Embedded Files
Descent with Modification: A Darwinian View of Life Theme: evolutionary change is based on the interactions between populations and their environment which results in adaptations (inherited characteristics) to increase fitness Evolution = change over time in the genetic composition of a population Historical process of science:-Aristotle: life-forms arranged on scale of increasing complexity-Old Testament/creationism: Earth ~6000 YO; perfect species each designed by God-Natural Theology: discovering creator’s plan by studying nature; to classify nature-Linnaeus: founder of taxonomy; binomial nomenclature -Domain – kingdom – phylum – class – order – family – genus – species -Dear king Philip came over for great spaghetti -Domains: Eubacteria, Archaea, Eukarya -Classification based on anatomy and morphology-Cuvier: paleontologist, studued fossils -deeper strata (layers) – very different fossils from current life -opposed idea of evolution-catastrophism – catastrophe destroyed many living species, then repopulated by immigrant species-Hutton/Lyell:-gradualism = geologic change results from slow and gradual, continuous process-uniformitatianism = earth’s processes same rate in pase and present à therefore earth is very old-slow and subtle changes in organisms à big change-Lamarck: published theory of evolution in 1809 -use and disuse: parts of body used à bigger/stronger (ex: giraffe neck) -inheritance of acquired characteristics: modifications can be passed on-importance: recognized that species evolve, although explanation was flawed-Malthus: -more babies born than deaths-consequences of overproducing within environment = war, famine, disease (limits of human pop) -struggle for existence-Charles Darwin -English naturalist -1831 joined the HMS Beagle for a 5-year research voyage around the world -collected and studied plant and animal specimens, bones, fossils -notable stop: Galapagos Islands-Darwin’s finch collection: the birds were all about the same size, but the shape and size of the beaks of each species were different-the vice-governor of the islands told Darwin that he could tell which island a particular tortoise came from by looking at its shell-Darwin waited 30 years before he published his ideas on evolution-Alfred Russell Wallace – published paper on natural selection first (1858)-Charles Darwin (1859): On the Origin of Species by Means of Natural Selection -Mechanism for evolution is natural selection-Darwin didn’t use ‘evolution’ but rather ‘descent with modification’ Adaptations – enhance an organism’s ability to survive and reproduce Ex: desert fox – large ears, arctic fox – small earsOverproduction of offspring leads to competition for resources Natural Selection vs. Artificial Selection-Natural: nature decides. Works on individual. Ex: beaks.-Artificial: man decides. Selective breeding. Inbreeding occurs. Ex: dalmations-Therefore if humans can create substantial change over short time, nature can over a long time Key Ideas of Natural Selection:-Competition for limited resources results in differential survival-Evolutionary Fitness: individuals with more favorable phenotypes more likely to survive and produce more offspring, and pass traits to future generations.-If environment changes or individuals move to new environment, new adaptations and new species mayarise-POPULATIONS EVOLVE NOT INDIVIDUALS Recap main ideas of Natural Selection1. Evolution is change in species over time2. There is overproduction of offspring, which leads to competition for resources3. Heritable variations exist within a population4. These variations can result in differential reproductive success5. Over generation, this can result in change in the genetic composition of the populationRemember – individuals DO NOT evolve. POPULATIONS EVOLVE Evidence for Evolution1. direct observations2. fossil record3. homology4. biogeography1. Direct Observations:Examples: -insect populations become resistant to pesticides-antibiotic resistance-peppered moth (pollution in city vs. country) 2. Fossil Record-Fossils = remains or traces of organisms from past-found in sedimentary rock-paleontology – study of fossils-show evolutionary changes that occur over time and origin of major new groups of organisms-prokaryotes (oldest fossils) à eukaryotes (fish – amphibians – reptiles – birds – mammals)-transitional forms = links to modern species 3. Homology-characteristics in related species can have underlying similarity even though functions may differ. Examples:-homologous structures: similar anatomy from common ancestors (eg. Forelimbs of human/cat/whale/bat)-embryonic homologies: similar early development (eg. Vertebrate embryos with tail and pharyngeal pouches)-vestigial organs: structures with little/no use (flightless bird wings)-molecular homologies: compare DNA and amino acid sequences-Convergent Evolution – distantly related species can resemble one another -similar problems lead to similar solutions -analogous structures: similar structires, function in similar environments ex: torpedo shape of shark, penguin, dolphin 4. Biogeography-biogeography = geographic distribution of a species-species in nearby geographic areas resemble each other-continental drift and Pangaea explains similarities on different continents-endemic species: found at a certain geographic location and nowhere else ex: marine iguanas in the Galapagos
Google Sites
Report abuse