On the Tendency of Variation and Natural Selection

Variation and Survival Organisms tend to produce more than enough offspring to replace themselves.

Variations and Adaptation If naturally occurring variations to alleles create organisms better suited to

Adaptation and Selection Even small changes to characteristics can produce significant advantages. The combined

Variation and Isolation Variations can occur at different rates in populations separated by a

Isolation and Speciation A population of squirrels separated from others of their species by

Geographic Isolation Animals that find their way to unpopulated lands find themselves in a

Coevolution Sometimes variation in one kind of organism can lead to the survival of

Paralellel Evolution Sometimes variations in very different animals lead to similar adaptations.

Paleontology and Fossils Not only do scientists compare and contrast the body parts of

Genetics and Biochemistry Variation is based on mutations. Mutations can be detected by analyzing

Science is a Continuously Changing Process Testable hypotheses Contains spaces that accommodate new discoveries

Slides: 20

Download presentation

On the Tendency of Variation and Natural Selection to Create New Species

Variation and Alleles

Variation and Survival Organisms tend to produce more than enough offspring to replace themselves. Naturally occurring variations will ensure that some offspring are more likely to survive.

Variations and Adaptation If naturally occurring variations to alleles create organisms better suited to the conditions of their environment, then those alleles will tend to be passed on to future generations.

Adaptation and Selection Even small changes to characteristics can produce significant advantages. The combined action of selection and variation over time can create dramatic differences.

Variation and Isolation Variations can occur at different rates in populations separated by a barrier. This is called genetic drift.

Isolation and Speciation A population of squirrels separated from others of their species by the Grand Canyon have varied enough to be a different color from the squirrels on the other side of the canyon.

Geographic Isolation Animals that find their way to unpopulated lands find themselves in a situation where the pressures of selection have changed.

Speciation and Finches

Coevolution Sometimes variation in one kind of organism can lead to the survival of variants in another type of organism.

Paralellel Evolution Sometimes variations in very different animals lead to similar adaptations.

Paleontology and Fossils Not only do scientists compare and contrast the body parts of living animals, but they also compare and contrast the structures found in fossils to the structures found in living animals.

Genetics and Biochemistry Variation is based on mutations. Mutations can be detected by analyzing DNA. Comparing the differences in DNA between two organisms can be used to determine how closely related they are.

Science is a Continuously Changing Process Testable hypotheses Contains spaces that accommodate new discoveries Supported by collections of data from diverse scientific backgrounds