Chapter 14 Flashcards
Who first explained natural selection as a mechanism of evolution in his writings?
Hint: C _ _ _ _ _ s D _ _ _ _ n.
Charles Darwin.
What is natural selection?
Individuals with beneficial traits are more likely to survive and pass these traits onto offspring.
What are adaptive phenotypes?
They are traits that are favorable in the environment.
True or false: favorable characteristics are universal.
False, favorable characteristics are usually suited to a particular environment.
What observations led Darwin to believe that species evolve rather than remain fixed? Hint:
1) F _ _ _ _ _ s resemble living organisms.
2) G _ _ _ _ _ _ _ _ _ _ l P _ _ _ _ _ _ s suggested that lineages change as organisms move to new habitats.
3) I _ _ _ _ _ s have diverse animal and plants that are related yet different from their mainland sources.
Fossils, Geographical Patterns, Islands.
What is descent with modification? Hint: think of finches with varying beaks to accommodate different food sources.
Organisms evolve from a common ancestor but develop different adaptations based on needs.
Evidence of evolution:
1) F _ _ _ _ l R _ _ _ _ _ s show that living organisms resemble once living organisms.
2) E _ _ _ _ _ s develop similarly.
Fossil Records, Embryos
What is a homologous structure? List an example. Hint: what do humans and bats have in common?
A structure derived from the same body part present in an ancestor. Humans and bats have similar bones in their arms, indicating they evolved from a common ancestor.
What is an analogous structure? List an example. Hint: how are birds and bats similar despite not being related?
They are similar-looking structures in unrelated lineages. Bats and birds have wings but are not related.
What is convergent evolution? Hint: why do birds and bats have wings despite not being related?
Two species can develop similar looking structures- despite not being related- if is an advantage in their environment.
What conditions must be present for the allele frequency of a gene to never change over generations?
1) Large P _ _ _ _ _ _ _ _ n
2) Random M _ _ _ _ g
3) No M _ _ _ _ _ _ n
4) No M _ _ _ _ _ _ _ n
5) No N _ _ _ _ _ l S _ _ _ _ _ _ _ n
Large Population, Random Mating, no Mutation, no Migration, no Natural Selection.
What happens when a population reaches Hardy Weinberg equilibrium? Hint: its genotype frequencies don’t c _ _ _ _ e over generations.
Change.
Mutation is r _ _e, but is the ultimate source of genetic variation. Mutation could change allele frequency.
Rare
Mutation is r _ _e, but is the ultimate source of genetic variation. Mutation could change allele frequency.
Rare
True or false: mutation could be adaptive (increases the frequency of good alleles) or deleterious (decreases the frequency of good alleles).
True.
True or false: migration DOESN’T increase and decrease frequency of good alleles
False, it could increase or decrease the frequency of good alleles.
What is genetic drift?
Refers to a change of allele frequencies in a SMALL population from generation to generation solely because of randomness in the chance for reproduction.
What is founder’s effect?
A few individuals migrate and become the founders of a new, isolated population away from their place of origin.
True or false: genetic drift merely increases the frequency of good alleles.
False, it could increase or decrease the frequency of good alleles.
True or false: Nonrandom mating can change genotype frequencies without changing allele frequencies.
True.
Natural selection does NOT increase the frequency of good alleles over generations.
False, those with good alleles are more likely to survive and pass on traits.
True or false: an allele is considered good or bad relative to its environment.
True.
What is disruptive selection?
Two extremes in an array of phenotypes become more common in a population.
What is directional selection?
Eliminates one extreme from an array of phenotypes.
