chapter 4 Flashcards
microevolution
- small scale evolution
- i.e. changes in allele frequency from one generation to the next
macroevolution
- large scale evolution
- i.e. a speciation event that occurs after hundreds or thousands of generations
what is the hardy-weinberg law of equilibrium?
set up to predict genotype frequencies in the next generations
the 5 conditions of the hardy-weinburg equilibrium
- no mutation
- no gene flow
- large population
- random mating
- no natural selection
hardy-weinburg equation
p^2 + 2pq + q^2 = 1
point mutations
- single dna sequence change happening (a single A/T/C/G changing to another letter)
- can be synonymous or non-synonymous
synonymous
ends up with the same amino acid
non-synonymous
ends up with a different amino acid
frameshift mutations
when you LOSE one of the base letters (A/T/C/G), then everything shifts, and you end up with a new amino acid
“reverse” mutations
inversion of amino acid sequences
spontaneous mutations
happen randomly
induced mutations
we all have dna repairing processes; on occasion it does not work and we end up with different types of mutations
chromosomal duplication mutations
- duplications of chromosomes
- i.e. trisomy 21 or klinefelter’s syndrome
lactose intolerance mutations
a mutation in the gene responsible for producing lactase, the enzyme that breaks down lactose
different types of mutations
- point mutation
- frameshift mutation
- reverse mutation
- spontaneous mutation
- induced mutation
- chromosomal duplication
- lactose intolerance
patterns of natural selection
- directional selection
- stabilizing selection
- disruptive selection
directional selection
- when one extreme form of a trait is favored
- i.e. larger brains in humans
stabilizing selection
- favors the average version of a trait
- i.e. birth weights in the middle of the range have a better chance of surviving and reproducing then higher or lower weights
disruptive selection
- when both sides of the extreme form of a trait is favored
- can lead to speciation of both extremes
lactase persistance
the continued production of the enzyme lactase into adulthood, allowing individuals to digest lactose
the connection between sickle-cell and malaria
if you are heterozygous, sicke-cell will help you with malaria
genetic drift
- a random change in the frequency of alleles
- i.e. the founder effect or bottleneck effect
the founder effect
- when a small group of individuals establishes a new population
- if a few individuals from a bird population colonize a distant island, the new island population may have different allele frequencies, potentially leading to significant evolutionary changes over time
the bottleneck effect
- when a significant portion of a population is suddenly reduced due to an event (like a natural disaster), leading to a loss of genetic diversity
- a forest fire wiping out a population of animals, the genetic makeup of the surviving small group may not represent the larger population from which it came
