Lecture 19 Natural Selection and Adaptation Flashcards
What are the two types of selection?
Artificial vs natural
What is fitness
Ability to contribute genetics to generations compared to others in terms of viability and fertility
What is fitness otherwise known as?
Darwinian fitness
What is selective advantage?
When some individuals are better adapted to the environment they live in Compared to other organisms
What is an adaptation?
Trait that makes an organism better able to survive and reproduce
Is an adaptation that same as an ancestral trait?
No
What is the significance of adaptation?
Origin of how a trait is maintained in given environment
What is artificial selection?
Selection by humans to obtain a goal
What happens under the umbrella of artificial selection? (3) DGV
Plants and animals are domesticated
Experiments in genetics regarding selection
Evolving of vaccines
What is natural selection?
selection by abiotic or biotic environment
Does natural selection have a goal?
No
Does natural selection affect all species?
Yes
What are different ways to study adaptation? (3) MAE
Monitor connection between alleles and traits with the environment
Analyze genomic diversity. Genes selected on by natural selection would stand out
Experiments in the field and lab
what is positive directional selection?
When even the tiniest adaptation can spread throughout and environments
What happens to the graph when the frequency of an allele reaches 1?
The graph levels out
What is negative selection?
the selective removal of alleles that are deleterious.
How is the mean of distribution shown on a graph?
tick below where the hill peaks
What is stabilizing selection?
individuals with moderate or average phenotypes are more fit
What is directional selection?
single phenotype is favoured, causing the allele frequency to shift in one direction continuously
What is disruptive selection?
selects for two or more extreme phenotypes that each have specific advantages over intermediates (very beginning and end of graph)
As seeds became harder to find what happens to beaks on of the finches on the Galápagos Islands?
They became bigger
What happened to the population of finches as the number of seeds decreased?
The population fell
What does disruptive selection lead to?
Trait divergence
What does disruptive selection require?
Spatial heterogeneity or discrete resources
What is the struggle to determine agents of natural selection?
Thousands of measurements of selection
Selection demonstrates differences in fitness and evolutionary traits
And yet
Few convincing causes can explain the agent of natural selection
Is Connecting evolution to ecology is difficult?
Yes
In the moth example Dark form was caused by a dominant gene, called the
Cortex gene
What happened to the dark moth population when Industrial pollution blacked bark on trees on which they lived
The dark moth increase
Where do the moth in light form dominat?
Rural areas
After introduction of the UK Clean Air Act what happened to the population of dark moths?
Result in decline of dark moth frequency
What does the evolutionary response to changes in pollution levels reflect?
reflects the time it takes for a forest to “go back to natural” as well as the frequency of the melanic allele
Which types of areas do light mice live?
In light areas
Which types of areas to dark mice live in?
In dark areas
Most common enzyme deficiency in humans?
G6PD
How does G6PD affect us?
Causes severe anemia
What is the benefit of G6PD?
protects against malaria
When malaria is absent what is the frequency of A allele, and selection of anemia?
Less frequecy of A allele
Selection against anemia
When malaria is present what is the frequency of A allele, and selection of anemia?
higher frequency of A allele
Selection for resistance
What is the benefit of historic genomes?
allow tracking of allele over a long period of time
Is Natural selection faster than genetic drift?
Yes
How does natural selection affect alleles compared to random chance?
Natural selection causes a higher frequency of alleles than random chance
What is Evidence of natural selection on vitamin D deficiency that is ancient to modern genomes in the UK?
Vitamin D requires UV radiation which is very little in the UK
What is the benefit of DHRC7 genes?
Aids in vitamin D metabolism
What was Long term experimental evolutionary study done on?
E coli
How many flask were populated when studying Ecoli
24
Over how many generations was Ecoli studied for?
75,000
What liquid of Ecoli propagated in?
Propagated in minimal glucose citrate medium
What was the population of Ecoli like in the first 10,000 years?
populations rapidly increased in fitness, then decreased in their fitness over time
What does the thawing out of frozen samples of Ecoli allow?
Thawing out allows comparison of fitness between new and old generations
What was Novel key innovation in one population after 33, 000 generations?
One strain evolve ability to grow on citrate
What are open questions about adaptation?
What is the importance of pre existing genetic variation in populations vs new mutations?
Do the same vs different genes contribute to convergent adaptations in unrelated species?
How much of the genome is subject to ongoing adaptations?
