Biology 1115 Chapter 23
Home > Flashcards > Print Preview
The flashcards below were created by user
on FreezingBlue Flashcards
. What would you like to do?
Natural selection acts on the __________________, but only __________ evolve.
- Phenotype of individuals
What is microevolution?
is a change in allele frequencies in a population over generations
What is an allele?
alterative variation of a gene that may produce distinguishable phenotypic results
What are the two process that produce genetic variation?
- sexual reproduction
Not all phenotypic variations are heritable, what is an example?
Natural selection can only act on variation with a ___________.
are changes in the nucleotide sequence of DNA.
Mutations cause ________ and _______ to arise.
Only mutations in cells that produce __________ can be passed to offspring
What is a point mutation? (2)
- change in one base in a gene
- doesn't change reading frame
Mutations in ____________ of DNA are often harmless.
why might mutations in a gene not affect protein production?
because of redundancy of the genetic code
Mutations that result in a change in protein production can be?
both harmful or increase the fit between organism and environment
How does sexual reproduction create new combinations?
sexual reproduction can shuffle existing alleles into new combinations
What is a population?
a localized group of individuals capable of interbreeding and producing fertile offspring
What is the lowest level evolution can act on?
what is a gene pool?
consists of alleles for all loci in a population
A locus is fixed if all individuals in a population are______________.
homozygous for the same allele
What does the Hardy-Weinberg Principle describe?
it describes a population that is NOT evolving
What does Hardy-Weinberg Principle state?
states that frequencies of alleles and genotype in a population remain constant from generation to generation
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2= 1
What is evolution?
a change in genetic composition of a population from generation to generation
what are the 5 conditions for non-evolving populations?
- no mutations
- random mating
- no natural selection
- extremely large population size
- no gene flow
The three factors that alter allele frequencies and bring about most evolutionary change are:
- genetic drift
- gene flow
- natural selection
Define genetic drift.
describes how allele frequencies fluctuate unpredictably from one generation to the next.
what is the most important thing that will help with genetic drift?
smaller the sample/population
Genetic drift tends to _________ genetic variation through losses of alleles
what is the founder effect?
occurs when a few individuals become isolated from larger population
what is the bottleneck effect?
a sudden reduction in population size due to a change in the environment.
Genetic drift is significant in ______ populations.
Genetic drift causes allele frequencies to change ___________.
Genetic drift can lead to a ______________ within populations.
loss of genetic variaion
Genetic drift can cause harmful alleles to become ___.
Define gene flow.
consists of the movement of alleles among populations
Gene flow tends to ____________ between populations over time.
Gene flow is more likely than mutation to ______________.
directly alter allele frequencies
Gene flow may either ___________ or ________ the fitness of a population.
decrease or increase
Define natural selection.
differential success in reproduction results in certain alleles being passed to the next generation in greater proportions
natural selection brings about adaptive evolution by acting on an organism's _______.
Only natural selection consistently results in ____________.
What mode of selection does directional selection favour?
favours individuals at one end or the other of the phenotypic range
What mode of selection does disruptive selection favour?
favours both extremes of the phenotypic range
What mode of selection does stabilizing selection favour?
favour intermediate variants and acts against extreme phenotypes
What would you like to do?
Home > Flashcards > Print Preview