Evolution

Genetic change in a population over the course of several

generations.

Evidence Supporting Evolution

• 1. The fossil record of change in earlier species

• 2. The chemical and anatomical similarities of related life forms

• 3. The geographic distribution of related species

• 4. Similarities in Embryology

The Fossil Record

• Remains of plants and animals found in sedimentary rock.

• This give us a record of changes to species over time.

• Each layer of strata contains fossils or organisms from the same relative time period.

Fossil Record

• Some fossils are good examples intermediate forms or transitional species

• They show the changes that take place in a species over a long period of time

• They show derived traits

Chemical and Anatomical Evidence

• DNA• Amino Acids• Body Structures

inherited from a common ancestor– Homologous

structures– Vestigial

Structures

Geographic Distribution

• Isolated areas have their own distinct plant and animal communities, adapting to different environmental pressures

• Before humans, Australia had over 100 species of marsupials, but very few placental mammals.

• Evidence that they evolved in isolation.

Similarities in Development

• Early stages or embryos can be similar

• Common cells and tissues grow in similar ways

Genetic Changes

• Natural populations have genetic diversity

• Those who are better able to survive, leave more offspring

• Their traits will be more common in the next generation

Antibiotic Resistance

• This same phenomenon of bacteria evolution speeded up by human actions occurs in our own bodies at times when an antibiotic drug is unable to completely eliminate an infection.  Doctors do not want to allow any potentially antibiotic resistant bacteria to survive so insist that all of the antibiotic is taken even after you feel better.

Speeding Up Evolution

• Organisms that reproduce quickly and in large numbers can show changes very quickly

• Insects and crop damage require new pesticides

Common Ancestors

• Anatomical similarities indicate that some species had a common ancestor

• Wolves and dogs show similarities to foxes

• For some, the common ancestor is more distant than for others