"nothing in biology makes sense except in the light of evolution” ~Theodosius Dobzhansky ( ) Photo by “davemee” flickr creative commons Evolution of Hip Hop Dances

How are humans speeding up Evolution? s&feature=youtube_gdata_playerhttps:// s&feature=youtube_gdata_player

Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale? Why is the sequence of DNA very similar in some groups of organisms but not in others? Why do the embryos of animals look very similar at an early stage?

Photo courtesy of Swamibu, Flickr Creative Commons

Marine Iguana, photo courtesy of mtchm, flickr creative commons Blue-footed booby, photo courtesy of stirwise, flickr creative commons

Giant tortoise, photo courtesy of Planetgordon, flickr creative commons Finch, photo courtesy of stirwise, flickr, creative commons

Darwin noted that there existed many finches on the islands, but while they had similarities, each was adapted to eating a particular type of island food He concluded that the finches all came from one ancestral species and evolved into many new species Cactus finch, photo courtesy of zrim, flickr creative commons

Darwin published this work to explain the variety of species that exist on the planet He proposed the “Theory of Evolution by Natural Selection ” Natural selection provided a mechanism for evolutionary change in populations.

Evidence supporting evolution Fossil record –shows change over time Anatomical record –comparing body structures homology & vestigial structures embryology & development Molecular record –comparing protein & DNA sequences Biogeography

Fossil Evidence Shows numbers extinct animals Shows similarities between extinct animals and animals that are alive today The earth’s layers show a time scale of species and when they appeared on earth (and when they died out)

Dinosaurs have always fascinated us, movies such as Jurassic Park capitalize on that fascination. How do we know what dinosaurs looked like? We create a picture based on the bones we find (fossils) and use modern reptiles to guess at their texture and skin color.

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

Fossils tell a story…

Primate Fossils AustralopithecusHomo erectusHomo sapien

Relative vs. Absolute Dating

Fossil

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

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

ex. The flippers of whales, and the wings of birds All forelimbs of vertebrates have the same pattern of bones Common ancestry

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

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

2 nd side note: Vestigial Organs – these are organs or parts that seem to have no function Why would whales have pelvis & leg bones if they were always sea creatures? Because they used to walk on land!

Ex: Embryological Development Embryos of different species develop in almost identical ways. Human fetus at 8 weeks

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

Biochemistry and DNA continued When comparing the DNA of one species to another, more similarities are found in species that are more closely related. Lion photo credit: ucumari Tiger photo credit: digitalART2

DNA

4. Biogeography Biogeography focuses on the study of how life forms are distributed over the geographical areas of the earth giving evidence to the theory of evolution. It provides knowledge of distribution through geological time on both species and the ecosystem. Speculation, glaciation, extinction and continual drift all provide explanations of how species spread and locate to various geographical locations through ecosystem energy exchanges.

These animals have evolved similar adaptations for obtaining food because they occupy similar niches. What can you infer about their phylogeny from their geographic locations? Convergent Evolution

Punctuated Equilibrium “instead of a slow, continuous movement, evolution tends to be characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms” The "punctuated equilibrium" theory of Niles Eldredge and Stephen Jay Gould was proposed as a criticism of the traditional Darwinian theory of evolution…what is it called?theory of evolution

Convergent Evolution 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 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? 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 They are usually geographically separated so that there is a barrier to the mixing of genes © 2008 Paul Billiet ODWSODWS

Direct observation of species change 1.Bacteria become resistant to antibiotics 2.Wolves were bred over many generations to become dogs (artificial selection) and then bred further to create a variety of breeds

3. Micro Evolution: Natural selection in action: the evolution of insecticide-resistance Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings N ew insecticides are effective, killing 99% of the insects. The few survivors resist the chemical attack. Only these resistant individuals reproduce, passing on their resistance. In each generation the percentage of insecticide-resistant individuals increases. In general, natural selection operates not to create variation, but to edit existing variation.

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings For patients treated with the drug 3TC, which interferes with genome replication in HIV, 3TC- resistant strains become 100% of the population of HIV in just a few weeks. Fig

Endosymbiotic Theory