Unit 3 notes
This presentation is the property of its rightful owner.
Sponsored Links
1 / 13

Unit 3 Notes PowerPoint PPT Presentation


  • 40 Views
  • Uploaded on
  • Presentation posted in: General

Unit 3 Notes. Evolution and Adaptations. Selective Pressure. Selective Pressures are the factors that cause young plants and animals in nature to fail to survive Examples of these include predators, parasites, drought, lack of food, and temperature extremes.

Download Presentation

Unit 3 Notes

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Unit 3 notes

Unit 3 Notes

Evolution and Adaptations


Selective pressure

Selective Pressure

  • Selective Pressures are the factors that cause young plants and animals in nature to fail to survive

    • Examples of these include predators, parasites, drought, lack of food, and temperature extremes.

  • Some organisms are better equipped to survive, by having genetic variations that provide protection

    • Examples of these include traits that allow the organism to blend in with its surroundings, making it easier to be hidden from predators


Selective pressure1

Selective Pressure

  • Other organisms that are lacking these traits generally end up being the predator’s dinner

  • Some organisms have genetic traits that may actually cause further harm to the organism

    • Examples of this include if the organisms’ genes slow it down or cause its exterior coloring to make it apparent with its background


Natural selection

Natural Selection

  • When specific traits are favored to assist in an organisms’ survival is known as natural selection

  • Charles Darwin and Alfred Russell Wallace discovered the concepts of natural selection.

    • When organisms are modified over many generations this is called biological evolution


Adaptations to the environment

Adaptations to the Environment

  • Selective Pressures are constantly being exerted on populations, causing the gene pool of the population to be tested

    • Fitnessis the ability of an organism to adapt for survival and reproduction based on the selective pressures being exerted on the organism


Limits of change

Limits of Change

  • Adaptation – the population of survivors may gradually adapt to the new condition through natural selection

  • Migration – the surviving population may migrate and find an area where conditions are suitable

  • Extinction – failing the first two possibilities, extinction is inevitable


Adaptations

Adaptations

  • In order for a population to successfully adapt to the environmental conditions, they need to have some individuals that possess the alleles (variations of genes or new combinations of genes) required to survive in the new conditions.

    • This is not the only requirement – the population must have enough organisms within it that possess the alleles in order to reproduce and carry on the population


Keys to survival

Keys to Survival

  • There are four keys to survival for a population

  • Geographical Distribution

  • Specialization to a given habitat or food supply

  • Genetic Variation within the gene pool of the species

  • The reproductive rate relative to the rate of environmental change


Keys to survival1

Keys to Survival

  • Less vulnerable species to be affected by changes in these keys are r-strategists

  • More vulnerable species to be affected by changes in these keys are K-strategists

  • Most organisms fall in between both of these


Genetic change

Genetic Change

  • Genetic change or adaptations occur over generations

    • An organism does not adapt within its lifetime genetically


Evolution of species

Evolution of Species

  • After all of the adaptations that occur over MANY generations the “final” product may be so different from the initial population that started the process that it is considered a new species

  • There is also a process where two or more species are developed from one individual species


Two species from one

Two Species From One

  • Reproductive Isolation

    • When the original population separates into smaller populations that do not interbreed with one another

  • Separated Subpopulations exposed to different selective pressures

    • As the populations are adapted to these pressures they begin to become so different that they are no longer considered the same species


Darwin s finches

Darwin’s Finches

  • Charles Darwin discovered a variation of species of finches in the Galapagos Island

    • What he observed was that the different finches had specific physical characteristics

    • The physical characteristics that each species has determines its feeding habits, making them different species.


  • Login