Evolution By Aimee Chavez

Species  Species: group of organisms that share similar characteristics and can reproduce among themselves to produce fertile offspring. Many characteristics are inherited and changes in these over time are evolution.

Lamarck  Jean Baptiste de Lamarck in 1809 believed that characteristics or traits, developed during a parent organism’s lifetime are inherited by offspring. It is called the inheritance of acquired characteristics.

Evolution  the change in the genetics of a species over time.

Darwin’s Model of Evolution  Darwin couldn’t explain WHY?  Darwin went on a voyage to the Galapagos Islands. He recorded observations about animals and plants. He thought that these organisms came from the main land.

Darwin  Darwin observed several species of finches. They were all similar except for differences in beak shape, body size, and eating habits. He thought those the birds had compete for food. Those better adapted to eat available food survived and produced more offspring. After many generations they became a separate species.

Natural Selection  Organisms with traits best suited to their environment are more likely to survive and reproduce. The traits are passed to more offspring.

The principles of Natural Selection  1.Organisms produce more offspring than can survive  2.S. Differences, or variations, occur among individuals of a species  3.Some variations are passed to offspring  4.Some variations are helpful. Individuals with helpful variations survive and reproduce better than those without these variations.  5.Over time, the offspring of individuals with helpful variations make up more of a population and eventually may become a separate species.

 Artificial Selection  carefully choosing individuals with desired traits.  Variation  An inherited trait that makes an individual different from other members of its species.  Results from mutations of permanent changes in genes. Over time more and more individuals of the species inherit the variations. Over time a new species can evolve.

 Competition: members of a large population compete for living space, food, and other resources. Those better able to survive are likely to reproduce and pass on their traits.  Overproduction: organisms produce more offspring than are able to survive.

Adaptations  Any variation that makes an organism better suited to its environment. Color shape behavior chemical makeup camouflage  When individuals move in (immigration) or move out (emigration) of an area they might bring in or remove genes and variations.

Geographic Isolation  Mountains, lakes or other geologic features isolate a small number of individuals from the rest of a population. Over time variation is more common in the isolated population. In addition gene mutations can occur.

Speed of Evolution  Gradualism: a slow, ongoing process by which one species changes to a new species. (Darwin)  Punctuated Equilibrium  A rapid evolution when the mutation of a few genes results in the appearance of a new species of a short period of time. (Bacteria)

Mutation  The process in which DNA changes result in new alleles. Can be helpful, harmful, or neutral.

Extinction  When the last individual of a species dies. Occurs due to destruction of habitat and introduction of new species. Humans can have an impact on habitat destruction.

Clues  1.Fossils  2.Embryology: the study of embryos and their development.  3.Homologous structures: body structures that are similar in origin and structure  4.Vestigial structures: structures that don’t seem to have a function  5.DNA: Can determine how closely related organisms are