Charles Darwin

LifelineBorn 1809Study (Edinburgh and Cambridge) 1825-1831Voyage of the Beagle 1831-36Retired to Down 1842The Origin of Species 1859Died 1882Darwins home at Down, near London

Darwins achievementsTransformed biological science Both style and contentStill the cornerstone of biology Now the cutting edge of psychologyTransformed attitudes of humanity to our place in the universe

Not just an evolutionistNot even a biologist to start withCollected beetles for funStudied geology more seriouslyConsidered himself a geologist throughout the Beagle voyage and for some time afterFamous for working out how coral atolls are formed

Natural selectionDeveloped theory in complete isolationIn face of violent (religious) oppositionWith no knowledge of geneticsWith no knowledge of DNAWith no knowledge of plate tectonics With no observations of natural selection actually occurring

Joining the Beagle VoyageNot paid for 5 years on Beagle. Actually, he had to pay! Was lucky to get onreplaced someone who was shot in a duelhis father opposed him goingMainly asked because of his class, to keep Captain Fitzroy companyIt was the making of him

Galapogos, 1835Portrayed as a Eureka experience. Actually, was hugely homesickDid not recognise significance until back in England, 1837.Worked out theory much later.First inkling of natural selection in 1838.Turtles & finches were key evidenceOn boat home, ate turtles, dumped shellsThought finches different species; didnt even label them properly

The Big Idea: Natural SelectionHe knew about fossilsCollected many for extinct animalsKnew about Lyells theory of evolution of geologyRead Malthus (an economist) on population and competition for resources. His ideas developed steadily over 20 yearsDarwins sand walk at Down: a daily thoughtful stroll

Alfred Russel WallaceThought of natural selection independentlyWrote to DarwinDarwin had been working on bookPublished a letter jointlyIt was Darwin who put in the hard yards collecting and documenting evidence to support theory

Natural SelectionProcess of change in populations over many generationsIndividuals with certain traits survive local environmental conditionsPass on favourable alleles to offspringEnvironment exerts selective pressureThis has led to biodiversity

Assumptions of Natural SelectionVariation-All members of a species display a variety of characteristics in their appearance and behavior. -Many are inherited.

Assumptions of Natural Selection2. CompetitionThe number of offspring produced by individuals in a species exceeds the number of offspring that will survive to adulthood

Assumptions of Natural Selection3. FitnessSome offspring, because of their differences, are better able to adapt to the conditions of the environment than others.

Assumptions of Natural Selection4. AdaptationThe better-adapted organisms pass on their characteristics to their offspring and, as a result, the population changes.

Natural Selection game

Descent with ModificationDarwin never used the word evolution in his book On the Origin of SpeciesUsed the term descent with modification instead

Artificial SelectionSelective pressure exerted by humans on populationsImprove or modify particular desirable traitsEg. Selective breeding in farm animals

Artificial SelectionIn food cropsWheat, corn, rice and veggies have all been selectively bredWild mustard plant has been modified to produce broccoli, Brussels sprouts, cabbage and cauliflowerBreed for nutritional value, as well as harvest yield and pest resistance

Designer DogsHow many breeds of dogs are there now?Examples:What do you get when you cross a Yorkie and a Poodle?Yorkie-poo

Designer DogsWhat about a Pug and a Beagle?PuggleOr a Bichon Frize and a Poodle?Bich-Poo

Designer DogsWhat about a Bull mastiff and a Shih-Tzu?

Consequences of Artificial SelectionIn dogs: respiratory problems (bulldogs) and hip dysplasia (labs)In crops: reduces genetic variation (monoculture)