National 5 BiologyKey Area 4:

Adaptation, natural selection and the evolution of species

National 4 BiologyKey Area 5:

Adaptations for survival

What caused all of these?

Cystic Fibrosis Haemochromatosi

s

Huntingdon’s Disease Tay-Sachs

Syndrome

A genetic disorder causing the body to absorb an excessive amount of iron

from the diet: the iron is then stored in various organs.

Cystic fibrosis is a genetic condition in which the

lungs and digestive system become clogged with thick sticky mucus

Huntington's disease is an inherited disease of the brain that damages

certain brain cells.This can affect movement, cognition

(perception, awareness, thinking, judgement) and behaviour

Tay-Sachs disease is a rare and usually fatal genetic disorder that causes progressive damage to the

nervous system.Symptoms usually appear at around

6 moths old and most affected children will die by the age of 3.

All of these conditions were caused by a spontaneous and random change or mutation in

a persons’ DNAThis mutation was inherited

from their parents.

Do you know what this is?

Malignant Melanoma (Skin cancer)

Not all mutations are inherited. Exposure to certain factors, UV light in sunlight can cause spontaneous

mutations that lead to cancer.

Factors that can lead to mutations

We now know that exposure to most radiation (UV, gamma and even X-rays) can be carcinogenic.

Exposure to some chemicals can also lead to a spontaneous mutation in our DNA that can lead to

cancer.

Factors that can lead to mutations

Mutations

A mutation is a spontaneous change to genetic material.

A mutagenic agent is a factor such as radiation (gamma or X-rays), UV light or some chemicals (e.g. those in cigarette smoke) that can increase the rate of mutations.

Antibiotic resistance• Random mutations in the DNA

of some bacteria have made them resistant to antibiotics

• The rise of the “superbug”• Major health concern

The Black Plague• In the 14th century the

black plague killed 30% of the population of Western Europe

• Why did the other 70% not die?

They had a mutation that made them resistance to the plague bacterium

Some mutations are ‘neutral’• Evidence of the mutations may be

visible• Makes no difference to the overall

health of the organism

Mutations can be….

Advantageous: e.g. bacterial resistance to antibiotics.

Neutral: e.g. Free Ear lobes or attached ear lobes.

Disadvantageous: Malignant Melanoma (skin cancer)

Why are mutations important?

• Mutations are the only source of brand NEW GENES (alleles) in a population.

• Mutations are important because they increase variation within a species.

• This allows species to adapt to be better suited their environment.

Mutations – The Science of Survival (45 minutes)

(Up to 21 minutes)

Adaptations

• An adaptation is an inherited characteristic that makes an organism well suited to its environment/niche. This can be physiological, structural and behavioural and help an organism survive and reporduce in their environment.

AdaptationsEach group has been given a set of

cards.Match up the organism with its

adaptations.Check your matches are correct and

draw out the following table in your jotter Organism Adaptation

Kangaroo Rat Adaptations

• Lives in a burrow underground• Nocturnal• Produces very concentrated urine• No sweat glands

Bilby Bandicoot Adaptations

• Large ears to radiate excess body heat• Lives in a burrow underground • Nocturnal• Produces very concentrated urine

Cacti Adaptations

Polar Bear Adaptations

Camel Adaptations

Extreme examples of interdependence

• All living things depend on each other

• Some plants and animals have evolved ‘hand in hand’ to help each other survive

• These relationships are very important because neither one can survive without the other.

Bull horn Acacia and Acacia ants• Bull horn acacia and

ants depend on each other in the following ways:

• a. large thorns provide nesting for ants,

• b. Beltian bodies (and nectar) provide food for ants,

• c. ants swarm to defend anything eating the tree,

• d. the ants clear an area around the base of the tree to reduce competition for nutrients

“Beltian Bodies”

Yucca and the Yucca moth

• For more than 40 million years there has been a relationship between yucca plants and yucca moths.

• The moth’s larvae depend on the seeds of the yucca plant for food, and the yucca plant can only be pollinated by the yucca moth.

Darwin & Natural Selection

Charles Darwin (1809 – 1882)

Theologist and self-taught naturalist.

Believed living things evolved.

Suggested evolution happed by natural selection or “survival

of the fittest”.

Gathered detailed evidence from voyages (e.g. The Galapagos Islands) to support his theory.

Darwin did not provide an explanation of how features

were passed on.

Where it all started …

• The Galapagos Islands

• Located approximately 1000km from the coast of Ecuador, South America.

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Darwin explored these islands from April through October 1835.

Inspired by the nature of the island chain

When and where he started thinking about what was to become his theory of evolution by natural selection.

Animals live there that are found nowhere else on earth.

This makes them endemic

25 years later in 1859 Darwin wrote“On the Origin of Species by Means of Natural

Selection”

• Two main points:1. Species were not created in their present form, but evolved from ancestral species.

2. Proposed a mechanism for evolution: NATURAL SELECTION

Survival of the Fittest

What does this mean? Can you think of any examples?