1. Lesson # 1: Evolution (Evolutionary Theorists)

3. James Hutton (1795) Scottish Geologist Geological Gradualism
theory which holds that profound change is the cumulative product of slow but continuous processes, often contrasted with catastrophism.
Present earth formed in past by the same processes that act currently
Long periods of time
 Earth must be millions, not thousands of years old

4. Thomas Malthus (1798) English Political Economist
Wrote “An Essay on the Principle of Population” on human condition as related to overproduction and limited resources
Predicts human population will grow faster than the space and food supplies needed to sustain it
Species have great powers of potential reproduction
Populations would increase exponentially if all individuals survived and reproduced
Growing population rates would contribute to a rising supply of labour that would inevitably lower wages. In essence, Malthus feared that continued population growth would lend itself to poverty

5. Jean Baptist Lamarck (1809)
French Invertebrate Natural Historian
Evolution of Life Forms
When environments change, organisms have to change their behaviour to survive
Use / Disuse
Long neck giraffes - if a giraffe stretched its neck for leaves this would make it longer. Meanwhile organs that organisms stopped using would shrink
Inheritance of Acquired Characteristics
Believed traits changed or acquired over an individuals lifetime could be passed down to its offspring (offspring would inherit the longer neck and continued stretching would make it longer still over several generations)
* Although his theory is flawed he was the first to propose a mechanism explaining how organisms change over time*

6. Charles Darwin (1831)
English Naturalist and child who loved to explore nature
Embarked on a five year survey voyage around the world on the HMS Beagle
Darwin collected a variety of natural specimens, including birds, plants and fossils The Pacific Islands and Galapagos Archipelago were of particular interest to Darwin, as was South America
Darwin noticed similarities among species all over the globe, along with variations based on specific locations, leading him to believe that they had gradually evolved from common ancestors
Natural Selection
Species successfully adapt to meet the changing requirements of where their natural habitat thrived, while those that failed to evolve and reproduce died off
A change in the genetic characteristics (allele frequencies) of a population over time
On November 24, 1859, he published a detailed explanation of his theory in his best-known work, On the Origin of Species by Means of Natural Selection.

7. 4 Steps of Natural Selection
Variation
Traits differ among individuals in a population
2) Heritability
Trait differences are passed on to offspring
3) Differential Reproduction
Only some individuals within a generation survive to reproduce and of those not all survive
4) Darwinian Fitness
Not all produce the same number of offspring
Survival of the Fittest
 Survival of the form that will leave the most copies of itself in successive generations

8. Charles Lyell (1833) Scottish Geologist
Wrote “Principles of Geology” Text
Processes occurring now have shaped earths geological features over a long period of time
Travelled Europe finding much evidence about rising / falling of sea levels, rock erosion
Uniformitarianism
Current geological processes occurring at the same rates observed today, in the same manner, account for all Earth’s geological features
Incorporated Hutton’s gradualism into his widely read book

9. Alfred Wallace (1858) British Naturalist Intelligent Evolution
No organ or attribute of an organism will be developed and retained unless it affords it a survival advantage, where utility cannot be found in a known organ or attribute, some other cause—an intelligent cause—must be called upon
Wallace emphasised environmental pressures on varieties and species forcing them to become adapted to their local conditions, leading populations in different locations to diverge
Developed a theory of evolution similar to the one Darwin was working on

10. Gregor Mendel (1854 - 1863) “Father or modern genetics”
Discovered the basic principles of heredity
Inheritance of certain traits in pea plants follows particular patterns
How inherited traits are passed between generations
Mendel worked on pea plants, but his principles apply to traits in plants and animals – they can explain how we inherit our eye colour and even tongue-rolling ability
Followed inheritance of 7 traits in pea plants that had 2 forms:
Pea shape (round or wrinkled)
Pea colour (yellow or green)
Flower colour (purple or white)
Flower position (terminal or axial)
Plant height (tall or short)
Pod shape (inflated or constricted)
Pod colour (yellow or green)

12. Mendel Continued
Mendel developed 3 principles of inheritance based on his experiments with pea plants.
Fundamental theory of heredity
Inheritance involves the passing of discrete units of inheritance, or genes, from parents to offspring
2) Principle of segregation
During reproduction, the inherited factors (now called alleles) that determine traits are separated into reproductive cells by a process called meiosis and randomly reunite during fertilisation
3) Principle of independent assortment
Genes located on different chromosomes will be inherited independently of each other

13. THE END!!