evolution - sihs science · 2018. 5. 13. · a. digestion in all organisms follows a very similar...

EVOLUTION

ENGAGEYou have heard that humans and chimpanzees are about 98.8% similar but what does that really mean? 

How many common genetic similarities do you think we have to these organisms?

Cat: 90%Cow: 80%Mouse: 75%Fruit Fly: 60%Banana: 50%

What is Evolution?⦿ Evolution is the change over time in

heritable traits • Occurs in populations, not individual organisms

Earth formed about 4.6 billion years ago.First forms of LIFE arose 3.5 billion years ago.

Early Earth

What was Early Earth like?

Atmosphere:

Methane, CO2, water, nitrogen, hydrogen, etc.

No OXYGEN!

NO OXYGEN?...Prokaryotic ANAEROBIC Species

What does the early atmosphere tell us about Earth’s first organisms?

Bacteria capable of photosynthesis emerges.

6CO2 6H2O C6H12O6 6O2Radiantenergy

→+ ++Oxygen

!Ozone

The Ozone layer trapped the oxygen from photosynthesis and created a new kind of atmosphere.

Many organisms could not adapt to oxygenated air and went extinct. Others evolved into aerobic species.

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PHOTOSYNTHESIS

Miller and Urey experiment showed that life could have formed out of the simple compounds present during early Earth. Hypothesized that it took millions of years for cells to form from these organic molecules.

Endosymbiotic Theory⦿ The endosymbiotic

theory proposes that eukaryotic cells arose from living communities formed by prokaryotic organisms.

⦿ Ex: Prokaryotes that use oxygen to generate ATP evolved into mitochondria.

⦿ Ex. Prokaryotes that carried out photosynthesis evolved into chloroplasts.

EXPLORE:What evidence supports Evolution?

FOSSILS – preserved remains of organisms.May be :

Imprint

Mold

Amber Petrified

190 Million Years Ago Today

Homologies⦿ Similarities between the anatomical

structures of species; same structure different function

Vestigial Structures⦿ Vestigial structures are anatomical structures that

still appear, but are no longer used!• Examples: Appendix in humans, pelvic bones in

whales• Suggests that these structures may have existed

at a previous time or in an ancestor; organisms evolved and structures not needed

Comparative Embryology⦿ Insects and

animals often have very similar embryonic development• Ex. All

vertebrates (have a backbone) have similar development

• Suggests a common ancestor

Geological Distribution

⦿ Similar animals are found in different locations around the world.

⦿ Animals ended up evolving similar features for their environment because of their location on earth

⦿ They look the same but live in different areas

Comparative Biochemistry⦿ Comparison of DNA and macromolecules between

organisms• Through gel electrophoresis• Tells us what organisms are closely related

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

DNA Fingerprints and EvolutionThe closer the match for DNA fingerprints, the closer the

evolutionary relationship of the two organisms.1 2 3 4

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#1?

Type of Evidence?

Type of Evidence?

baby elephant in womb

Type of Evidence?

Type of Evidence?

ELABORATEVIDEO

EVALUATEWhich most accurately summarizes the evolutionary relationship between prokaryotic and eukaryotic cells?

A. Both cells are about the same age according to the geologic time scale, because of similar cell membranes, DNA, and chemical compositions.

B. Eukaryotic cells are considered younger than prokaryotic cells, because of the more advanced organelles and processes within eukaryotic cells.

C. Both cells are about the same age according to the geologic time scale, because of similar energy transformation processes and nutrient flow.

D. Eukaryotic cells are considered older than prokaryotic cells, because of the more advanced organelles and processes within eukaryotic cells.

EVALUATEWhich would most likely be biochemical evidence of evolution?

A. Digestion in all organisms follows a very similar pathway.

B. Humans, whales, and bats all have similar looking forelimbs.

C. Fish, bird, rabbit, and human embryos all have gill slits and tails.

D. Chimpanzees and humans have a similar gene for producing hemoglobin.

EVALUATEAccording to scientists, the atmosphere of early Earth was unable to support organisms that perform aerobic respiration. Which best explains the reason for this?

A.The poisonous gases killed off all living organisms.B. There was an absence of water.C. There was an absence of oxygen.D. The air was too dense to support life.

Evolution and Natural Selection

ENGAGE:Survival of the FittestWhich organism is most fit?

EXPLORE:Virtual Evolution Games

Charles Darwin⦿ Charles Darwin is best

known for his contributions to the Theory of Evolution.

⦿ On a five year voyage on a ship called the Beagle, Darwin recorded his observations of organisms and fossils found along his journey.

⦿ This led Darwin to develop the idea of evolution and natural selection.

Natural Selection⦿ “Survival of the Fittest” means that those

organisms best adapted to their environment will survive, reproduce, and pass on genes• “Fittest” means best adapted, not strongest!

Survival of the Fittest

msnbcmedia.msn.com

www.uwyo.edu

www.arktimes.com

firemice.wordpress.com

not the biggest…not the strongest…not the bravest…not the fastest……IT IS the FITTEST!pixdaus.com

Adaptations⦿ Any heritable trait an organism has that helps

it to survive.⦿ If an organism does not have adaptations to

best fit its environment, it will die.

What are some adaptations of the owl?

Factors Influencing Natural Selection

● Overproduction of offspring● Genetic variation● Competition for limited resources● Selection

Overproduction of Offspring

Overproduction - a species reproduces more offspring than the environment can support; only some will survive into adulthood.

● Species have the potential to increase exponentially, but environmental factors (resources, relationships in food web) maintain lower population numbers.

Genetic VariationVariaton - organisms (within populations) exhibit individual variation in appearance and behavior.

● Genetic Recombination○ Dominant and Recessive alleles in genes, along with

polygenetic traits , lead to individual organisms with different phenotypes

● Mutations○ Changes in DNA sequences can introduce both good

and bad new traits into a population (ex. Immunities, resistant bacteria, pesticide resistant plants)

Competition

Organisms COMPETE for limited resources.

○ Food, water, space, and mates

Selection● Changing environments select for specific phenotypes.

○ Those organisms with favorable adaptations survive, reproduce, and pass on their alleles to future generation

○ Over time, the accumulation of favored alleles leads to a change in species (change over time = evolution)

Role of Disease Agents in Natural Selection⦿ Organisms are constantly

changing and adapting.• Ex: bacteria

⦿ Humans often use antibiotics to combat harmful bacteria.

⦿ Some bacteria are born with a natural resistance (adaptation) to the antibiotic.

⦿ These bacteria will survive and reproduce, creating a group that are resistant to the drugs. • MRSA

Role of Disease Agents in Natural Selection

⦿ Pesticide Resistance in Plants

⦿ Antivirals: Medicine used for viral infections• Ex: Tamiflu

⦿ Passive Immunity: Immunity to certain diseases is given from mother to baby at birth

⦿ Active Immunity: Immunity acquired through exposure to a disease• Ex: Vaccines: artificial exposure• After exposure, your body builds up an immunity

Geographic Isolation⦿ When mountains, islands, etc. keep a

population isolated, the species will meet different environmental challenges, change and evolve independently than the original population

Speciation⦿ Evolutionary process by which new

biological species arise.

ELABORATEUnique Bird Beak Physique

EVALUATEWhich is the best description of how natural selection changes a species over time?A. survival of the organisms that occupy the largest

area in an environmentB. survival of the strongest organisms in an environmentC. survival of the organisms genetically best adapted to

the environmentD. elimination of the smallest organisms by the largest

organisms

EVALUATEA crop is treated with a pesticide and 98% of the insects are killed. What will most likely happen to the remaining insects?A.They will die off due to a decrease in their population size.B. They will migrate to another area.C. They will mate with a different species of insect to ensure survival.D. They will reproduce and pass on resistant genes.

EVALUATEWhich best describes active immunity?A. The resistance developed in an organism by its own

production of antibodies in response to an exposure to an antigen, a pathogen, or to a vaccine.

B. A resistance acquired through breastfeeding newborns.

C. A resistance acquired by the overuse of antibiotics causing weak bacteria to die and resistant bacteria to multiply.

D. Resistance developed by regularly washing hands with soap and water as an effective way to prevent bacterial infections.