Physical Anthropology Week 3
Physical Anthropology Week 3 Anth 385
Edinboro University of Pennsylvania
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This 5 page Class Notes was uploaded by Danielle Johnson on Wednesday February 17, 2016. The Class Notes belongs to Anth 385 at Edinboro University of Pennsylvania taught by Dr. Barbian in Spring 2016. Since its upload, it has received 21 views. For similar materials see Intro Physical Anthropology in anthropology, evolution, sphr at Edinboro University of Pennsylvania.
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Date Created: 02/17/16
Physical Anthropology Week 3 2/8/2016 Natural Selection ● Types ○ Directional ○ Stabilizing ○ Disruptive ■ Bimodal ■ With breeding isolation can lead to speciation ■ Can account for high degree of sexual dimorphism Evolution ● Occurs at the level of the population ● Occurs at the net level ● Three types ○ Parallel ■ Develope of similar structures that occur independently and are probable due to similar evolutionary conditions ■ look very much alike even though millions of evolutionary years, because the same evolutionary characteristics are being selected for ■ Examples ● New World Monkey and Old World Monkey ● haven’t had a common ancestor in 35 million years ● Old World Monkey more closely related to humans than the New World Monkey ○ Convergent ■ Development of structure in remotely related forms that superficially resemble each other ■ have similar environmental pressures and fit a particular niche ■ Examples ● Dolphins and a shark ● Birds and Bats ○ Divergent ■ Closely related species become more morphological divergent due to different evolutionary pressures ● examples Humans and Chimps Darwin’s Failures ● Unable to explain source of variation ● Failed to know mechanism by which parents transmit traits Summary Physical Anthropology Week 3 2/8/2016 ● Great Chain of Being/USsher concept of earth and life forms ● Systematic classification (Linnaeus) With the recognition that humans fit within the animal kingdom ● Attempts to account for fossils invoke divine intervention (Cuvier,Lamarck) ● Geology leads to understanding that natural process alter earth ● Malthus points out that not all members of a species will survive ● Darwin not working in a vacuum ● Darwin placed humankind directly in place with the biotic world ● Need to understand Darwin’s Theory of Evolution, types of selection and evolution Genetics and Evolution Gregor Mendel 18221884 ● In school bright but not successful (was not privileged like Darwin) ● Financial difficulties lead to joining the monastery in Moravia (Czech) (1840s) ● 1860s published his genetic theories ● Not thought important until rediscovered in the early 1900s Mendel’s Contributions ● Discrete physical unit responsible for each trait ● passed from parent to offspring through the generations ● passage determined by mathematical laws Reasons for Success ● Followed progress of hybrids through a number of generations ● Selected plants that possessed contrasting characteristics ● Used a large number of plants (the multiple generations/ crosses) ○ the pea plants had either or choice of variation (only 2 choices of variation/ nothing in the middle) ○ bigger the sample size the better the patterns can be seen ( was breeding 100s 1000s of pea plants) allowed for the patterns to be seen Color of the peas Yellow and Green ● self crossed his plants to create true breeders ● than crossed them with each other ● made all Yellow Generation ● crossed the all Yellow Generation together Physical Anthropology Week 3 2/8/2016 ● got 3 yellow peas :1 green peas ○ this is the 3 to 1 ratio ○ this means the true breeders have 2 of each trait,YY and yy but when they cross they get a generation oYy and Yy the capital yellow Ys being dominant over the lower case green ys. Mendel’s Experiments ● Hypothesized that green trait not lost or altered ● Yellow trait simply dominant and green trait recessive ○ Green trait is hidden behind the yellow trait ● Some plants breed true = homozygous ( if its two yellow plants they will never allow the green trait to show up again) ○ if its recessive will automatically know that its homozygous ● Other still possessed the green trait= heterozygous ( if its two yellow plants they will eventually allow for the green trait to show up again) ○ Will always look the same as the homozygous dominant ● Parental generation all homozygous ○ Yellow = YY, Green = yy ● Crossbreeding of the parental generation ○ YY x yy ● Crossbreeding of the F1 generation ○ 3:1 phenotypic ratio Yellow:Green ○ 1:2:1 genotypic ratio YY:Yy:yy Principle of Segregation ● Genes occur in pairs. During the productions of gametes (offspring), the pair is separated and each gamete (offspring) contains only one of the pair. Dihybrid Cross Yellow Smooth Pod Parent X Green Wrinkled Pod Parent = F1 Generation: 4 Yellow Smooth Pod Children= F2 Generation: 9 Yellow Smooth Pod Children, 3 Green Smooth Pod Children, 3 Green Smooth Pod Children, 3 Yellow Wrinkled Pod Children, 1 Green Wrinkled Pod Children Principle of Independent Assortment ● Distribution of one pair of genes does not influence the distribution of other pairs of genes ○ Crossing Over Exception ○ (Mendel Rounded his results making it so he had a good ratio) Physical Anthropology Week 3 2/8/2016 Dihybrid Cross RrYy RrYy RY Ry rY ry x RY Ry rY ry Gametes Gametes RY Ry rY ry RY RRYY RRYy RrYY RrYy Ry RRYy RRyy RrYy Rryy rY RrYY RrYy rrYY rrYy ry RrYy Rryy rrYy rryy Terminology ● Locusspot on the DNA ● Allelehow the gene is ● Dominant ● Recessive ● Mendelian traits ○ only two genes and two alleles ■ Examples that do occur in humans (hitchhikers thumb, rolling of the tongue) ■ most higher organisms are (many) more than two genes ● Polygenic traits ○ multiple alleles and multiple genes for those traits ■ causes people to be expressed differently from those traits ● Codominance ○ Make a nice blend of the parents ○ Do not apply to Mendel’s laws ■ Snap Dragons P Generation 1 Pure Red x 1 PureWhite ↓ F1 Generation Pink ↓ F2 Generation 1 Red: 2 Pink: 1 White Physical Anthropology Week 3 2/8/2016
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