Chapter 20: Microevolution Flashcards
What are continuous traits that can be measured?
Quantitative
What are discrete character states or categories called?
qualitative
What are the two sources of phenotypic variation?
- environmental
- genetic
What are the two sources of genetic variation?
- rearrangement of existing alleles
2.mutations producing new alleles
_______ variation is where there are differences in alleles within a population
genetic
________ is the change in allele frequency within a population over time
microevolution
_______ _______ is the study of properties of genes in a population
population genetics
________ results in a change in the genetic composition of a population
evolution
T or F: Natural populations contain substantial genetic variation
True
genetic variation is required for ______ to occur
evolution
What are five ways to measure genetic variation?
- lengths of simple sequence repeats (SSRs)
- Sequences of individual genes
- Karyotypes
- whole genome sequencing
- single nucleotide polymorphisms
What principle predicts genotype frequencies?
Hardy Weinberg principle
With the Hardy Weinberg equilibrium, proportions of genotypes do not change in a population long as:
1.
2.
3.
4.
5.
- no mutation takes place
- no genes are transferred to from other sources
- mating is random
- The population size is very large
- No selection
frequency of first allele is __
p
frequency of the second allele is __
q
What is the hardy-weinberg principle equation?
p^2+2pq+q^2= 1
If all 5 assumptions for Hardy-weinberg equilibrium are true, allele and genotype frequencies do not ______ from one generation to the next
change
What makes populations vary from Hardy-Weinberg equilibrium?
- Natural selection might favor homozygotes over heterozygotes
- Individuals may choose to mate with genetically similar individuals
- Influx of individuals from other populations
- Mutations occurring
What are the five agents of evolutionary change?
- Mutation
- Gene flow
- Nonrandom Mating
- Genetic Drift
- Selection
What agent of evolutionary change:
-rates generally low
-other evolutionary processes usually more important in changing allele frequency
-ultimate source of genetic variation
-makes evolution possible
mutation
What agent of evolutionary change:
-movement of alleles from one population to another
-animal physically moves into new population
-drifting of gametes or immature stages of plants or animals into an area
-pollen and seeds can travel long distances
gene flow
What agent of evolutionary change:
- assortative mating
-disassortative mating
nonrandom mating
What type of mating has:
-phenotypically similar individuals mate
-increases proportion of homozygous individuals
assortative mating
What type of mating has:
-phenotypically different individuals mate
-produces excess of heterozygotes
disassortative mating
What agent of evolutionary change:
- in small populations, allele frequency may change by chance alone
-magnitude of genetic drift is inversely related to population size
-can lead to the loss of alleles in isolated populations and uncommon alleles are more vulnerable
-founder effect
-bottleneck effect
Genetic drift
What type of genetic drift is
-one or a few individuals disperse and become the founder of a new, isolated population
founder effect
What type of genetic drift is where a drastic reduction in population size due to drought, disease, other natural forces
Bottleneck effect
Endangered species experience severe population bottlenecks, which result in the loss of ______ _______
genetic variability
_______ favors some genotypes over others
selection
_______ selection- breeder selects desired characteristics
artificial
_______ selection- environmental conditions determine which individuals produce the most offspring
natural
______ relatives can harbor higher diversity than cultivated crops
wild
What three conditions must be met for evolution by natural selection to occur
1.
2.
3.
- variation must exist among individuals in a population
- variation among individuals must result in differences in the number of offspring surviving in the next generation
- variation must have a genetic basis
T or F: Natural selection is a process
TRUE
_______ is the historical record, or outcome, of change through time
evolution
result of ______ driven by natural selection is that populations become better adapted to their environment
evolution
selection to match _______ _______
is where :
- enzyme allele frequencies often vary with latitude
- allele frequencies of enzyme lactate dehydrogenase in fish vary geographically
- enzyme formed by these alleles function differently at different temperatures
climatic conditions
Selection for ______ and ______ ________
is where evolution of resistance to antibiotics in many disease-causing pathogens
pesticide, microbial resistance,
_________ is where individuals with one phenotype leave more surviving offspring in the next generation than individuals with an alternative phenotype
fitness
The most fit phenotype is assigned fitness value of ___
1
What are the four components of fitness:
1.
2.
3.
4.
1.survival
2. sexual selection
3. number of offspring per mating
4. traits favored for one component may be a disadvantage for others
selection favors phenotypes with the greatest _______
fitness
phenotype with greater fitness usually increases in _______
frequency
males and females usually differ in how they attempt to maximize ______
fitness
reproductive strategies:
females evaluate a male’s quality and then decide whether to ____
mate
______ ________ refers to the energy and time each sex invests in producing and rearing offspring
parental investment
______ have a higher parental investment
females
______ face very different selective presssures
sexes
in _______ care, mater choice should be more equal
biparental
______ selection has competition for mates
sexual
________ selection- competitive interactions between members of one sex
intrasexual
_______ selection-mate choice
intersexual
______ _____ characteristics used to combat other males or to persuade members of opposite sex
secondary sexual
_______ _______- differences between sexes
sexual dimorphism
______ ______- selects for features that increase probability that a male’s sperm will fertilize theeggs
sperm competition
________ selection- individuals of one sex ( usually males) compete with each other for the opportunity to mate
intrasexual
_______ selection has the active choice of a mate
intersexual
______ ______ - only genetically superior mates survive with a handicap such as a long tail that is a hinderance in flying
handicap hypothesis
______ _______- evolution in males of signal that exploits preexisting biases
sensory exploitation
some courtship displays appear to have evolved from a predisposition in females to respond to certain ______
stimuli
__________-________ selection: is where fitness of a phenotype depends on its frequency within the population
Frequency-dependent
__________ frequency-dependent selection:
-rare phenotypes favored by selection
-rare forms may not be in “search image”; preyed upon less frequently
negative
__________ frequency-dependent selection
- favors common form
-tends to elimante variation
positive
_______ selection is where selection favors one phenotype at one time and another phenotype at another time
oscillating
________ selection’s effect will be to maintain genetic variation in the population
oscillating
___________ advantage:
Heterozygotes are favored over homozygotes
heterozygote
What is an example of heterozygote advantage?
sickle cell allele
_______ operates on all the genes for the trait
selection
Selection changes the population depending on which ______ are favored
genotypes
What are the three types of selection?
- disruptive
- directional
- stabilizing
_________ displacement can cause disruptive selection
character
______ selection acts to eliminate intermediate types
disruptive
_______ selection is where it acts to eliminate one extreme
directional
_________ selection is where it acts to eliminate both extremes
stabilizing
________ selection often occurs in nature when the environment changes
directional
_________ selection makes intermediate more common by eliminating extremes
stabilizing
________ and _______ _____ may counter selection
mutations and genetic drift
In nature, _______ rates are rarely high enough to counter selection
mutation
_______ is nonrandom
selection
_______ _______ is random
genetic drift
________ may decrease an allele favored by selection
genetic drift
________ usually overwhelms drift except in small populations
selection
Gene flow can be
1.
2.
constructive
constraining
_______ gene flow, spread beneficial mutation to other populations
constructive
_______ gene flow can impede adaptation by continual flow of inferior alleles from other populations
constraining
What are the two limits of selection?
- multiple phenotypic effects of alleles
- lack of genetic variation
________ variation may not genetic basis
phenotypics
What are the five agents of Microevolutionary change?
- mutation
- gene flow
- genetic drift
- natural selection
- nonrandom mating
________ is heritable change in DNA
mutation
_________ effect on genetic variation is that introduces new genetic variation into population; does not change allele frequencies quickly,
mutation
mutation effect on average fitness is:
unpredictable effect on fitness; most mutations in protein-coding genes lower fitness
________ is the change in allele frequencies as individuals caused by chance
gene flow
The _____ ______effect on genetic variation is where it may introduce genetic variation from another population
gene flow
speciation can result from long-term _______
microevolution
Species limits can be tested by measuring _______ frequencies
allele
