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Biology

Ch 16

QuestionAnswer
T/F Mendel's work on inheritance was published after Darwin's lifetime. false
Which 2 important factors was Darwin unable to explain without an understanding of heredity? He did not know the source of the variation that was so central to his theory. He could not explain how inheritable traits were passed from one generation to the next
3 Fields that collaborate today to explain evolution. 1genetics 2molecular biology 3evolutionary theory
A collection of individuals of the same species in a given area is a _______________ population
The combined gentic information of all members of a particular population is a ________________ gene pool
T/F The gene pool typically contains just one allele for each inheritable trait false
The number of timmes that an allele occurs in a gene pool compared with the number of times other alleles occur is called the __________ of the allele. relative frequency
Sources of Genetic Variation 1Mutations 2Genetic Shuffling
What is a mutation? any change in a sequence of DNA
Why do mutations occur? because the mistakes in the replication of DNA or as a result of radiation or chemicals in the environment
T/F Mutations can be lmtd to a single base of DNA true
T/F Mutations always affect lengthy segments of a chromosome false
T/F Mutations always affect an organisms phenotype false
T/F Mutations always affect an organisms fitness false
T/F Most inheritable differences are due to gene shuffling that occurs during the production of gametes true
T/F Sexual reproduction is a major source of variation in many populations true
T/F Sexula reproduction can produce many dif. phenotypes true
T/F Sexual reproduction can produce many dif. genetic combinations true
T/F Sexual reproduction can change the relative frequency of alleles in a population false
T/F The number of phenotypes produced for a given trait depends on how many genes control the trait true
T/F Most traits are controlled by a single gene false
T/F Natural selection on single-gene traits cannot lead to changes in allele frequencies false
If a trait made an organisms less likely to survive and reproduce, what would happen to the allele for that trait? It would disappear from the gene pool completely or fewer copies of an allele would be passed down to future generations
If a trait had no effect on an organisms fitness, what would happen to the alelle for that trait? The allele that produces this trait will not be under pressure from natural selection, and its frequency will remain unchanged
3 Ways natural selection can affect the distributions of phenotypes 1Directional selection 2Stabilizing Selection 3Disruptive Selection
What is directional selection? Individuals at one end of the curve have higher fitness then individuals in the middle or at the other end
What is stabilizing selection? Individuals near the center of the curve have higher fitness than individuals at either end
What is disruptive selection? Individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle
An increase in the average size of beaks in Galapagos finches is an example of ________ selection directional
T/F The weight of human infants at birth is under the influence of disruptive selection. false
T/F Natural selection is the only source of evolutionary change false
Random change in allele frequencies in small populations is called ________ genetic drift
A situation in which allele frequencies change as a result of the migration of a small subgroup of a population is known as the ____________ founder effect
What is an example of the founder effect? The evolution of several hundred species of fruit flies found on dif. Hawaiian Islands that descended from the same mainland population
What does the Hardy-Weinberg principle state? Allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change
The situation in which allele frequencies remain constant is called _________ genetic equilibrium
5 Conditions req to maintain genetic equilibrium 1Random mating 2Very large population 3No movement into/out of population 4No mutations 5No natural selection
Why is large population size important in maintaining genetic equilibrium Genetic drift has less effect on large populations
What is speciation? The formation of new species
T/F Individuals in dif species can have the same gene pool false
What does it mean for 2 species to be reproductively isolated from each other? Members of 2 populations cannot interbreed and produce fertile offspring
What must happen in order for new species to evolve? Populations become reproductively isolated from each other
3 Ways reproductive isolation occurs 1behavioral 2geographic 3temporal
When does behavioral isolation occur? 2 populations are capable of interbreeding but have dif. in courtship rituals or other types of behavior
T/F E and W meadowlarks are an example of behavioral isolation true
When does geographic isolation occur? 2 populations are separated by geographic barriers such as rivers, mountains, or bodies of water
Abert and Kaibab squirrels in the SW are an ex. of ___________ isolation geographic
T/F Geographic barriers guarantee the formation of new species false
What is an example of temporal isolation? 2 or more species reproduce at dif times (pollination)
T/F The basic mechanisms of evolutionary change cannot be observed in nature false
Hyp tested by Grants: T/F The finches beak size/shape -enough inheritable variation to provide raw material for nat. selection The dif. finch species are descendants of common mainland ancestor true/false
Hyp tested by Grants: T/F Differences in the finches' beak size/shape produce dif in fitness that cause nat selection, The evolution of finches is proceeding slow/gradually true/false
Observ. by Grants: T/F Dif. in beak size=more imp. for survival during wet season, When food for finches was scarce, individuals with the largest beaks were less likely to survie false/false
Observ by Grants: T/F Big beaked birds tend to mate w/ small beaked birds, Average size beak increased dramatically false/true
Speciation probably occurred in Galapagos finches 1Founders arrive 2Separation of populations 3Changes in the gene pool 4Reproductive isolation 5Ecological competition 6Continue evolution
Created by: K1