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,