E VOLUTION – CHANGES OVER TIME Life Science – 7 th grade.

EVOLUTION – CHANGES OVER TIME

Life Science – 7th grade

S7L5 – Students will examine the evolution of living organisms through inherited characteristics that promote survival of organisms and the survival of successive generations of their offspring.

S7L5a – Explain that physical characteristics of organisms have changed over successive generations (e.g. Darwin’s finches and peppered moths of Manchester).

S7L5b – Describe ways in which species on earth have evolved due to natural selection.

S7L5c – Trace evidence that the fossil record found in sedimentary rock provides evidence for the long history of changing life forms.

UNIT 6 –EVOLUTION (STANDARDS)

TOPIC: Evolution

KEY LEARNING: Through natural selection, organisms evolve and adapt to survive and fossils provide evidence of an organism’s presence on Earth.

UNIT ESSENTIAL QUESTION: What type of evidence supports life existed and changed before our time?

UNIT 6 - EVOLUTION: STUDENT LEARNING MAP

CONCEPT 1: Fossils and Pangaea

Lesson Essential Questions: 1. How are fossils formed?2. How is the age of fossils determined?3. How do fossils support the theory of Pangaea?

Vocabulary: evolution, gradualism, punctuated equilibrium, Pangaea, continental drift, fossil, relative dating, radiometric dating

UNIT 6 - EVOLUTION: SLM

THEORY VERSUS FACT

FactA scientific observation known to be true.

TheoryA broad concept, thought to be true because it explains many facts.

EVOLUTION

EvolutionChange over timeInvolves geneticsIncludes adaptations-a trait that helps an organism survive and reproduce.

FIVE TYPES OF FOSSILS –S7L5C Imprint- Sediment fills an organisms track Mineralized- Minerals seep into pores of wood

or bone, dissolve the organic matter, then crystallize retaining its cell structure shape.

Frozen- organism trapped in mud, tar, then temperature drops fast & organism freezes instantly! (rare) Ex: Ice Age

Fossils in amber- sticky resin of certain cone-bearing plants/trees traps insects/organisms. DNA can be extracted. Ex: Jurassic Park

Cast- organism decomposes and leaves a cavity (space) that fills with sediment or minerals.

SOLID FORMS OF PLANTS AND ANIMAL FOSSILS S7L5C

(MADE FROM SEDIMENT: MUD, SAND, OR VOLCANIC ASH)

FOSSIL RECORD: DETERMINING A FOSSIL’S AGE –S7L5C Absolute Dating

VS.

Estimating the age of SEDIMENTARY rocks or fossils by comparing the amount of radioactivity elements to others.*Can be inaccurate

Relative Dating

In an undisturbed area, where younger rock layers are deposited on top of older rock layers.*Earthquake or plate movement can disrupt accuracy.

FOSSIL RECORD : AGE OF FOSSILS (S7L5C)

GEOLOGIC TIMELINEDATING THE AGE OF FOSSILS (S7L5C)

THEORY OF CONTINENTAL DRIFTPANGEA

Earth formed 4.6 BYA (Billion Years Ago)

1915, Alfred Wegener studied similar plant and animal fossils found on different present-day continents.

He theorized continents once formed one giant supercontinent called Pangaea.

Then, 245 MYA, Continental drift -Movement of Earth’s continents took place due to tectonic plates shifting.

http://vimeo.com/14258924

http://www.tectonics.caltech.edu/outreach/animations/drift.html

(S7L5a,b) Speed of Evolution:

When the continents drifted, this led to

changes….

Gradualism-A slow, ongoing process by which one species

changes to a new species

versus

Punctuation equilibrium-Rapid evolution that comes

about when the mutation of a few genes results in sudden

change (appearance) of a new species

CONCEPT 2: Charles Darwin and Natural Selection

Lesson Essential Questions: 1. What is Darwin’s role in the theory of

evolution?2. What are the different speeds of evolution?3. What are the four parts of Darwin’s theory of

evolution by natural selection?

Vocabulary: fossil, finches, peppered moths,camouflage, variation, overproduction, natural selection, competition, adaptation.

UNIT 6 SLM: S7L5A –NATURAL SELECTION, S7L5B-CHANGE IN PHYSICAL CHARACTERISTICS

CHARLES DARWIN: VOYAGE ON HMS BEAGLE

•1831-left England

•Sept. 15,1835 -Visited Galapagos Islands off coast of South America

•1836 –Returned England

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CHARLES DARWIN (S7L5A,B) Studied plants and animals as a naturalist on

HMS Beagle - British ship.

Observed and hypothesized finch species that were geographically isolated from each other.

Darwin reasoned that finch populations over time evolved adaptations that aided in their survival on different island environments resulting in new species.

Adaptation- a trait (genetic characteristic) that improves an organisms ability to survive and reproduce in a certain environment

Examples: (beak, fur, camouflage)

Speciation- new species occurs from 3 events: Separation, Adaptation, and Division

DARWIN’S FINCH’S ON GALAPAGOS ISLANDS AND SOUTH AMERICABEAKS DIFFER – TYPES OF FOOD EATEN (SMALL – LARGE)

DARWIN’S FINCH’S (S7L5A) VESTIGIAL STRUCTURES - EXAMPLE: BEAKS

•Probing bit-insect eater-feeds in trees. (4)•Probing bit-insect eater that uses a twig or cactus spine to probe insects. (3)•Grasping bit-insect eater that feeds in trees. (2)•Crushing bit-cactus seed eater. (1)

DARWIN’S FINCH’S (S7L5A)

"Calmodulin is a protein that binds and activates certain enzymes, which triggers a signal that eventually turns specific genes on or off," explains Arkhat Abzhanov, an evolutionary biologist at Harvard. The signals alter the behavior of cells responsible for beak sculpturing.

DARWIN’S FINCH’S (S7L5A)As climate changes in the Galapagos the finch’s changed body size, beak size, and beak shape (a measure of width, length and depth).

In 1983, after heavy rains, depth of average finch beak returned to pre-drought size, and "evolutionary change" reversed. Explore Evolution, p. 93

NATURAL SELECTION (S7L5B) A Process by which individuals that are

better adapted to their environment are more likely to survive and reproduce than other members of the same species.

Involves genetics; not environment

Occurs over many generations (can’t see it happening)

Other terminology

‘Survival of the fittest’‘Only the strong survive’

NATURAL SELECTION (S7L5B)Overproduction

Too many offspring; not enough resources (food, water, living space) usually die.

CompetitionFor resources food or mates; competing

against other offspringVariations

Differences between individuals of same species

SelectiveWhen the environment “selects” organisms

with helpful traits

QUIZ BELOW

http://www.sciencechannel.com/games-and-interactives/charles-darwin-game.html

DARWIN - TREE OF LIFE

“organized beings represent a tree, irregularly branched, some branches far more branched – Hence Genera.” (ABCD-Different species branch off from 1).

CLADOGRAM (TREE OF LIFE): (S7L5A,B,C)

Cladogram: A diagram or model of relationships between extinct and living species.

Each branch in the diagram represents a group of organisms that descended from that species.

http://evolution.berkeley.edu/evosite/evo101/IIHistory.shtml

PBS video Clips: Whale Evolution and Fish w/ Fingers Evolution Clip Videos

http://www.pbs.org/wgbh/evolution/educators/teachstuds/unit3.html

PRESENT TIME

CHARLES DARWIN FOLDABLE/BROCHURE/NEWSLETTER

Must include the following items:Cover page (name, date, class period, title)Mini bio on Charles DarwinPhilosophy of evolutionWhat did Darwin contribute to science?Describe what he learned about the finches.Describe what he learned about peppered

moths.Each page/section should include a pictureFinal page/section should have resource(s)

listed (MLA style)DUE: TUESDAY, APRIL 2

RESOURCES

http://ncse.com/creationism/analysis/oscillationshttp://www.news.harvard.edu/gazette/2006/08.24/31-finches.html