EVOLUTION

Look at this picture which shows the process of evolution

Using only one word explain the meaning of evolution

CHANGE

And from a biological

point of view?

Let's work out a more specific definition …..........

Struggle

Adaptation

Enviroment

Selection

Competition

Heritable

Population

Offspring

Species

BestBest

Evolution: process of change in the

inherited traits of a population of organisms

from one generation to the next

(processed at the level of the genes)

How does evolution occurr ?

Promotes diversity of characters in the offsprings

by providing genetic variation

SEXUAL

REPRODUCTION

Offers the opportunity to produce recombinant types

that can make the population better able to keep up

with changes in the environment.

OFFSPRING ARE GENETICALLY UNIQUE FROM:

Crossing over

Indipendent assortment (2 n possibilities)

Random fusion of gametes

MUTATIONS

the row material ofevolution

They provide the genetic diversity

that makes natural selection possible.

Somatic cellGerm line

cell

Phenotyipic change in the offspring

NATURAL

SELECTION

Organism with favorable traits are more likely to survive

and

to leave more offspring better suited for their enviroment

In this image appears Alfred Wallace and Charles Darwin, both came up with the theory of evolution.

Look trough these web sides, work in pairs and make an interview each other with questions like these:

•Where and when they were born; •Where and when they died;•What they did;•Their nationality;•They were known because.…;•The problems associated with their theory….

•http://en.wikipedia.org/wiki/Alfred_Russel_Wallace•

Charles Darwin – the boy

Charles Darwin was born on 12th February 1809 in Shrewsbury, England.

He went to boarding school in Shrewsbury and in 1825 went to Edinburgh University to study medicine.

Whilst in Edinburgh Darwin investigated marine invertebrates and started to develop a growing interest in natural history.

In 1827, at the age of 18, Darwin realised he did not like the study of medicine and could not bear the sight of blood or suffering. He left Edinburgh for Cambridge University with the idea of becoming a clergyman.

Charles Darwin – the young man

Whilst at Cambridge Darwin met a number of people who were influential in shaping his career.

His cousin William Darwin Fox, who was a keen collector of beetles.

John Henslow, who studied and lectured on plants.

Professor Adam Sedgewick, who taught him about geology during an expedition to Wales in 1831.

In August 1831, Henslow wrote to Darwin inviting him to become a naturalist for Captain Fitzroy on the survey ship the Beagle.

The mission of H.M.S. Beagle The mission of H.M.S. Beagle was to map the oceans and was to map the oceans and collect oceanographic and collect oceanographic and biological information around biological information around the world. The map indicates the world. The map indicates the ship's path, and the inset the ship's path, and the inset shows the Galapagos Islands, shows the Galapagos Islands, whose organisms were an whose organisms were an important source for Darwin's important source for Darwin's ideas on natural selection.ideas on natural selection.

Darwin and the Voyage of the BeagleDarwin and the Voyage of the Beagle

1831 - 18361831 - 1836

Charles Darwin and Natural SelectionCharles Darwin and Natural Selection

An idea that would change the world

Charles Darwin developed his

theory of evolution by natural selection

using FOUR important OBSERVATIONS

which led him

to TWO DEDUCTIONS.

Female rabbit

Female pig (Meishan)

Up to 60 kitten

Up to 7 kittens

One of Darwin’s first observations was that

all living things are capable of producing

more offspring than are needed to replace

their parents.

Chick

Do they all survive to become adults?

1. All organisms produce more offspring than survive to adulthood

Both Darwin and Wallace were influenced by the ideas of the economist Thomas Malthus, who in 1798published An Essay on the Principle of Population.

Malthus argued that because the rate of human population growth is greater than the rate of increase in food production, unchecked growth inevitably leads to famine

Darwin saw parallels throughout nature.

English economist Thomas Robert Malthus (1766 - 1834)

Herds of many animals live on the plains of Africa: wildebeest, zebra, gazelles etc.

Each year many of the females give birth to young, but the overall population sizes..............

Darwin’s second observation was that the numbers of many different species of animals and plants tend to stay fairly constant

over long periods of time.

2. Populations remain more or less constant in numbers

There are a number of factors which keep the population numbers stable, including competition for food, predation and disease

Darwin’s third observation was that all living things vary slightly in colour, shape, size or behaviour.

Look at these giraffes.............

Do they belong to the same specie?

Are they identical?

3. Members of the same species show

variation in characteristics

Different colourings and skin patterns found in the giraffe.

Which is the differerence between these characteristics?

4. Some characteristics are inherited and so passed on to the next generation

Darwin’s fourth observation was that many features are passed on from parent to offspring.

Some inherited characteristics are quite easy to see in humans:

Eye colour

Hair colour

Some are not so easy to see:

Blood group Mendel 1822-1884

“Change through use and disuse”:

When environments changed, organisms had to change their behavior to survive.

If a giraffe stretched its neck for leaves, for example, a "nervous fluid" would flow into its neck and make it longer. Its offspring would inherit the longer neck, and continued stretching would make it longer still over several generations.

Meanwhile organs that organisms stopped using would shrink.

French biologist Jean Baptiste Lamarck (1744–1829)

“The inheritance of acquired characteristics”

4. Some characteristics are inherited and so passed on to the next generation

ObservationsObservations:

1. All organisms produce more offspring than survive to adulthood

2. Populations remain more or less constant in numbers

3. Members of the same species show variation in characteristics

4. Some characteristics are inherited and so are passed on to the next generation

DEDUCTIONS? CONCLUSIONS?

Describe what's happening in these pictures..............

Pigeon and sparrow

Polar bears

Spider and fly

A. All organisms are involved in a struggle for survival.

Striped tigers and leopards spots: WHY?

It is an adaptation to the enviroment in which they live. Camouflage themselves to ambush their prey too

Pygmy seahorse camouflaged against fan coral

B. Some individuals are better adapted

to their environment than others.

Male African lionSilverback mountain gorilla

Survival of the fittestThe individuals that are best adapted to their environment are most likely to survive and have the chance to reproduce, therefore passing on their useful adaptations to the next generation.

Those individuals that are the least well adapted do not survive long enough to breed.

These ideas formed the basis of Darwin’s theory of evolution by natural selection.

Alfred Russel Wallace,was studying the biota of the Malay Archipelago.

Wallace asked Darwin to evaluate the manuscript, in which Wallace proposed a theory of natural selection almost identical to Darwin's.

At first Darwin was dismayed, believing that Wallace had preempted his idea.

English naturalist, explorer, geographer, anthropologist, and biologist Alfred Russel Wallace (1823 –1913)

24 Novembre 1859

The origin of species

A population showing variation in colour.

Continuous or discontinuous?

There is lots of food so your population survives and reproduces. Add 5.

The bright yellow of some of your offspring attracts predators. All but two of them get eaten.

There’s lots of food and hiding places for the green andblue, but the red ones can’t hide and get eaten.

Plenty of food and its spring so another 10 offspring are born, they are a variety of colours.

Plenty of food and its spring so another 10 offspring are born, they are a variety of colours.

It’s winter and 5 of your population die

Its mating time again, blue and green mate and produce 5 green and 2 blue offspring. A mutation also produces 2 red offspring

Its mating time again, blue and green mate and produce 5 green and 2 blue offspring. A mutation also produces 2 red offspring

There is lots of food, and all reproduce 2 offspring, but the white are better at finding water and hiding from predators so they produce 5 offspring

There is lots of food, and all reproduce 2 offspring, but the white are better at finding water and hiding from predators so they produce 5 offspring

The bright red colour attracts mosquitoes carrying a deadly disease. They all die.

The bright red colour attracts mosquitoes carrying a deadly disease. They all die.

It is a particularly hot summer, blue and green are poor temperature regulators; white and yellow, which reflect heat, are more likely to survive.

It is a particularly hot summer, blue and green are poor temperature regulators; white and yellow, which reflect heat, are more likely to survive.

When food is plentiful again the remainder mate and produce 5 offspring some white and some yellow.

When food is plentiful again the remainder mate and produce 5 offspring some white and some yellow.

A scientist finds this population and reports that this species occurs in two colours. He says they have adapted to their habitat. What does he mean?

What is the population?Has it changed?