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Objective 6 Notes. Evolution, Natural Selection & Adaptations. 1. Vocab. Evolution A genetic change in a population over time Note: individuals do not evolve, only populations show change Theory A well supported explanation of a scientific phenomenon Fitness

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Objective 6 Notes

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Objective 6 notes

Objective 6 Notes

Evolution, Natural Selection & Adaptations


1 vocab

1. Vocab

  • Evolution

    • A genetic change in a population over time

      • Note: individuals do not evolve, only populations show change

  • Theory

    • A well supported explanation of a scientific phenomenon

  • Fitness

    • The ability of an organism to survive and reproduce in a given environment


2 charles darwin

2. Charles Darwin

  • From 1831-1836, a young naturalist called Charles Darwin toured the world in HMS Beagle.

  • Where food was limited, competition meant that only the fittest would survive.

  • This would lead to the natural selection of the best adapted individuals


3 assumptions of the evolutionary theory

3. Assumptions of the Evolutionary Theory

  • The earth is billions of years old

  • Time + small changes = large changes

  • Mutations can be beneficial


3 natural selection

3. Natural Selection

  • The process by which individuals that are better suited to their environment survive and reproduce most successfully

  • Also called:

    • Survival of the Fittest

  • Artificial Selection


3 natural selection1

3. Natural Selection

  • Types


4 mechanisms of evolution

4. Mechanisms of Evolution

  • Genetic Variation

    • Mutations

    • Meiosis (crossing over)

  • Natural Selection

  • Reproductive Isolation


5 evidence of evolution

5. Evidence of Evolution

  • Fossil Records

  • Homologous Structures

  • Analogous Structures

  • Vestigial Structures

  • DNA


Fossil record

Fossil Record

  • Fossils are preserved evidence of dead organisms

  • Assumes that it takes a long time for sediment to accumulate

  • Assumes that the dead organism had offspring

  • Assumes that there are millions of years separating each sediment layer.


Homologous structures

Homologous Structures

  • Structures that have a similar structure (anatomy) from one organism to another.

  • Example: limbs

    • Human leg v. Whale flipper

      • Both contain bones called femur, tibia, fibula, etc.

      • Similar structure but different functions


Analagous structures

Analagous Structures

  • Structures that have a similar function (physiology) but different structure between organisms.

  • Example: Wings

    • Butterfly wing v. Bird wing

    • Both enable flight, but are very different structures


Vestigial structures

Vestigial Structures

  • Defined as a structure that serves no useful function in an organism.

  • Most common citations of this are not accurate:

    • Coccycx: without it humans cannot pass solid waste.

    • Appendix: might have immune/lyphatic functions

    • Tonsils: have immune and lyphatic functions

    • Eyebrow/lash: keeps sweat/dust/particles out of eyes

    • Body Hair: mechanoreceptors at base, traps heat, offers protection from sun rays


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