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James Thomson

Lecture 14 Darwin , Age 22 Darwin notice: many plants – big diversity, therefore some species are really far away from each other  Wind pollination is not effective Single plants are common in the tropical, fertilize through pollinators, not the wind. Largely evergreen. Eglossine Bees – Janzen 1971, 23 km per day Pest pressure hypothesis – survival of seeds is larger when seedlings are more far from the parent. Reason: pest pressure. Ant-plant mutualism in Acacia(mutualism): thorns has a hole, where live ants. Ants protects the plant from herbivores, plant in his turn provides everything for ants living. Feed on proteins and nectar. Experiment: used the chemical to de ant the trees -> beetles flew on the trees and killed them. Devil’s garden: no vegetation under the trees Duroia hirsuta. Also found ants, which lived in the trees, ants produced acid which killed other plants around -> no competition Giant Amazon Water Lily: difference between wild and botanical garden 2) Epiphytes – the plant that grows on another plant Common in tropics. Darwin thought they are parasitic. They are not. Epiphytic life form has evolved independently in many unrelated families = convergent evolution Bird dispersal, have colorful flowers to attract birds. 2 flowers hypothesis: if pollinated already white, if needs to – blue. 3) found fossils of extinct mammals in Brazil. Patagonia: abrupt treeline governed by abiotic factors Familiar and unfamiliar animal groups. Eg. Swans: black & white, bumble bees: too dark(hard conditions -> to be warm prefer dark fur), Darwin rhea, 4) Galapagos islands: young, volcano islands, long-distance dispersal, a lot of variation among the species, 5 weeks – foundation of the theory of evolution. Now – UNESCO worlds heritage site. How cacti came to the desert: birds pollination Lecture 15. Genetics 1. Variation 2. Heredity 3. Selection – Darwin ne this but not th e others Genotype – combination of genes Phenotype – what we observe, natural selection operates on that Genome – all of the genes in the organism, entire DNA + non-coding regions Gene: the functional unit of inheritance, DNA sequence composed of codons(3 nucleotides that makes up the genetic code) Where does the genetic variation comes from?  Mutation – ultimate source of all genetic variation  Recombination: shuffles up all of the genetic variations that exist  Gene flow: movement of genes from one population to another  Hybridization: mating with another species Independent assortment & recombination during meiosis generates enormous diversity( > 9 million possible gamete combinations) Most genetic variability in a population results from sexual reproduction, but mutation is still an ultimate source of variability Mutations in Fruit Fly Homeotic mutation – leg on a head McClintock 1983 Nobel Prize for Physiology – Medicine Jumping genes or mobile geneti
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