Unit A: Biological Diversity

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Unit A Biological Diversity

• Topic 1 Biological Diversity and Survival

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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.

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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.

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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

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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.