Descent with Modification A Darwinian View of Life 01 14 2015 Three key observations about life The striking ways in which organisms are suited for life in their environments The many shared characteristics unity of life The rich diversity of life o Evolution the descent with modification The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species 01 14 2015 Aristotle viewed species as fixed unchanging Had the greatest influence of western culture o Did not believe in evolution even though most greek philosophers did meaning evolution was not accepted o Life forms could be arranged on a ladder of increasing complexity o Each life form was permanent and perfect Carolus Linnaeus developed the binomial format for naming species Binomial naming system opposed evolution Ascribed resemblances among species to the pattern of their creation Georges Cuvier father of paleontology and first to accept the concept of extinction Still opposed evolution Hutton father of modern geology concept of geological gradualism Lyell expands on Hutton idea of uniformitarianism Geological action change results from slow continuous actions rather than from sudden events o Earth must be much older than the widely accepted age Jean Baptiste de Lamarck compared living species with fossil forms First to propose mechanism for how life evolved Two basic theoretical principles to explain evolution o Use and disuse the idea that parts of the body that are used extensively become larger and stronger while those that are not used deteriorate o Inheritance of acquired characteristics states organisms could pass their modifications off to their offspring Giraffes necks grew larger and longer because they continuously stretched and used the muscles and passed it to their offspring Lamarck proposed that organisms have innate tendency towards increasing complexity perfection Descent with modification by natural selection explains the adaptions of organisms and the unity and diversity of life Darwin focuses on adaption 01 14 2015 Adaptions inherited characteristics of organisms that enhance their survival and reproduction in specific environments o Accumulation of changes to environmental characteristics o Adaption to environment and origin of new species closely over period of time related 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 Wallace and Origin of Species 1844 Darwin composed thoughts into essay on descent with modification due to natural selection o however he did not publish the essay in fear that he would be criticized and a fight would start between philosophers 1858 Alfred Wallace in South Pacific o developed own hypothesis of natural selection while working Both Wallace s manuscript and parts of Darwin s essay presented to Linnaean Society of London in 1858 for publication Tree of Life Reflects History Darwin s metaphor for history of life branching tree with multiple branding from common trunk to tips of living twigs symbolic of diversity of contemporary organisms Extinct lineages help explain morphological gaps that sometimes exists between related groups of organisms Origin of Species Analyzed 1 Focused on role of natural selection in adaption Broken down by Ernst Mayr Five Observations o All species have such great fertility o Most populations are normally stable in size o Individuals of a population vary extensively in their characteristics o Much of their variation is heritable o Natural resources are limited Origin of Species Analyzed 2 Leading to three inferences o Individuals inherited traits give higher probability of surviving and reproducing in a given environment have more offspring o Unequal ability to survive changes the gene pool in favor of favorable characteristics in each generation depending on the environmental changes Artificial Selection Natural Selection Large changes could be achieved by artificial selection o Domestic dog breeds o Descendants of wild mustard Differential reproduction success higher fitness o Leads to adaption of organisms to environment Population variation arises by chance o Mutations Natural selection is not by chance o Environment selects for those with criteria for reproductive success Variation and overproduction common to all species o Makes natural selection possible Operating in different contexts over vast spans of time Populations groups of interbreeding individuals belonging to particular species and sharing geographical area o Smallest unit capable of evolving Evolution is supported by an Overwhelming amount of Scientific Evidence 01 14 2015 Four types of data that document the pattern of evolution and illuminate how it occurs Direct observations homology fossil records and biogeography Direct Observations of Evolutionary Change Natural selection in response to introduced species When soapberry bugs are introduced to a new food source with seeds closer to the surface of the berry the beak length was shorter than the ones that feed on the original diet The Evolution of Drug Resistant Bacteria Resistant strains of bacteria and viruses can proliferate quietly o Best example is MRSA staphylococcus aureus o Started in 1943 when penicillin became he first widely used antibiotic o MRSA individuals who survived methicillin treatments and reproduced at higher rates than did other individuals o A drug does not create resistant pathogens it selects for resistant individuals that are already present in the population Natural selection favors characteristics in a genetically variable population that provide an advantage in the local environment Homology similarity in characteristics resulting from a shared ancestry Anatomical and Molecular Homologies o Homologous structures structures in different species that are similar because of common ancestry o Anatomical homology may be present only in the early stages of development in some animal species o Vestigial structures left over structures of marginal importance to the organism Had importance generations ago but no longer Remnants of features that served a function in the organisms ancestors o All forms of life use essentially the same genetic code all species descended from a common ancestor o Convergent evolution the independent evolution of similar features in different lineages o Analogous a resemblance in which species share features