BIG IDEA 15: DIVERSITY AND EVOLUTION OF LIVING ORGANISMSDescription   A. The scientific theory of evolution is the organizing principle of life science.

B. The scientific theory of evolution is supported by multiple forms of evidence.

C. Natural selection is a primary mechanism leading to change over time in organisms.

Benchmark Number & Descriptor

SC.7.L.15.1 Recognize that fossil evidence is consistent with the

scientific theory of evolution that living things evolved from earlier species.

SC.7.L.15.2 Explore the scientific theory of evolution by recognizing and

explaining ways in which genetic variation and environmental factors contribute to evolution by natural selection and diversity of organisms.

SC.7.L.15.3 Explore the scientific theory of evolution by relating how the

inability of a species to adapt within a changing environment may contribute to the extinction of that species.

WHAT’S THAT?

CHANGE OVER TIME

Evolution: Scientists have reason to believe that many

species of organisms have changed overtime.

Evidence of change is found within the Earth’s crust.

FOSSILS Evidence of organisms in the past are

based on the following information: Fossil Record Geographic Distribution of Living

Species Homologous Body Structures Similarities in Embryology

FOSSILS

Helps organize fossils by their ages and similarities

Older fossils found may not be around anymore; whereas fossils found in newer layers of Earth’s crust maybe related to today’s organisms.

Imprint in a rock of an organism, leaf, or feather

Cast of an animal track, shell, etc.

Petrifaction of bone or wood

Organism frozen in ice Insects/organisms

trapped in amber

Fossil Record Types of Fossils

FOSSILS

Fossils found in lower layers of rock are said to be older than those found near the surface.

Comparison of radioactive and non-radioactive elements in a rock can predict age of rock and the fossil in it.

Relative Dating

Radiometric Dating

FOSSILS

Similar animals found in different locations are said to be the product of different lines of descent from the same ancestors

GEOGRAPHY

OTHER EVIDENCE OF EVOLUTION

Body parts that are similar in structure and origin might show a common ancestor between organisms.

Example: Bird wing, bat wing, and

dolphin flipper each have about the same number of bones and blood vessels

HOMOLOGOUS STRUCTURES

OTHER EVIDENCE OF EVOLUTION

A body part that still exists but has no function for that organism

Past ancestors may have had a use for these structures.

Examples: Whales have a pelvic

bone but no legs.

VESTIGIAL STRUCTURES

OTHER EVIDENCE OF EVOLUTION

The study of how an organisms embryo develops

Similarities suggest an evolutionary relationship.

EMBRYOLOGY

OTHER EVIDENCE OF EVOLUTION

A way to see if organisms are related is to study their DNA.

Organisms that have similar DNA are said to have similar ancestors.

Example: Dogs closest relatives are

bears. All primates may have

evolved from the same ancestors.

DNA

SPEED of EVOLUTION

Steady, slow ongoing process

Evidence of intermediate forms of species exist.

Rapid evolution by mutation

No middle form found

Example: Bacteria

Changes quickly to resist medications

GRADUALISMPUNCTUATED EQUILIBRIUM

KNOWLEDGE CHECK

1. How are fossils important evidence for the theory of evolution?

2. Whose DNA would be closest to matching yours, your parents, or a first cousin? Why?

3. List and give an example of three examples of evolution.

4. Distinguish between the two speeds of evolution.

KNOWLEDGE CHECK

1. How are fossils important evidence for the theory of evolution? They provide evidence of how species have changed over time.

2. Whose DNA would be closest to matching yours, your parents, or a first cousin? Why? Your parents because they are your closest relatives.

3. List and give an example of three examples of evolution. Homologous structures: dolphin flipper, bat wing; vestigial structures: hip bones in snakes; embryology: humans have gill slits and a tail bone during development.

4. Distinguish between the two speeds of evolution. Gradualism – change takes place over time; fossils show intermediate changes.

Punctuated Equilibrium – rapid change, no fossil record, bacteria

WHO WILL BE THE NEXT

SURVIVOR?

IDEAS of EVOLUTION

1809, created a theory on how species evolve overtime

He believed offspring receive traits that their parents develop during their lives.

Traits that were not used by their parents were lost, and offsprings did not inherit them. Theory of Acquired

Characteristics Example: If a parent was a weight lifter and gained

large muscles from working out, the offspring produced would be born with large muscles.

Lamarck’s ideas were rejected.

Jean Baptiste de Lamarck

Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves.

IDEAS of EVOLUTION

Mid 1800’s, Darwin traveled to the Galapagos Islands.

Darwin observed that characteristics of many plants and animals vary greatly among the islands.

Darwin hypothesized separate species may have arose from an original ancestor.

Darwin figures that species with traits best fitted for their natural environment survived and were able to reproduce. Theory of Natural Selection

Charles Darwin

Darwin wondered why so many different but closely related finches lived on islands just a few miles apart.

Theory of Natural Selection

Organisms which are better adapted to their environment are able to survive and to reproduce.

Main Ideas about Natural Selection: Organisms differ; variation is inherited. Organisms produce more offspring than survive. Organisms compete for resources. Organisms with advantages survive to pass

those advantages to their children. Species alive today are descended with

modifications from common ancestors.

Natural Selection

KNOWLEDGE CHECK

1. Compare Lamarck’s and Darwin’s ideas of evolution.

2. Why is reproduction a factor in Natural Selection?

KNOWLEDGE CHECK

1. Compare Lamarck’s and Darwin’s ideas of evolution.

Lamarck – organisms inherit acquired traits. Darwin – those organisms that survive are able to

pass traits off to their offspring.

2. Why is reproduction a factor in Natural Selection? In order for traits to be passed on, reproduction has to occur. The more offspring that are produced, the greater the chance of species survival.

CHANCES of SURVIVAL

SURVIVING In order for a species to survive,

organisms must adapt to their environment.

Adaptations can include: Adapting to hunting Insecticide resistance Competition for mates Physical adaptations Behavioral adaptations

Hey! I’m a walking

stick. I look just like a stick you’d find on the ground.

SURVIVING

Animals of a species which are hunted for a specific reason may become extinct, while those animals of the same species who lack what is wanted will survive.

Adaptation to Hunting

AFRICAN ELEPHANTS

These elephants have been hunted for their Ivory tusks. Today, 15% of African elephants do not have tusks. More tuskless elephants have survived and therefore are able to pass the tuskless trait to offsprings.

SURVIVING

To help control the insect population, many insecticides have been created. This is also true for bacteria

and antibiotics. The bacteria and insects

become resistant and do not die off and therefore are able to reproduce and pass the resistant traits along.

Insecticide Resistance

Pesticide application can artificially select for resistant pests. In this diagram, the first generation happens to have an insect with a heightened resistance to a pesticide (red). After pesticide application, its descendants represent a larger proportion of the population because sensitive pests (white) have been selectively killed. After repeated applications, resistant pests may comprise the majority of the population.

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SURVIVING

Survival of individual organisms does not necessarily mean survival of an entire species.

Reproduction has to occur in order for next generations to occur.

Many times, organisms will only mate with other organisms that have specific looks.

If an organism does not posses these certain traits and mating does not occur, that particular organism may die out.

Competition for Mates

SURVIVING

Camouflage allows an animal to blend into its environment. 

Mimicry allows one animal to look, sound, or act like another animal to fool predators into thinking it is poisonous or dangerous. 

Physical Adaptations

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SURVIVING

Instinctive Behaviors Happen naturally and do

not need to be taught Examples:

Migration: an animal or group of

animals moving from one region to another and then back again.

Reasons: better climate better food safe place to live safe place to raise young go back to the place they

were born

Behavioral Adaptations

EXTINCTION If a species

cannot adapt to its environment, it may become extinct. All of the

organisms of a specific species must die in order to become extinct.

Extinction may happen over a long period of time or in an abrupt manner. Mass extinctions

have occurred when sudden changes in climate happen, such as the ice age or if a natural disaster occurs, such as a volcanic eruption.

EXTINCTION

KNOWLEDGE CHECK

1. How is the tuskless trait a survival characteristic for some elephants?

2. Doctors are beginning to see a problem with everyone using antibacterial hand soap. Why?

3. List one physical and one behavioral adaptation.

KNOWLEDGE CHECK

1. How is the tuskless trait a survival characteristic for some elephants? Tuskless elephants are less likely to be hunted; therefore, they will have a better chance to reproduce.

2. Doctors are beginning to see a problem with everyone using antibacterial hand soap. Why? Bacteria are beginning to become resistant to these soaps since they are being used in excess.

3. List one physical and one behavioral adaptation. Physical – camouflageBehavioral - migration