Lecture 14 - BIO220

Cultivated and they were clonally propagated 35z 36 6

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Unformatted text preview: nialist policies contributed and exacerbated the disaster • Lumper variety: • Large yield, lots of carbohydrates, and lots of calories • Some reports suggest an Irish person ate an average 2 3 kg of potatoes per day • The potato was the sole food source for ~1/3 of the Irish population – Topics for history, sociology, religion, and political science classes – Here our focus is on the biological mechanisms • Only 1 3 genotypes of potato were cultivated, and they were clonally propagated 35z 36 6 04/03/2013 Yields, Monocultures, Polycultures Potato yield (x 1000 tons) Enter Phytophthora infestans, potato blight • An Oomycete – Fungus like eukaryotes, but distinct from Fungi – Can disperse by spores in the wind First year of blight • Nearly a monoculture •1 3 genotypes • Clonal propagation ensures no mixing of genetic variation Year Superior Alternative • Potato yields fell dramatically Genetically – Potatoes rot in the ground – Starvation and disease ensued • Upon pathogen attack: • Natural & artificial selection are impotent without genetic variation • No improved resistance possible • Remains a cautionary tale to this day about the risk of monocultures that lack genetic variation 37 38 -The fungi was able to kill potatoes bc there is no genetic v ariation -Natural and Artificial selection cannot help us in this c ircumstance! -There is no genetic variation there for these forces to act o n! General Implications • Societal: -Failure to apply general principles of Mendelian genetics and Dar winian e volution can have profound social and human health effects -Ignoring evolution because it is "inconvenient" can have affects on: agriculture, medicine, etc. • Biological: -We can use evolutionary genetic principles to… -Discover regions of the genome under past artific. select. -Improve future agricultural crops -Design sensible plating schemes to reduce risks of MONOCULTURE devastation 39 7...
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This document was uploaded on 01/27/2014.

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