ANSC 313 Lecture Notes - Lecture 26: Naked Neck, Heterosis, Genetic Distance
LECTURE 20!
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genetic diversity!
4000- 5000 domestic breeds remain!•
+ 40 species !•
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initial genetic diversity!
selection of numerous breeds based in various traits!•
color!◦
size !◦
wool type!◦
carcass quality!◦
disease resistance!◦
selection has changed the phenotype quit dramatically from the ancestor that was first •
domesticated !
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loss of genetic diversity!
less variability!•
less options to respond to:!•
economic opportunities!◦
environmental issues!◦
food security!◦
biosecurity !◦
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reasons to conserve rare breeds!
to save potentially useful genes!•
naked neck chicken!◦
hot climates!‣
texas longhorns!◦
for a time, used on heifers for calving ease !‣
gave tiny calves!‣
food security!•
heterosis!•
to overcome selection plateaus!•
insurance policy!•
environmental changes!◦
social changes (animal wellfare)!◦
cultural!•
larger immigrant population!◦
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how to conserve?!
live animals!•
cryopreservation!•
sperm, eggs, embryos!◦
cells- cloning!•
DNA!•
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conserve which animals?!
genetic distance to other species!•
value or potential value!•
