Population Change (Evolution)

Coach Devlin Marcum

Levels of Classification• There are 8levels of classification of

living things.• Domain• Kingdom• Phylum• Class• Order• Family• Genus• Species• Most of classification also known as

taxonomy was done by Swedish scientist Carolus Linnaeus (Carl von Linnae)

• He used genus and species names to give all living things a scientific name in a system called binomial nomenclature.(Ex. Canis lobo = wolf; Felis leo= lion; Homo sapien = human

Dichotomous Keys• 1. Sex female---2

1. Sex male---5    2. Hair color red---Susan    2. Hair color brown or blond---33. Hair color blonde---Jane3. Hair color brown---4    4. Glasses worn---Donna    4. Glasses not worn---Linda5. Pants jeans---Caleb5. Pants slacks---6    6. Hair color black--James    6. Hair color brown--Zach

• Sample Dichotomous Key

http://aitc.oregonstate.edu/resources/pdf/activity/potato_key.pdf

A dichotomous key is a very useful tool in helping scientists classify organisms.

Dichotomous means “2 fork” or “2 branch”

It is a series of statements of characteristics that help lead you to correctly identify organisms.

How are organisms different?

• Organisms differ in many ways.

Where the live/environmentHow they reproduce

(sexually/asexually)What they eat

(herbivore/carnivore/omnivore/photosynthesis/decomposer)

How they obtain food (predator/scavenger)

How they obtain matesHow they escape predators.

• A characteristic that helps an organism survive and reproduce in its environment is called an adaptation.

• Some adaptations are physical, such as fur or scales.

• Other adaptations are behaviors that help an organism find food, protect itself, or reproduce.

Do species change over time?

• Since life first appeared on Earth, many species have died out, and many new species have appeared.

• Scientists observe that the inherited characteristics in populations change over time.

• Scientists think that as populations change over time, new species form.

• The Fossil Record By studying fossils, scientists have made a timeline of life that is known as the fossil record.

• The fossil record organizes fossils by their estimated ages and physical similarities.

• Comparing organisms in the fossil record can reveal how organisms have changed over time.

Fossil Evidence

• Scientists can use two methods to determine the age of objects in sedimentary rocks.

• One of those methods is known as relative dating.

• Relative dating examines a fossil’s position within rock layers to estimate its age.

• Law of Superposition- in sedimentary rocks the oldest layers are at the bottom and get younger as you go up towards the surface.

Relative Ages/Superposition

Fossil Evidence (Whale)

Darwin’s Theory

• In the 1800s, scientists were beginning to see evidence of change in the fossil record, but no one was able to explain how change happens until Charles Darwin.

• Darwin signed-on for a five-year voyage around the world and worked as a naturalist.

• His observations helped him form a theory about how change happens.

Darwin’s Theory (cont.)

• Darwin’s Finches Darwin noticed that the finches of the Galápagos Islands were a lot like those in Ecuador. And the finches on each island differed from the finches on the other islands.

Darwin’s Theory (Cont.)• Ideas About Population

Darwin was influenced by an essay that described the reasons that human populations do not grow uncontrollably.

• Darwin knew that the populations of all species are limited by starvation, disease, competition, and predation.

• Darwin reasoned that the offspring of the survivors inherit traits that help the offspring survive in their environment.

• In 1859, Darwin published a famous book called On the Origin of Species by Means of Natural Selection.

• In his book, Darwin proposed the theory that change in populations happens through natural selection.

• Natural selection is the process by which organisms that are better adapted to their environment survive and reproduce more successfully than less well adapted organisms do.

Natural Selection

Evidence of Change