Download Population genetics is the study of evolution from a genetic

Name: _______________________
Chapter 16 Vocabulary
Directions: Fill in the appropriate vocabulary term based on your vocabulary notes
1. _______________________ is the study of evolution from a genetic point of view.
2. Because the shape of the curve looks like a bell, it is called a __________________. In nature, many
quantitative traits in a population—such as height and weight—tend to show variation that follows this
pattern.
3- 5. Variations in genotype arise in three main ways. (1) __________________ results from flawed copies
of individual genes. (2) __________________ is the reassociation of genes in a diploid individual.
Recombination occurs during meiosis by the independent assortment of genes on nonhomologous, or
different, chromosomes and by crossing-over between genes located on homologous chromosomes. (3) The
_______________________________ is essentially a game of chance played by individual gametes.
6. Population geneticists use the term __________________ to describe the total genetic information
available in a population.
7. ________________________ is determined by dividing the number of a certain allele (five instances of
the A allele) by the total number of alleles of all types in the population (10 gametes, each with either an A or
an a allele).
8. A _________________________ is equal to the number of individuals with a particular phenotype
divided by the total number of individuals in the population.
9. The __________________________________________, is based on a set of assumptions about an ideal
hypothetical population that is not evolving:
1. No net mutations occur; that is, allele frequencies do not change overall because of mutation.
2. Individuals neither enter nor leave the population.
3. The population is large (ideally, infinitely large).
4. Individuals mate randomly.
5. Selection does not occur.
10-11. ________________________, the movement of individuals into a population, and
____________________, the movement of individuals out of a population, can change gene frequencies.
12. ___________________ is the process of genes moving from one population to another.
13. ___________________________ is the phenomenon by which allele frequencies in a population change
as a result of random events, or chance. In small populations, the failure of even a single organism to
reproduce can significantly disrupt the allele frequency of the population, as can greater-than-normal
reproduction by an individual, resulting in genetic drift.
14. In another example of nonrandom mating, individuals often select a mate that has similar physical
characteristics and therefore probably has some similar genes. The selection of a mate based on similarity of
characteristics is called _________________________.
15. In _____________________________, individuals with the average form of a trait have the highest
fitness. The average represents the optimum for most traits; extreme forms of most traits confer lower fitness
on the individuals that have them.
16. In _____________________________, individuals that display a more extreme form of a trait have
greater fitness than individuals with an average form of the trait.
17. In _____________________________, individuals with either extreme variation of a trait have greater
fitness than individuals with the average form of the trait.
18. Females tend to choose the males they mate with based on certain traits. This is referred to as
_____________________________. In order to leave offspring, a male must be selected by the female.
19. The process of species formation, ___________________, results in many related populations of
organisms.
20. For many years, scientists used the internal and external structure and appearance of an organism—its
________________________—as the chief criterion for classifying it as a species.
21. According to the _____________________________, as proposed by German-born, American biologist
Ernst Mayr, a species is a population of organisms that can successfully interbreed but cannot breed with
other groups.
22. _____________________________is the physical separation of members of a population. Populations
may be physically separated when their original habitat becomes divided.
23. _____________________________results from barriers to successful breeding between population
groups in the same area.
24-25. There are two broad types of reproductive isolation: _____________________________, which
occurs before fertilization, and _____________________________, which occurs after fertilization.
26. The fossil record seems to indicate that many species existed without change for long periods of time.
The periods of stability were separated by an “instant” change in terms of geologic time. That is, a change
occurred in a few thousand, rather than a few million, years. Scientists call this pattern of species formation
_____________________________. The punctuated part of this term refers to the sudden shift in form that
is often seen in the fossil record.