Flashcards
Natural and Artificial Selection
Cards in this deck (35)
- 1Artificial Selection: The modern dairy cow
- 2What is Polypoidy?doubling of the diploid nucleus, so that the nucleus can contain more than one diploid set of chromosomes.
- 3Artificial Selection: Modern Bread Wheat
- 4What is Evolution?Change in allele frequency. The complete range of alleles present in a population is called the gene pool. New alleles are usually generated by mutations in genes.
- 5Allele FrequencyHow often an alleles occurs in a population. Its usually given as a percentage.
The frequency of an allele in a population changes over time - evolution. - 6How does Natural Selection work?
- 7When is an allele advantageous?With the right selection pressure. Without a selection pressure, natural selection won't take place.
- 8Stabilising Selection
- 9DIRECTIONAL SELECTION
- 10What is Genetic Drift?A process by which evolution occurs. Instead of environmental factors affecting which individuals survive, breed and pass on their alleles, chance dictates which alleles are passed on.
- 11How does Genetic Drift work?
- 12How do Natural Selection and Genetic Drift work alongside each other?To drive evolution, but one process can drive evolution more than the other than depending on population size.
- 13When does evolution by genetic drift have a greater effect?Evolution by genetic drift usually has a greater effect in smaller populations where chance has a greater influence. In larger populations chance variations in alleles frequency tend to even out across the whole population.
- 14What is a Genetic Bottleneck?An event (i.e. natural disaster) that causes a big reduction in the population's size, leading to a reduction in gene pool. (i.e. Peppered moth during Industrial Revolution)
- 15What is the purpose of the Founder effect?It describes what happens when just a few organisms from a population start a new population and there are only a small number of different alleles in the initial gene pool.
- 16Founder Effect:
- 17What are other reasons for which the founder effect may occur?Migration leading to geographical separation or if a new colony is separated from the original population for another reason, such as religion.
- 18What is the purpose of the Hardy-Weinberg Principle?iIt predicts the frequency of alleles in a population won't change from one generation to the next.
- 19Which conditions should be met for the Hardy-Weinberg Principle to be true?Large populations where there's no immigration ,emigration, mutations or natural selection. There also needs to be random mating - all possible genotypes can breed with all others.
- 20What do the Hardy-Weinberg equations do?They can be used to estimate the frequency of particular alleles and genotypes within populations.
- 21What happens if the allele frequencies do change between generations?This means that immigration, emigration, natural selection or mutations have happened.
- 22Hardy Weinberg allele frequency: Hardy Weinberg Genotype frequency:p + q = 1
p^2 +2pq +q^2 = 1 - 23Artificial selection in dogsModern pedigree dog breeds are all descendent from single wolf-like ancestor. Each breed has gone through many generations of artificial selection to produce the dogs we know today. Pedigree dogs e.g. pugs: flat, squashed up faces - breathing problems due to exaggerated features.
- 24What does a reduced gene pool tend to result in?An increased incidence of genetic disease. Problems like there mean that there are ethical issues surrounding the use of artificial selection.
- 25Define speciesA group of similar organisms that can reproduce to give fertile offspring.
- 26Define SpeciationThe development of a new species. It occurs when populations of the same species become reproductively isolated- changes in allele frequencies cause change in the phenotype that mean they can no longer breed together to produce fertile offspring.
- 27When does geographical isolation happen?When physical barrier divides a population of species - floods, volcanic eruptions and earthquakes. Conditions on either side of the barrier will be different, e.g. different climate. Because environment>different on each side, different characteristics will be more common due to nat.select. (because there are different selection pressures).
- 28Why will allele frequency change in each population?Because different characteristics will be advantageous on each side.
Mutations will take place independently.
The changes in allele frequency will lead to changes in phenotype frequencies, e.g. the advantageous characteristics will be more common on that side. - 29What happens eventually after Natural Selection has taken its course?Individuals from different populations will have changed so much that they won't be able to breed with one another to produce fertile offspring. The two groups become separate species. ALLOPATRIC SPECIATION.
- 30Why does reproductive isolation occur?Because changes in the alleles and phenotypes of the two population prevent them from successfully breeding together. Changes: Seasonal, Mechanical, or Behavioural.
- 31Seasonal ChangesSeasonal changes - individuals from the same population develop different flowering or mating seasons, or become sexually active at different times of the year.
- 32Mechanical ChangesChanges in genitalia prevent successful mating.
- 33Behavioural ChangesA group of individuals develop courtship rituals that aren't attractive to the main population.
- 34What is Sympatric Speciation ?Speciation without geographical- A population doesn't have to become geographically isolated to become reproductively isolated. Random mutations occur within a population, resulting in changes, preventing members of that population breeding with other members of the species.
- 35Example of Sympatric Speciation
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- A level Biology Flashcards on Natural and Artificial Selection, created by Sara R on 17/02/2017.
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- Sara R
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