EVOLUTION

CHANGE Look at this picture which shows the process of evolution Using only one word explain the meaning of evolution

And from a biological point of view? Let's work out a more specific definition …..........

Best Selection Species Struggle Fittest Offspring Heritable Adaptation Enviroment Heritable Species Adaptation Change Survival Evolve Population Competition Struggle

(processed at the level of the genes) 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: Indipendent assortment (2 n possibilities) Crossing over Random fusion of gametes

They provide the genetic diversity that makes natural selection possible. MUTATIONS the row material of evolution Phenotyipic change in the offspring Somatic cell Germ line cell

Organism with favorable traits are more likely to survive and 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.

Darwin and the Voyage of the Beagle 1831 - 1836 The mission of H.M.S. Beagle was to map the oceans and collect oceanographic and biological information around the world. The map indicates the ship's path, and the inset shows the Galapagos Islands, whose organisms were an important source for Darwin's ideas on natural selection.

An idea that would change the world Charles 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.

Up to 7 kittens Female pig (Meishan) Female rabbit Up to 60 kitten

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

English economist Thomas Robert Malthus (1766 - 1834) Both Darwin and Wallace were influenced by the ideas of the economist Thomas Malthus, who in 1798 published 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.

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..............

2. Populations remain more or less constant in numbers 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. There are a number of factors which keep the population numbers stable, including competition for food, predation and disease 2. Populations remain more or less constant in numbers

Look at these giraffes............. Do they belong to the same specie? Are they identical? Darwin’s third observation was that all living things vary slightly in colour, shape, size or behaviour.

3. Members of the same species show variation in characteristics Different colourings and skin patterns found in the giraffe. 3. Members of the same species show variation in characteristics

Which is the differerence between these characteristics?

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

French biologist Jean Baptiste Lamarck (1744–1829) “The inheritance of acquired characteristics” “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.

DEDUCTIONS? CONCLUSIONS? Observations Observations: 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 4. Some characteristics are inherited and so passed on to the next generation DEDUCTIONS? CONCLUSIONS?

Describe what's happening in these pictures.............. Pigeon and sparrow Describe what's happening in these pictures.............. Spider and fly Polar bears

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

to their environment than others. B. Some individuals are better adapted to their environment than others.

Silverback mountain gorilla Survival of the fittest The 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. Silverback mountain gorilla Male African lion These ideas formed the basis of Darwin’s theory of evolution by natural selection.

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

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

The bright red colour attracts mosquitoes carrying a deadly disease 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?