Charles Darwin ( ) Sailed around the world

Darwin found…many unique species

How did tortoises and birds differ among the islands of the Galapagos? Each island had its own type of tortoises and birds that were clearly different from other islands Each island had its own type of tortoises and birds that were clearly different from other islands

Galapagos Turtles

What did Darwin’s Travels reveal? The diversity of living species was far greater than anyone had previously known!! The diversity of living species was far greater than anyone had previously known!! These observations led him to develop the theory of evolution!! These observations led him to develop the theory of evolution!!

What do you think evolution is? or What do you think “evolution” means? Turn to a partner and discuss.

Evolution is when organisms change over time. So, modern organisms descended from ancient ones

Convergent Evolution Species exposed to the same selective pressure in different parts of the world tend to develop the same adaptations Species exposed to the same selective pressure in different parts of the world tend to develop the same adaptations Even though they may be completely unrelated Even though they may be completely unrelated e.g. the placental wolf and the marsupial thylacine or Tasmanian wolf e.g. the placental wolf and the marsupial thylacine or Tasmanian wolf Thylacine Thylacinus cynocephalus Wolf Canis lupus © 2008 Paul Billiet ODWSODWS

Convergent evolution led to mimicry Why do these pairs look so similar? Why do these pairs look so similar? Monarch male = poisonousViceroy male = edible flybee mothbee

Divergent Evolution Populations of a species that are separated and evolve under different selective pressures develop different adaptations as they diverge Populations of a species that are separated and evolve under different selective pressures develop different adaptations as they diverge They are usually geographically separated so that there is a barrier to the mixing of genes They are usually geographically separated so that there is a barrier to the mixing of genes © 2008 Paul Billiet ODWSODWS

Evidence supporting evolution Fossil record Fossil record shows change over time shows change over time Anatomical record Anatomical record comparing body structures comparing body structures homology & vestigial structures homology & vestigial structures embryology & development embryology & development Molecular record Molecular record comparing protein & DNA sequences comparing protein & DNA sequences Artificial selection Artificial selection human caused evolution human caused evolution

1. Fossil record Layers of rock contain fossils Layers of rock contain fossils new layers cover older ones new layers cover older ones creates a record over time creates a record over time fossils show a series of organisms have lived on Earth fossils show a series of organisms have lived on Earth over a long period of time over a long period of time

Fossils tell a story…

Primate Fossils AustralopithecusHomo erectusHomo sapien

Relative vs. Absolute Dating

Relative Dating Can determine a fossil’s relative age Can determine a fossil’s relative age Performed by estimating fossil age compared with that of other fossils Performed by estimating fossil age compared with that of other fossils Drawbacks – provides no info about age in years Drawbacks – provides no info about age in years

Absolute dating Can determine the absolute age in numbers Can determine the absolute age in numbers Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Is performed by radioactive dating – based on the amount of remaining radioactive isotopes remain Drawbacks - part of the fossil is destroyed during the test Drawbacks - part of the fossil is destroyed during the test

Carbon-14 Dating

2. Anatomical record Animals with different structures on the surface But when you look under the skin… It tells an evolutionary story of common ancestors

Homologous structures Structures that come from the same origin Structures that come from the same origin homo- = same homo- = same -logous = information -logous = information Forelimbs of human, cats, whales, & bats Forelimbs of human, cats, whales, & bats same structure same structure on the inside on the inside same development in embryo same development in embryo different functions different functions on the outside on the outside evidence of common ancestor evidence of common ancestor

Homologous Body Structures

But don’t be fooled by these… Analogous structures Analogous structures look similar look similar on the outside on the outside same function same function different structure & development different structure & development on the inside on the inside different origin different origin no evolutionary relationship no evolutionary relationship Solving a similar problem with a similar solution How is a bird like a bug?

Analogous structures Dolphins: aquatic mammal Dolphins: aquatic mammal Fish: aquatic vertebrate Fish: aquatic vertebrate both adapted to life in the sea both adapted to life in the sea not closely related not closely related

Vestigial Organs traces of homologous organs in other species traces of homologous organs in other species Organ that serves no useful function Organ that serves no useful function e.g. Appendix

Vestigial organs Hind leg bones on whale fossils Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures? Because they used to walk on land!

In your notes…. In one sentence, write your answer to the following question….. In one sentence, write your answer to the following question….. What is the difference between homologous and analogous structures? What is the difference between homologous and analogous structures?

*Similarities in *Similarities in Embryology Embryology In their early Stages of development, chickens, turtles and rats look similar, providing evidence that they shared a common ancestry.

Embryological development

3. Molecular record LampreyFrogBird Dog MacaqueHuman Comparing DNA & protein structure Comparing DNA & protein structure everyone uses the same genetic code! everyone uses the same genetic code! DNA DNA  compare common genes  compare common proteins  compare common genes  compare common proteins number of amino acids different from human hemoglobin

How do we know natural selection can change a population? How do we know natural selection can change a population? we can recreate a similar process we can recreate a similar process “evolution by human selection” “evolution by human selection” 4. Artificial selection “descendants” of wild mustard

Questions for you…… What do you think artificial selection is? What do you think artificial selection is? Do you think the use of artificial selection is a “good thing?” Why or why not? Do you think the use of artificial selection is a “good thing?” Why or why not?

Artificial Selection nature provides variation, humans select variations that are useful. nature provides variation, humans select variations that are useful. Example - a farmer breeds only his best livestock Example - a farmer breeds only his best livestock

Selective Breeding Humans create the change over time “descendants” of the wolf

Artificial Selection …and the examples keep coming! I liked breeding pigeons!

Artificial Selection gone bad! Unexpected consequences of artificial selection Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance

Insecticide resistance Spray the field, but… Spray the field, but… insecticide didn’t kill all individuals insecticide didn’t kill all individuals variation variation resistant survivors reproduce resistant survivors reproduce resistance is inherited resistance is inherited insecticide becomes less & less effective insecticide becomes less & less effective

Natural Selection The traits that help an organism survive in a particular environment are “selected” in natural selection The traits that help an organism survive in a particular environment are “selected” in natural selection

Natural Selection and Species Fitness Overtime, natural selection results in changes in the inherited characteristics of a population. Overtime, natural selection results in changes in the inherited characteristics of a population. These changes increase a species fitness (survival rate) These changes increase a species fitness (survival rate)

Summary of Darwin’s Theory 1. Organisms differ; variation is inherited 2. Organisms produce more offspring than survive 3. Organisms compete for resources 4. Organisms with advantages survive to pass those advantages to their children 5. Species alive today are descended with modifications from common ancestors

Any Questions??