Chapter 3 : Natural Selection Flashcards
What is evolution?
Change in frequency of individual organisms that differ genetically in one or more traits over time
What does natural selection operate on?
Traits (phenotype)
What are traits determined by?
Genotype
What are phenotypes controlled by?
Gene expression, environmental influence, and interactions of many genes
What is the primary source of genetic variation?
Genetic mutation
What is passed on in the process of inheritance?
Genes and their mutation
What do some traits cause in relation to fitness?
Survival and reproductive advantages
What does the example of the peromyscus polionotus (beach mice) illustrate?
Phenotypic variation
What does the a-MSH do to produce eumelanin?
It binds to Mc1R
What does the a-MSH produce?
Eumelanin (brown)
What does the ASP do to produce phaeomelanin (light)?
It blocks the a-MSH
What does ASP produce?
Phacomelanin
What does a mutation do to a protein?
Changes its shape and function
What can a mutation in the Mc1R gene lead to?
It inhibits a-msh binding and therefore alters phenotype frequencies
How does a phenotype that better matches and organisms environment affect them?
Higher fitness and higher ability to produce offspring more likely
What level does evolution by natural selection operate on?
The population level
What does natural selection do to populations over time?
Changes the frequencies of phenotypes/genotypes
What does fitness mean in terms of evolution?
The success of an entity in leaving descendants (their genes and alleles) to the next generation
What is another strong driving force in evolution?
Random processes like the environment suddenly shrinking
What does evolution by natural selection lack?
Foresight, meaning that it operates on current conditions and genetic variation
What is modern synthesis?
The combination of the principles of Mendelian genetics with evolution by natural selection
What is the norm of reaction?
A curve that represents the phenotype expressed by a given genotype as a function of environmental conditions
What is an adaptive trait?
Traits that enhance the ability to survive andreproduce in a given environment
What is pleiotropy?
The ability of a single gene to have multiple effects
What is antagonistic pleiotropy?
The same gene that codes for beneficial effects also codes for deleterious effects in other contexts
What did Lenski’s E.coli experiment show?
What are the three conditions of natural selection?
Variation, inheritance, and differential
