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Continuous Variation Intermediates Present. Character controlled by many
genes.. Usually affected by environment.
Discontinuous Variation Few/No Intermediates. Generally controlled by single gene.
Inter-specific Variation Difference between species [Basis of classification]. Morphology,
physiology, behaviour, genetics.
Intra-specific Variation Within a species. E.g. Dogs
Meiosis Shuffles Alleles so gametes contain a random mixture.
Sexual Reproduction Male gametes fuse randomly with female gametes. Alleles from different
individuals are combined in zygote.
Mutation Mistakes in DNA replication. E.g. Different base code changing the amino
acid type in a protein.
Environmental Affect characteristics of organism. E.g. UV exposure darkens skin.
Evidence: Fossils - Change over geographical time scale, DNA- Base sequences, Molecular- Amino Acid sequences
Behavioural E.g. Avoiding hottest time of day, Sentry Duty to evade predators. Escape
Physiological Correct/Appropriate functioning E.g. opening/closing stomata in response to
CO2, light, humidity/water stress.
Anatomical/Structural Blubber- Insulation. Large Ears in Elephants = Cooling. Long roots in
xerophytes = greater water source.
Able to produce large numbers of Dogs 10 pups. Cod- 250,000- 500,000 eggs. Mushroom millions
offspring of spores.
Populations stay constant over Competition for survival - otherwise populations would rapidly
Offspring similar to parents. Offspring inherit some characteristics from their parents.
Variations exists within population. Some are better adapted to the environment than others. More likely
to survive and pass on characteristic to offspring. Survival of the
Food Availability. Disease.
Allopatric Populations are
physically separated by a
geographical barrier. E.g.
Sympatric Populations not physically
or genetic.…read more