0
Evolution occurs because biological organisms reproduce with variation, and variants reproduce at different rates.
Genetic variation is the result of genetic mechanisms such as reproductive recombination and spontaneous mutation. These mechanisms ensure that each offspring is a unique combination of alleles. Alleles are "rival" variants of genes with a specific "function". For many genes, having one allele rather than another will result in some difference in expression, resulting in turn in a difference in phenotype, which might result in a behavioural difference, a difference in appearance, or a difference in metabolic rate, for instance.
It stands to reason then, that it is possible that different variants react to circumstances differently. A variant with slightly longer intestines might find it easier to process certain foods, opening up a new niche for itself and its offspring. A variant with slightly longer fur might find it easier to venture into colder areas to gather food, again giving it and its offspring access to a new niche.
If the circumstances are thus that a particular trait or combination of traits makes it likely that a variant has a higher average number of offspring than its rival variants, then this will result in an increase of the number of alleles representing this variation in the next generation. This trend can, if these circumstances remain the same, persist until the great majority of the population possesses these successful traits.
Together, the emergence of new traits through reproductive variation, the spreading of successful traits and the decline of less successful traits through reproductive differential success, are called evolution, and the mechanisms behind these trends are the reason that evolution happens.
What else can I help you with?
Does evolution occur in individuals or in population?
Evolution occurs in population not in an individual.
Did evolution occur in the permian period?
Yes. Evolution ocurred in all geologic periods.
What are some draw backs of selective breeding?
You do not allow evolution to occur, for you are evolution in selective breeding.
How is variation related to evolution?
The more variation there is in a group of specimens, the more evolution can occur between them.
Why did evolution not occur in down syndrome?
Down Syndrome is a the addition of an extra chromosome and not really related to evolution. It is more of a genetic mutation that causes this event to occur.
How do variations occur?
During evolution, chromosomal cariation in structure cannot occur due to
For a mutation to affect evolution it must occur in?
For a mutation to affect evolution, it must occur in the DNA of reproductive cells (sperm or egg cells) so that it can be passed on to offspring. Mutations that occur in somatic cells (non-reproductive cells) do not directly impact evolution as they are not inherited by future generations.
When will convergent evolution occur?
It already has in some instances
What is a mechanism by which evolution can occur?
Selective Breeding of course!
Under what circumstances would evolution not occur if?
Evolution would not occur if there is no genetic variation within a population, no selection pressure, or if there is no reproduction and passing on of genes to the next generation.
Does evolution continue to occur in organisms today?
Absolutely. Evolution isn't an historical process; it is on-going as long as there is life.
What are the divisions of evolution?
Evolution is sometimes described as macro-evolution, which is the long-term evolution of an entire new species, and micro-evolution, which is largely to do with less significant evolutionary changes within a species. Many creationists accept the existence of micro-evolution, but say that macro-evolution does not occur.
