Characteristics of Ice Age evolution and adaptations

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Characteristics of Ice Age evolution and
adaptations

• Matt Williams
• Brian Prall
• Matt Lyerly

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Questions

• How do populations adapt to their niche during
  climate changes?
• What phenotypic changes were found in animals
  that allowed for their population to survive and
  prosper in Ice age conditions?
• How did climate affect the survival of various
  species?

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Definitions

• Refugium-a location of an isolated or relict
  population of a once widespread animal or plant
  species.
• Younger Drias- also known as The Great Freeze
  time from 12,900-11,500 years ago
• Older Drias- 1000 years prior to Younger Drias.

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What causes an Ice Age?

• Milankovitch theory proposes that the process
  is the orbital eccentricity of the earth around
  the sun (Gribbin 1989)
• Other factors such as tectonic movement and ocean
  currents play an effect, but it is not yet
  determined (Hewitt 1994)

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Climax of The Ice Age
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The Polar Front
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Factors of the Ice Age That Enhance Evolution

• Highly selective environments
• Change in overall geographic environments
• Division of existing populations by new
  geographic barriers
• New geographic areas/paths
• Induced founder effect on islands due to change
  in the sea level

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Factors of the Ice Age That Enhance Evolution
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Factors of the Ice Age that Inhibit Evolution

• Short-term/reversible changes in the environment
  may not be enough time for speciation
• Each time the environment reverts from extreme
  cold, selection would lower Ice Age suited
  individuals
• Migrations do not allow for genetic changes to
  accumulate

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Flexible Adaptations and Examples

• Flexible adaptations features that allow for
  individuals to survive in variable or varying
  environments (Lister 2004)
• Can be accomplished through
• Behavioral
• Broad-use adaptations
• Ecophenotypic plasticity (difference in
  phenotypes that are the result of environmental
  characteristics instead of gene expression)

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Ice Age Cod

• Ice Age Circulation Patterns
• Cod habitat range
• Genetic Analyses

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Ice Age Brown Bears
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Ice Age Brown Bears

• Researchers examined a series of
  permafrost-preserved bear bones
• Performed DNA sequencing and Phylogenetic
  Analysis
• Clades in East Beringian brown bears
• Climate Effects

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In-detail Example Red Deer
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In-detail Example Red Deer

• Red deer Cervus elaphus
• Broad-use adapation
• Mesodont teeth
• Allowed for deer to both graze for food from
  grasses/low plants as well as consume soft leaves
  from shrubs
• Behavioral adapation
• Deer will seek food only when available
• Some eat sea-weed (only consumed during low tide)

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In-detail Example Red Deer

• Red deer Cervus elaphus
• Ecophenotypic plasticity
• Changes in the rumen (stomach) are found
• Deer that eat mostly grass have an open rumen
  with small papillae (typical of other grazing
  species)
• Deer that mostly browse on leaves will develop
  large, flat papillae (typical of other browsing
  species)
• Change develops in two to three weeks

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Additional Examples

• Domestic Swine
• If raised at 5oC, the animals develop
  shorter/stockier legs and a thicker coat than
  those swine raised at 30oC
• Mice
• Mice that are raised in colder conditions will
  grow shorter tails, than those in warmer
  conditions, to prevent heatloss and frostbite

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Fitness by Distribution

• Some species increase their success by quickly
  expanding their range as the Ice Age progresses
• Many species also expand southward during an Ice
  Age and Northward during periods of warming
• This tends to create subspecies and less Genetic
  diversity

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In-detail Meadow Grasshopper Chorthippus
parallelus
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Meadow Grasshopper Chorthippus parallelus
Hewitt (1996) Grasshopper movement based on DNA
data
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Chorthippus parallelus

• Durring periods of warming in the last ice age
  many Populations including Chorthippu Parrallalus
  spread through out Europe and Western Russia.
• When the temperature in these areas began to
  fluctuate the species was divided
• Researchers used DNA to track the varying
  sub-species origins.
• The two events of the last ice age that caused
  the greatest population decrease were the Younger
  Dryas 12,800 to 11,500 and Older Dryas 1000 years
  prior.

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Expansion during cooler and warming periods
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Traits allowing for continued survival
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Further Research

• Exploring genetic relationship of birds
• Song cannot be fossilized, nor can coloration
• Determining relationship and survival of reptiles
  during the ice age

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Results

• Some organisms had traits that allowed them to
  survive, while other were not able to
• Populations took advantage of expanding ranges,
  leading to new populations and eventually
  evolution
• Climate change lead to less diversity among
  certain species

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References

• http//www.dodo.blog.br/wp-content/uploads/2007/08
  /ferahgo.jpg
• hepokatti.net/nurmiheinasirkka.jpg
• www.quantum-conservation.org/ESB/Ursus20arct
• Bigg, G., Cunningham, C., Ottersen, G., Pogson,
  G., Wadley, M., Williamson, P. 2008. Ice-age
  survival of Atlantic cod agreement between
  palaeoecology models and genetics. Pro. R. Soc.
  275 163-173.
• Hewitt, G. 1996. Some genetic consequences of ice
  ages, and their role in divergence and
  speciation. Biol. J. Linn. Soc. Lond. 58
  247-276.
• Leonard, J., Wayne, R., Cooper, A. 2000.
  Population genetics of Ice Age brown bears.
  Evolution. 97 1651-1654.
• Lister, A. 2004. The impact of Quaternary Ice
  Ages on Mammalian Evolution. Phil. Trans. R. Soc.
  Lond. 359 221-241.
• ORegan, H. 2008. The Iberian Peninsula
  corridor or cul-de-sac? Mammalian faunal change
  and possible routes of dispersal in the last 2
  million years. Quat. Sci. Rev. 27 2136-2144
• Provan, J., Bennet, K. Phylogeographic insights
  into cryptic glacial refugia. Trends Ecol. Evol.
  23 565-571.