Evolution Flashcards
Evolution
The process of change in the inherited characteristics if populations of animals over time.
What are the 5 basic mechanisms that enable evolutionary change to happen?
Natural Selection, Genetic Drift, Gene Flow, Mutation, and Gene Shuffling
Natural Selection
“Survival of the fittest”
Ex) A predator eats more purple butterflies than yellow because the yellow are more camouflaged then purple. The surviving butterflies pass along their genes.
Genetic Drift
Randomly occurring change in the genetic makeup of a population over time.
Ex.) A wildfire wipes out most of the purple butterflies and not yellow. The lucky survivors pass on their genes.
Gene Flow
The result of movement of genes from one population to another also known as migration.
Ex.) A purple butterfly leaves a purple population and joins a yellow population. The migrant interbreeds with members of yellows and in doing so, introduces its purple genes to the yellow population
Mutation
A change in the genetic material of an organism that is subsequently inherited by its offspring. The chance alteration can happen through deletion or insertion of a single base in a DNA molecule.
Occasionally, single mutations may produce large effects but generally evolutionary change is the result of many mutations.
Gene Shuffling
The genetic uniqueness of individual humans and all other sexually reproducing organisms results from the reshuffling of parental genes.
Offspring are not genetically identical to each other (except identical twins), nor to the parents, but show various combinations of their parents’ genes. New gene combinations, and hence genetic variation, is introduced into a population through the mechanism of sex.
Peppered Moth Evolution and the Industrial Revolution
The 3 variations occurred as a result of genetic mutations.
Natural selection led to the darkest moths becoming more abundant, since the industrial population made them blend in better to the blackened trees that the moths rest on during the day.
Speciation
The process whereby new species evolve from a single ancestral species.
This occurs for a number of reasons, including geographical isolation arising from habitat fragmentation. If a small population is isolated from the main group and its members can only share genes with each other’s over time they will evolve independently to the point where, if they come back in contact with the original group, they could not interbreed
Divergent Evolution
New descendants species become significantly different from their common ancestors. These series of changes arise as a product of Earth’s Dynamic environments, which vary from place to place and from time to time.
Ex.) all life on land has diverged from water-living ancestors, and all living species of mammal have diverged from a common ancestral mammal that lived alongside the dinosaurs.
Convergent Evolution
Sometimes, different organisms will evolve similar characteristics to adapt to the environment that they inhabit.
Ex.) the similarity in body forms of whites, seals, and penguins is the result of similar adaptations to similar ways of life. The common factor is the adaptation of a streamlined body shape, with reduced limbs for a more efficient swimming motion.
Ex.) Wings have evolved independently in birds and bats for flight.
Coevolution and mutual dependency
Ex.) Some flowers rely on hummingbirds for pollination wile some hummingbirds rely on specific flowers for nectar. They have coevolved in terms of shape and color to accommodate each other’s survival.
