In the next generation that trait increases in frequency above the frequency in the current generation.
It will increase in frequency.
Change in the allele frequency within the gene pool. ?
Evolution, of course. Evolution can happen without natural selection in some cases; drift, flow. Generally though, natural selection causes evolution and then, by definition, would come first.
No, but adaptive change would be difficult. Remember, evolution is the change in allele frequency over time in a population of organisms. Mutation, genetic drift, genetic flow and other processes would continue without natural selection.
The absence of the selection pressure malaria. Without selection, in the form of the malarial environment, the sickle cell allele will be lost in the overall US population. Even the heterozygous condition is somewhat deleterious and, statistically without malarial selection pressure the allele will be selected out.
Allele frequency is stable
Change in the allele frequency within the gene pool. ?
When nothing happens to exert strong population pressure on that population, natural selection favors the allele frequency already present. When mutations cause new traits, natural selection weeds these traits out because they're not as efficient as the others.
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).
Adaptive change is the province of natural selection and natural selection is one of the main drivers of evolution. Natural selection selects from the individuals variations in a population of organisms on, basically, reproductive success and this adaption is passed on to progeny which changes the allele frequency in the population which is evolution.
Perhaps not much as the recessive allele is masked in heterozygous condition. Depends on penetration and expresivity of the lethal allele, but any homozygous expression is fatal, so one can expect negative frequency selection; the freqiency is kept low by selection.
In terms of a population, evolution is just the change of allele frequencies over time. Natural selection can cause certain advantageous alleles to increase in frequency, and detrimental alleles to decrease in frequency.
Evolution, of course. Evolution can happen without natural selection in some cases; drift, flow. Generally though, natural selection causes evolution and then, by definition, would come first.
Evolution is the change in allele frequency over time in a population of organisms. By mutation, genetic drift, gene flow and natural selection.
Recessive genes are replaced by dominant genes over time and unfavorable genes die out.
No, but adaptive change would be difficult. Remember, evolution is the change in allele frequency over time in a population of organisms. Mutation, genetic drift, genetic flow and other processes would continue without natural selection.
A simplified explanation. Natural selection is the nonrandom survival and reproductive success of randomly varying organisms who by this reproductive success change the allele frequency over time in populations of organisms, which is evolution.
The absence of the selection pressure malaria. Without selection, in the form of the malarial environment, the sickle cell allele will be lost in the overall US population. Even the heterozygous condition is somewhat deleterious and, statistically without malarial selection pressure the allele will be selected out.