EVOLUTION

THE EVOLUTION OF EVOLUTIONARY THEORY

BEFORE DARWIN

•CREATIONISM = first explanation of diversity observed = separate creation of each organism by a supernatural being

HOW TO DISTINGUISH A SPECIES?

  • Differences in appearance  Reproductive isolation
  • Today’s Definition of SPECIES:

GREEK PHILOSOPHERS

•PLATO – “Ideal Form” = object on earth , although minor variations do occur due to the imperfections of our world

•ARISTOTLE – “Scala Naturae” = ladder for classifying and naming nature by God

EVOLUTION BEFORE DARWIN & WALLACE

•BEFORE 1700’S – Creationism was unchallenged

•LEAVING EUROPE- observed a greater diversity and variety within species and started to think about the possibility that species could change over time

•DISCOVERY OF FOSSILS – William Smith discovered that fossils in lower rock were more primitive and changed to more advanced forms as well as some fossils of extinct forms

•BUFFON – original creation of a few species that evolved over time producing the modern species

•CUVIER - CATASTROPHISM – catastrophes produced layer of rock and made species extinct and after each catastrophe, new species were created

•Hutton & Lyell - UNIFORMITARIANISM – the same forces (wind, water , volcanoes) that change geology also produced the rock layers and the ever changing earth

DARWIN & WALLACE

•Independently, both provided evidence that the

EVIDENCE OF EVOLUTION

Why is it called a Theory

•A scientifictheoryis a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supportedtheories but reliable accounts of the real world.

FOSSILS

• leading from an ancient, primitive organism to a modern form

•even though the fossil record is not complete we can form a picture from the fossils we do have. Some animals are better represented than others - like the horse

COMPARATIVE ANATOMY

•Evolution predicts that organisms that evolve in similar environments (even if these organisms are not related)

•Evolution also predicts that organisms with recent common ancestors even if used for different functions

Convergent Evolution

•Convergent Evolution - where two unrelated species have (a whale and a shark)

•Analogous structures - the outwardly similar structures, like the wings of a fly and the wings of birds

Divergent Evolution

•Divergent Evolution - where two related species have (bat, human, whale arm bones)

•Homologous structure – internally similar structures (due to recent common ancestor) but with different functions – like limbs of mammals

SIMILARITIES IN EARLY DEVELOPMENT

•Embryos of many different animals look similar

•this shows that similar genes are at work

VESTIGIAL STRUCTURES

• , like the pelvic bones of whales, the appendix in humans

BIOCHEMICAL & GENETIC ANALYSIS

•Similarities between organism's DNA and protein structures show relationships. are more closely related than others.

DNA Changes

In most cases, the DNA sequencing and Genetic Analysis supported phylogenetic trees of life, however some changes did occur

•

•the addition of 3 Domans level of taxonomy

ARTIFICIAL SELECTION - EVOLUTION CAN BE OBSERVED!

•Artificial selection is the to produce specific desirable features in a population.

•All dog breeds have been created via artificial selection

•Cows have been breed over the years to produce more milk and become larger

RIGHT BEFORE OUR EYES

•Natural Selection can also be observed today!

  • peppered moths
  • insects become resistant to pesticides
  • bacteria become resistant to antibiotics

PEPPERED MOTHS

•Peppered moths in Britain showed a shift in coloration after the industrial revolution. Moths were generally light colored to match the background of lichens on trees. Soot from factories turned the bark of trees to a darker coloration, darker colored moths increased in number because they were better camouflaged on the dark trees.

ADDITIONAL NOTES

•The variations upon which natural selection works are produced by

•Natural selection does not produce , it produces organisms best suited for a particular environment.

•It is a common misconception the evolution - its simply not true. A seal is adapted for water, but its not a good design for a prairie. When an environment changes, many populations can go extinct because they are no longer suited to an environment (dinosaurs)

MONKEYING AROUND

•It is also a common misconception that if humans evolved from earlier primates, then we shouldn't have monkeys at all (since they would have all evolved to humans) - again this is erroneous, monkeys aren't "driven" to become humans, as long as their suited for their environment, the process of natural selection won't facilitate any major changes, there are a variety of primates, just like there is a variety of cats - but more on human evolution later.