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Do Now. What different ways do these animals use to move about? What traits does each animal have that help it move about as it does?. Unit 5 Evolution. Ch. 15 Darwin’s Theory of Evolution. The Puzzle of Life’s Diversity.

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do now
Do Now

What different ways do these animals use to move about?

What traits does each animal have that help it move about as it does?

unit 5 evolution

Unit 5 Evolution

Ch. 15 Darwin’s Theory of Evolution

the puzzle of life s diversity
The Puzzle of Life’s Diversity
  • Evolution - modern organisms have descended from ancient organisms (change over time)
  • Theory - a well-supported, testable explanation of phenomena that have occurred in the natural world
voyage of the beagle
Voyage of the Beagle
  • Charles Darwin contributed most to our understanding of evolution
  • He made observations & collected evidence that led him to propose a hypothesis about the way life changes over time
voyage of the beagle1
Voyage of the Beagle
  • That hypothesis, now supported by a large amount of evidence, has become the theory of evolution
darwin s observations
Darwin’s Observations
  • Darwin collected the preserved remains of ancient organisms - Fossils
  • Some of these fossils resembled organisms that were still alive
  • Others looked unlike any creature ever seen
darwin s observations1
Darwin’s Observations
  • The Galapagos Islands influenced Darwin the most
  • He observed that the characteristics of animals & plants varied among the different Islands
darwin presents his case
Darwin Presents His Case
  • Darwin published the results of his work in a book, On the Origin of Species
  • In his book, he proposed a mechanism for evolution called natural selection
  • He stated that evolution has been taking place for millions of years, & continues in all living things
  • Friday “Dangerous Mind” Movie on Darwin (complete worksheet) Remember!!! Reward Friday
home work monday
Home Work (Monday)
  • Computer time required at home or library. One page required

Choose 1 to write about

  • Compare Darwin’s and Wallace’s theories.
  • Compare and contrast both Darwin’s and Wallace’s careers and background.
  • Genetics Test
an ancient changing earth
An Ancient, Changing Earth
  • Hutton & Lyell helped scientists recognize that Earth is millions of years old
  • They also noted that the processes that changed Earth in the past are the same processes that are changing Earth now
lamarck s evolution hypothesis
Lamarck’s Evolution Hypothesis
  • The year that Darwin was born, Lamarck published his hypothesis
  • He proposed that by selective use or disuse of organs, organisms acquired or lost certain traits during their lifetime
  • Over time, this process led to change in a species
population growth
Population Growth
  • English economist, Malthus, published a book, noting that babies were being born faster than people were dying
  • He stated that if the human population continued to grow unchecked, sooner or later there would be insufficient living space & food for everyone
inherited variation artificial selection
Inherited Variation & Artificial Selection
  • Artificial selection - nature provided the variation, & humans selected those variations that they found useful
  • It has produced diverse plants & animals by selectively breeding for different traits
evolution by natural selection
Evolution by Natural Selection
  • Struggle for existence - the members of each species compete regularly to obtain food, living space, & other necessities of life
    • Predators that are faster & better at catching prey are more likely to survive
evolution by natural selection1
Evolution by Natural Selection
  • Fitness - the ability of the organism to survive & reproduce in its specific environment.
    • Fitness is the result of adaptations
evolution by natural selection2
Evolution by Natural Selection
  • Adaptation - any inherited characteristic that increases an organisms’ chance of survival
    • Successful adaptations allow organisms to become better suited to their environ. & thus better able to survive
evolution by natural selection3
Evolution by Natural Selection
  • Individuals that are better suited to their environ., with adaptations that enable fitness, survive & reproduce most successfully - Survival of the Fittest
evolution by natural selection4
Evolution by Natural Selection
  • Since it is similar to artificial selection, Darwin referred to survival of the fittest as - Natural Selection
  • In both AS & NS, only certain individuals of a population produce new individuals
evolution by natural selection5
Evolution by Natural Selection
  • However, in NS, the traits being selected, & therefore, increasing over time, contribute to an organism’s fitness
  • NS takes place without human control or direction
evolution by natural selection6
Evolution by Natural Selection
  • NS results in changes in the inherited characteristics of a population, that increase a species’ fitness in its environ.
  • Over time, NS produces organisms that have different structures, & occupy different habitats
evolution by natural selection7
Evolution by Natural Selection
  • As a result, species today look different from their ancestors
  • Each living species has descended, with changes, from other species over time - Descent with Modification
evolution by natural selection8
Evolution by Natural Selection
  • Descent with modification also implies that all living organisms are related to each other
  • Common descent - all species (living & extinct) were derived from common ancestors
evidence of evolution
Evidence of Evolution
  • Darwin argued that living things have been evolving on Earth for millions of years
  • Evidence of this could be found: in the fossil record, the geographical distribution of living species, homologous structures of living organisms, & similarities in early development
evidence of evolution1
Evidence of Evolution
  • The Fossil Record:
    • Darwin noticed that the sizes, shapes, & varieties of related organisms preserved in the fossil record, changed over time
evidence of evolution2
Evidence of Evolution
  • Geographic Distribution of Living Species:
    • Darwin realized that similar animals in different locations were the product of different lines of evolutionary descent
evidence of evolution3
Evidence of Evolution
  • Homologous Body Structures:
    • Homologous structures - structures that have different mature forms but develop from the same embryonic tissues
    • Not all homologous structures serve important functions
    • Organs of many animals are so reduced in size that they are just vestiges, or traces, of homologous organs
evidence of evolution4
Evidence of Evolution
  • Homologous Body Structures:
    • Vestigial organs- may resemble miniature legs, tails, or other structures, a trace of a homologous structure
evidence of evolution5
Evidence of Evolution
  • Similarities in Early Development:
    • The early stages or embryos, of many animals with backbones are very similar
summary of darwin s theory
Summary of Darwin’s Theory
  • Individual organisms differ, & some of this variation is heritable
  • Organisms produce more offspring than can survive, & many that do survive do not reproduce
summary of darwin s theory1
Summary of Darwin’s Theory
  • Because more organisms are produced than can survive, they compete for limited resources
  • Individuals best suited to their environ., survive & reproduce most successfully
summary of darwin s theory2
Summary of Darwin’s Theory
  • These organisms pass their heritable traits to their offspring
  • This process of NS causes species to change over time
summary of darwin s theory3
Summary of Darwin’s Theory
  • Species alive today are descended with modification from ancestral species that lived in the distant past
  • This process, where diverse species evolved from common ancestors, unites all organisms on Earth into a single tree of life