Mutation, Variation & Adaptation
By Dr π Rat
Mutations
A change in the
base sequence in
DNA
•Can occur randomly (naturally)
•Or can be deliberately caused in the laboratory
by scientists or by mutagens in the environment
•Inherited if occur in the gametes
•Not always harmful
http://www.accessexcellence.org/
Mutation during Mitosis
• Only affects new body cells.
• The mutation cannot be
passed on to the affected
individual’s offspring.
Examples:
Individual with two
differently coloured eyes
Skin cancer as a
consequence of UV damage
Mutation during Meiosis
• Mutation occurs during the formation of gametes (eggs,
sperm, pollen).
• The zygote will be mutated if a mutated gamete is
creating it.
• Every subsequent cell of the new organism will be
mutated (mitosis).
• The mutation will be passed on to the next generation
(inheritable mutation).
Natural Mutations: ALBINOS
• Little or no pigmentation in the eyes, skin, and hair (or in
some cases in the eyes alone).
• Inherited an altered copy of a gene that does not work
correctly.
• The altered gene does not allow the body to make the
usual amounts of a pigment called "melanin".
• True albinos have pink eyes and skin.
Albinos
These are not
albinos; they
have pigmented
eyes.
White Bengal
Tiger
Variations
• Either/or or discrete variation – you either have it or you
don’t; usually produced by a single gene with a dominant
or recessive allele (expressed as a % of the population).
E.g. tongue rolling
• Continuous variation - (expressed as a bell shaped
curve)
E.g. hand span, size, shoe size, colouring
• Non-inheritable variations
Non-inheritable Variation
• Variation resulting from the organism’s
lifestyle or environment are called
non-inheritable.
• Example:
Neptune’s Necklace seaweed
in high wave action areas
 small beads
in calmer water  bigger beads
Variation of Phenotype triggered by
temperature – Non-inheritable Variation
• Tuatara eggs are
turning out as
follows:
cold temperature
 females
warm temperature
 males
Variation of Phenotype triggered by
pH – Non-inheritable Variation
• Hydrangeas
change their
colour with
the pH of the
soil:
• Alkaline soil
makes them
go red
• Neutral and
acidic soil
makes them
go blue
Variation of Phenotype triggered by
Light – Non-inheritable Variation
Leaf size of
trees
changing
with the
light
intensity
(and wind
exposure)
Variation of Phenotype triggered by
Wind – Non-inheritable Variation
Variation of Phenotype triggered by
Wind – Non-inheritable Variation
Phenotype
Genotype + Environment  Phenotype
Phenotype = how the organism looks
• is dependent on the genotype plus
• non-inheritable (environmental) effects.
Mutation is the Mother of Evolution
• Mutation is the source of all variation
• Variation gives an opportunity for adaptation:
If the varied new organism has an advantage relative to
its non-mutated siblings, it will be more successful to
survive and it will adapt better to its environment.
• E.g.
Antibiotic-resistant bacteria
Pesticide resistant bugs
Adaptations
Organisms need to have special features which help
them to survive in their habitat.
These special features are called ADAPTATIONS.
For example: You have plenty of adaptations to survive in
your habitat.
Your fingers are an excellent adaptation.
Without their ability to grip you would not be able to do all of
that schoolwork!
Can you think of other adaptations that you have?
Types of Adaptations
Anything that helps an organism survive better in its
environment is an adaptation.
There are three basic types of adaptations
• Structural adaptations (how something is built)
• Behavioural adaptations (what an organism does)
• Physiological adaptations (what happens inside an
organism, its bio-chemistry)
Structural Adaptations
are design features in the organism (plant or animal) that
help it to survive better in its habitat.
•
•
•
•
•
•
Examples
A bird has wings to fly
An elephant has a trunk to grab food
A Kiwi has a long beak to probe for worms
Alpine plants grow close to the ground
You have two feet for upright walking
Worms are long and thin
Behavioural Adaptations
are learned actions or “innate” actions (a behaviour an
animal is born with) or movements that make an
organism survive better.
Examples
• A chicken scratches the ground to find worms for food
• A stick insect stops moving when it sees a predator bird
• A hedgehog rolls itself into a ball when attacked by a dog
• A plant turns its leaves towards the sun
• Small fish swim as a school
Physiological adaptations
Are biochemical features of an organism that help it to
survive better in its habitat.
Examples
• You are warm-blooded so that you can move faster in
spite of very cold temperatures.
• Tropical fish require temperatures of 25°C or higher in
order to have their digestive enzymes work (they starve
to death in cold water despite having plenty of food)
• Dogs can digest meat but not cellulose (cell walls of
plants)
• Sheep can digest cellulose but not meat
What type of Adaptations are the
following?
• Mimicry
• Hibernation
What type of Adaptations are the
following?
• Migration
• Camouflage
Table of Adaptations:
Name of
organism
Feature
Type of
adaptation
Function
Reason
Rabbit
big ears
structural
better
hearing
to escape
predators
behavioural
physiological
structural
behavioural
physiological
List Adaptations for the following
totara
Totara tree
List Adaptations for the following
piwakawaka
Fantail
List Adaptations for the following
aihe
Hector’s
Dolphin
List Adaptations for the following
kōtare
NZ Kingfisher
List Adaptations for the following
katipo
Katipo Spider
Human Intervention
Selective Breeding
The selection of certain
seeds or animals for
reproduction in order to
influence the traits inherited
by the next generation.
Selective Breeding in Farming
• We select desirable traits in plants
and animals we work with.
• We do not breed from weak or
undesirable organisms.
• Over decades of “selective
breeding” the genetics of our
“domesticated” animals and plants
has changed from “wild”
organisms.
• The feral traits have been bred
out of the stock or cultured plants.
Genetic Engineering
The selective, deliberate change of
genes (genetic material) by man.
The technique of removing,
modifying or adding genes to a
DNA molecule in order to change
the information it contains.
French genetic researchers created Alba for artist Eduardo Kac.
Thanks to genes borrowed from a jellyfish, the albino rabbit glows
green when placed under special lighting. In regular light, Alba
appears like any other furry white rabbit. But place her under a
black light, and her eyes, whiskers and fur glow a otherworldly
green.
"Glow in the dark" fish. these genetically modified fish
were developed by a Taiwanese aquatic firm, Taikong
Group. They are planning to reproduce these fish in
numbers and sell them for pets.
Scientists in the agriculture department of the
Hebrew University in Rehovot have genetically
engineered a chicken that has no feathers.