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bio 117 lecture2

Terms

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land uplift and subsidence
through time with strata always formed underwater and the gaps between successive strata being times of uplift above sea level
factors that favor preservation
1) rapid burial, 2) possession of hard parts
genetic homology
common strands of DNA across many organisms
how are fossils formed
1) organic (entire) preservation [a) antiseptic burial, b) freezing], 2) mineral profusion, 3) molds and casts, 4) footprints and trails, 5) coprolites
indirect dating
uranium-lead method (half-life of U235 decay to Pb207, radio isotope dating volcanic intrusions running through the fossil bearing strata, the stratum is older than the intrusion
A study on Daphne Major (island) with Geospiza fortis
a) vary in beak shape and size, b) tribulus fruit pits are tough to crack and avoided when other seeds are available, c) rain stopped largest beak sizes survived best, other seeds became available-bills smaller, chose males with large beaks as mating partners (sexual selection)
oscillating selection
evolutionary changes with the ebb and flow of weather and differential food availability
structural homology
traits in two organisms that are similar because they were derived from a single trait in a common ancestor (vertebrate limb bones)
weather induced food availability
classic case of microevolution in Darwin's finches on Galapagos Isles
geological record
record of geological activity as appearing in the layers of rocks and sediment over geological time
fossil record
record or history of life forms preserved from the past and occurring in the geological record
silent mutations
changes in amino acid sequences that do not affect protein function, increase to fixation in populations at a steady rate
direct dating
a) carbon-14 or radio carbon (half life of C14 decay to N14=5,568 years), b) potassium-argon (half-life of K40 decay to Ca40+argon gas= 1.3BYA
background on darwn's finches
a) originated from a mainland "grassquit" ground finch, b) 14 different species now eat seeds, buds and insects on the galapagos islands, c) bills differ in relation to food type, d) only a few species occupy each island
what geological events affect the fossil record
1) continental drift, 2) land uplift and subsidence, 3) volcanic activity, 4) weathering/erosion
freezing
woolly mammoth found in siberian permafrost
coprolites
fossilized excrement
fossils
any recognizable structure of organic origin(once living) preserved from the geological past
embryology (developmental homology)
the pouches of higher vertebrates disappear during development, as do the necessity of gills but the presence of pouches in the embryo suggest a common ancestor to all vertebrates
direct enumeration
a) growth rings (trees), b ) varves (anual deposit patterns), 1) seasonal runoff [corse slit vs fine clay], 2) snow accumulation [layering of fine winter vs coarse summer]
volcanic activity
ash (favors fossil formation), lava (destroys organisms and formations)
antiseptic burial
in oil seeps and asphalt bogs, mastodon found in a peat bog
footprints and trails
dinosaur footprints, worm burrows
how fossils are dated
1) direct enumeration (counting the years), 2) direct dating (radioisotope dating of fossil or the strata touching it, 3) indirect dating
invasive species
causes local changes in phenotypes and gene frequency of native species because of sudden increases in competition
molecular clock
the fossil record can be supplemented with the information on the amino acid and DNA sequences in living species
weathering and erosion
land uplift carries dead animals into adjacent lakes and seas for rapid burial, but also destroys some of the most recent records in strata
macroevolution
the change from one major taxonomic group into another
microevolution
changes in gene frequency within a species that produce differences in characteristics from one population to the next
Generalities from the fossil record
a) major increases in structure/species complexity requires millions/billions of years, b) life began in the sea, c) rapid burial in aquatic sediment is the most important way that fossils are formed
vestigial traits
non-functional trait in one species that is homologous to a functional trait in an ancestral species (coccyx=tailbone and appendix)
brief history of geological principles, the geological record and fossil record
geologist Charles Lyell, provided evidence of the geological processes responsible for establishing the fossil record, Darwin was influenced by the research of Lyell, who published the book in 1830 entitled
molds and casts
sediment around buried organism becomes hardened before the organism disintegrates forming a mold
mineral perfusion
replacement of original tissue of buried organism, petrified forest
antibiotic resistance
tuberculosis had a single gene mutation
continental drift
land masses have broken up, drifted adn collided over millions of years, more ancient the organism the more likely you are to find similar species separated by vast distances

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