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Unit A: Biological Diversity

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Unit A: Biological Diversity Topic 1: Biological Diversity and Survival Variations Variations are differences between organisms caused by genetic and environmental ... – PowerPoint PPT presentation

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Title: Unit A: Biological Diversity


1
Unit A Biological Diversity
  • Topic 1 Biological Diversity and Survival

2
Variations
  • Variations are differences between organisms
    caused by genetic and environmental factors. A
    genetic difference could include being born with
    gray eyes. An environmental factor could include
    height and nutrition. Eating a poor diet will
    result in a shorter person than if that same
    person ate a healthy diet with protein and
    calcium.

3
Variation Between Species
  • There is variation between species, and within a
    species. Biological diversity is the number and
    variety of organisms in an area. The more
    biological diversity in an area, the healthier
    the environment of this area.
  • A species is a single class of living things.
    Only members of the same species can reproduce
    healthy offspring.

4
Variation Inside a Species
  • There may be variation inside a species
    (different breeds of dogs), but as long as
    reproduction is possible, the organisms belong to
    the same species.
  • A lion and tiger can, very rarely, produce
    offspring together however, the liger cubs
    never live past three months. Therefore lions and
    tigers are two different species.

5
Speciation
  • Speciation is the process where one group of one
    species, gradually adapts to its own habitat and
    becomes so different genetically, that it becomes
    its own species. Lions and tigers were once part
    of the same species, but over time, and through
    evolution, they have diverged into two species.

6
Variations and Adaptations
  • Variations occur all the time. Every organism has
    their genetic material change randomly when they
    are developing in the womb. A certain variation
    becomes common in a group or species when it
    helps the organism adapt to its environment.
    There are two kinds of adaptations

7
Structural Adaptations
  • I. Structural Adaptations adaptations that are
    physical, resulting in changes to the bodily
    structure. An example would be the adaptation of
    the polar bear to have white fur, allowing polar
    bears to camouflage themselves in snow.
  • A human example would be our brains which have
    evolved to have large areas devoted to thinking
    and planning. This structural adaptation has
    allowed us to work together and use tools.

8
Behavioural Adaptations
  • II. Behavioural Adaptations Adaptations that
    change the way a species act. An example would be
    the tendency to hunt in packs (lions, wolves) or
    alone (shark, snakes).
  • A human example would include shivering when you
    are cold.

9
Importance of Variation
  • Variation is a good thing for survival. If the
    members of a species are too similar, than one
    catastrophe could wipe out the entire species. In
    the Middle Ages 1/3 the population of Europe and
    Asia died from the Bubonic Plague. Had there been
    less variation in the human species, the entire
    human populations in these areas might have been
    wiped out.

10
Importance of Variation
  • The same thing applies to different species.
    Because different species of dinosaurs were
    similar genetically, most of the species were
    wiped out 60 million years ago.

11
Diversity Index
  • The diversity index is a measurement that
    measures the health of an ecosystem. It compares
    the diversity of the number of species (runs) in
    an ecosystem with the of organisms. The more
    variety in kinds of species in an ecosystem, the
    higher the diversity index.
  • DI of Runs / of Organisms

12
Bottleneck Events
  • Catastrophic events which can wipe out a
    species/population.
  • One such event occurred 70000 y.a. Human species
    reduced to 1000-10000.
  • Survivors now better suited to volcanic
    eruptions.
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