Discussion Papers for final exam.txt
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Discussion Papers for final exam.txt
outlines of bacterial evolution
looked at Eubacteria (not archaeobac)
Saw conserved INDELS
: showed Gram + are most ancient (monoderm) - ancestral, and Gram - are more recent (diderm)
Deinococci are intermediates
1. thick cell membrane of 1 plasma membrane & pep-glycan cell wall
2. Thin cell wall w/2 plasma membranes & pep-glycan cell wall
3. Thick cell wall w/2 plasma membranes
Lonhiemne et al. 2010
Argued opposite of Embly & Martin
Said Endo-membranes (internal membranes) evolved 1st, BEFORE Endosymbiosis of mitochondria and chloroplasts.
: nuclear membrane evolved prior to mitochondria
Embly, ™, Martin W. 2006
Eukaryotic evolution changes & challenges
Argued opposite of Lonheimne
Said Proto-mitochondrian may have evolved 1st, BEFORE nuclear membranes
This done by endosymbiosis
Endosymbiont that evolved into pro-mitochondrian
Bell, Philip 2004.
Viral Eukaryogenesis Theory
1st to evolve is Eukaryotic nucleus w/linear chrom…may have evolved from dsDNA virus
3rd genome important
: dsDNA virus, which infected host cell w/out lysing it immediately
: archaeobacterial cell (provides the genes needed for REP, TRANSCRIPTION & TRANSLATION)
: Provides METABOLISM for 1. glycolysis, 2. Krebs, 3. oxidative phosphorylation
Evolved from eubac symbiont, which becomes mitochondriont
BEST job explaining features of euk vs. pro
Alvarez & Asaro 1990
Cretaceous/Tertiary extinction @ 65MYA caused by METEOR impact
Use data from newly discovered crater
: Chicxulub crater @ Yucatan Peninsula of Mexio
K/T extinction @ 65MYA may have been caused by Deccan Traps volcanic activity in India
Sereno, P 1999.
Evolution of Dinosaurs
Dinosaurs experienced # of ADAPTIVE Radiations & REGIONAL extinctions B4 K/T extinction…but this killed off the last of the non-avian dinosaurs
Regional extinction ie
Alvarez & Muller, 1984.
Evidence from crater ages form periodic impacts on Earth
1st to postulate periodicity of meteorite impacts
Statistical evidence for a 28MY periodicity to meteor impacts during past 250MY!
Raup & Sepkoski, 1986.
Periodic extinction of families & genera
Est. timeline of 26 MY periodicity of major MARINE extinctions over past 250MY!
Diversification and extinction in the history of life
NO EVIDENCE of Periodicity to Mass extinctions in Marine or Terrestrial habitats over the past 600MY!
: bad genes or bad luck?
Argued all extinctions may be due, at least in part, to meteorite impacts.
Looked at Meteors in the FOSSIL record
Rohde & Muller 2005.
Cycles in Fossil Diversity
Statistical significant support for hypothesis that MARINE EXTINCTIONS follow a 62MY CYCLE!
This occurs during Paleozoic, Mesozoic & Cenozoic Eras
May be attributed to galactic movements of SOLAR system
Ward P. 2006
Impacts from the Deep
All major extinctions in the past may share common feature
: global warming (although may be due to volcanic or meteor)
Starts w/INCREASE in CO2 levels, which increase temps in atmosphere & oceans
Leads to INCREASE in CH4 building from ocean floor (worse than CO2 for ozone layer)
Leads to INCREASE in Hydrogen SULFIDE building from ocean floor (animals cannot tolerate this)
leads to ANOXIA
This Hydrogen SULFIDE increase caused the Permian/Triassic boundary (Paleozoic end and start of Mesozoic) around 251MYA…then there was a SLOW recovery period that followed
Dinosaurs were best adapted to survive b/c have BEST respitory tracts
Gould & Lewontin, 1979.
Spandrels of San Marco
: May be more important when explaining what appear to be Adaptation vs. selective forces
Linnen et al. 2009.
On origin & spread of an adaptive allele in deer mice
: 8000yrs ago occurred in deer mice living in Sand Hills of Nebraska. Have been preserved by Natural selection (mutation changes color from brown-->tan)
On Origin of species - Sterility of Hybrids
F1 Hybrid Sterility (intrinsic post-zygotic mechanism)
: NOT be of any SELECTIVE advantage of any of the organisms that possess it
Coyne & Orr. 2004
F1 hybrid sterility & F1 hybrid inviability Could EVOLVE by SELECTIVE forces