case 4 Flashcards
evolution
What is Directional selection?
Directional selection: shifts the overall makeup of the population by favoring variants that are at one extreme of the distribution. Occurs when conditions favor individuals exhibiting one extreme of the phenotypic range, thereby shift a population’s frequency curve for the phenotypic.
de curve veschuift
What is Disruptive selection:
favors variants at both of the distribution. Occurs when condition favors individuals in both extremes of a phenotypic range over individuals eith intrtmediate phenotypes.
de curve word tweecurve met de hoogste punt van de vorige curve nu de tal tussen de twee nieuwe curve
What is the difference between intrasexual selection and intersexual selection?
Intrasexual selection is competition in the same sex for sexual mating. Individuals of one sex compete directly for mates of the opposite sex. (not necessarily fighting also in looks) Intersexual selection is one sex has a preference over another certain sex (this can lead to diseases like sickle cell or malaria (heterozygous advantage makes individual resistant to malaria)) Individuals of one sex are choosy in selecting their mates from the other sex.
What is homology and analogy?
Homology is underlying similarities but functions differently. Similarities resulting from an common ancestor. Analogous features share in information but not common ancestry.
What is a p value?
How certain, how accurate
What is the bottleneck effect.
a sudden change in the environment, such as a fire or flood may drastically reduce the size of a population. A severe drop in a population size can cause bottleneck effect.
What is the founder effect?
When a few individuals become isolated from a lager population, this smaller group may establish a new population whose gene pool diggers from the source population.
What is gene flow?
the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes. Gene flow can result in two populations combining into a single population with a common gene pool. Allele transferred by gene flow can also effect how well populations are adapted to local environmental conditions
Explain frequency dependence selection and the negative and positive from it.
- Frequency-dependent selection: the fitness of a phenotype depends on how common it is in the population.
- Negative Frequency Dependence selection
Occurs when there is an increase in relative abundance and a decrease in fitness. THis type of selection favours traits that help maintain genetic diversity in a population. (Like left handedness as an advantage in combat)
- Positive Frequency Dependence Selection: THe fitness of a phenotype or genotype depends on the composition of a population.THe fitness of a phenotype increases as it becomes more popular in a population. Leads to reduced genetic diversity. (Fish that have the same colouration are more likely to form groups with each other than with other fish that look different. And this reduces genetic diversity).
what is phylogency
the evolutionary history of a species of group of species.
Explain an phylogenetic tree
The beginning is the rood than you get the branch the end is the tip.
What are the conditions of hardy-weinberg equilibrium and the consequence if condition does not hold.
Explanation, start condition than if it does not hold.
- No mutations
The gene pool is modified if mutations occur or if entire genes are deleted or duplicated
- Random mating
If individuals mate within a subset of the population, such as near neighbors or close relatives (inbreeding), random mixing of gametes does not occur and genotype frequencies change.
- No natural selection
Allele frequencies change when individuals with different genotypes show consistent differences in their survival or reproductive success - Extreme large population size
In small populations, allele frequencies fluctuate by change over time (a process called genetic drift) - No gene flow
By moving alleles into or out of populations gene flow can alter allele frequencies.
For what is hardy Weinberg used.
The hardy-weinberg equilibrium approach describes a population that is not evolving
Give the observations from natural selection and evolution in summary.
Observation 1&2; individuals in a population differ in their heritable traits. Observation 3: organisms produce more offsprings than be supported
Give the conclusions of natural selection and evolution in summary
Conclusion 1: individuals that are well adapted on average survive longer (an thus leave more offsprings) conclusion 2: over time selected characteristics will increase in frequency in the population.
