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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Evidence 1
Evidence #1

Fossil Record

Evidence of evolution 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 evolution1
Fossil Evidence of Evolution




the course

of life through


Fossil evidence of evolution2
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 evolution3
Fossil Evidence of Evolution

Fossil of Archaeopteryx

Fossil evidence of evolution4
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 evolution5
Fossil Evidence of Evolution

Whale “missing links”

Fossil evidence of evolution6
Fossil Evidence of Evolution

Evolutionary change in body size and toe reduction of horses

Fossil record activity
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
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


  • Fossil Record Activity

  • Analysis of phylogenetic trees and adaptive radiation

Evidence 2
Evidence #2


Di vergent evolution

  • 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
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

Con vergent evolution
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 morphology3
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

Convergent evolution
Convergent Evolution

Convergence among fast-swimming predators


  • 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.”

The evidence for evolution



The evidence for evolution

Yellow Jacket

Sand Wasp

The evidence for evolution


Honey Bee

The evidence for evolution

Sryphid Fly

Paper Wasp

The evidence for evolution

Coral Snake

Colubrid Snake

The evidence for evolution



The evidence for evolution

Catkin (plant)


Evidence for evolution 2 morphology4
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


  • Homologous structures coloring assignment and questions

Evidence 3
Evidence #3


The evidence for evolution

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


  • Embryology Video and video questions

Evidence 4
Evidence #4

DNA Comparison

Evidence of comparative dna
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


  • DNA comparison WS (need codon chart)