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
Natural Selection Galapagos 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 n Berry eater Insect eaters Seed Cactus eaters Beak shape varies depending on diet
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 -1895 Majerus, M. 2004 The Peppered Moth: decline of a Darwinian Disciple. Lecture to the British Humanist Association, 12 th February 2004 Updated 01/10/2006
Mutations Some 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 Summary: Human Influence on characteristics and behavior. • Domestic Animals – Ex: Chickens, Dogs, Cows • Plants: – Ex: Corn, Brasilica, Fruit hybrids
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 - epilepsy Dalmatians - hereditary deafness
Domestic Animals • Various animals that have been tamed and made fit for a human environment.
Selective Breeding Look, there they are again!
Selective Breeding In Animals Animal Characteristic Improved Cattle Beef and Milk Production Pig Growth Rate and Litter Size Sheep Wool Quality and Quantity Chicken Growth Rate and Egg Production Behaviour, Appearance and Abilities Dog
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 Plants Plant Characteristic Improved Maize Oil Content and Size of Cob Tomato Size, Colour and Flavour Wheat Apple Height (being the same height makes it easier to harvest ) Size, Colour and Flavour Beans Colour of Bean
Selective Breeding (done by man) Hybrid Fruits How many types of apples are there?
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.
GROWING NERVE CELLS. . . GLOW IN THE DARK MICE http: //www. youtube. com/watch? v=n 0 Uzd. YRn. Mt. Y
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, 1 st mammal •
Which type of selection does man control, Natural Selection or Selective Breeding and why do you think so ?