Natural Selection

False – no perfect organism False ~ results from genetic variation Slide # 2 True or False Evolution is a theory about the origin of life. False 2. Organisms are always getting better through evolution False – no perfect organism 3. Natural selection involves organisms trying to adapt False ~ results from genetic variation 4. Evolutionary theory is invalid because it is incomplete and cannot give a total explanation for the biodiversity we see around us. False ~ All scientific theories are works in progress . As new evidence is discovered, theories are revised or even disproven

Evolution: E-: out of; from Volvere: to roll or turn Important Vocabulary Adaptation: Ad- : towards (direction) apt-: fitting or fitted 1. Species: A group of organisms whose individuals can breed together to produce fertile offspring. 2. Population: A localized group of individuals belonging to the same species. 3. Evolution: A slow change in a population over time. 4. Adaptation: any structural or physiological change that gives an organism an advantage in the environment.

Charles Darwin explained how Natural Selection could cause a population to adapt & change over time. (“population” will change -not an “individual”)

Route of Darwin’s 5 Year Trip Slide # 6 Route of Darwin’s 5 Year Trip Galapagos Islands Darwin spent a lot of time and collected a lot of specimens from the Galapagos Islands.

Charles Darwin: An Unlikely Evolutionist Who was Charles Darwin? 1809: English naturalist Went on a 5 year voyage on the HMS Beagle as an unpaid scholar Collected plants & animals during journey Darwin did not set out to develop a theory of evolution Observations and specimens collected helped Darwin formulate his theory of evolution Charles Darwin

Darwin’s Observations Slide # 8 Darwin’s Observations In Argentina, Darwin saw earthquakes raising the earth several feet Shells of marine animals found far inland & at great heights in Andes Mts Fossils of huge sloths & armadillo-like animals (both extinct) – similar to modern forms Animals on Galapagos were similar but not same as those on mainland S. America & Antarctica Galapagos penguin 14 inches tall 5 lbs Eat small fish & sardines Nests in burrows Chinstrap penguin 28 inches tall 9-14 pounds Eat small fish & krill Build nests out of small stones

Darwin’s Observations on the Galapagos Islands Finches on Galapagos resemble mainland finch, but there were more types on the islands

The Work of Lyell Influenced Darwin’s Ideas Charles Lyell – English geologist 1830: On the Principles of Geology Natural forces & processes that shaped ancient Earth are the same forces acting on Earth today. EX: Rain erodes mountains & molten rock pushes up to create new ones. Earth’s geologic features formed as a result of __________________ ___________________. Must take millions of years to change _______________ 2. Darwin read Lyell’s work while on his voyage & agreed with Lyell’s conclusions

Malthus: Organisms have more offspring than nature can support

The Work of Malthus Influenced Darwin’s Ideas Slide # 12 The Work of Malthus Influenced Darwin’s Ideas 1798: Thomas Malthus --Economist Essay on the Principle of Population Said that plants and animals tend to have more offspring than nature can support Food production increase at a slower rate than population Darwin read Malthus’s essay after he returned from his voyage Darwin concluded that all organisms produce more offspring than the population can support Thomas Malthus

Lamarck’s Theory of Use and Disuse 1801: Theory of Inheritance of Acquired Characteristics “Theory of inheritance of acquired characteristics” & “Use and disuse” If an organism changes in order to adapt to its environment, those changes are passed on to offspring. (We now know that individual organism cannot change or adapt to their environment) Said that changes in organisms occur to help an organism reach perfection. Problem?: __________________________________

Example of Lamarck’s Hypothesis

Darwin explained Evolution by Natural Selection Slide # 15 Darwin explained Evolution by Natural Selection 1859: Darwin published On the Origin of Species Proposed that natural selection was the mechanism for evolution. Individuals vary in one or more traits & there can be slight differences in their ability to survive & reproduce. Nature selects those individuals w/ favorable traits to leave more offspring that are better suited (FIT) for their environment. Published 25 years after Darwin wrote it!

Evidence that Supports Evolution: Fossil Record 1. Fossil: preserved remains (bones, teeth, shells) or evidence (imprint or footprint) of ancient organisms.

Geographic Distribution of Living Species Convergent: Con-: together, with, jointly Verge-: to move or incline in a certain direction 1. Biogeography: the geographical distribution of species in relation to geography and other species 2. Influenced by continental drift 3. Leads to __________________ evolution: the appearance of apparently similar structures in organisms in different lines of descent

Homologous Structures Homo- : same, common -logos: relation, reasoning, computation -ous: possessing, full of Homologous structures: similar structures; different functions Structures develop from same clump of embryonic cells Provides evidence that four-limbed vertebrates descended from a common ancestor.

Pelvis & femur bones are vestigial in whales Vestigial Structures Vestigial Vestige: a mark, trace, or sign -al: having the form or character Pelvis & femur bones are vestigial in whales Vestigial structures: structures or organs that are reduced in size; do not seem to serve a useful function

Similarities in Embryology Hollow dorsal nerve cord Notochord Pharyngeal pouches Postanal tail The embryos of vertebrates are very similar during early development. 2. The same groups of embryonic cells develop in the same order and in similar patterns to produce tissues & organs. 3. Implies common genes are involved

Post Darwin: DNA Evidence Supports Evolution We can compare DNA sequences to which are most closely related We can compare amino acid sequences to which are most closely related Why didn’t Darwin use DNA evidence in developing his theory? It had not yet been discovered!