Species members have different gene-allele combinations and so have different trait combinations {variation, species}|.
causes
Mutations or allele recombinations cause genetic variation. Sex increases variation by increasing gene combination.
causes: selection
Evolution typically changes population allele ratios. Climate changes increase variation by increasing environment variety. Isolation increases variation by increasing environment variety.
amount
On average, 6% of vertebrate genes vary from wild type. On average, 15% of plant and invertebrate genes vary from wild type.
effects
Most changes are not adaptive. Species with greater genetic variation evolve faster, because they can use more environmental niches.
effects: duplication
Gene duplication and body part duplication allow duplicates to perform new functions, while originals perform old functions.
effects: whole body
Isolated changes can happen, but, to be adaptive, changes must work together with whole body, which then evolves in response to changes. For example, brain and body evolved together. Finger muscles, bone, nerves, blood supply, and brain motor-and-sensory finger regions evolved together, because dexterity required linked development.
Biological Sciences>Biology>Evolution>Variation
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Date Modified: 2022.0224