3 - Ch 21: Evolution Of Populations Flashcards
Microevolution meaning
Change in alelle frequencies in pop over gen, small changes in species over time
Phenotypic vs genetic variation
Genetic: differences in genes (whats passed down)
Phenotypic = differesences in physical
Discrete vs quantitative variation
Discrete - clear categories (eye color: blue, brown, green)
No blending!
-single gene location (Either or traits)
Quantitative - range of measurements (height , weight)
- multiple genes, 1 phenotypeo
refers to the average amount of genetic variation within a population. It measures how often individuals in a population have two different versions (alleles) of a gene,
Average heterozygosity
Refers to difference sin dna sequence of a gene bw indiv in population
Nucleotide variability
Refers to The genetic differences can be spread out across different locations, with some areas having more genetic variety than others.
Spatial genetic variation
2 causes of spatial genetic variation
- Geographic barriers (mountains, rivers)
- Environmental factors (climate differences)
2 causes of spatial genetic variation
- Geographic barriers (mountains, rivers)
- Environmental factors (climate differences)
It is a measure of how frequently new genetic changes happen in an organism or population.
Mutation rate
process during sexual reproduction where genetic material from two parents is combined to create new genetic combinations in their offspring.
Sexual recombination
2 causes of sexual recombination
Independent assortment and crossing over
Why is rna mutation rate fast
Single helix
Low mutation rates lead to population changes with __
Large Populations
Populations meaning
Group of indiv species in same place
total collection of all the genes and their variations (alleles) in a population. It includes all the genetic information available for reproduction in that population.
- it contains total traits that can be passed
Gene pool
5 H-W Assumptions for non evolving population
- No mutations
- Random mating
• pollinators going to each flower at same rate - No natural selection
• no animal prefer to eat pink or white flower - Big population size
- No gene flow
Let’s assume nothing is happening” and then testing if anything different or interesting shows up.
What is this called
Null model
Hardy - weinberg theory
describes the conditions under which allele frequencies in a population remain stable (not changing) from generation to generation,
meaning no evolution is occurring.
Genetic drift meaning
random change in the gene pool of a small population over time.
- It happens by chance, rather than through natural selection,
- can cause certain traits to become more or less common in a population.
4 effects of genetic drift
- Significant in small populations
- Reduce genetic variation
- Cause allele to change at random
- Harmful allele to become fixed
What is gene flow and whats it caused by
- gain or loss of alleles
Cause by
1. Movement of fertile indiv/ gametes
2. Reduce differences bw populations
Founder effect vs bottleneck in genetic drift
Founder effect = A small group starts a new population, losing genetic diversity.
Bottleneck effect = A large population is drastically reduced, causing a loss of genetic diversity.
3 modes of selection and explain them
Directional selection: One extreme trait is favored.
Disruptive selection: Both extremes are favored, and the middle is not.
Stabilizing selection: The middle trait is favored, and extremes are reduced.
Evolutionary vs relative fitness
Evolutionary fitness is the overall ability to survive and reproduce.
Relative fitness compares an individual’s reproductive success to others in the same group.
