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When does disruptive selection occur?
Disruptive selection occurs when there is selection against the heterozygous individual, causing the population of homozygous dominant and homozygous recessive individuals to increase, splitting the population into two groups corresponding to the dominant/recessive alleles.
Which natural selection select against both extremes?
Stabilizing selection.
What worm has natural selection against?
The cuckoo finch has evolved to out-compete the downy woodpecker in acquiring food, which has led to natural selection against the downy woodpecker.
How does natural selection work for or against an organism?
Natural selection reduces the number of fertile offspring an organism may raise.
Are dominant or recessive alleles easier to remove by selection?
Natural selection favors whatever allele provides a selective advantage, so in theory it can operate on either. However, if a recessive allele provides an advantage it will soon shift and become the dominant allele, so it could be argued that natural selection favors dominant alleles. This is only partly true. A dominant gene always has some effect on the characteristics of the organism, even if the owner only has one of them. A recessive gene only affects the characteristics if there is no equivalent dominant gene to mask the effect. If both parents possess the recessive gene there is a chance the offspring will have two of them and this will show in their characteristics. When this happens, natural selection operates on the recessive gene. Much of the time, a recessive gene is present but natural selection does not affect it because there is a dominant gene that masks the effect. If natural selection favours the recessive gene, the dominant gene will quite quickly disappear from the population. This does not make the recessive gene 'dominant' it's just tht there's no longer any competition. If selection favours the dominant gene however, the recessive gene can linger in the population for much longer, because even when it is present, it is not selected against for most of the time. That is why conditions like heamophilia survives for a long time in humans, and you suddenly discover a white deer after many years in a herd of brown deer.
Which type of natural selection in which the mean characteristics of a population are preserved?
This type of natural selection is called stabilizing selection because the mean traits of the population are being selected for against the immediate environment.
How environmental factors contribute to evolution by natural selection.?
Environmental factors ARE evolution by natural selection. The immediate environment is the selector of the organisms that are differentially successful against the immediate environment.
Does natural selection cause changes in the environment?
No, natural selection is the environment! The variant organism is selected against the immediate environment where it survives and reproduces better than it's conspecifics.
Why does selection act faster against a harmful dominant allele than a harmful recessive allele?
Selection acts faster against a harmful dominant allele because individuals with the allele will show the harmful trait, making them more likely to be removed from the population. In contrast, harmful recessive alleles are only expressed in homozygous individuals, making it harder for selection to act on them as carriers of the allele may not exhibit the harmful trait.
Which force of evolution makes a population more alike?
Stabilizing selection occurs when the extreme forms of some trait are selected against by natural selection. It is a force of natural selection which causes evolution (definition: change of allele frequency in a population divided by time).
Is considered an important factor in natural selection?
Mutation is the important " starter " of the adaptive change engendered by natural selection. Variation is key to selection and without variation in organisms there would be nothing to select from for the survival and reproductive success of the organism against the immediate environment.
What process would most likely act against any offspring with an allele for cataracts?
natural selection
