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There are on the chromosomes stretches of DNA that do nothing. Their only purpose is provide matching stretches so the chromosomes match-up during fertilization. In here mutations occur but have no 'large' effect on the phenotype of the life-form. (If enough of them occur then the chromosome become of a different length and certain mating pairs can no longer match-up, but that takes a while to get a difference in length that really matters.)
Geneticists use these stretches and the changes in them to track evolutionary path-ways.
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What are the pressures of natural selection?
Everything from available food to climate will cause the changes we see in natural selection. Random mutations occur constantly and when those mutations are beneficial for life, the genetic code is more likely to be passed on to future generations.
How does natural selection affect variation?
Variation naturally occurs in populations as new traits arise from random mutations. However, through natural selection only those traits that are beneficial to the organism are passed on to the next generation. Any harmful mutations are naturally weeded out.
How does environmental pressure affect natural selection?
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.
What causes the allele frequencies to changes?
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.
Why do living things evolve?
Natural selection (survival of the fittest) means that valuable adaptations and mutations have the greatest number of surviving descendants.
Which mutations are NOT subject to natural selection - lethal physiological neutral or morphological?
Neutral mutations confer no benefits or handicaps and are therefore not affected by natural selection.
Natural selection is due to?
beneficial mutations
What are the three things biodiversity emerges from?
extinction, natural selection, and mutations
How does slow change over time occur genetically?
Through mutations in DNA, and natural selection of advantageous mutations.
What are the pressures of natural selection?
Everything from available food to climate will cause the changes we see in natural selection. Random mutations occur constantly and when those mutations are beneficial for life, the genetic code is more likely to be passed on to future generations.
How do natural selection cloning and selective breeding lead to evolutionary change?
The only thing that causes evolution is Mutations due to forced natural selection of desired alleles.
How does natural selection affect the frequency of mutatons?
Natural selection works on mutations that are already in place. The environmental changes will select for certain mutations if the selective pressure is supplied long enough for several generations of offspring to carry a higher percentage of the mutation.
Are new alleles made by natural selection?
No - natural selection does not create new alleles. Variation in alleles needs to exist in the population in order for natural selection to occur. Natural selection will involve the change in allele frequencies over time, but it does not create new alleles. New alleles are the result of mutations.
What causes mutations?
sunlight, radiation, and smoking
Explain the role of mutations in evolution?
Mutations are the material upon which natural selection acts. Evolution is a two sided coin. One side is mutation; the other side is natural selection. Without mutation there is no significant variation. Mutations are, however, ubiquitous. Every organism is a mutant. Evolution can be summarized as the non random survival of randomly varying replicators.
Why are mutations and conjugation important for natural selection in prokaryotes?
Becauase they need to adapt to the new environment to enter the bodies
How does natural selection affect variation?
Variation naturally occurs in populations as new traits arise from random mutations. However, through natural selection only those traits that are beneficial to the organism are passed on to the next generation. Any harmful mutations are naturally weeded out.
