Adaptation and Variation
Organisms constantly face environmental challenges that limit their
ability to survive. (______________, _________, ____________,
_________________________________)
Organisms that survive long enough to reproduce can pass the genes
that helped them to survive.
________ of a species and their interaction with their environment
explain why some species thrive while others become extinct.
Adaptations and survival
Adaptation:
I.e.: camouflage and hibernation
Mimicry:
Adaptations are the result of ___________, accumulative changes
that help the organism ________ and ___________.
Variations: ___________, __________ or ______________
differences between individuals. Environment determines whether a
variation is positive or not.
Interaction with environment is important to adaptation and
variation because environments _____________.
The English Peppered Moth is an example of variation to adaptation
Shows how the proportions of some __________ __________ in a
population __________ in response to a change in ____________.
Moth is ______ for birds as they sleep during the day. The gene
pool contains _______ moths and ________ _________ moths
Before mid-19th century tree barks were light in colour because of
lichen growth on the bark
The flecked moths were ____________ to the tree bark; black
moths were _________ on because easily seen. Flecked moths were
able to __________ and ________, black moth population was low.
During the next 50 years the _____________________ occurred
and smoke from factories painted the tree barks dark in colour.
Flecked moths were now _______ seen and _______ upon, and as a
result the population numbers ___________. Black moth now able
to reproduce and thrive, population numbers increased.
Shows how moth population changed over span of several moth
generations.
In 1950’s England cleaned up the pollution, what do you think
happened?
Variation within a Species
Why does genetic variation occur?
Mutation:
Occurs ___________ when the DNA is copied (mitosis or meiosis).
Some mutations occur because of ________ (environmental agents)
Some mutations are _________ or lethal while some are
________.
If mutation happens in a _____________ it disappears when the
organism dies. If it occurs in a ________, the mutation may be
passed down to succeeding generations as a new allele. I.e. the
starting point of genetic variation in a population
Selective advantage: genetic advantage of one organism over its
competitors. Over time the advantage causes the organism to be
favoured for survival and reproduction. I.e. Daphnia
For populations such as viruses and bacterial that reproduce very
quickly, a mutation could survive long enough to be passed down and
provide a selective advantage for subsequent generations i.e.
Bacterial resistance and antibiotic resistance.