Chapter 22 Evolution History development of evolutionary time 1 Aristotle 427 347 BC Plato s student a Did recognize that there were grades of complexity scala naturae i Humans were at the top ii Thought species were fixed and unchanging iii This was the basic view for almost 2000 years 2 Carolus Linnaeus 1707 1778 a Founder of taxonomy b Described numerous species i Major taxonomic levels kingdom phylum class order family genus species c Binomial nomenclature 2 names d Main point recognition that some organisms were more similar than others could place them into groupings 3 Cuvier catastrophism did not believe in evolution Largely developed paleontology a b Fossils impression of organisms in mineralized rock c Most in sedimentary rock layers of sediment in marine aquatic habitats i Recognized that the fossils represented organisms that lived at successively older time periods ii There were several extinctions d Catastrophism periodic events where species were wiped out by some major environmental catastrophe 4 James Hutton and Charles Lyell a Geologic considerations b Geological gradualism i Large geologic formations geologic formations can be explained by every day weathering processes ii River cuts out a canyon 1 Big changes by gradual change over LONG periods of time iii Earth must be over 6000 years old 5 Jean Baptiste Lamarck 1744 1829 1809 work a 1st formal theory of evolution transformism b Idea of use and disuse i Use a muscle and it becomes larger don t use it and it stays small ii Inheritance of acquired characters giraffes stretched neck a few mm increase in length increased neck length passed on to their offspring 6 Charles Darwin 1809 1882 a HMS Beagle 1831 1836 unpaid position naturalist i Collected numerous specimens ii Species in different habitats differed in adaptations 1 Different beak shape and depth in Galapagos finches iii Darwin took decades to publish nervous in 1844 he wrote an essay and asked his wife to publish it if he died iv Darwin published an essay after reading manuscript by Alfred Wallace who had v the same conclusions July 1 1858 Darwin and Wallace both presented their theories of natural selection b Charles Darwin 1859 Published The Origin of Species includes several hypotheses i Major points Life arose once all animals are descendants of a common ancestor 1 The Earth is very old previously thought only a few thousand 2 3 Species multiply by splitting into daughter species 4 Evolution proceeds via gradual changes in populations 5 Major agent of evolutionary change is natural selection 7 Natural Selection a Behind the theory i Observation 1 fertility populations would increase exponentially if all individuals reproduced ii Obs 2 most populations are stable iii Obs 3 resources are limited INFERENCE there is a struggle for existence iv Obs 4 individuals vary v Obs 5 many of these traits are heritable traits INFERENCE those most adapted will have a higher reproductive success relative term 1 Pass traits to offspring GENOTYPE PHENOTYPE 8 What is natural selection a Not survival of the fittest based on differential reproductive success b Individuals with greater reproductive success than others in the population have higher fitness 9 What is an evolutionary unit what evolution acts on a Not an individual you can t change your genetic makeup b Smallest unit population group of individuals of single species in a given area c Individuals that are best suited to their environment have more offspring than others in the population d Their offspring with the adaptive traits will make up a large proportion of the next generation i Over time the average type found in the population may change 10 Differences in reproductive success Lamarck vs Darwin a Lamarck would say that ducks would stretch their feet in order to develop webbed feet etc Darwin would say some ducks were born with webbed feet some were born without The ones with webbed feet were more suited for the environment so they were more likely to survive 11 Evidence of Evolution WHICH IS A LOAD OF BULL CRAP a Biogeography study of distribution where organisms are i Species are more related to those nearby in a different habitat than those in a similar habitat on another continent 5t b Fossil Record c Comparative anatomy common ancestor i Supports changing body forms change over time divergent lines of evolution ii Supports other predictions predict prokaryotic cells before eukaryotic cells i Homologous characters characteristic shared between organisms with a ii Mammal forelimbs very different uses but the same infrastructure iii Vestigial traits remnants of structures present in the ancestor 1 Whales do not have hind limbs but they still retain pelvic and leg bones d Evolutionary constraints evolution can only modify what exists it edits i Back and knee problems od bipedal humans are the result of adapting structure originally evolved to support four legged mammals ii New alleles or traits come from DNA mutations natural selection may make this new allele more common or eliminate it from one population e Comparative embryology i Ontogeny recapitulates phylogeny ii Ontogeny series of developmental stages iii Phylogeny patterns of relatedness iv Vertebrate embryos go through stages with gill pouches in fish these develop into gills in humans into the Eustachian tube f Molecular biology supports that all organisms are related i Universal genetic code DNA PROTEINS ii Similar chemical pathways glycolysis Krebs cycle electron transport iii Similar sequence 12 Natural selection in action a Beak depth i Dry season average depth increases 1 Birds have to eat larger seeds 2 Birds with larger beaks have more offspring than those with smaller beaks ii Wet season average decreases 1 Plenty of small seeds preferred 2 Birds with larger beaks do not have more offspring than those with smaller beaks 13 Pesticides 14 Staphylococcus aureus a Has evolved resistance to several antibiotics b 1945 strains resistant to penicillin now strains are resistant to methicillin c Frequency of methicillin resistant has increased MRSA 15 Artificial Selection a Selecting traits in dogs b Selecting traits in agriculture