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.
The variations in populations. Each organisms has varying degrees of survivability and reproductive success and the first job of natural selection, winnowing, is this choosing among the variants.
There are four requirements for natural selection to occur: 1. There is variation in a trait. 2. At least some of the variation in heritable. 3. That variation contributes to differential reproductive success. 4. More individuals are born than survive and reproduce.
The presence of predators and changes in environment.
Variation within populations causes a natural selection of individual organisms for their, ultimately, reproductive success.
Limited food.
Heritable variation.
Genetic variation
differential reproductive success caused by genetic variation is necessary for the process of natural selection.
Adaptation does not allow for natural selection: natural selection causes adaptation.
An organism with a charecteristic that is more helpful to its survival will be more likely to survive and breed than one without that characteristic.
1. Mutation 2. Migration (Gene Flow): both immigration and emigration. 3. Genetic Drift 4. Sexual Selection (Non-random mating) 5. Natural Selection: those most fit survive to pass on their genes to the next generation.
Without variation natural selection would have nothing to select from that would confer survivability and reproductive success. on the organisms being selected against the organisms conspecifics and the immediate environment. Mutation and sexual recombination provide the main sources of this variation that is needed to make selection work. Mutation is the variation presented that causes the real adaptive change that can lead to speciation.
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
Compete? The need to be a moron. Complete? The lack of natural selection.
differential reproductive success caused by genetic variation is necessary for the process of natural selection.
Natural selection is what causes adaptation.
Adaptation does not allow for natural selection: natural selection causes adaptation.
An organism with a charecteristic that is more helpful to its survival will be more likely to survive and breed than one without that characteristic.
No, it's exactly the other way around: natural selection causes adaptation.
Natural selection
Overproduction
the presence of predators
Natural selection usually causes a species to change gradually