.
 
Choose Answer

· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o As a population shrinks, will more individuals have heterozygote advantage? No, there will be fewer heterozygotes due to genetic drift.
        o Will homozygo sity within individuals in the population decline? No, it will increase.
        o Will the few remaining individuals be tough, healthy and fertile? No, they will likely be sickly and sterile.
        o Will the population adapt quickly if the environment changes? No, there will not be variation to be selected upon.
        o Will there be a loss of genetic variation? Yes.
        o Will deleterious alleles become fixed due to chance? Yes, due to more genetic drift.
 
Reflect on Process

· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that as a population declines in number genetic variability goes down, leading to sickly individuals that may carry two copies of deleterious alleles, and less variation for adapting to new conditions?