Hook Video: Battle of Kruger
Introducing Evolution
Evolution – The relative change of the gene pool
(alleles) of a population that occurs over
generations.
Variation Within Species
Variations – structural, functional, or physiological
differences between individuals within a species.
• Variations are created by the different
combinations of genetic information (alleles) that
offspring inherit from their parents.
The kittens in this litter
have different fur colour
and patterns, partly
because each
kitten inherited a
different combination
of alleles from its
parents.
What is the ultimate source of genetic variation?
Mutation – a permanent change in the genetic
sequence (DNA) of an organism and the only source of
new genetic variation (new alleles). This is only true if
the mutation alters the DNA– in a gamete, so that DNA
can be passed on to offspring.
Mutations can occur spontaneously during DNA
replication (S-phase), or caused by mutagens (eg. UVradiation)
Variations & Adaptations
Adaptations – structural, behavioural, or
physiological processes that help an organism
survive and reproduce in a particular environment.
Camouflage
allows this stick
insect
(Eurycnema
goliath) to blend
in with its
environment and
avoid being
eaten by
predators.
Many owls such
as this barn owl
(Tyto alba) can
sneak up on their
prey because of
another
adaptation: fluffy
feathers make
their flight quite
silent.
Types of Adaptations:
 Mating Rituals: Dancing and/or Singing –
Behavioural adaptation
 Hibernation – Physiological adaptation
Hibernation allows
ground squirrels to
survive in climates
with harsh winters.
They reduce their
metabolism in
order to conserve
energy.
 Mimicry – Structural adaptation
Mimicry - an adaptation in which harmless species
physically resemble a harmful species. Predators
avoid the harmless species as much as they do the
harmful one.
The viceroy butterfly
(top) has coloration
similar to the badtasting species
monarch butterfly
(bottom).
Hornet Moth:
- looks like a hornet, but is
completely harmless.
Io Moth (Automeris io):
– spread their wings to reveal a
startling eyespot pattern,
used to deter predators.
Infer.......
How could the camouflage of individual stick
insects help the survival of a population of stick
insects?
• Organisms constantly face environmental
challenges that limit their ability to survive.
• Severe weather, famine, and competition for
food, space and mates are all challenges to
survival.
• Environmental conditions determine whether
a variation in an individual has a positive,
negative, and/or neutral effect.
• Individuals with a helpful variation are more
likely to survive and have a higher chance of
passing on the genetic information (alleles)
• A characteristic may not give an individual a
particular advantage now but may become
critical for survival later as the environment
changes.
Selective Advantage – a genetic advantage
that favours an organism’s chance of survival and
reproduction, usually in a changing environment.
Eg. Antibiotic-Resistant Bacteria
E.g. When a human was born
with a thumb
E.g. Drought resistant frutis