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Changes Over Time. SOL: BIO 8 a-e . Standard BIO 8 a-e The student will investigate and understand how populations change through time. Key concepts include: a) evidence found in fossil records;

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changes over time

Changes Over Time

SOL: BIO 8 a-e

Standard BIO 8 a-eThe student will investigate and understand how populations change through time. Key concepts include:
  • a) evidence found in fossil records;
  • b) how genetic variation, reproductive strategies, and environmental pressures impact the survival of populations;
  • c) how natural selection leads to adaptations;
  • d) emergence of new species; and
  • e) scientific explanations for biological evolution.
theory of evolution
Theory of Evolution
  • Science is made up of many ideas, theories, and laws. Many of these ideas have gone through many changes throughout the years.
  • Our job as life-long learners is to examine all the evidence concerning a particular topic.
  • Evolution is part of the Core Knowledge curriculum for Biology.
  • The origin of life is a sensitive subject for many people. There are many theories concerning the change in things over time.
  • You may hold a different view than what will be presented as part of the Core Knowledge curriculum.
  • Out goal is to explore the theory of evolution from a scientific standpoint, not to discount any other theories on the origin of life.
charles darwin
Charles Darwin

The Father of Evolution

  • Darwin’s World (1809 - 1875)
  • Height of the British colonial period.
  • Beginning of the Industrial Revolution.
  • New Ideas:
    • Taxonomy of Carolus Linnaeus
    • Lyell’s “Principles of Geology”

Binomial System of Nomenclature

Carolus Linnaeus (1707 – 1778)

Believed in the “Fixity of Species”

charles lyell
Charles Lyell
  • Father of Geology
Suggests that sedimentary rock is very old – therefore the species that are represented in this rock must also be old.
  • Most fossils are found in sedimentary rock.
  • Older fossils will be found below younger fossils.
knowledge check
Knowledge Check

Who was Linnaeus?

Who was Lyell?

If Lyell looked at fossils is a cross section of sediment, would the fossils more towards the surface be older or younger than those below? Why?

charles darwin1
Charles Darwin

At the age of 22, he joined a 5 year expedition aboard the HMS Beagle to map the coast of South America


Charles Darwin’s Theory of Evolution:

1. Members of a population have heritable variations.(Inheritance of traits)


2. In a population, more individuals are produced than the environment can support. They compete for food and shelter. (overpopulation- struggle for survival).


3. Some individuals have adaptive characteristics that enable them to survive and reproduce better than other individuals (survival of the fittest).


4. An increasing number of individuals in succeeding generations have these adaptive characteristics (natural selection)

knowledge check1
Knowledge Check

Summarize the four components of Darwin’s theory of evolution.


Darwin described his theory in the form of a long essay which he called

“On the Origin of Species”.


Concerned about the public’s response to his ideas(remember what happened to Galileo)

Arranged to publish his work … AFTER HIS DEATH !!


Charles Darwin

At age 50 (1859)

At age 65 (1874)


Charles Darwin

Before publication

After publication

Through his observations made in the Galapagos Islands, Charles Darwin formulated a theory of how species change over time, called natural selection.
Natural selection is governed by the principles of genetics.
  • The change in the frequency of a gene in a given population leads to a change in a population and may result in the emergence of a new species.
  • Natural selection operates on populations over many generations.
knowledge check2
Knowledge Check

What was the name of Darwin’s book?

On what island did Darwin make observations that lead him to develop his ideas about natural selection?

Explain how natural selection can be observed in a population.

  • A change in successive generations of organisms, due to random mutation and changes in the organisms’ surroundings
Evolution takes place through a set of processes that include:
    • mutation,
    • adaptation,
    • natural selection,
    • extinction.
  • Genetic mutations and variety produced by sexual reproduction allow for diversity within a given population.
  • Many factors can cause a change in a gene over time.
  • Mutations are important in how populations change over time because they result in genetic changes to the gene pool.

Mutation- a change in the DNA

A mutation may result in a:

1.favorable change or adaptation in genetic information that improves a species’ ability to exist in its environment


Mutation- a change in the DNA

2. an unfavorable change that does not improve a species’ ability to exist in its environment.


Mutation- a change in the DNA

3. in a change in the genetic information that neither harms nor helps the species.

  • Adaptations are structures, functions, or behaviors that enable a species to survive.
  • Depending on the rate of adaptation, the rate of reproduction, and the environmental factors present, structural adaptations may take millions of years to develop.
natural selection
Natural Selection
  • the survival and reproduction of the individuals in a population that exhibit the traits that best enable them to survive in their environment.
  • The Survival of the Fittest
natural selection1
Natural Selection
  • Populations produce more offspring than the environment can support.
natural selection2
Natural Selection
  • The unequal ability of individuals to survive and reproduce leads to the gradual change in a population, generation after generation over many generations.
natural selection3
Natural Selection
  • Organisms with certain genetic variations will be favored to survive and pass their variations on to the next generation.
These five canine species evolved from a common ancestor through natural selection


African wilddog




Thousands tomillions of yearsof natural selection

Ancestral canine

When humans choose organisms with specific characteristics as breeding stock, they are performing the role of the environment
  • This is called “artificial selection”

Example of artificial selection in plants: five vegetables derived from wild mustard

artificial selection in animals dog breeding
Artificial Selection in Animals: Dog Breeding

German shepherd

Yorkshire terrier

English springerspaniel


Golden retriever

Hundreds tothousands of yearsof breeding(artificial selection)

Ancestral dog

the evolution of insecticide resistance is an example of natural selection in action
The evolution of insecticide resistance is an example of natural selection in action

Chromosome with geneconferring resistanceto insecticide

Additionalapplications of thesame insecticide willbe less effective, andthe frequency ofresistant insects inthe populationwill grow



knowledge check3
Knowledge Check

What is evolution?

Identify the four processes of evolution. Explain how each process can lead to evolutionary change.

  • no longer in existence; "the extinction of a species"
If a species does not include traits that enable it to survive in its environment or to survive changes in the environment, then the species may become extinct.
Individuals of a population exhibit a range of variations in a trait as a result of the variations in their genetic codes.
The evidence for evolution is drawn from a variety of sources of data, including:
    • the fossil record,
    • radiometric dating,
    • genetic information,
    • the distribution of organisms,
    • anatomical and developmental similarities across species.
fossil record
Fossil Record
  • Although there is not a complete record of ancient life for the past 3.5 billion years, a great deal of modern knowledge about the history of life comes from the fossil record.

“Ice Man”

Scorpion in amber

distribution of species
Distribution of species
  • Most marsupials live in Australia
  • This supports the theory of continental drift.
  • Organisms that can breed and produce FERTILE offspring.
adaptive radiation
Adaptive Radiation
  • where species all deriving from a common ancestor have over time successfully adapted to their environment via natural selection
homologous structures
Homologous Structures
  • Body parts in different organisms that have similar bones and similar arrangements of muscles, blood vessels, and nerves and undergo similar embryological development, but do not necessarily serve the same function; e.g., the flipper of a whale and the forelimb of a horse.
homologous structures1
Homologous Structures





vestigial structures
Vestigial Structures
  • Features that apparently serve no function in an organism and are allegedly holdovers from an evolutionary past. Such features, though no longer useful, are presumed to have been useful in ancestral species.

EX.: appendix in humans, whale pelvis, tiny snake pelvic and limb bones, and the eyes in cave-dwelling salamanders and fish that are completely blind.

developmental similarities
Developmental Similarities
  • Many species have very similar embryonic development.
  • The embryo of a chicken, a pig, and a fish are almost identical at certain points in their development.
Stephen Jay Gould’s idea of punctuated equilibrium proposes that organisms may undergo rapid (in geologic time) bursts of speciation followed by long periods of time unchanged.
  • This view is in contrast to the traditional evolutionary view of gradual and continuous change