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Recall: Evolution Theory by Natural selection

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Title: Recall: Evolution Theory by Natural selection


1
Recall Evolution Theory by Natural selection
2
Evidence for Evolution
1.  The Fossil Record 2.  Biogeography  3.
 Anatomy 4.  Embryology  5.  Molecular Biology 6.
Artificial Selection (last class)  
Watch this http//www.youtube.com/watch?vfaRlFsY
mkeY
3
Era Period Years Ago Major Events
Precambrian 4.5 billion First living cellsBacteriaPhotosynthesisAlgaeFirst invertebrates
Paleozoic               Cambrian 590 million AlgaeMarine Invertebrates
Paleozoic               Ordovician 505 million ArthropodsMollusksFirst fishFungi
Paleozoic               Silurian 438 million Many fishTrilobitesVascular PlantsPlants on LandArthropods on Land
Paleozoic               Devonian"Age of Fishes" 408 million Lots o' fishesFirst amphibians and insects
Paleozoic               Carboniferous 360 million MossesMany amphibiansFirst reptiles
Paleozoic               Permian 286 million Mass marine extinctionAmphibian declinePangaea
Mesozoic"Age of Reptiles"                                                                    Triassic 248 million First mammalsDinosaursPangaea begins to separate
Mesozoic"Age of Reptiles"                                                                    Jurassic 213 million Dinosaurs dominateFirst birds
Mesozoic"Age of Reptiles"                                                                    Cretaceous 144 million Flowering plantsMass extinction
Cenozoic"Age of Mammals"                                                   Tertiary 65 million Birds,mammals, insects flourishContinents in modern positions
Cenozoic"Age of Mammals"                                                   Quaternary 2 million to present First hominidsIce AgesExtinction of giant mammals (mammoth)
4
1. Fossil Evidence
  • Layers of sedimentary rock contain fossils
  • New layers cover older ones, creating a record
    over time
  • When fossils are arrayed in the order of their
    age, a progressive series of changes are seen
  • The younger fossils are more similar to existing
    species than older ones

5
  • Fossils can tell us 
  • - Body size - Weight -Age
  • - Location - Migration -Cause of extinction
  • - Diet - Common origins (missing links)

6
The Fossil Record
  • The Fossil record is incomplete many gaps
  • Reasons
  • Species with delicate bodies dont fossilize
  • Species may not have lived in conditions that
    allow it to fossilize
  • Fossils havent been found

7
HOW DO FOSSILS FORM?
  • Dead animals and plants buried by sediment under
    right conditions hardened into fossils
  • Bones or material may decay, but water or
    minerals seep into the impression left by the
    original material
  • Water and minerals continue to dissolve the
    original material, but maintain its impressions
    that hardens into rock over time

Burgess Shale fossil beds (British Columbia)
8
Archeopteryx- a transitional fossil
Transitional Fossils Fossils that show
the intermediate states between an ancestral form
and its descendants -provide the missing link
between past and present species
  • First bird 150 mya
  • Transition b/t dinosaurs and birds
  • Birds are thus considered reptiles
  • Found in southern Germany

9
Eustheoteron
Animal Armageddon Eustheopteron
http//animal.discovery.com/videos/animal-armagedd
on-eusthenopteron.html
10
Transitional Fossil Tiktaalik
  • Neil Shubin- University of Chicago
  • Assumption
  • Land vertebrates evolved from lobed-finned fish
  • Observations
  • The first fossils of lobe-finned fish 390 MYA.
  • The earliest fossils of land vertebrates 360 MYA.
  • Most of these fossils in freshwater deposits.

11
Transitional Fossils - Tiktaalik
  • Based on the Theory of Evolution . . .
  • Shubin Predicts
  • The transition to land occurred 390 360 MYA
  • The transition occurred in freshwater ecosystems.
  • Fossils of transitional species would be found in
    freshwater sedimentary deposits from about 375
    MYA

12
Transitional Fossil - Tiktaalik
13
Transitional Fossil - Tiktaalik
  • Shubin discovers Fishapod!
  • Four limbs with webbed fins and sturdy wrist
    bones
  • Neck and shoulders
  • Thick ribs
  • Flattened skull

A missing link from sea to land animals
http//www.youtube.com/watch?vHyJAV-Jf9do Transit
ional Tetrapod Fossil - YouTube
14
Ancestor of Modern Whales
  • Transition fossil Ambulocetus had hind limb

15
Seymouria
  • Amphibian or reptile?

Therapsid
mammal or reptile?
16
FOSSIL RECORD HISTORY OF THE HORSE
Modern horses one toe become hoof others remain
vestigial bumps higher up the legs
17
Evolution of the Horse
18
Ardipithecus Ramidus
http//www.youtube.com/watch?vEC9aIth1ah4 The
Analysis of Ardipithecus ramidus -- One of the
Earliest Known Hominids - YouTube
19
2. Biogeographical evidence
  • Biogeography the study of the global
    distribution of species, including the history
    and causes of this distribution.
  • Closely related species are usually found in
    areas that are geographically close to each other
  • Fossils of the same species can be found on the
    coastlines of neighbouring continents.
  • As the continents drifted away from Gondwana,
    they became isolated from other land masses
  • Once isolated, populations unique, or endemic, to
    these islands evolved.

20
Darwins Hypothesis
Show me the evidence?
  • Remote (volcanic) oceanic islands became
    populated by species that arrived by water or
    air. These species evolved into new species.
  • Evidence
  • Islands are often missing plants and animals
    common on continents
  • Only species that can fly, float or swim can
    inhabit islands
  • No rabbits in S. America
  • No amphibians, very few mammals on the Galapagos
    islands
  • Marsupials (i.e. pouched mammals ) found in
    Australia S. America
  • Lemurs only in Madagascar island

21
  • Summary table Species on remote islands
  • Darwin thus considered
  • species have evolved
  • Evo. is the best explanation for why isolated
    islands had many species found nowhere else
  • and why these species bore a resemblance to those
    on nearest continental land mass.

22
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