Biology 2- BIOL 1362 Week 3 Notes Chapter 19 and 11
Biology 2- BIOL 1362 Week 3 Notes Chapter 19 and 11 BIOL 1362
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This 7 page Class Notes was uploaded by Alexis Clowtis on Tuesday February 9, 2016. The Class Notes belongs to BIOL 1362 at University of Houston taught by CHEEK in Spring 2016. Since its upload, it has received 50 views. For similar materials see Biology 2 in Biology at University of Houston.
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Date Created: 02/09/16
Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek- 2/2/2016 Chapter 19- Darwin and Natural Selection -Darwin was invited along with a ship captain as a friend in the same social class so captain didn’t go crazy like last experience they had- 1830’s -Biodiversity got Darwin interested Ideas about life on Earth Species are permanent Aristotle (350 BCE –“before common era”) o Spp fit on a scale of increasing complexity (we put us on top, bacteria at bottom) th Linneaus (1707-78)- 18 century o Gave us classification system (kingdom, phylum, etc) o Came up with Binomial nomenclature: Turdus migratorius (Genus(capitalized) species(NEVER capitalized)) o Grouped similar species into hierarchical categories based on morphology= body form o Kingdom Phylum Class Order Family Genus species King Phillip Came Over For Good sushi (did not originate name for domain) Earth is Changing Hutton (1700’s)- Scottish, published in 1973, geologist o First geologist to propose earth’s physical features/forms occurred by gradual processes that we can still see operating Lyell (late 1700s, early 1800s)- English geologist, Principles of Geology o Take Hutton’s further-geological processes operate today at the same rate as in the past (=earth is reallyyyy old) which contradicts other scientists of their time that say it’s only 6,000 years old Clicker- inference of Hutton’s proposition- earth must be very old because geological processes are very slow Hutton and Lyell inference: the earth is old, older than 6,000 years Species Change Cuvier (lived 1769-1832) o Was aware of fossils and what they were and that they were different from today’s o Species go extinct due to catastrophes o All created at same time, all killed off Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek- 2/2/2016 Lamarck (1744-1829) o Argued a lot with Cuvier o Fossils are ancestors of species we see today o Species can change into new species o Proposed mechanisms for how species could change During lifetime of organism, may acquire some changes giraffe example: short neck stretched to reach leaves and passed down length of neck to offspring who then stretched it more o Acquired characteristics being passed onto offspring (Arnold Schwarzenegger’s musclesoffspring born with huge muscles) o Proposed mechanisms Use and disuse (ex. Appendix) Inheritance of acquired characteristics o Could have validity applied to changes in adult gametes Timeline: Darwin Proposes that Species change by Natural Selection Natural selection: a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits Darwin’s observations and inferences (map) First hand observations of geological processes o Had Lyell’s book with him (geology) o Got to see fossilized sea organisms like oysters on mountains o Experienced earthquake off beach of Chile and saw how beach moved o Finding fossils of ocean organisms high in Andes mountains o Conclusion: Lyell is right, Earth is old Observations: spp in temperate South America more similar to spp in tropical South America than to temperate spp in Europe (climate is not what seems to be causing similarity, it’s because geographic location) Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek- 2/2/2016 o Spp on Galapagos islands resembled South America mainland, but were different from mainland and elsewhere in the world Inference: distribution of species he sees might be explained by Earth’s geological history (nobody knows of plate tectonics yet) Darwin’s Observations Members of a population vary in their inherited traits o Ex. Human’s skin, hair, etc. All spp can produce more offspring than their environment can support o Read Thomas Malthus (economist) who said people are poor because too many humans Darwin’s Inferences Individuals who inherited traits five them a higher probability of surviving leave more offspring- “survival of the fittest” Differential survival and reproduction can lead to an accumulation of favorable traits in the population over many generations (good traits stick out through generations, those with bad traits don’t reproduce as much) o *1 individual organism cannot change itself to fit in its environment to survive- if they have it, they make it, those with the less fit traits die Natural selection opposes acquired traitslonger necks got more food so they had the most babies and the shorter necks die off Adaptation= inherited trait that enhances survival reproduction IN CURRENT, LOCAL ENVIRONMENT Inference: new species could develop from ancestral species by gradual accumulation of adaptations to different environment o Ex. Insect eater vs seed eater beaks of same species o Camouflage as a way to ambush prey or avoid predator Clicker- Flower mantid camouflage is to ambush prey because other insects pollinate those flowers it hides on (From Dr. Cheek’s slides) Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek-2/4/16 Descent with modification- (coined by Darwin)=evolution All living spp descended from one ancestor Darwin proposed that history of life is like a tree, kind of like a family tree o Multiple branches from common trunk Branch point red dot is most recent common ancestor Natural Selection: mechanism of descent with modification Individuals that inherit certain traits survive better and reproduce more in their current, local environment Compared to artificial selection o Pigeons- humans picking traits in birds and breeding them to create new subspecies o Cruciferous veggies- kale is a plant humans have selected for different parts of wild mustard (bud=cabbage, flower and stem=broccoli) Comparing Selection Processes Artificial selection Natural selection Variation in heritable trait Variation benefits humans Variation is due to rather than their inheritance in parts to aid sustainability in their survival environment Selection pressure Human desire Survival of the fittest in current environment Trait Desirable to humans Necessary for survival in the current, local environment Frequency of trait Humans breed species More frequent in those with a certain trait until who survive and there is a subspecies with reproduce; becomes more that trait frequent as generations go on Selection pressure: condition that affects survival and reproduction eg. Food type available, predators, female preferences for male characteristics Sexual selection- females are investing more in reproduction than males (eggs are more “expensive” energy wise) 1859- Wallis wrote manuscript which is what pushed Darwin to publish; not actually a fight like in book, more of a collaboration Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek-2/4/16 Implications of Darwin’s idea Earth is very old and changing Species weren’t created individually all at once Species are changing due to natural selection and new ones are still being created All species are descended from a single common ancestor (written in a book) Clicker- Natural selection can: act only on heritable characteristics that vary in a population—natural selection just goes for good enough, NOT best structure for particular function Leftover adaptation: structure that may have aided survival and reproduction in an ancestral species or past environment but doesn’t anymore Vestigial organs: ex. Appendix OR Biproducts of another characteristic o Vertebrae blood is red because of the light reflecting properties of hemoglobins Chapter 11- Mendelian Inheritance Gregor Mendel (1822-1884) Australian monk, math guy, experiment with peas, Darwin didn’t know about Mendel’s work, publishes in 1866 No one knows about chromosomes- nobody knew what was being passed to offspring Hypothesis about heredity: 1. Blending hypothesis=characteristics of parents mix like paint in offspring 2. Particulate hypothesis= each parent has particles of “something” they pass on; offspring has shuffled particles of mom/dad (blue/red) a. Heritable “particles” of parents are shuffled at fertilization b. Offspring characteristics depend on which parental “particles” inherited Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek-2/4/16 Mendel’s Laws of Inheritance: Character: inheritable feature that varies between individuals o Could be chemical or morphology Trait: variant of a character o Ex. Character=color of hair, trait=red hair P: parental generation (relative term we have to designate) F1: first filial generation (offspring) F2: second filial generation (offspring of F1) Mendel’s Methods Experimented with characters with 2 distinctly different traits o Purple flowers and white flowers P (P1) were true-breeding pants; either showed 1 character or the other (had that trait for generations) o Takes pollen from white and pollinates purple (artificial reproduction) o Looks at peas-seeds of plant 1. Removes immature stamens containing pollen from one flower 2. Adds pollen from another flower (source of male gamete) to carpel (home of egg) of F parent 3. Allow ovary and seeds to ripen (ovary=seed shell) 4. Plant seeds=F1=purple Mendel’s question: is the genetic contribution of white flowers lost or hidden? Crossed F1 plants F2 contained 705 purple flowers and 224 white flowers o 3:1 ratio “particle” for white flower still present in F1 but hidden o “Dominant” and “recessive” coined by Mendel Obtained 3:1 ratio for 7 more characters Biology 1362- 8:30am TTH SW 102 Doctor Ann Cheek-2/4/16 Clicker- Mendel’s results support Particulate Hypothesis Mendel’s Law of Segregation Mendel’s model of inheritance o Characters come in different versions Ex. Flower can be purple or white Law: 2 characters separate from each other (segregate) when gametes form o Characters end up in different gametes Predicting offspring phenotype and genotype o Phenotype= appearance Purple/white flower o Genotype= genetic make- up PP, pp 1 letter to represent character, upper/lowercase to represent version of character If P1 genotype is known then you can figure out possible gamete genotypes are known
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