Evolution Flashcards
The 1918 flu pandemic triggered a ‘cytokine storm’
What is this?
When people with strong immune systems are more likely to be affected severely
How does the immune system recognise influenza?
By detecting a protein on the viral surface called hemagglutinin
The process by which ne w genetic variants sweep a population is
Positive slection
A phenotypic characteristic that has made it more likely for an organism to survive and reproduce is
An adaptation
What is a phenotype?
A physical expression of an organisms genes
What name is given to traits which are determined by genes to some degree
Heritable traits
When did the field of poulation genetics begin to develop?
What triggered this?
1930s and 1940s
The rediscovery of George Mendel’s publications
Which field seeks to undestand the patterns of genetic variance, as well as the underlying mechanisms which cause changes in gene frequency?
Population genetics
What name is given to the different forms of a gene?
Alleles
Alleles are found at
Loci
What name is given to the sum of all alleles at alll loci in a population?
The gene pool
What produced many important crops such as cabbage and brussel sprouts?
The artificial selection of a european species of wild mustard
Why can one genotype produced a variety of phenotypes?
Environmental factors can influence devlopment, impactnig the way in which the genotype is expressed
What name is given to local interbreeding groups?
Mendelian populations
What is a polymorphic population?
One that has more than one allele at a locus
What is the allele frequency of a monomorphic population at a given locus?
1
The allele is fixed
What describes a populations genetic structure?
Allele frequency
Genotype frequency
What models describes the conditions under which evolution does not occur?
Hardy-weinberg equilibrium
What prediction can be made using the Hardy-Weinberg model?
Approximate gene frequencies can be estimated from allele frequencies
What can restore genetic variance in a population?
Mutations
Rates at which mutations occur on a single locus are
Low
Little deviation from Hardy-Weinberg equilibrium
What is a population bottleneck?
A period in which only a small number of individuals within a population are succesfuly reproducing
What effect does a population bottleneck have on genetic variation?
It decreases it substantially
What is the founder effect?
Loss of genetic variation in the establishment of new populations
What does natural selection act on directly?
The phenotype
Which evolutionary effect confers adaptation?
Natural selection
What determines the fitness of a phenotype?
The relative rates of survival and reproduction of individuals with the phenotype
Do changes in reproductive rates across a population change the genetic structure?
Not usually
What effect preserves average characteristics?
What happens to the bell curve?
Stabilising selection
It is squeezed tighter
What effect shifts characteristics over time?
What happens to the bell curve?
Directional selection
It shifts to the right/left
What effect favors characteristics in opposite directions from the mean?
What happens to the bell curve?
Disruptive selection
It becomes bimodal
The effect that favours traits improving ability to compete for mates is
Intrasexual selection
The effect that favours traits making individuals more attractive to mates is
Intersexual selection
What kind of selection may favour traits that decrease survival rates?
Sexual selection
What is an ‘honest signal’
A demonstration of ability to survive in an environment
What kind of mutations does natural selectrion not act on?
Neutral mutations
What effect can change the frequency of neutral mutations?
Genetic drift
What are the short term disadvantages of sexual reproduction?
Recombination breaks up adaptive combinations
Seperation in to gender reduces overall reproductive rate
Give some advantages of sexual reproduction
Eliminates deleterious mutations
Repairs errors in DNA
Variation can aid defense against pathogens
What is muller’s ratchet?
When an asexual organism accumulates deleterious mutations over time.
What is the rare case in which an asexual organism can lose a deleterious mutation
Back mutation
How does sexual reproduction affect natural selection?
It does not act directly.
It generates new combinations of alleles for natural selection to act upon
