Term
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Definition
| A group that includes all the members of a species living in a given area. |
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Term
| At what level is evolution detected (studied)? |
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Definition
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Term
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Definition
| The total of all alleles in a population; for a single gene, the total of all alleles of that gene that occur in a population. |
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Term
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Definition
| For any given gene, the relative proportion of each allele of that gene in a population. |
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Term
| How is the allelic frequency calculated? |
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Definition
| Frequency of B = (# of B alleles in population)/(# of total alleles in population) |
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Term
| How do population geneticists define evolution? |
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Definition
| The changes in allele frequencies that occur in a gene pool over time. |
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Term
| What is the name of the mathematical model that was developed to show characteristics of a hypothetical population that is not evolving? |
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Definition
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Term
| What is an equilibrium population? |
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Definition
| A population in which allele frequencies and the distribution of genotypes do not change from generation to generation. |
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Term
| What conditions must be met for allele frequencies to be in equilibrium within a population? |
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Definition
There must be no mutation
There must be no gene flow or movement of alleles into or out of the population.
The population must be very large.
All mating must be random, with no tendency for certain genotypes to mate with specific other genotypes.
There must be no natural selection; all genotypes must reproduce with equal success. |
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Term
| Are natural populations typically in equilibrium? Why or why not? |
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Definition
| NO b/c many fail to meet the requirements and violate one or more of the conditions that must be met. |
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Term
| Why are mutations important to evolution? |
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Definition
| The mutations are new alleles or variations in which other evolutionary processes can work. They are the foundation of evolutionary change and w/o them there would be no evolution. |
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Term
| Why aren't mutations considered to be goal-directed? |
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Definition
| They happen and may be either helpful or harmful or neutral. The effect depends on the environmental conditions, which the organism has little or no control over. |
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Term
| Provide two examples of gene flow. |
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Definition
1. Baboons live in troops and young males often leave the troop and join another, and therefore carry their alleles of their original troop to another troop.
2. Flowering plants' pollen can be carried to flowers of a different population of its species and fertilize eggs, adding its collection of alleles to the gene pool. |
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Term
| What is the main evolutionary effect of gene flow? |
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Definition
| It is to increase the genetic similarity of different populations of a species. |
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Term
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Definition
| A change in allelic frequencies of a small population purely by chance. |
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Term
| What size population does genetic drift have the largest impact on? |
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Definition
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Term
| What are two causes of genetic drift? |
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Definition
| Population bottleneck and the founder effect |
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Term
| What is a population bottleneck? What might cause a population bottleneck to occur? What effect does it have on allelic frequencies and genetic variability? |
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Definition
| A population bottleneck is the result of an event that causes a population to become extremely small; may cause genetic drift that results in changed allele frequencies and loss of genetic variability. A natural catastrophe or overhunting may cause this to occur. |
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Term
| What species recently went through a bottleneck? What was the cause? |
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Definition
| The elephant seal recently went through a bottleneck. The cause was overhunting. |
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Term
| Why are species with very small population sizes likely to undergo evolutionary changes that increase their risk of extinction? |
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Definition
1. Mating choices are limited and a high proportion of matings may be between close relatives.
2. Not all alleles are present in small populations - inevitable loss of genetic diversity. |
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Term
| Describe two risks of low genetic diversity. |
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Definition
1. The fitness of the population as a whole is reduced by the loss of advantageous alleles that underlie adaptive traits.
2. A genetically impoverished population lacks the variation that will allow it to adapt when environmental conditions change. |
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Term
| What is the founder effect? Give an example of the founder effect in the human population. |
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Definition
| It is the recruit of an event in which an isolated population is founded by a small number of individuals, may result in genetic drift if allele frequencies in the founder population are by chance different from those of the parent population. Ex: Genetic defects known as Ellis-van creveld syndrome is more common among the Amish population in Lancaster County. |
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Term
| Describe 3 ways mating is not random in populations. |
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Definition
1. Organisms have limited mobility and tend to remain near their place of birth, hatching, or germination.
2. Offspring of a given parent live in the same area, and there is a good chance that those who mate will be related to their reproductive partners causing inbreeding.
3. Assortative mating - individuals have a preference or bias that influences their choice of mates. |
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Term
| What key points about evolution are illustrated by penicillin resistance in bacteria? |
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Definition
1. Natural selection does not cause genetic changes in individuals.
2. Natural selection acts on individuals, but it is populations that are changed by evolution.
3. Evolution is a change in the allele frequencies of a population owing to unequal success of reproduction among organisms bearing different alleles.
4. Evolution is not progressive; it does not make organisms "better." |
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Term
| What does the term "fitness" refer to in evolution? |
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Definition
| The reproduction success of an organism, relative to the average reproductive success in the population. |
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Term
| What is the main "driver" of natural selection? |
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Definition
| Differences in reproduction. Individuals bearing certain alleles leave more offspring (who inherit those alleles) than do other individuals w/different alleles. |
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Term
| How does natural selection ultimately affect the genotype of an organism? |
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Definition
| Natural selection affects the phenotypes, appearance/behavior, but inevitably affects the genotype b/c genotypes and phenotypes are closely tied. |
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Term
| Why do some phenotypes reproduce more successfully than others? |
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Definition
| Some phenotypes have better adaptions to their particular environment than others. |
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Term
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Definition
| Characteristics that help an individual survive and reproduce. |
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Term
| What determines which types of traits will help an organism to survive and reproduce? |
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Definition
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Term
| What is one of the major agents of natural selection in the biotic environment? |
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Definition
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Term
| What is coevolution? In what type of relationship is coevolution often seen? |
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Definition
| Coevolution is the evolution of adaptions in two species due to their extensive interactions with one another, such that each species acts as a major force of natural selection on the other. It is found in predator-prey relationships. |
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Term
| Describe how predator/prey relationship between wolf and deer causes coevolution. |
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Definition
| The deer and wolves causes the slower deer to die out b/c they get eaten and the faster ones to live and reproduce. The clumsy wolves die b/c they cannot catch the quick deer. |
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Term
| What is sexual selection? Provide an example. |
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Definition
| It is a type of natural selection that acts on traits involved in finding and acquiring mates. Ex: A male's colors, displays, and structures |
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Term
| Why do females prefer males with elaborate ornaments and displays? |
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Definition
| The offspring will gain the healthier alleles b/c color/displays often means that the male is healthier too. |
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Term
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Definition
| A type of natural selection that favors one extreme of a range of phenotypes. |
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Term
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Definition
| A type of natural selection that favors the average phenotype in the population. |
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Term
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Definition
| A type of natural selection that favors both extremes of a range of phenotypes. |
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Term
| What is balanced polymorphism? |
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Definition
| It is where 2 or more phenotypes are maintained in a population. |
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Term
| The presence of two different forms of hemoglobin in Africa is an example of balanced polymorphism. Explain why the normal and sickle cell allele have developed this relationship. |
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Definition
| This is b/c the people heterozygous for the disease are favored b/c they have resistance to malaria and do not have the disease. |
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