Term
| What helped lead Darwin to his theory of why species changed? |
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Definition
| Malthus’ essay on limits to population growth and struggle |
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Term
| Because of the struggle for existence, forms that are better adapted to survive will leave more.... |
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Definition
| offspring and automatically increase in frequency from one generation to the next |
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Term
| What is natural selection the logical result of? |
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Definition
Superfecundity
Variation
Heritability |
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Term
| Why do organisms compete for survival? |
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Definition
| Organisms produce more offspring than - given the limited amounts of resources - can ever survive |
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Term
| What does the struggle for existence take place within? |
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Definition
| a web of ecological relations |
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Term
| Why does an organism compete most closely with other members of its own species? |
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Definition
| because they have the most similar ecological needs to its own. |
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Term
In every species, more eggs are produced than can survive to the adult stage
Why does excess fecundity exist? |
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Definition
| because there are inadequate resources in nature to support all the eggs that are laid and all the young that are born |
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Term
| What provides the preconditions for natural selection? |
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Definition
| The excess fecundity, and consequent competition to survive in every species |
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Term
| Review Slide 6 in Presentation 7 |
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Definition
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Term
| What are the 4 conditions for natural selection to occur? |
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Definition
Reproduction
Variation in individual characters among the members of the population.
Heritability
Variation in the fitness of organisms according to the state they have for a heritable character. |
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Term
| What is heritability (broad definition)? |
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Definition
| the proportion of variation (or variance) in a phenotypic character in a population that is due to individual differences in genotypes. |
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Term
| What is heritability (narrow definition)? |
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Definition
| the proportion of variation (or variance) in a phenotypic character in a population that is due to individual genetic differences that will be inherited in the offspring |
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Term
| When does natural selection occur? |
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Definition
| When we have differential survival and reproduction. |
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Term
| Describe what it means to have higher fitness? Describe the process. |
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Definition
- individuals in the population with some characters must be more likely to survive and reproduce
- The average number of offspring left by an individual with a certain genotype relative to the number of offspring left by an average member of the population or relative to the number produced by individuals of other genotypes. |
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Term
| In natural selection, why does incidental selection of other features occur? |
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Definition
| Because they are correlated with the fatures that are being selected. |
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Term
| Review Slide 12, Class 7. IT'S INTERESTING! |
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Definition
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Term
| What is the definition of adaptation? |
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Definition
| a phenotypic variant that results in the highest fitness among a specified set of variants in a given environment |
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Term
| For a character to be regarded as an adaptation, it must be a... |
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Definition
| derived character that evolved in response to a specific selective agent |
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Term
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Definition
| the evolution of a function of a character other than the function the character originally adapted to fulfill. |
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Term
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Definition
a
phenotypic variant that results in the highest fitness among
a specified set of variants in a given
environment |
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Term
| What does directional selection cause? |
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Definition
| causes a consistent directional change in the form of the population through time. |
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Term
| What does Stabilizing selection tend to do? |
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Definition
| keep the form of the population constant. |
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Term
| What does disruptive selection do? |
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Definition
| favors forms that deviate in either direction from the population average. |
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Term
| What are the four types of selection? |
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Definition
| Disruptive, directional, stabilizing, no selection |
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Term
| What are the two different types of variation in biology? |
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Definition
-characters of an organism which can vary among individuals at both the phenotypic and the genetic levels.
-variation in the fitness of individuals. |
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Term
| What are the 5 levels of variation in nature? |
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Definition
The morphologic level
The physiological level
The cellular level
The biochemical level
The DNA level |
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Term
| What are some sources of genetic variation in a population? |
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Definition
| mutation, recombination, migration |
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Term
| What is the "original" source of genetic variation? |
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Definition
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Term
| ? between chromosomes produces new chromosomes. |
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Definition
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Term
| if there is no ?, recombination and migration would not generate new genetic variants. |
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Definition
| pre-existing allelic variation |
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Term
| What are the 4 types of genetic mutations? |
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Definition
synonymous mutation
amino acid changing mutation
frame-shift mutation
stop mutation |
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Term
| Mutations do not arise in the direction of ? |
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Definition
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Term
| Filter variation by natural selection to produce adaptations: random or not random? |
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Definition
|
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Term
| Natural selection is the ? survival of ? variants. |
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Definition
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Term
| 5 Factors affecting the distribution of variation in natural populations |
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Definition
Natural Selection
Mutation
Genetic Drift
Inbreeding
Migration |
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Term
| When does random sampling occur? |
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Definition
| whenever a smaller number of successful individuals (or gametes) are sampled from a larger pool of potential survivors and the fitnesses of the genotypes are the same. |
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Term
| What kind of important evolutionary effects can random sampling have? |
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Definition
| genetic drift and the founder effect |
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Term
| Genes that form a new generation are a ? from the parental generation |
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Definition
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Term
| The frequency of alleles with the same fitness will ? through time |
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Definition
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Term
| If there are two alleles at a locus, and they have the same fitness, random sampling can cause their... |
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Definition
| relative frequencies in a population to change. |
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Term
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Definition
| Random changes for a gene in allele frequencies between generations |
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Term
| What does the rate of change of gene frequency by random drift depend on? |
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Definition
| the size of the population |
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Term
| Are random sampling effects more important in a bigger or smaller population? |
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Definition
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Term
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Definition
| the specific location of a gene or DNA sequence on a chromosome |
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Term
| The Hardy-Weinberg ratios are for neutral alleles at a locus and the Hardy-Weinberg result suggested that... |
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Definition
| the genotype (and gene) ratios are stable over time. |
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Term
| In a small population, gene frequencies drift about; one of the genes will eventually be fixed: and only then will... |
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Definition
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Term
| In a small population, gene frequencies drift about; one of the genes will eventually be fixed: and only then will... |
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Definition
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Term
| What is the true equilibrium of the Hardy-Weinberg system in a small population? |
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Definition
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Term
| Over the long term, in Hardy Weinberg Ratios, what causes the population to "march" towards homozygosity (decline in heterozygosity) at a locus? |
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Definition
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Term
| The rate of decline in heterozygosity is often used as a measure of what? |
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Definition
| the rate of genetic drift within a population. |
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Term
The rate of decline in heterozygosity is often used as a measure of the rate of genetic drift within a population.
If this process occurs in a large number of independent, non-interbreeding populations, the genetic composition of the populations would...? |
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Definition
|
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Term
| At any time, what does an allele’s probability of fixation equal? and what is it not affected by? |
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Definition
| its frequency at that time;its previous history of change in frequency. |
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Term
| The probability is finite, however, and if enough neutral alleles, at enough loci, and over enough generations, are randomly drifting in frequency, one of them will eventually.. |
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Definition
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Term
| For any allele, is fixation by random drift very probable or improbable? |
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Definition
|
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Term
| What is the founder effect? Who is credited with describing the founder effect? |
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Definition
| “The establishment of a new population by a few original founders (in an extreme case, by a single fertilized female) which carry only a small fraction of the total genetic variation of the parental population.”; Ernst Meyer |
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Term
| What is the he founding effect quite ineffective at? |
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Definition
| reducing genetic variation. |
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Term
| What is the most likely explantation for isolated populations often having exceptionally high frequencies of otherwise rare alleles? |
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Definition
| the founding population had a disproportionate number of those rare alleles. |
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Term
| Give an example of the founder effect and explain why it is an example of that? |
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Definition
| European Bison- last one killed in the wild in 1927, but 50 still survived in zoos. Today's population of approximately 3,000 has descended from about 12 individuals |
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Term
| Describe the founder effect being evident in amish communities |
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Definition
Ellis-van Creveld syndrome, involves not only short stature but polydactyly (extra fingers or toes), abnormalities of the nails and teeth, and, in about half of individuals, a hole between the two upper chambers of the heart.
It has been traced back to one couple, Samuel King and his wife, who came to the area in 1744. |
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Term
| Natural selection will act to eliminate any allele that decreases the ...? |
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Definition
|
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Term
| What is recurrent disadvantageous mutation? |
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Definition
| Selection can never finally eliminate the gene, because it will keep on reappearing by mutation. |
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Term
| In recurrent disadvantageous mutation, what is the equilibrium between? |
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Definition
| the mutant gene's creation, by recurrent mutation, and its elimination by natural selection. |
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Term
| What does the theory of neutral drift predict? |
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Definition
| populations should be completely homozygous |
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Term
| Give two examples of reduced polymorphism because of genetic drift. |
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Definition
By 1900 hunting of the northern elephant seal off the Pacific coast had reduced its population to only 20 survivors. The population today exceeds 100,000. However, these animals are homozygous at every one of genes that has been examined.
The lack of genetic variability in cheetahs is so profound that cheetahs will accept skin grafts from each other. 52/52 genes tested showed no polymorphisms. |
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Term
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Definition
| a form of nonrandom mating, which occurs when individuals are more likely to mate with relatives than nonrelatives. |
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Term
| With inbreeding in a finite population, ? is increased and ? is decreased over the Hardy-Weinberg level generated by random mating even though the allelic frequencies do not change each generation. |
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Definition
| homozygosity; heterozygosity |
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Term
| The important point is that inbreeding can happen in any breeding system with a small population, and becomes more likely the smaller or larger? the population |
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Definition
|
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Term
|
Definition
| The great tit- the less eggs hatch the more likely it is to inbreed because of less members in a population |
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Term
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Definition
| Gene flow between populations is due to movement of individuals from one population to another. |
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Term
| If unopposed by other factors, what does gene flow do? |
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Definition
| homogenizes the populations of a species or brings all populations to the same allele frequencies. |
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Term
| What happens in the absence of gene flow or low gene flow between populations? |
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Definition
| allele frequencies will differ among populations. |
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Term
| Genetic difference among populations typically correlates with...? |
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Definition
|
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Term
| What is effective population size? |
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Definition
| the number of individuals in a population who contribute offspring to the next generation. |
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Term
| Factors affecting the distribution of variation in natural populations? |
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Definition
Natural Selection
Mutation
Genetic Drift
Inbreeding
Migration |
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Term
| Any factor which increases the chance that copies of the same gene will combine in the same individual in the production of the next generation will lower what? |
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Definition
| the effective population size relative to the total number of adults |
|
|
Term
| What are the factors affecting the distribution of variation in natural populations? |
|
Definition
Natural Selection
Mutation
Genetic Drift
Inbreeding
Migration |
|
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Term
| In response to selection on phenotype, genotype frequency... |
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Definition
|
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Term
| Selection only works directly on ? not ? |
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Definition
|
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Term
| Selection only works directly on phenotype not genotype, which reduces or increases genotype frequency only as far as... |
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Definition
| how close the one to one match is between genotype and phenotype |
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Term
| The response to selection or evolution for polygenic traits (e.g., beak thickness) depends on the |
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Definition
| heritability of the trait |
|
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Term
| high narrow-sense heritability then have a large amount of |
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Definition
| additive genetic variability |
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Term
| What does directional selection reduce additive genetic variability with ? |
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Definition
|
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Term
| When ? are fitter than the ?, therefore, natural selection will maintain a polymorphism. |
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Definition
| heterozygotes; homozygotes |
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Term
|
Definition
| having multiple phenotypes within a population |
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Term
| What is one of several possible explanations for the existence of genetic variability in natural populations? |
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Definition
|
|
Term
| What is an example of heterozygous advantage? |
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Definition
| sickle cell anemia in areas of malaria in Africa. |
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Term
| When does frequency-dependent selection occur? |
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Definition
| when the fitness of a genotype depends on its frequency. It is possible for the fitness of a genotype to increase (positively frequency-dependent) or decrease (negatively frequency-dependent) as the genotype frequency in the population increases. |
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Term
| What is a Mendelian Population? |
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Definition
| a group of interbreeding, sexually reproducing individuals with a common set of genes: the gene pool. |
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Term
| The genetic composition of a population can be described in terms of what? |
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Definition
| frequencies, or relative abundances, in which alternative alleles are found. |
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Term
| Genotypes differ in ? from one population to another. |
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Definition
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Term
| What is population genetics concerned with? |
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Definition
| gene frequencies and genotype frequencies, and with the processes influencing these frequencies. |
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Term
| What is the most important, most fundamental body of theory in evolutionary biology? |
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Definition
|
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Term
| The coherence of an evolutionary hypothesis will usually remain in doubt until...? |
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Definition
| the hypothesis is expressed in the form of a population genetic model. |
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Term
| What does allele frequency measure? |
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Definition
| the frequency in the population of a particular allele relative to other alleles at one gene locus. |
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Term
| Why is H-W an equilibrium? |
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Definition
| because the new frequency of A or p’ is the same as the old frequency of A or p |
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Term
| What are the assumptions for the Hardy-Weinberg equilibrium? |
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Definition
Large population and random mating
No mutation, migration, and natural selection |
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Term
| What are the predictions for the Hardy-Weinberg equilibrium? |
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Definition
Allelic frequencies remain constant from generation to generation
2. Genotypic frequencies stabilize (will not change) after one generation in the proportions
HWE = AA: p2 Aa: 2pq aa:q2 |
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Term
| Three sources of interest in the Hardy-Weinberg ratio? |
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Definition
Historical and Conceptual interest
Deviations direct future research
Theoretical interest |
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