evolution module Flashcards
natural selection
alters gene frequencies, only mechanism that consistently leads to adaptive evolution
microevolution
change in allele frequencies in a population over generations
4 processes to produce evolution
- formations of new alleles 2. altering gene # and position 3. rapid reproduction 4. sexual reproduction
genetic variation
makes evolution possible, variation in individual genotype leads to variation in individual phenotype
mutation
change in nucleotide sequence of DNA. can cause new genes to be made. only mutations that are made in cells that produce gametes will be passed to offspring
harmless mutation
mutation that occurs in the non coding part of the DNA, mutation that does not effect the protein because of redundancy
harmful mutation
mutation that changes the way a protein is made and results in the protein being broken
beneficial mutation
Produces a new protein that helps the organism to survive in the world
harmful altering # of gene sequence
mutations that delete parts of the loci, and also duplicate large numbers of chromosome segments
less harmful altering # of gene sequence
duplication of smaller parts of of DNA can increase the genome size. Duplicated genes have the ability to take on new functions by further location
Rapid reproduction
mutation rates are lower in plants/animals and much higher in viruses
sexual reproduction
Can shuffle existing alleles into new combos of genotypes, cannot produce new alleles, but shuffling new alleles is more important than new alleles
Hardy-Weinberg principle
describes whether a population is evolving or not . If a population does not meet these criteria, it IS evolving
hardy-weinberg conditions (5)
- no mutations 2. random mating 3. no natural selection 4. extremely large population size 5. no gene flow
genetic drift
smaller sample=greater chance of deviation from a predicted result, describes how allele frequencies fluctuate unpredictably between generations, reduces genetic variations
founder effect
occurs when a few individuals become isolated from a larger population
bottleneck effect
sudden reaction in population size due to a change in the environment. The resulting gene pool may no longer look like the original gene pool
relative fitness
contribution an individual makes towards the gene pool of next generation relative to the contribution of others
directional selection
favors individuals at one end of the phenotypic range
disruptive selection
favors individuals at both ends of the extreme phenotypic range
stabilizing selection
favors intermediate variants and acts against extreme phenotypes
sexual selection
natural selection for mating success
sexual dimorphism
marked as differences between sexes in secondary sexual characteristics, result of sexual selection
intrasexual selection
within a sex, same sexes are competing for mates of the opposite sex ((often males)
intersexual selection
individuals of one sex are choosy in selecting mates from the other sex
diploidy
maintains genetic variation in form of hidden recessive alleles
balancing selections
natural selections maintains stable frequencies of of 2+ phenotypic forms in a population frequency
dependent population
fitness of phenotype depends on how common it is in the population
heterozygote advantage
individuals who have heterozygous genes at a particular locus have greater fitness than those who have homozygous genes.
effects of gene flow
- reduce differences between populations over time 2. more likely than mutations to change allele frequencies directly 3. can decrease fitness of a population
