Natural Selection(Environmental)

vs.Selective Breeding

(Human Influences)

Environmental And

Human Influences

Natural Selection• Process by which

organisms that are most suited to their environment survive and reproduce most successfully.

Selective Breeding• Method of breeding

that allows only those organisms with desired characteristics to produce the next generation.

Charles Darwin• Born 02/12/1809 – Shrewsbury, England• Father was a medical doctor, and paternal grandfather (Erasmus

Darwin) was a famous botanist• Attended medical school, but could not stand the sight of blood and

turned to natural history• HMS Beagle Voyage from 12/27/1831 - 10/02/1836• Influenced by the writings of Thomas Malthus – “An Essay on the

Principle of Population”• Pushed by Alfred Wallace (1858) who independently hit upon the

idea of Natural Selection to complete and publish his great work “On the Origin of Species – by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life”

• Darwin’s Theory supplanted Lamarck’s (French, 1809) Theory that simple creatures “strived” to become more complex

Darwin’s Voyage

• Charles Darwin– Set sail on the HMS Beagle in 1831 as the ship’s

naturalist– Arrived in the Galapagos Islands in 1835– Observed that the animals on the islands were similar

to those on the mainland

Darwin’s Voyage• Galapagos Animals

– The Galapagos animals, while similar, were also different from island to island as well as to the mainland

– Most obvious difference were the sizes and shapes of the finches’ (small birds) beaks

– Sizes and shapes of the beaks were adapted to what the birds ate

Natural SelectionGalapagos Islands• Charles Darwin described

how organisms might change over time based in part to his observations of the finches Galapagos Islands.

• The Islands are geographical different.

• The island’s geography (environment) cause different types of species to be selected.

Darwin’s Voyage• On the Origin of Species (Darwin’s book, 1859)

– For the 20 years that followed his return to England Darwin studied plants, animals and adaptations

– Darwin wrote about how species can change gradually over many, many generations and become better adapted to new environmental conditions.

Galápagos Finches

Beak shape varies depending on dietBerr

y eater

Insect eaters

Cactus eaters

Seed eaters

Evolution

• The gradual change in a species over time.

Natural Selection

Organisms that are better adapted to an environment are more likely to survive and reproduce than organisms that are less well adapted.

Adaptations

Katydids have camouflage to look like leaves.

Non-poisonous king snakes mimic poisonous coral snakes.

Factors that affect Natural Selection:

Overproduction most species produce far more offspring than will/can survive

Overproducers Producers

mature rapidly  mature slowly

short-lived: most die before they reproduce

live long lives: low juvenile mortality rate 

have many offspring - tend to overproduce

have few offspring at a time

invest little in individual youngsters 

care for their young

population not regulated by density: boom and bust population figures

population stabilizes near carrying capacity

Factors that affect Natural Selection:

Competition: since food and resources are limited, the offspring have to compete to survive

Darwin called it: “Struggle for existence”

Factors that affect Natural Selection:Variation: Members within a species exhibit individual differences – these differences must be inheritable

Natural selection won’t work in a population of clones! Remember that a key to variation is sexual reproduction.

Factors that affect Natural Selection:Survival to reproduce: Only those individuals

within a population that survive to reproduce are considered successful (“Survival of the fittest”).

Fit individuals pass on to a portion of their offspring the advantageous characteristics.

Changes in the Environment

Example, the pepper moth.Originally, the pepper moth was white, which was

good because it could blend in.

Then, trains were invented and the soot they produced covered the trees. Making the trees black. The moths that were black could now survive better.

How many moths do you see in . . .

Picture #1

Picture #2

Picture #3

 

The Peppered Moth

In Great Britain there are two forms of peppered moth--dark and light forms.

Before the industrial revolution, which of the two moths in the picture were the most common and why?

(Look at the back ground.)

After the Industrial Revolution, which of the two moths were the most common and why? (Look at the background.)

Since smoke pollution has decreased in the UK, the light colored moths have started to become more common again. The process which took place after the industrial revolution is beginning to be reversed. By 2019, the dark moths are only expected to make up 1% of the peppered moth population in Britain.Modified From:Bibliography

Proffitt, F. 2004 In defense of Darwin and a Former Icon of Evolution. Science 304:1894-1895Majerus, M. 2004 The Peppered Moth: decline of a Darwinian Disciple. Lecture to the British Humanist Association, 12 th February 2004

Updated 01/10/2006

MutationsSome species are more susceptible to mutations. Some mutations allow the animal to survive; other mutations do not allow the animal to survive. The mutations that are not decrease the chance of survival remain.

Natural Selection

Summary: Environmental Influence cause organisms to be selected that adapt the best.

Man: Artificial Selection

• Selective breeding as practiced by humans on domesticated plants and animals….

• For example: Dogs

Selective Breeding

• Domestic Animals– Ex: Chickens, Dogs, Cows

• Plants:– Ex: Corn, Brasilica, Fruit hybrids

Summary: Human Influence on characteristics and behavior.

HYBRIDIZATION

-Crossing dissimilar individuals to bring together the best traits of both organisms

-Produces hybrids: * Hybrids can be different species

crossed together or different types within the same species.

GOLDEN DOODLE PUGGLE

Designer breeds or mutts?

INBREEDING

Inbreeding = continued breeding of similar individuals (ex. pure breed dogs)

-Has risks… increases breed’s susceptibility to disease & deformities

EX: Golden retrievers - epilepsyDalmatians - hereditary deafness

Domestic Animals• Various animals that have been tamed and

made fit for a human environment.

Look, there they are again!

Selective Breeding

Selective Breeding In AnimalsAnimal Characteristic

ImprovedCattle Beef and Milk Production

Pig Growth Rate and Litter Size

Sheep Wool Quality and Quantity

Chicken Growth Rate and Egg Production

Dog Behaviour, Appearance and Abilities

Would this cow survive in nature?

 

• Did nature or man cause there to be Brussels Sprouts?

Which ear of corn do you want?

Selective Breeding In PlantsPlant Characteristic

ImprovedMaize Oil Content and Size of Cob

Tomato Size, Colour and Flavour

Wheat Height (being the same height makes it easier to

harvest )

Apple Size, Colour and Flavour

Beans Colour of Bean

Hybrid Fruits

How many types of apples are there?

Selective Breeding (done by man)

 

MANIPULATING DNA

How are changes made to DNA?

Scientists use their knowledge of the structure of DNA & its chemical properties to study & change DNA molecules  

*This is GENETIC ENGINEERING

GENETIC ENGINEERING= making changes in the DNA code of a living organism

TRANSGENIC ORGANISMS

Contains genes from other species

1.Microorganisms (bacteria)2.Animals (mouse; medical uses)3.Plants (agricultural uses)

*Genetically Modified Crops

Gene causes these mice to glow in the dark. Normally, the gene is found in jellyfish.

http://www.youtube.com/watch?v=n0UzdYRnMtY

GROWING NERVE CELLS...GLOW IN THE DARK MICE

CLONING•member of a population of genetically

identical cells produced from a single cell•easy to clone single cell organisms•multicellular organisms more difficult to

clone•a twin is a natural clone•1997 - Dolly the sheep cloned, 1st mammal

Which type of selection does man control, Natural Selection or Selective Breeding and why do you think so ?