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Evolution and the Evolution and the EnvironmentEnvironment

(AQA)

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AdaptationAdaptation

Organisms are ADAPTED to the habitat they live in. In other words, they have special features that help them to survive. Some examples:

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Long, deep roots.

Large body.

Leaves are spines/thick cuticle.

Spines.

Water collection.

Store water.

Reduce water loss.

Prevent animals eating it.

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CompetitionCompetitionAny living species competes with each other. They may compete for:

- Living space

- Food

- WaterIn addition to this competition, the population of a species can be affected by predators, disease, migration etc

Get off my land

Yum!

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Red squirrel. Grey squirrel.

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19/04/23Red Squirrel Grey Squirrel

Food Seeds, buds, flowers, leaves and fruit.

Seeds, nuts, buds, insects, bird eggs and fungi, depending on the time of year.

Habitat Woodland that contains a fair proportion of conifer trees.

Very adaptable. Prefers mature broadleaved woodlands.

Breeding

One or two litters a year, usually of about 2-3 young.

If conditions are good, two litters are produced each year, consisting of 1-8 young.

Size 280-350g 400-800g.

Status Native. Introduced from USA 1876.

In Wales A few places, e.g. Clocaenog Forest in North Wales (<100).

Widespread.

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Predators and PreyPredators and PreyA PREDATOR is an animal that hunts and eats another animal

The PREY is the animal it eats, for example…

Consider the populations of these two animals over time:

Hey! I ordered a

steak

Population of animal

Time

Rabbit

Fox

Prey Predator

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VariationVariation“Variation” is the name given to differences between individuals of the SAME species.

Variation is due to GENETIC or ENVIRONMENTAL causes. For example, consider dogs:

1) Ways in which they are the same:

2) Ways in which they are different:

19/04/23Where is this information Where is this information stored?stored?

Section of a chromosome:

Genes for eye colour

Genes for hair

colour

Genes for blood group:

Different species have different numbers of chromosomes. Humans have 46 (23 pairs) in every cell.

19/04/23Where is this information Where is this information stored?stored?

Slide 43

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KaryotypeKaryotype

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Sexual ReproductionSexual Reproduction

The human egg and sperm cell (“GAMETES”) contain 23 chromosomes each.

When fertilisation happens the gametes fuse together to make a single cell called a ZYGOTE. The zygote has 46 chromosomes (23 pairs) and contains information from each parent.

We have similar characteristics to our parents due to genetic information being passed down in genes through gametes:

19/04/23Sexual vs. Asexual Sexual vs. Asexual reproductionreproduction

Sexual reproduction:•2 parents are needed

•Offspring will have “pairs” of chromosomes

•This will cause genetic variation

Asexual reproduction:•Only 1 parent needed

•Offspring are GENETICALLY IDENTICAL to parent (“clones”)

“Snuppy” – the first cloned

dog (Aug 05)

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Cloning PlantsCloning PlantsPlants can reproduce ASEXUALLY. The offspring are genetically ________ to the parent plant and are called _________. Two examples:

1) This spider plant has grown a rooting side branch (“stolon”) which will eventually become __________.

2) A gardener has taken cuttings of this plant (which probably has good characteristics) and is growing them in a ____ atmosphere until the ____ develop.

Words – clones, damp, independent, roots, identical

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Cloning AnimalsCloning AnimalsMethod 1 – “Embryo transplants”

A developing embryo is “split” before the cells specialise and the identical embryos are implanted into host

mothers.

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Cloning AnimalsCloning AnimalsMethod 2 - Fusion

Host mother

Clone

Mimi

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Selective breedingSelective breeding

I raise cows. Each type of cow is good at a certain job. The Friesian cow

produces large quantities of milk, the Jersey cow

produces very nice milk and the Hereford cow produces lot of beef.

If, for example, I want lots of milk I would only breed Friesian cows with each other – this is SELECTIVE

BREEDING.

Friesian

Jersey

Hereford

19/04/23Selective breeding vs. Selective breeding vs. CloningCloningAdvantages Disadvantages

Cloning

Selective breeding

19/04/23Selective breeding vs. Selective breeding vs. CloningCloningAdvantages Disadvantages

Cloning

1) Allows large numbers of organisms with good characteristics to be produced

2) Very efficient

1) Causes reduced numbers of alleles

2) Loss of variation could harm survival chances if the environment changes

Selective breeding

1) Produced organisms with favoured characteristics

2) Very efficient and economically viable

1) Causes reduced numbers of alleles

2) Loss of variation could harm survival chances if the environment changes

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Genetic ModificationGenetic Modification

Possible uses of genetic modification of organisms:

-Improving crop yield

-Improving resistance to pesticides

-Extend shelf-life

-Manufacture a certain chemical (e.g. insulin)

-Convenience

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Genetic engineeringGenetic engineering

Insulin is a hormone produced by the pancreas to help control blood sugar levels. Diabetics can’t produce enough insulin and often need to inject it.

Insulin can be made by genetic engineering:

19/04/23Genetic engineering - Genetic engineering - InsulinInsulin

Step 1: Using RESTRICTION ENZYMES “cut out” the part of the human chromosome that is responsible for producing insulin.

Step 2: Using another restriction enzyme cut open a ring of bacterial DNA (a “plasmid”). Other enzymes are then used to insert the piece of human DNA into the plasmid.

Step 3: Place the plasmid into a bacterium which will start to divide rapidly. As it divides it will replicate the plasmid and make millions of them, each with the instruction to produce insulin. Commercial quantities of insulin can then be produced.

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EvolutionEvolution

Charles Darwin (1809-1882)

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EvolutionEvolutionEvolution is the slow, continual

change of organisms over a very long time. All living things on the Earth

have developed from the first simple life forms that arrived 3,000,000,000

years ago.

One of the effects of evolution is that species will become better adapted to their environment. If these species don’t adapt they may become extinct due to being unable to deal with any of these factors…

1) Increased competition

2) Changes in the environment

3) New diseases

4) New predators

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The “Evolution Tree”The “Evolution Tree”

Family Hominidae

(Great Apes)

Family Hylobatidae (Lesser Apes)

Subfamily Hominidae

Subfamily Ponginae

Tribe HominiTribe Panini

Tribe Gorillini

HumansChimpanzees

GorillasOrangutans

Gibbons

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Evidence for EvolutionEvidence for Evolution

The Grand Canyon

Fossil records

“Missing links”

Humans with tails

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EvolutionEvolutionMy key observations:1) All living things produce more

offspring than survive to adulthood

2) In spite of this, population sizes remain roughly constant

3) Variation exists among species4) Characteristics can be passed on

from one generation to the next.

These observations led me to the conclusion that species evolve over a along period of time by a mechanism called “Natural Selection”. The main evidence for this is from fossil records.

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Natural SelectionNatural Selection1) Each species shows variation:

2) There is competition within each species for food, living space, water, mates etc

4) These survivors will pass on their better genes to their offspring who will also show this beneficial variation.

Get off my land

Gutted!

Yum

3) The “better adapted” members of these species are more likely to survive – “Survival of the Fittest”

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A smaller example…A smaller example…Consider the four steps of natural selection in the example of some bacteria that has become resistant to penicillin:

1) Variation – some strains of bacteria are resistant and some aren’t.

2) Competition – The non-resistant bacteria are killed by the penicillin.

3) Survival of the fittest – the resistant bacteria survive.

4) Passing on of genes – the resistant bacteria reproduce and pass on their adaptations to their offspring.

Bacteria

Penicillin

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Darwin vs LamarckDarwin vs LamarckDarwin wasn’t the first to come up with evolution – he was simply the one credited with explaining how it worked (i.e. Natural Selection). An earlier scientist called Lamarck explained evolution by different means:

Jean Baptiste Lamarck

(1744 - 1829

The giraffe has a long neck because it “stretches” its neck to reach the food, and these long necks are passed on to

their offspring. Organs which aren’t used will eventually

disappear.

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Population and PollutionPopulation and Pollution

The human population is growing exponentially:

Population

Time

This has a number of effects on the environment:

Bigger population means…

Building – more

buildings needed

Farming –less land

available for crops

Waste –more waste needs to be disposed of

Quarrying and mining –

raw materials and sources of energy are

being used up

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PollutionPollutionHumans pollute the Earth in a number of ways:

Water – with sewage, fertiliser or toxic chemicals

Air – with smoke or gases such as sulphur dioxide

Land – with toxic chemicals, pesticides and waste

NO, NO2

and CO

Acid rain

Power stations produce CO2, SO2 and NO2

Cars produce NO, NO2 and CO

These gases produce acid rain (which affects tress and buildings) and worsens the greenhouse effect

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Pollution IndicatorsPollution Indicators

Lichens in very clean air

Lichens in clean air

Lichens in slightly dirty air

Lichens can be used as air pollution indicators:

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Pollution IndicatorsPollution Indicators

In dirty water leeches and midges will survive

In average water more species (like the dragonfly and cranefly) will survive

In clean water a lot more species (like the mayfly and caddisfly) will survive

The quality of water can be monitored by looking at the species of insect in the water:

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DeforestationDeforestation

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DeforestationDeforestation

Why it happens Effects

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The Greenhouse EffectThe Greenhouse EffectWe get heat from the sun:

A lot of this heat is _______ back into space.

However, most of it is kept inside the Earth by a layer of gases that prevent the heat escaping by _______ and then re-radiating it back again.This is called the _________ Effect. It has always been around, but is

currently being made worse due to:

1) Burning (releasing CO2)

2) __________ (removing trees that remove CO2)

3) Increased micro organism activity (from rotting ______)

4) Cattle and rice fields (they both produce _______)

These changes will cause GLOBAL WARMING and RISING SEA LEVELSWords – methane, radiated, absorbing, deforestation, waste, greenhouse

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Sustainable DevelopmentSustainable DevelopmentSustainable development is all about preserving the world

for tomorrow. There are three main strands:

1) Economic development

2) Social development

3) Environmental protection

Examples of sustainable development include:

1) Replanting trees after chopping them down

2) Limiting the number of fish allowed in a catch

3) Protecting endangered species

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