Genetic variation. If there were no variation in the genes/phenotype then natural selection would have nothing to select from.
genetic variation
The characteristic within the population that causes natural selection to occur is that individuals within a given population are not all identical because they vary. The other characteristic that causes natural selection to occur is that some variants are better than the others.
There must be genetic variation, the variation must be heritable, and there must be differential reproduction (due to competition).
Natural selection seems to be the only selection that can drive speciation with powerful adaptive change. Sexual selection seems to stay within the species and both gene flow and genetic drift do not seem to drive speciation very well.
A population will most likely evolve when there is a small population, mutations exists, natural selection may take place, nonrandom mating occurs, and/or gene flow may occur. Sexual selection, genetic drift, Gene flow, Mutation, and natural selection are five ways a population can evolve. Sexual selection is natural selection arising through preference by one sex for certain characteristics in individuals of the other sex. Genetic drift is variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce. Gene flow is the transfer of alleles or genes from one population to another. Mutation is the changing of the structure of a gene, resulting in a variant form that may be transmitted to subsequent generations, caused by the alteration of single base units in DNA, or the deletion, insertion, or rearrangement of larger sections of genes or chromosomes. Natural selection is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution.
In its simplest definition, evolution is the change of allele frequencies within a population over time. There are two main ways an allele can change in frequency: # Natural selection-- alleles that are beneficial will rise in frequency due to natural selection, while those that are detrimental will fall in frequency (and even be lost entirely) # Genetic Drift-- alleles can change in frequency from generation to generation due to chance factors, such as sampling error. It is the primary reason for frequency change in selectively neutral alleles. Very small populations are particularly prone to this kind of change, although all finite populations experience genetic drift to some degree.
Variations within populations is what natural selection is " looking " for. That one variant of a population is somewhat better able to survive and reproduce than other variants against the backdrop of the immediate environment is natural selection.
genetic variation
The characteristic within the population that causes natural selection to occur is that individuals within a given population are not all identical because they vary. The other characteristic that causes natural selection to occur is that some variants are better than the others.
Charles Darwin's theory of evolution by natural selection related to the origin of structural and physiological adaptations because : Natural selection is when a certain organism adapts to its environment changes . For example , The Box Jellyfish has been existing befor the Dinasours which eventually helps us understand that it adapted to the changes in its environment in order for it to not extinct . It might have become the predator of its habitat or used camouflage to survive .
Natural selection is driven by differences in reproductive success between variants within the same population.
Variations within a population
Genetic Variation is a measure of the genetic differences there are within populations or species. For example, a population with many different alleles at a locus may be said to have a lot of genetic variation at that locus. Genetic variation is essential for natural selection to operate since natural selection can only increase or decrease frequency of alleles already in the population
The answer lies within
Crossing-over increases the genetic variation within a population, which is required for natural selection to act upon.
No, mutation and sexual recombination are the sources of variation and natural selection selects from those variations presented to it against the immediate environment.
Selective breeding is the process whereby one controls the breeding patterns of biological entities to yield specific traits. This can also mean forcing breeding to boost recessive traits in a population.Natural selection, on the other hand, results only in populations that express traits that allow for survival and further reproduction within a given environment (selection pressure).
The answer below is partly right, but natural selection actually does not act on an individual. As stated below, individuals within a population of a given species are selected based on physical trains which benefit, but not for the survival of the animal itself. It is important to note that in Darwin's Theory of Natural Selection, environmental change does not create new alleles but rather select from the gene pool of a population that has the allele which would benifit in a given condition. Thus, natural selection act on a population and its gene pool rather than the individuals. Yes. According to Charles Darwin's theory of natural selection, individuals within a population of a given species are "selected" based on physical traits which benefit the survival of the animal. However, they are only "selected" thanks to the individuals that die, because they are not physically suited for survival as well as the others. Natural selection acts directly only on those to die, because it is technically the only physical "act" or determining factor that demonstrates Darwin's theory. All the rest simply has to do with the animals left over, which simply breed as usual inevitably creating better and better animals, while natural selection picks off all those that are not quite good enough.