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Characteristics of Ice Age evolution and adaptations. Matt Williams Brian Prall Matt Lyerly. Questions. How do populations adapt to their niche during climate changes?
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Characteristics of Ice Age evolution and adaptations Matt Williams Brian Prall Matt Lyerly
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?
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.
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)
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
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
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)
Ice Age Cod • Ice Age Circulation Patterns • Cod habitat range • Genetic Analyses
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
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)
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
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
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
Meadow Grasshopper Chorthippus parallelus Hewitt (1996) – Grasshopper movement based on DNA data
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.
Further Research • Exploring genetic relationship of birds • Song cannot be fossilized, nor can coloration • Determining relationship and survival of reptiles during the ice age
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
References • http://www.dodo.blog.br/wp-content/uploads/2007/08/ferahgo.jpg • hepokatti.net/nurmiheinasirkka.jpg • www.quantum-conservation.org/ESB/Ursus%20arct • 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. • O’Regan, 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.