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Regents Biology 2006-2007 Evidence for Evolution by Natural Selection.

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Presentation on theme: "Regents Biology 2006-2007 Evidence for Evolution by Natural Selection."— Presentation transcript:


2 Regents Biology Evidence for Evolution by Natural Selection

3 Regents Biology A BRIEF HISTORY...  Charles Darwin  The person who was most influential to our understanding of evolution.  In 1831, at age 22, he joined the crew of the HMS Beagle as a naturalist for a 5 year voyage around the world.

4 Regents Biology Darwin’s Findings  After Darwin returned to England in 1836 he filled notebooks with his ideas about species diversity and the process that he would later call evolution.  He did not rush to publish his ideas because they disagreed with the fundamental scientific beliefs of his day.  He asked his wife to publish his ideas when he died.

5 Regents Biology Wallace’s Essay  In 1858, another naturalist, Alfred Russell Wallace wrote an essay describing his work in Malaysia that summarized the same ideas Darwin had been thinking about for 25 years.

6 Regents Biology Origin of Species  Suddenly Darwin had incentive to publish the results of his work.  In 1859, his book On the Origin of Species presented evidence and proposed a mechanism for evolution that he called natural selection.


8 Regents Biology Evolution is NOT goal-oriented §An evolutionary trend does not mean that evolution is goal-oriented. §Surviving species do not represent perfection. §There is random chance involved as well §Traits happen— Well suited to an environment, OR NOT! Evolution is the survival of the fittest, but sometimes it is survival of the just good enough.

9 Regents Biology 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  Artificial selection  Human-caused evolution

10 Regents Biology 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)

11 Regents Biology Fossils tell a story… the Earth is old Life is old Life on Earth has changed

12 Regents Biology Fossil of Archaeopteryx  lived about 150 mya  links reptiles & birds Today’s birds descended from ancestral species Evolution of birds

13 Regents Biology Transition from sea to land  2006 fossil discovery of early tetrapod  4 limbs  Missing link from sea to land animals

14 Regents Biology Land Mammal ? ? ? ? Where are the intermediate fossils? Ocean Mammal Complete series of transitional fossils We found the fossil — no joke!

15 Regents Biology 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

16 Regents Biology Compare the bones  The same bones under the skin  limbs that perform different functions are built from the same bones How could these very different animals have the same bones?

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

18 Regents Biology But don’t be fooled by these…  Analogous structures  look similar on the outside  same function  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?

19 Regents Biology Analogous structures  Dolphins: aquatic mammal  Fish: aquatic vertebrate  both adapted to life in the sea  not closely related Watch the tail!

20 Regents Biology Vestigial organs  Structures on modern animals that have no function  remains of structures that were functional in ancestors  evidence of change over time  eyes on blind cave fish  human tail bone

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

22 Regents Biology Convergent evolution  3 groups with wings  Does this mean they have a recent common ancestor? Flight evolved 3 separate times — evolving similar solutions to similar “problems” Flight evolved 3 separate times — evolving similar solutions to similar “problems” NO! They just came up with the same answer!

23 Regents Biology Convergent evolution led to mimicry  Why do these pairs look so similar? Monarch male poisonous Viceroy male edible flybeemothbumblebee Which is the fly vs. the bee? Which is the moth vs. the bee?

24 Regents Biology Too close to call for hungry birds!!

25 Regents Biology Yuck!!!

26 Regents Biology Comparative embryology  Development of embryo tells an evolutionary story  similar structures during development all vertebrate embryos have a “gill pouch” at one stage of development

27 Regents Biology 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

28 Regents Biology Building “family” trees Closely related species are branches on the tree — coming from a common ancestor

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

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

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

32 Regents Biology Unexpected consequences of artificial selection Pesticide resistance Antibiotic resistance

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

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