How do lethal recessive alleles remain in the population?

Explain how a lethal recessive allele can be maintained in a population. Lethal recessive alleles can be maintained if the individual organisms with them die before they reproduce.

Why does the recessive allele remain in the population?

While harmful recessive alleles will be selected against, it’s almost impossible for them to completely disappear from a gene pool. That’s because natural selection can only ‘see’ the phenotype, not the genotype. Recessive alleles can hide out in heterozygotes, allowing them to persist in gene pools.

Why doesn’t the recessive allele disappear from the population?

It is almost impossible to totally eliminate recessive alleles from a population, because if the dominant phenotype is what is selected for, both AA and Aa individuals have that phenotype. Individuals with normal phenotypes but disease-causing recessive alleles are called carriers.

Why the Huntington’s lethal allele remains in the human population?

Research on the evolutionary genetics of this disease suggests that there are two main reasons for the persistence of Huntington’s in human populations: mutation coupled with weak selection. The diagram at right shows how the Huntington’s allele is passed down.

IT IS SURPRISING:  What gives rise to new alleles genes in a population?

What condition allows for recessive genes to be preserved in the population?

If recessive alleles were continually tending to disappear, the population would soon become homozygous. Under Hardy-Weinberg conditions, genes that have no present selective value will nonetheless be retained.

Which is easier to remove from a population dominant or recessive alleles?

It is actually much easier to select against a dominant allele than it is to select against a recessive one, because if an individual has a dominant allele, the trait is exhibited.

Are lethal alleles common in humans?

], meaning the individual lethal alleles are generally rare, as predicted by mutation–selection balance.

What is special about Huntington’s disease that maintains this dominant and lethal disorder in the population?

Because the onset of Huntington’s disease is slow, individuals carrying the allele can pass it on to their offspring. This allows the allele to be maintained in the population. Dominant traits can also be maintained in the population through recurrent mutations or if the penetrance of the gene is less than 100%.

How can a lethal recessive gene stay in the gene pool?

Explain how a lethal recessive allele can be maintained in a population. Lethal recessive alleles can be maintained if the individual organisms with them die before they reproduce.

How can an allele that has a negative effect persist in a population?

They may be maintained by mutation

The mutation producing the deleterious allele may keep arising in the population, even as selection weeds it out. For example, neurofibromatosis is a genetic disease causing tumors of the nervous system.

IT IS SURPRISING:  What does it mean to have an extra 21 chromosome?