Evolution Notes Evolution is just a theory isnt

Evolution Notes

Evolution is ‘just’ a theory isn’t it? Yes it is…. but what is a theory anyway? • Popular Definition of a guess or “hunch”. Theory - a “_____” • Scientific Definition of a Theory - a well-substantiated explanation of an aspect of _____ the natural world. • Scientific Theories are based evidence facts, and have on _______, tested in many ways. been ______

Where did the Theory of Evolution come from? The theory of evolution was thought of Charles ______ Darwin and by both _______ Alfred ______ Russell _______. Wallace ______

Charles Darwin studied traits of Galapagos Islands organisms on the ____ and developed theory of evolution natural ____. selection by ______

Alfred Russell Wallace studied Malay traits of organisms on the _____ Archipelago of islands and coined survival of the fittest ”. the term “_________

What is Evolution? Evolution is the process of species changing over time ________ to better suit their environment. • Species: a group of organisms that can mate with one ____ another to produce fertile offspring. ______ This is an Agrias butterfly from South America

• Species change over time because of mutations and _______ natural selection. ____ changes • Mutations: ______ Point of to an organism’s Mutation DNA made during ______. meiosis • Mutations create variations in a ____ population.

Natural Selection • In Natural Selection organisms with traits best suited to favorable _____ their environment are more likely to reproduce. survive and ______ Which color variation do you think is better suited to survive?

The Process of Natural Selection 1. Overproduction: organisms in a offspring population produce more ____ than their environment can support. survive long • Not all offspring will ______ enough to reproduce. Green Sea Turtles lay 100 eggs in a “clutch” Only one or two will survive to adulthood

The Process of Natural Selection 2. There must be variations within ____ the species. • Variation: differences _____ traits among _____ between individuals of the same species.

Variations must be inherited _______ from an organism’s parents.

The Process of Natural Selection struggle to ______ survive in 3. Organisms _______ their environment. disease competition & • Starvation, ______, predation limit populations of all ____ species.

Organisms that survive the struggle have helpful variations of _____ traits (adaptations) ______ survive that help them ______. o Adaptations: features that make an environment so it organism suited for its _____ reproduce , & pass its genes/ can survive, _____ alleles onto its The environment offspring. changes and it becomes too cold for dogs with short and medium fur.

Here’s an example of Evolution in action. This is happening all over the world! What is the flies adaptation?

The Process of Natural Selection 4. Selection (successful reproduction): The members of a population inherited that have ____ helpful variations of traits will be more likely survive and to ______ reproduce ____. A saddleback tortoise from Pinzón Island

How do new species form? speciation : the formation That’s called _____ of a new species as a result of evolution. one species Speciation occurs when ___ evolves into ___ two different ______ species that ______ can’t reproduce with each other anymore.

How do new species form? group of 1. Separation - when a _____ separated from individuals becomes _____ the rest of the population. Can be caused by a newly formed canyon, ______ movement of mountain range, lake or ____ plates Earth’s tectonic _____.

How do new species form? groups 2. Adaptation - Separated ______ affected by natural continue to be ____ selection in their new, different ____ traits can be Different _____ environments. ____ favored and over many generations can _______ spread through the population. ______ Kaibab squirrel Abert squirrel The formation of the grand canyon separated the Tassel-Eared squirrel population. Over time the different environments favored different traits causing the formation of two new species.

How do new species form? 3. Reproductive Isolation - Over time the populations can become separated _____ NOT be able so different that they may ____ successfully with each other mate _____ to _____ anymore. The populations are now different ______. species two ____ considered to be ___

This example shows how the finches on the Galapagos Islands may have evolved.

Is there Evidence for Evolution? Lots…. . fossil genetic biological

Fossil Evidence fossil ______ record is all of the fossils that • The _____ have been found. examining the fossil record we can see • By _____ what lived in the past. • Comparing organisms in the fossil record provides evidence for how organisms have changed over time ________.

Land Mammal ? Do we have any fossil evidence for intermediate species. ? ? ?

All of these are intermediate species

• Biological Evidence Embryology – The study of early development in organisms ____. o During early development the _____, embryos of a shark, a rabbit, and a gorilla look similar. This suggests an evolutionary relationship among _____ all vertebrates.

Homologous Structures • Homologous Structures are similar different functions. structures with ____ bone ____ structure of the human The ____ arm, the front leg of a cat, the front flipper of a dolphin, and the wing of a similar bat are all ______. o

Vestigial Organs/Structures Vestigial Organs show some organisms are related to modern ____ ancestors. o hip For Example: Whales have small ___ bones.

Genetic Evidence Scientists can tell how closely organisms comparing their ____. DNA are related by ____ similar the DNA, the more The more ______ related the organisms are closely ______ (possibly evolved from common ancestor).

How do we show evolutionary relationships? branching _______ diagrams to show • Use ____ organisms are related. • Branching diagrams (cladograms) show characteristics organisms _____ share which _______ and when these organisms ______. evolved

grouped in the diagram by • Organisms are _______ shared _______ derived _______ characteristics. their ______ trait that o Derived characteristic: a ____ organisms _____ share two or more kinds of _____ with their most recent common ancestor ____. These are the derived characteristics

more derived ______ characteristics The ____ more closely organisms share, the ____ related the organisms probably are. ______ o The house cat is more closely related to the lion because they have the most characteristics in common (having hair, mammary glands, birthing live young & retractable claws).

Each characteristic listed on the shared by the diagram is only ______ organisms _____ above it. ____ o The Brown bear has the characteristics of hair, mammary glands & birthing live young. It does not have retractable claws and the ability to purr. These characteristics are listed above the Brown bear in the diagram, therefore it does not have them.

higher on the Characteristics shown _____ diagram are more _____ recent than the _______ characteristics below them. o The ability to purr is listed highest (or last) on the diagram. This means it is the most recent characteristic to evolve and only the house cat has it. The characteristic of having hair & mammary glands is listed first on the diagram. This means it evolved first, or it is the oldest characteristic in the diagram. All organisms in the diagram have this characteristic.