Palaeobiology: how extreme environments drive evolutionary change in large organisms Lecture content What is an extreme environment The palaeontological record The palaeontological record

Palaeobiology: how extreme environments drive evolutionary change in large organisms Lecture content What is an extreme environment The palaeontological record The palaeontological record www.phwiki.com

Palaeobiology: how extreme environments drive evolutionary change in large organisms Lecture content What is an extreme environment The palaeontological record The palaeontological record

Berger, Kevin, Contributing Writer has reference to this Academic Journal, PHwiki organized this Journal Palaeobiology: how extreme environments drive evolutionary change in large organisms Robin Allaby r.g.allaby@warwick.ac.uk Lecture content DEEP TIME the palaeontological record mass extinctions speciation explosions possible mechanims as long as speciations SHALLOW TIME Life coming out of the ice: the last ice age palaeogenetics archaeogenetics What is an extreme environment temperature (either hot or cold) chemistry (unfavourable conditions: CO2, H20, 02 etc.) violent

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The palaeontological record The palaeontological record oxygen levels over time carbon dioxide levels over time The 5 mass extinctions mass extinctions occur at period boundaries

Mass radiations followed extinctions. Extinction 1. Ordovician Extinction2. Devonian

Extinction 3. Permian – the big one Extinction 4. Triassic Extinction 5. Cretaceous

Impact of a 6 mile diameter asteroid The Chicxulub crater is pretty big! Mass extinction causes 1. Ordovician Ice age (unknown) 2. Devonian Ice age (biotic probably) 3. Permian Global warming (unknown cause) 4. Triassic Global warming (volcanic activity possibly) 5. Cretaceous Asteroid impact What did mass extinctions kill Large organisms (e.g. dinosaurs) Specialized organisms (e.g. climax community of Carboniferous as long as ests, such as lycopod trees Lepidodendron; e.g. no entirely carnivorous or herbivorous fauna after the Cretaceous event)

Species turnover in addition to extreme environments: the tale of therapsids vs dinosaurs Dimetrodon Pristeroognathus Replacement rather than competition extreme environment Does Darwinian evolution happen at all How do mass extinctions increase evolutionary divergence Decrease predation pressure, allowing novelties to become established Decrease competition, allowing previously non-competitive species to rise (more ecological space) Extreme environmental (stressful) conditions can be associated with increased genetic variability Change in the ‘fitness l in addition to scape’ caused by extreme environment

TE expansions linked to punctuated equilibrium in addition to ‘evolvability’ high TE content, low diversity = evolvable high TE content, high diversity = stasis low TE content = stasis Coelocanthus Branchiostomus Myotis Does environmental extremity determine the mode of evolution Phyletic gradualism (as Darwin expected) Punctuated equilibrium (caused by extreme environments) Phyletic gradualism in the palaeontological record Sheldon 1987 Nature 330:561-563

Punctuated equilibrium in the palaeontological record Williamson 1981 Nature 293:437-43 BUT see Van Bocxlaer et al 2008. Different environments have different evolutionary rates Onshore: rich in fossil species (see Hoffmann in addition to Parsons 1997 p.187) Dry habitats: origin of angiosperms (Coiffard et al 2007.) See Mestre et al 2009 as long as deep sea colonization Near shore: horseshoe crabs (300 Mya) Highly specialized, lots of gradual co-evolution e.g. predator prey, pollinating systems (Parsons 1994) How does environment drive evolution evolutionary patterns determined by intensity of biotic interactions which differ in different environments fluctuating environments can clear ecological space continuous fluctuating conditions can prevent adaptation intermittant stresses can increase genetic variability normally unexpressed

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Extreme environments in recent history: evidence from Palaeogenetics in addition to archaeogenetics directly examine evolutionary change are morphological changes associated with speciation is there more going on that we cannot see due to morphological stasis Pleistocene-Holocene Megafaunal extinctions Hofreiter in addition to Stewart 2009 Current Biology 19:R584-94

Recolonization from refugia Hewitt 2000 Nature 405:907-913 Brown bear recolonization Barnes et al 2002 Science 295:2267-70 Arctic foxes did not contract with glaciers Dalén et al 2007 Proc. Natl. Acad. Sci USA 104:6726-9

Extreme environments in the Holocene: drought tolerance Palmer et al 2009 PLoS One 4:e6301 This barley has the transcription factor as long as 6-row, but has evolved back into 2 row by another means to cope with drought stress. Punctuated evolution in cotton during the Holocene

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