Anthro Chapter 2 Notes
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Proposed the concept of species in 17th century. Recognized groups of plants and animals could mate and produce fertile offspring. Called them species. Also recognized species share traits with others and grouped them into genus (pl. genera). First to use genus and species in the way we do today.
Authored Systems of Nature in 18th century. Standardized and established the system of binomial nomenclature. Added order and class to species and genus. Four level system basis for taxonomy. Also included humans. Believed in fixity of species.
Charles's grandfather. Wrote poem that said life originated in the sea and all life shares a common ancestor. Introduced many ideas that inspired grandson Charles later.
Georges-Louis Leclerc de Buffon
Recognized dynamic relationship between the external environment and living forms. Wrote Natural History which recognized different regions have different plants and animals (major concept in biogeology). Recognized that factors in environment drives change in species.
Suggested that animals adapt to changes in environment which would lead to increased or decreased use of certain body parts. Consequently those body parts become modified. Unused parts would disappear over time. Physical changes occurred in response to need. Certain "fluids and forces" would concentrate at a point until it was modified. These instant modifications would then be passed to offspring. Coined the term biology. Opponent of Georges Cuvier.
Opponent of Lamarck. Introduced concept of extinction. Never grasped dynamic concept of nature and believed in fixity of species. Proposed catastrophism.
Wrote An Essay on the Principles of Population which inspired Darwin and Wallace both. He was interested only in population control but Darwin and Wallace both expanded his theories to include all organisms, even humans. There must be constant competition for food and water, and it is this competition between individuals that is key to understanding natural selection.
Considered founder of modern geology. Friend of Darwin. Argued that geological processes we see today are the same as those in the past. Theory called geological uniformitarianism was first proposed by James Hutton but Lylell demonstrated how it all contributed to today's landscape. Said earth must be older than previously suspected. Came up with the concept of "Deep Time".
Father taught her to gather fossils from cliffs near town of Lyme Regis. Earned a living selling fossils to collectors. Discovered the first complete fossil of Ichthyosaurus, and the first Pleiosaurus fossils. Became known as one of the world's leading "fossilists" by sharing her knowledge. Wasn't acknowledged in scientific journals because a woman of lowly financial status. Achieved some recognition recently.
General interest in nature as a child. Sent to Edinburgh University as child after mother's death. Father sent him to medical school since he was only interested in hunting. Edinburgh where introduced to Lamarck and others. Left after 2 years. Went to Cambridge to study theology although not interested in religion. Became immersed in natural science there. After graduation was invited on expedition on HMS Beagle around the world. Boarded Beagle believing in fixity of species but developed doubts during journey. Famous stop on Galapagos that he realized the finches had evolved to adapt to isolated conditions. After returning and marrying his cousin he worked on the concept of natural selection. Concept borrowed from animal breeders. By 1830 had realized variation withing species was crucial. Then read Malthus' essay on population control and realized what was favorable survived and what wasn't favorable didn't. Didn't publish until got a letter from Wallace and realized he was about to be scooped.
Alfred Russel Wallace
Little formal education and modest background. In 1855 published article on species descending from other species that got Lyllel to urge Darwin to publish. In 1858 sent Darwin a paper "On the Tendency of Varieties to Depart Indefinitely from the Original Type", which made Darwin realize he had to publish or Wallace would get credit for the same idea.
8 Principles of Natural Selection
- 1. All species are capable of producing offspring at a rate faster than food supplies increase.
- 2. There is biological variation within all species.
- 3. Since in each generation more offspring are produced than can survive, and because of limited resources, there is competition among individuals.
- 4. Individuals who possess favorable varitations or traits (for example, speed, resistance to disease, protective coloration) have an advantage over those who don't have them. In other words, they have greater fitness because favorable traits increase the likelihood of survival and reproduction.
- 5. The environmental context determines whether or not a trait is beneficial. What is favorable in one setting may be a liability in another. Consequently, the traits that become most advantageous are the results of a natural process.
- 6. Traits are inherited and passed on to the next generation. Because individuals who possess favorable traits contribute more offspring to the next generation than others do, over time those favorable traits become more common in the population. Less favorable characteristics aren't passed as frequently, so they become less common over time and are "weeded out". Individuals who produce more offspring in comparison to others are said to have greater reproductive success.
- 7. Over long periods of time, successful variations accumulate in a population, so that later generations may be distinct from ancestral ones. Thus, in time, a new species may appear.
- 8. Geographical isolation also contributes to the formation of new species. As populations of a species become more geographically isolated from one another, for whatever reason (for example, distance or natural barriers such as oceans), they begin to adapt to different environments. Over time, as populations continue to respond to different selective pressures (that is, different ecological circumstances), they may become distinct species. The 13 species of Galapagos finch are presumably all descended form a common ancestor on the South American mainland, and they provide and example of the role of geographical isolation.
4 Fundamentals of Evolutionary Change
- 1. A trait must be inherited if natural selection is to act on it.
- 2. Natural selection can't occur without population variation in inherited characteristics.
- 3. Fitness is a relative measure that changes as the environment changes.
- 4. Natural selection can act only on traits that affect reproduction.
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