The Evidence for Evolution
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The Evidence for Evolution. Evidence #1. Fossil Record. Evidence of Evolution #1 – Fossil Record. Fossils are the preserved remains of once-living organisms Rock fossils are created when three events occur organism buried in sediment calcium in bone or other hard tissue mineralizes

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The Evidence for Evolution

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The Evidence for Evolution


Evidence #1

Fossil Record


Evidence of Evolution #1 – Fossil Record

  • Fossils are the preserved remains of once-living organisms

  • Rock fossils are created when three events occur

    • organism buried in sediment

    • calcium in bone or other hard tissue mineralizes

    • surrounding sediment hardens to form rock


Fossil Evidence of Evolution


Fossil Evidence of Evolution

Fossil

records

document

the course

of life through

time


Fossil Evidence of Evolution

  • Fossils document evolutionary transition

  • The oldest known bird fossil is the Archaeopteryx

  • It is intermediate between bird and dinosaur

  • Possesses some ancestral traits and some traits of present day birds

  • Archaeopteryx was first found in 1859


Fossil Evidence of Evolution

Fossil of Archaeopteryx


Fossil Evidence of Evolution

Recent discoveries

  • Four-legged aquatic mammal

    • Important link in the evolution of whales and dolphins from land-dwelling, hoofed ancestors

  • Fossil snake with legs

  • Tiktaalik: a species that bridged the gap between fish and the first amphibian

  • Oysters: small curved shells to large flat shells


Fossil Evidence of Evolution

Whale “missing links”


Fossil Evidence of Evolution

Evolutionary change in body size and toe reduction of horses


Fossil Record Activity

  • Gradualism – slow gradual change in a population over time

    • Uniformitarianism; constant, small changes in the environment result in slow changes in the population

  • Punctuated Equilibrium – fast change in a population in a short period of time (punctuated) followed by little/no change over a long period of time (equilibrium)

    • Mass extinctions are a cause of the quick change in a population


Adaptive Radiation

  • A single species has evolved, through natural selection and other processes, into diverse forms that live in different ways

  • An example is the different varieties of finches that were found on the different islands that Darwin visited. Each variety was perfectly fit for the different islands’ environments.

  • However, they all descended from a common ancestor


Activities

  • Fossil Record Activity

  • Analysis of phylogenetic trees and adaptive radiation


Evidence #2

Morphology


DivergentEvolution

  • when one species becomes many different species to fill available niches

    • Adaptive Radiation: periods of evolution in which organisms form new species due to adaptations that allow them to fill different niches in the community. i.e. Darwin’s Finches on the Galapagos Islands

    • Homologous Structures


Evidence for Evolution #2 – Morphology

  • Homologous Structures -Similarity in structure due to common decent (had a common ancestor), regardless of the different environments in which they now live; same structure, different function

    i.e.- human hands, whale fins, bat wings


Evidence for Evolution #2 – Morphology


Evidence for Evolution #2 – Morphology


Convergent Evolution

  • the appearance of apparently similar structures/ features in organisms of different lines of descent.

    • Analogous structures

    • Birds & Bats

    • Dolphins & Sharks

    • Penguins & Seals


Evidence for Evolution #2 - Morphology

  • Analogous Structures - Similar structures based on naturally selected adaptations for the same function in different organisms but that did NOT result from a common ancestor

  • i.e – wings in birds, bats, insects


Analogous Examples


Convergent Evolution

Convergence among fast-swimming predators


Mimicry

  • A phenomenon in which an individual gains an advantage by looking like the individuals of a different species.

  • “A mimic is any species that has evolved to appear similar to another successful species in order to dupe predators into avoiding the mimic, or dupe prey into approaching the mimic.”


Monarch

Viceroy


Yellow Jacket

Sand Wasp


Dronefly

Honey Bee


Sryphid Fly

Paper Wasp


Coral Snake

Colubrid Snake


Mantid

Orchid


Catkin (plant)

Caterpillar


Evidence for Evolution #2 - Morphology

  • Vestigial Structures - Remnants of once useful structures (in ancestral species) but that no longer serve a purpose in this specific species (although could still be useful in similar species)

    i.e. – human appendix, hind limbs of snakes and whales


Vestigial Examples


Vestigial structures of a whale


Blind Salamander


Blind Cave Fish


  • Feel your gums above your canine teeth

  • vestigial roots


Activity

  • Homologous structures coloring assignment and questions


Evidence #3

Embryology


Dolphin Embryo


Human Embryo

  • Figure 2.4.1. Cat and human embryos in the tailbud stage. A cat embryo is shown on top, a human embryo below. Note the post-anal tail in both, positioned at the lower left below the head of each. The human embryo is about 32 days old.

Cat Embryo


OOPS!


Activity

  • Embryology Video and video questions


Evidence #4

DNA Comparison


Evidence of Comparative DNA

  • All creatures on Earth are descendents of a common ancestor.

  • Therefore:

    • we have the same mode of inheritance

      • Genes on chromosomes made of DNA

    • Why we have similar nucleotide and gene sequences


Evidence of Comparative DNA


Evidence of Comparative DNA


Activity

  • DNA comparison WS (need codon chart)


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