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Introductory Biology in-class interactive lecture on evolution. We will use an attribute table to make a phylogenetic tree based on 3 lines of evidence. Observations of habitat and eating habits Observations of skeletons Observations of gene sequences

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Introductory Biology in-class interactive lecture on evolution.

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Introductory biology in class interactive lecture on evolution l.jpg

Introductory Biology in-class interactive lecture on evolution.


We will use an attribute table to make a phylogenetic tree based on 3 lines of evidence l.jpg

We will use an attribute table to make a phylogenetic tree based on 3 lines of evidence

  • Observations of habitat and eating habits

  • Observations of skeletons

  • Observations of gene sequences

  • After each observation we will modify our tree


Black bear ursus americanus terrestrial omnivore l.jpg

Black bear (Ursus americanus)Terrestrial Omnivore


Harp seal phoca groenlandica l.jpg

Harp Seal (Phoca groenlandica)


Harp seal phoca groenlandica aquatic terrestrial carnivore l.jpg

Harp Seal (Phoca groenlandica)Aquatic & Terrestrial, Carnivore


Hippopotamus amphibius terrestrial aquatic herbivore l.jpg

Hippopotamus amphibiusTerrestrial & Aquatic, Herbivore


Sea otter enhydra lutris aquatic carnivore l.jpg

Sea Otter (Enhydra lutris)Aquatic, Carnivore


King penguin aptenodytes patagonicus aquatic terrestrial carnivore l.jpg

King Penguin (Aptenodytes patagonicus)Aquatic & Terrestrial, Carnivore


Harbor porpoise phocoena phocoena aquatic carnivore l.jpg

Harbor Porpoise (Phocoena phocoena)Aquatic, Carnivore


Blue whale balaenoptera musculus aquatic omnivore l.jpg

Blue Whale (Balaenoptera musculus)Aquatic, Omnivore


Now draw a tree similar to this example based on diet habitat l.jpg

Now draw a tree similar to this example based on diet & habitat


Skeletal evidence l.jpg

Skeletal evidence

  • Skeletons provide strong evidence that all vertebrates share a common ancestry

  • Skeletal evidence comes from species that are now living and from fossils of species that have become extinct


Several fossil discoveries show how amphibians descended from fish l.jpg

Several fossil discoveries show how amphibians descended from fish

  • These fossils are literally half fish, half amphibian

  • Fossils that show transitions between species are called “transitional fossils”

Ichthyostega


Fossil record also clearly shows the reptile to mammal transition l.jpg

Fossil record also clearly shows the reptile to mammal transition

  • Examples of features that are part reptilian and part mammalian:

    • Jaw joint

    • Tooth

    • Ribs on neck vertebrae

Lycaenops -- a carnivorous therapsid


Vestigial bones also provide more evidence of common ancestry among vertebrates l.jpg

Vestigial bones also provide more evidence of common ancestry among vertebrates

  • Pelvic girdle in some snakes, tailbone in humans

  • Remnants of structures with important functions in ancestors but no longer used


Vestigial pelvic bones in whales did their ancestors have legs l.jpg

Vestigial pelvic bones in whales -- did their ancestors have legs?


Homologous structures in mammal skeletons demonstrates common ancestry l.jpg

Homologous structures in mammal skeletons demonstrates common ancestry

  • Features, like the bones of mammals, are said to be homologous, because they share a common structural pattern

  • Conclusion: all mammals are derived from a common ancestor


Slide18 l.jpg

Bear


Seal skeleton l.jpg

Seal skeleton


Hippopotamus l.jpg

Hippopotamus


Sea otter l.jpg

Sea otter


Penguin l.jpg

Penguin


Porpoise l.jpg

Porpoise


Whale l.jpg

Whale


Now draw a tree similar to this example based skeletal features l.jpg

Now draw a tree similar to this example based skeletal features


Molecular biology evidence l.jpg

Molecular biology evidence

  • A common genetic code for all living things is evidence that all are related

  • Comparison of DNA among living organisms has strengthened and clarified our understanding of evolutionary relationships


Genes from other organisms that also occur in h sapiens deep genetic homologies l.jpg

% Genes from other organisms that also occur in H. sapiens: deep genetic homologies

  • Mouse - 86%* Fruit fly - 44%

  • Nematode worm - 25% Yeast - 30%

  • Amoeba - 22% Mustard (plant) - 19%

  • E. coli (bacterium) - 9%*Of those genes now identified in mice, 86% of them also occur humans


Common ancestry of organisms explains many puzzles such as the distribution of the hb gene l.jpg

Because it was present in a common ancestor billions of years ago!

Hb

Common ancestry of organisms explains many puzzles such as the distribution of the Hb gene

Hb

Hb

  • Puzzle posed earlier: The hemoglobin gene is widely distributed throughout living organisms. Why?

Hb

Hb

Hb

Hb

Hb


Hemoglobin again how molecular biology is used to estimate dates of common ancestry l.jpg

Hemoglobin (again) - how molecular biology is used to estimate dates of common ancestry

  • All vertebrates have genes that make hemoglobin

  • Like many other genes, hemoglobin genes mutates at a fairly constant rate, even if they are in different animal groups

  • Rate of change can be used to estimate how long ago groups or organisms diverged from one another!

* Changes per 100 codons


Using molecular biology evidence to draw phylogenetic trees l.jpg

Using molecular biology evidence to draw phylogenetic trees

  • Evolutionary relationships are reflected in the similarity of DNA and proteins among species

  • The closer the match between sequences, the more recent the common ancestor


Closely related species have similar dna and proteins similarity reflects ancestry l.jpg

Closely related species have similar DNA (and proteins). Similarity reflects ancestry.


Two related species start with similar dna but mutations occur making their dna different l.jpg

Two related species start with similar DNA, but mutations occur, making their DNA different

  • Assume species A & B just arose from the same common ancestor

    • There DNA is the same (or nearly so)

    • Each of their proteins are the same

  • With time mutations make their DNA (and proteins) different

  • Computers can align regions of DNA that did not change

Computer alignment:


Computers build phylogenetic trees based on sequence data l.jpg

Computers build phylogenetic trees based on sequence data


Slide34 l.jpg

A portion of the aligned sequences


Part of the aligned dna sequences l.jpg

Part of the aligned DNA sequences


Now draw a tree similar to this example based on dna sequence data l.jpg

Now draw a tree similar to this example based on DNA sequence data


Phylogenetic tree from dna data l.jpg

Phylogenetic tree from DNA data


About the hippo whale relationship l.jpg

About the hippo-whale relationship

  • DNA data suggested hippos as whale’s closest land relative but there was no fossil evidence to support this theory

  • Recent discovery of 47 million year old fossils from a proto-whale provided fossil evidence -- hippo’s and whales are closely related

  • Key fossil evidence -- the hippo has a distinctive ankle bone and so does the proto-whale!


Recent discoveries of transitional fossils show that whale ancestors did have legs l.jpg

Recent discoveries of transitional fossils show that whale ancestors did have legs

Ambulocetus

(the walking whale)

Carl Dennis Buell


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