Evolution: A change in a kind of organism over time. The process of modern organisms coming from ancient organisms

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Evolution is a scientific theory. There is much evidence to support evolution

First suggested changes overtime Stated that changes are adaptations acquired in one’s lifetime due to selective use or disuse of certain traits These traits would then be passed on to their offspring, but not through genes; forces

Desire to do something led to adaptations Example: Giraffes kept stretching their necks over generations until they could reach the leaves.

Joined the crew of the HMS Beagle for a 5 year survey adventure. ( ) Naturalist; wanted to study and observe different species.

Darwin noted that the island were very small and varied greatly Some hot, dry and nearly barren Other islands had greater rainfall and had more diverse vegetation He noted the tortoises’ shape of their shell corresponded to their different habitat

Studied finches on each island Noticed similar types of finches had small beak adaptations depending on available food sources

1859- “The Origin of Species by Means of Natural Selection”  Stated that organisms evolved  Mechanism for evolution called Natural Selection  Presented evidence that evolution has been taking place for millions of years – and continues in all living things

1-Variation: Each organism has it’s own variations in it’s struggle for existence 2-Competition-Organisms compete for natural resources 3- Pop. Growth-Organisms produce more offspring than can survive 4- Differential reproduction- Those organisms best suited to the environment will survive and pass along their genes to their offspring

Results in changes in the inherited characteristics of a population. These changes increase a species’ fitness in its environment Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift.

Peppered moths - England 1850’s - light color (few were dark) Early 1900’s - pollution darkened tree trunks Light moths eaten Dark moths camouflaged - increased Recently - pollution controls - trees lighten Light moths increase in number again

In artificial selection, nature provided the variation, and humans selected those variations that they found useful Ex. Dogs, Vegetables, Cows

Common descent- principle that all living things were derived from common ancestors Fossil record  Fossils show the links between species  Radioactive dating can tell how old the fossils are  Scientists calculate the half-life of certain isotopes, like Carbon-14, in the fossil to determine the age in years.

Similar structures are evidence of a common ancestor. Selection causes modifications for different environments. Homologous structures - different functions but common ancestry. Vestigial organs - small or incomplete organs with no apparent function.

Implication: the vestigial organ served a function in the ancestor of the organism, but not its present holder Examples

Embryo - developing organism Early stages of development are similar More closely related organisms have more similar embryological patterns

Universal genetic code - evidence of evolution. All living things are made up of the same 4 nucleotides: A,G, C, T Many of the same DNA sequences, or genes, are exact or similar depending on how closely related we are

The evolutionary process by which new species arise. Arise for different reasons, but reproductive isolation and geographic isolation are the most common Reproductive isolation is when no mating occurs between species for so long that sexual selection changes or having offspring Geographic occurs when species are separated by a barrier, such as a mountain range or a river

Abert squirrel and Kaibab squirrel - used to be same population. About 1 million years ago - Colorado river changed course and split population. Kaibab is a subspecies of the Abert squirrel.

Washington- two populations of sockeye salmon became established One spawning in a river and one along a lake beach. Sockeye salmon bury their eggs and spawn in different kinds of locations, and in a variety of environments, even in a small system such as this. When new populations become established at different sites, you'd expect them to evolve different adaptations, and that's in fact what happened. Body depth in males Size of breeding females

Definition: when the environment puts similar selective pressure on different species. Results in similar adaptations for organisms that are not closely related. Example: fish do not have same immediate ancestor as whales. Bird wing vs. insect wing