PKA: Answer on your own paper and turn in to Ms. Deel

• 1. Do populations of organisms change over time? How do you know?

• 2. Why would organisms need to change?• 3. Is there evidence that any organisms living

today have experienced any change?• 4. What factors would contribute to any

change?

What did this organism look like when it was alive?

http://www.sciencemag.org/site/multimedia/slideshows/343.6169.dino/dino.slideshow.html

Horse Evolution Lab

www.docstoc.com

www.itsokaytobesmart.com

What changes occurred and why?

www.fillthevoid.org

http://www.sepa.duq.edu/darwin/education-tools-horseFeet.shtml

Fossils

• Fossils: Any trace or remains of an organism that has been preserved by a natural process

• Comparing structure of fossils with present day organisms allows us to infer evolutionary relationships

www.mindbodyspiritonline.co.uk

• Evolution: Change over time– Geological Evolution: the evolution of the Earth

itself

– Organic Evolution: the evolution of living things

• Most of the time organisms decay without leaving a trace causing the fossil record to be incomplete

• Why would organisms that die not be fossilized?– Not in sedimentary rock– Decay quickly– Get eaten– Ex- tropical rain forest organisms decay too fast

• Fossils are found in Sedimentary rock

www.en.uni-muenchen.de

Sedimentary rocks are formed by sediment that is deposited over time, usually as layers at the bottom of lakes and oceans.

Types of Fossils

• 1. Amber and Ice

• 2. Bones and Petrification

• 3. Molds, Casts, and Imprints

Age of fossils

• 1. Relative dating– Age determined by relating fossil to others

• Use index fossils- fossils found only during on period of time

• Law of Superposition: Layers on the top were deposited later than layers on the bottom; layers on the bottom are older than on the top

Law of Superposition

tle.westone.wa.gov.au

Which layer is the youngest? Oldest?

ufo-connguoi-thuongde.blogspot.com

http://quizlet.com/4079105/relativeabsolute-age-datingfossils-flash-cards/

• 2. Absolute Dating– Radioactive dating gives more precise time

• Radioactive Dating: use rate of decay of radioactive elements found in organisms to find their absolute age.– Ex: carbon dating

• The universe is full of naturally occurring radioactive elements. Radioactive atoms are unstable

• Over time, radioactive “parent atoms” decay into stable “daughter atoms.”

• Half life: how many years it takes for half of the amount of an element to decay.

Radioactive Decay Example

• Carbon-14 has a half life of 5,730 years. If the original amount of C-14 in a dead horse is 14g, how old is the organism if the amount of C-14 is currently 7g? If 3.5g is left?

• 5,730 years• 11,460 years

• Evolution is the change in the inherited characteristics of populations over successive generations

• Darwin vs. Lamarck

ciencialibrecolombia.wordpress.com

Lamarck

• 1. Tendency towards perfection- all organisms have the urge to become better.

• 2. Use and Disuse- organisms can alter their traits by use or disuse

• 3. Acquired characteristics- the traits that an organism acquires during a lifetime will be passed on to offspring

Darwin

• 1. Overproduction- Each species produces more offspring than can survive to adulthood

• 2. Competition/Struggle- Because of overproduction, organisms must compete for resources like water, shelter, food, escape predators

• 3. Genetic Variation- variations or differences occur among members of the same species

Darwin

• 4. Survival of the fittest/ Natural Selection- Organisms with traits that make them well adapted to their environment have a better chance of surviving to adulthood to reproduce and therefore passing on their well adapted genes to the next generation

• 5. As natural selection continues over generations, species change and become better adapted to their environment= EVOLUTION

Whose theory was correct?

Example: Giraffes

• Using the theories to explain why giraffes have such long necks

Example: Giraffes

• Lamarck:1. Giraffes want longer necks 2. They stretched their necks a lot to reach leaves high on trees3. They passed the long neck trait they acquired on to their offspring

Example: Giraffes

• Darwin:1. Over production- too many giraffes2. Struggle- not enough food, leaves high on trees3. Variation- Giraffes with short, medium, and long necks

Example: Giraffes

– Darwin Continued: 4. Natural Selection- the giraffes with the long necks could reach the higher leaves and survive to reproduce more than others

5. After generations the giraffes with short and medium necks died out and long necked giraffes increased in the population.

Example: Darwin’s Finches

• Using the theories to explain who finches where there are large, hard seeds to eat have evolved large thick beaks.

Example: Darwin’s Finches

• Lamark:1. Finches want bigger beaks.2. Finches use their beaks a lot and they got thick3. They passed the thick beak trait they acquired on to their offspring

Example: Darwin’s Finches

• Darwin:1. Over production- too many finches2. Competition- not enough food, only large seeds3. Variation- Finches with small, medium, and large beaks

Example: Darwin’s Finches

– Darwin Continued: 4. Natural Selection- the finches with the large thick beaks could open seeds and survive to reproduce more than others

5. After generations the finches with short and medium beaks died out and large beaked finches increased in the population.

Evidence of Evolution, Evolution of Populations

• Evolution- a change in a population over time

• Gene pool- all genes in a population

• Population- groups of interbreeding individuals that live in the same place at the same time

How are these structures alike?How are they different?

Evidence that organisms descended from a common ancestor

• 1. Homologous body structures: Structures that have different mature forms but develop from the same embryonic tissue.

• Ex- The forelimbs of vertebrates

www.bio.miami.edu

• 2. Vestigial structures: Structures that no longer function or function less than in an ancestor, but are present because they are left over from an ancestor.

• Ex- Tailbone in humans, appendix in humans, wisdom teeth in humans, toe on a boa

• 3. Similarities in Embryology: The more similarly the embryos of different organisms develop the more closely related they are.

• 4. Darwin’s Finches: there are 13 species of finches on the Galapagos that descended from 1 common ancestor from the mainland of South America. Similar because inherited similar DNA from common ancestor, different because environmental pressures caused natural selection.

• 5. Antibiotic Resistance in Bacteria:• Back to Darwin’s idea’s– Overpopulation- too many bacteria– Struggle- antibiotics– Variation- some bacteria have genetic resistance

to antibiotics, some do not

– Survival of the fittest- the bacteria that are resistant survive and reproduce more

– Evolution-there is an increase in antibiotic resistant bacteria

• 6. Pesticide resistance in Tobacco Budworm – Over time the Tobacco Budworm has become

resistant to pesticides. Using Darwin’s Theory to explain this phenomenon

– 1968-tobacco budworm infestation; farmers sprayed pesticide and killed budworms

– 1969-small infestation; farmers sprayed; pesticide didn’t help

– 1970- infestation; farmers sprayed; pesticide didn’t work

• 7. Sickle Cell Anemia & Malaria:• Sickle Cell Anemia is a deadly genetic disease;

causes blood cells to form a sickle shape; gene common in tropical Africa and Asia

• Malaria- leading cause of death in Africa; a pathogenic disease caused by a protist that is transmitted by the bite of a certain mosquito found in tropics

Why has natural selection not eliminated the harmful gene?

• AA- does not have sickle cell, NOT resistant to malaria

• Aa- does not have sickle cell, resistant to malaria

• Aa- has sickle cell anemia, resistant to malaria

• Individuals heterozygous have a better chance of surviving and reproducing

www.mhhe.com

Toothpick Fish Lab

www.ripleyaquariums.comWeedy Sea Dragon

Natural Selection Depends on:

• Variation• Struggle• Survival of the “fittest”

• Remember natural selection is based on the LAWS OF GENETICS

• Sources of Variation in a gene pool• 1. Crossing over- exchange of genes from one

homologous chromosome to another

www.phschool.com

• 2. Sexual reproduction• 3. Mutation- change in genetic material (only

source of NEW gene type)• 4. Migration- the movement of organisms into

or out of a population

• 5. Isolation- a group of organisms becomes separated from its original population– Organisms can be separated by:• Geography (by river, mountains) OR• Reproduction (mate at different times, places, etc)

• The isolated population may have different environmental pressure and therefore different genes may be selected for.

• This may cause the isolated population to become very different from the original population.

• Isolation often leads to speciation.• Speciation- the development of a new species• Ex- Squirrels around the Grand Canyon; A

group become isolated on the other side and become a different species because of different environments

• How new species can emerge:

• Genetic variation → environmental change→ natural selection→ new species

Rate of Species Survival

• The two evolutionary "strategies" :• r-selection for those species that produce

many "cheap" offspring and live in unstable environments

• K-selection for those species that produce few "expensive" offspring and live in stable environments.

R-Selected Example

http://education-portal.com/academy/lesson/r-selected-species-examples-definition-quiz.html#lesson

K-Selected Example

www.acuteaday.com

• Of course, the animal or plant is not thinking: "How do I change my characteristics?"

• Natural selection is the force for change• But, natural selection has produced a

gradation of strategies, with extreme r-selection at one end of the spectrum and extreme K-selection at the other end.

r Unstable environment, density independent K Stable environnent, density dependent interactions

small size of organism large size of organism

energy used to make each individual is low energy used to make each individual is high

many offspring are produced few offspring are produced

early maturity late maturity, often after a prolonged period of parental care

short life expectancy long life expectancy

each individual reproduces only once individuals can reproduce more than once in their lifetime

type III survivorship pattern in which most of the individuals die within a short time but a few live much longer

type I or II survivorship patternin which most individuals live to near the maximum life span

Rate of Evolution

• Gradualism- process of evolution by slow change (remember the evolution of horses)

• Punctuated Equilibrium- species remain unchanged for millions of yeas suddenly die off with a short time and new species take over. Ex dinosaurs died off which allowed mammals to take their place

• Adaptive Radiation- when a single species or small group of species evolves into many different forms.

• Ex- After the dinosaurs died out there were a few species of mammals that then evolved into many different forms of mammals. They filled the places of the dinosaurs

Types of Evolution

• Divergent Evolution- different species develop from a common ancestor.– Ex- Grizzly bears and Polar bears have a common

bear ancestor, but different climates selected for different climates selected for different variations

• Convergent Evolution- unrelated organisms have similar traits due to similar environments – Ex- sharks and dolphins are unrelated but live in

similar environments and eat the same things so same color patterns and shape

Types of Natural Selection

• 1. Directional Selection- results in species having one extreme of a trait.– Ex- male cardinals, resistant bacteria

www.sparknotes.com

• 2. Disruptive Selective- results in species having both extremes of a trait; can lead to speciation – Ex- frogs

www.sparknotes.com

• 3. Stabilizing Selection- results in species having average of the same trait– Ex human birth weight

www.sparknotes.com

en.wikipedia.org

• Using the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed. As a result, the distribution of neck length shifted to favor individuals with long necks.

• Directional Selection

• Imagine a plant of extremely variable height that is pollinated by three different pollinators, one that was attracted to short plants, another that preferred plants of medium height and a third that visited only the tallest plants. If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants.

• Disruptive Selection

• A plant that is too short may not be able to compete with other plants for sunlight. However, extremely tall plants may be more susceptible to wind damage. Combined, these two selection pressures select to maintain plants of medium height. The number of plants of medium height will increase while the numbers of short and tall plants will decrease.

• Stabilizing Selection