Exam II Flashcards
1
Q
(first notes)
Genetic Diversity (in populations)
A
Five Big Sources
- Mutation
- Gene Flow
- Non-Random Mating
- Genetic Drift
- Natural Selection
2
Q
Mutation
A
- changes to DNA sequence
- creates new alleles (form of a gene)
- dominant
- recessive
- deleterious
- lethal
- rate of mutation is very low (1 in 100,000 cell divisions per gene)
- somatic mutations are largely irrelevant to evolution-not inherited
- germ line mutations can be inherited
3
Q
Gene Flow
A
- introduction of alleles from outside the population
- dispersal
- immigration brings alleles into your population
- emigration takes alleles
- reproduction then transmits to next generation
4
Q
Non-Random Mating
A
- creates non-random genotype frequencies
- genotype: combination of alleles
- assortative mating: mates chosen based on similarity
- creates homozygotes
- inbreeding as extreme case
- disassortative mating: mates chosen based on dissimilarity
- creates heterozygotes
- hybrid vigor as extreme case
5
Q
Genetic Drift
A
- random fluctuations in allele frequencies due to “sampling”
- fluctuations in allele frequencies occur among generations
- in large populations, fluctuations are cyclic
~ no long-term change in allele frequencies - in small populations, fluctuations can cause elimination of some alleles
~permanent change in allele frequencies
6
Q
Genetic Drift- Founder Effect
A
- occurs when new population is established
- only small number of individuals from source population
- limited genetic (allelic) diversity in new population
- classic examples: islands
7
Q
Genetic Drift- Bottleneck Effect
A
- occurs when population is reduced to very small numbers
- only small number of individuals survive
- eliminates genetic (allelic) diversity in next generation
- classic examples: endangered species (think cheetahs)
8
Q
Natural Selection
A
- some alleles (or allele combinations) confer an advantage
- this advantage is called fitness which refers to:
- survival and reproduction
- if “who wins and who loses” is tied to the fitness differences of their heritable traits, then natural selection is occurring
9
Q
Patterns of Selection
A
- Directional selection: traits at one end of the continuum of possibilities are more fit (peak shifts)
- Stabilizing selection: traits at one end of the continuum of possibilities are more fit (distribution gets narrower)
- Disruptive selection: traits at one end of the continuum of possibilities are more fit (two peaks form)
10
Q
(second notes)
Prokaryotes
- metabolic diversity
- bacteria v. archaea
A
- kary: refers to nucleus (pro- do not have)
- characteristics
- unicellular
- ver small
- no nucleus
- no organelles
- circular DNA (not literally circular, but very short)
- metabolic diversity
11
Q
Metabolic Diversity (Photoautroph)
A
- photoautotroph (photosynthesizers)
- source of carbon: CO2
- source of energy: light
~ oxygenic: like eukaryotes; use H2O as electron donor; O2 evolved as byproduct - chemoautotroph
- source of carbon: CO2
- source of energy: inorganics
~ oxidize inorganic substances to take electrons
~ equivalent of using metals as substitute for the sun
11
Q
Metabolic Diversity (Photoautroph)
A
- photoautotroph (photosynthesizers)
- source of carbon: CO2
- source of energy: light
~ oxygenic: like eukaryotes; use H2O as electron donor; O2 evolved as byproduct
12
Q
Metabolic Diversity (Chemoautotroph)
A
- chemoautotroph
- source of carbon: CO2
- source of energy: inorganics
~ oxidize inorganic substances to take electrons
~ equivalent of using metals as substitute for the sun
13
Q
Metabolic Diversity (Photoheterotroph)
A
- photoheterotroph
- source of carbon: organics
- source of energy: light
~ photosynthesis can make ATP, but not fix carbon
~ carbon must be absorbed
14
Q
Metabolic Diversity (Chemoheterotroph)
A
- chemoheterotroph
- source of carbon: organics
- source of energy: organics
~ the eaters: “eat” to get carbon and to get energy
~ you and me and prokaryotes
