Charles Darwin

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

Darwin’s achievements Transformed biological science Both style and content Still the cornerstone of biology Now the cutting edge of psychology Transformed attitudes of humanity to our place in the universe

Not just an evolutionist Not even a biologist to start with Collected beetles for fun Studied geology more seriously Considered himself a geologist throughout the Beagle voyage and for some time after Famous for working out how coral atolls are formed

Natural selection Developed theory in complete isolation In face of religious opposition With no knowledge of genetics With no knowledge of DNA With no knowledge of plate tectonics With no observations of natural selection actually occurring

Joining the Beagle Voyage Not paid for 5 years on Beagle. Actually, he had to pay! Was lucky to get on his father opposed him going Mainly asked because of his class, to keep Captain Fitzroy company It was the making of him

CHARLES DARWIN Video: Who Was Charles Darwin? https://www.youtube.com/watch?v=6GNUlZhE_jE

Galapagos, 1835 Portrayed as a “Eureka” experience. Actually, was hugely homesick Did not recognise significance until back in England, 1837. Worked out theory much later. First inkling of natural selection in 1838. Turtles & finches were key evidence On boat home, ate turtles, dumped shells Thought finches different species; didn’t even label them properly

The Big Idea: Natural Selection Darwin’s sand walk at Down: a daily thoughtful stroll He knew about fossils Collected many for extinct animals Knew about Lyell’s theory of “evolution” of geology (uniformitarianism) Read Malthus (an economist) on population and competition for resources. His ideas developed steadily over 20 years

Alfred Russel Wallace Thought of natural selection independently Wrote to Darwin Darwin had been working on book Published a “letter” jointly It was Darwin who put in the hard years collecting and documenting evidence to support theory

Natural Selection Process of change in populations over many generations Populations have genetic diversity Environment exerts ‘selective pressure’ (food, climate, predators, etc.) Individuals with certain traits survive local environmental conditions Pass on favourable alleles to offspring

Assumptions of Natural Selection Variation -All members of a species display a variety of characteristics in their appearance and behavior. -Variation among individuals is (at least in part) heritable.

Assumptions of Natural Selection 2. Competition number of offspring produced by individuals in a species exceeds the number of offspring that will survive to adulthood

Competition

Assumptions of Natural Selection 3. Fitness Some offspring, because of their differences, are better able to adapt to the conditions of the environment than others and be more successful at surviving and reproducing.

Assumptions of Natural Selection 4. Adaptation Individuals with most favourable variations (those who are better at surviving and reproducing) are naturally selected.

“Descent with Modification” Darwin never used the word ‘evolution’ in his book On the Origin of Species Used the term ‘descent with modification’ instead

Natural Selection

Artificial Selection Selective pressure exerted by humans on populations Improve or modify particular desirable traits Eg. Selective breeding in farm animals

Artificial Selection In food crops Wheat, corn, rice and veggies have all been selectively bred Wild mustard plant has been modified to produce broccoli, Brussels sprouts, cabbage and cauliflower Breed for nutritional value, as well as harvest yield and pest resistance

Artificial Selection In food crops: Wheat, corn, rice and veggies have all been selectively bred Wild mustard plant has been modified to produce broccoli, Brussels sprouts, cabbage and cauliflower Breed for nutritional value, as well as harvest yield and pest resistance

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

Designer Dogs What about a Pug and a Beagle? Puggle Or a Siberian Husky and German Sheppard? Gerberian Shepsky

Yorkshire Terrier and Maltese? Morkie! Mr. Alex Ander Dickie

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