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Stabilizing selection reduces variation in a population by favoring the average phenotype, while selecting against extreme phenotypes. This can lead to a decrease in genetic diversity within the population as individuals with extreme traits are less likely to survive and reproduce. Over time, stabilizing selection tends to maintain a stable, intermediate phenotype.
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What effect does mutations have on variation?
Mutations are a source of genetic variation as they introduce new alleles into a population. They can lead to differences in physical characteristics, behavior, or susceptibility to diseases within a species. Over time, mutations can contribute to evolution by providing the raw material for natural selection to act upon, ultimately driving changes in a population.
Does natural selection require small population size?
No. Natural selection works in all populations. However, new alleles spread more slowly in large populations; the large size has a stabilizing effect. So one should expect large populations to change more slowly than smaller populations.
What is a genetic drift and when does it occur?
Genetic drift is the spread of specific random variations throughout the gene pool in the absence of specific selection pressures. There's always random variation in the population, but there aren't always changes in the environment for the population to adapt to. So natural selection, in stead of moving the population towards adaptation, might select from that random variation to move 'sideways', as it were, to a state that's equally well-adapted to the environment as what came before, but different. As random variation may produce many variants that are, more or less, equally well-adapted to their environment, the direction of evolution that results is more or less random. Because variations may spread throughout small populations faster than throughout large populations, and because a large gene pool has a stabilizing effect on the spread of variations, small populations drift faster than large populations.
Types of genetic drift?
There are two main types of genetic drift: population bottleneck and founder effect. Population bottleneck occurs when a population's size is drastically reduced, leading to a loss of genetic diversity. Founder effect occurs when a small group of individuals establishes a new population with limited genetic variation.
How are the bottleneck effect and founder effect related as examples of genetic drift in population genetics?
The bottleneck effect and founder effect are both examples of genetic drift in population genetics. The bottleneck effect occurs when a large population is drastically reduced in size, leading to a loss of genetic diversity. The founder effect happens when a small group of individuals establishes a new population, leading to a limited gene pool. Both effects can result in changes in allele frequencies and genetic variation within a population.
Why would stabilizing selection change the shape of a graph of phenotypes?
Stabilizing selection favors individuals with traits that are average or intermediate, reducing the frequency of extreme phenotypes. As a result, the distribution of phenotypes shifts towards the mean, leading to a narrower and taller bell-shaped curve on the graph. This change indicates a decrease in phenotypic variation, as the extremes are selected against, promoting a more uniform population. Over time, this stabilizing effect can enhance the fitness of the population in a stable environment.
What do stabilizing selection and directional selection have in common?
They both decrease genetic variation .
What are the two types of genetic drift?
There are two types of genetic drift, there is a the population bottle neck effect and the founder effect. The population bottle neck effect is when a population greatly decreases in size due to some random ecological event and the small population has a greater chance of genetic variation. The founder effect is a variation of the bottle neck effect in which a small portion of a larger population to branch off or get "isolated" from the larger population and have a greater chance of genetic variation. Have fun and hope this helps.
What do stabilizing selection and directional selection have in?
Aside from both being natural selection, not much. Let us use height in humans as our example.Stabilizing selection, the regression to the mean, keeps the height of humans pretty much with a normal distribution as the human environment is the whole earth. So humans are not too tall, or too short, generally ( pygmies excluded ), over all the human range and various environments.Now, with directional selection there would be a tendency for the human population to grow taller, or shorter over generations. We have seen this effect on humans in ancient times, Homo florensis, but in modern time stabilizing selection of human height, averaging out, is the norm.
How do mutations relate to natural selection?
Mutation, a copying error in the replication of DNA, can give rise to variation in an organisms phenotype and if this new phenotype is beneficial to survival and reproductive success ( as little as 1% ) it will be selected naturally against the immediate environment, then if this so selected organism leave many descendents with the same beneficial traits then the populations gene pool will change in allele frequency and you have evolution. ( a 19th century sentence Darwin would be proud of! )
What effect does mutations have on variation?
Mutations are a source of genetic variation as they introduce new alleles into a population. They can lead to differences in physical characteristics, behavior, or susceptibility to diseases within a species. Over time, mutations can contribute to evolution by providing the raw material for natural selection to act upon, ultimately driving changes in a population.
When does the new lizard population had less genetic variation than the original population because of?
the founder effect (Study Island)
The variation in the population as measured by the standard deviation has little or no effect in determining the size of a sample selected from the population True or False?
The answer is False
Does natural selection require small population size?
No. Natural selection works in all populations. However, new alleles spread more slowly in large populations; the large size has a stabilizing effect. So one should expect large populations to change more slowly than smaller populations.
What is a genetic drift and when does it occur?
Genetic drift is the spread of specific random variations throughout the gene pool in the absence of specific selection pressures. There's always random variation in the population, but there aren't always changes in the environment for the population to adapt to. So natural selection, in stead of moving the population towards adaptation, might select from that random variation to move 'sideways', as it were, to a state that's equally well-adapted to the environment as what came before, but different. As random variation may produce many variants that are, more or less, equally well-adapted to their environment, the direction of evolution that results is more or less random. Because variations may spread throughout small populations faster than throughout large populations, and because a large gene pool has a stabilizing effect on the spread of variations, small populations drift faster than large populations.
Types of genetic drift?
There are two main types of genetic drift: population bottleneck and founder effect. Population bottleneck occurs when a population's size is drastically reduced, leading to a loss of genetic diversity. Founder effect occurs when a small group of individuals establishes a new population with limited genetic variation.
What are the 2 things necessary for evolution to occur?
Answer 1Two broad processes that make evolution possible are 1 : directional forces including mutation , migration and selection and 2: nondirectional forces that include random genetic drift , bottleneck effect , founders effect ,and chance variations .Answer 2Evolution is most commonly described as a combination of reproductive variation and differential reproductive success.Reproductive variation in itself is a "non-directional" phenomenon, that produces mostly random variations. Differential reproductive success (or: natural selection) is a "directional" phenomenon, that basically acts as a mechanism limiting the set of "directions" produced by random variation.
