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Animal Breeding Reviewer Cheat Sheet (DRAFT) by

Notes for Animal Breeding (ANSC 103)!

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Animal Genetics

study of principles of inheri­tance in animals

Animal Breeding

applic­ation of principles of animal genetics with the goal of improv­ement of animals

3 AREAS IN THE STUDY AND APP'N OF ANIMAL GENETICS

Mendelian Genetics
from Gregor Johann Mendel (1822–­1884), an Austrian monk, experi­menting on common garden pea
 
1865 – Laws of Partic­ulate Inheri­tance (disse­rta­tion)
describing the principles of transm­ission of genetic material from one generation to the next
 
1900 – redisc­overy of Mendel's law
Carl Correns (1864–­1933), Hugo de Vries (1948–­1935), Erich Tschermak
 
1901 – William Bateson (1861–­1926), British geneticist
produced the first evidence of inheri­tance with experi­ments with chickens
  
coinci­den­tally, provided the classical definition of genetics as a field of study, i.e. as a science dealing with heredity and variation seeking to discover laws governing simila­rities and differ­ences in indivi­duals related by descent
  
leading promoter of Mendelian genetics vs Biomet­ricians (biolo­gical mathem­ati­cians) in the first two decades of the 20th century
  
coined technical terms such as homozy­gote, hetero­zygote, allelo­morph
 
1906 – Willhelm Johanssen (1857–­1927), Danish botanist
introduced the terms gene, genotype, and phenotype
Population Genetics
study of Mendelian genetics in popula­tions of plants and animals
 
basic founda­tion: Hardy-­Wei­nberg Law
1908 – Godfrey Harold Hardy (1877–­1947), English mathem­atician
  
Willhelm Weinberg (1862–­1937), German physician
 
usually limited to the inheri­tance of qualit­ative characters which are influenced by only a small number of (major) genes
 
study why charac­ter­istics become fixed or continue to exhibit variation in natural popula­tions
import­ance: design of selection strategies to increase frequency of desirable genes or examples:
  
Meishan pigs for prolif­icacy – around 12 offspring
  
dwarf gene in poultry
  
Booroola gene in sheep for multiple births
  
double muscling gene in Pietrain pigs and Belgian blue cattle
Quanti­tative Genetics
concep­tually the most difficult of the three areas
 
hypoth­esis: many genes contribute to expression of traits
 
effects of individual genes can seldom be seen or measured, e.g. milk yield, growth rate, litter size
 
compli­cations due to random influence of the enviro­nment and other non-ge­netic factors mask the combined effects of many genes influe­ncing the trait
 
quanti­tative genetics is the most important of the three areas because:
response to selection for quanti­tative traits generally has much more potential monetary value than those for simply­-in­herited traits
 
Ronald Aylmer Fisher (1890–­1962), British statis­tician and geneti­cist, and Sewall Green Wright (1889–­1988), American geneticist
reconciled Mendelians and biomet­ricians
 
Mendelian results: in terms of freque­ncies of genotypes and phenotypes
 
biomet­ricians results: in terms of correl­ations and regres­sions (before rediscover of Mendel's laws)
e.e. Francis Galton (1822–­1911), Karl Pearson (1857–­1936)
  
Fischer and Wright: demons­trated that Mendelian freque­ncies were the basis of biomet­rical correl­ations

HISTORY OF ANIMAL BREEDING

started before recorded history with domest­ication of animals
some cases accidental
 
intent­ional selection for more friendly and tractable animals
dogs (12,000 years ago)
 
foundation for progress in selection for quanti­tative traits
record of perfor­mance (ROP)
 
reliable identi­fic­ation system
FATHER OF ANIMAL BREEDING
Sir Robert Bakewell (18th century, 1725–1795)
Shire horses, Old Longhorn cattle, Leicester sheep
  
"like begets like" – superior parents are more likely to produce superior progeny than are inferior parents
therefore, "­breed the best to the best!"

HISTORY OF ANIMAL BREEDING

started before recorded history with domest­ication of animals
some cases accidental
 
intent­ional selection for more friendly and tractable animals
dogs (12,000 years ago)
 
foundation for progress in selection for quanti­tative traits
record of perfor­mance (ROP)
 
reliable identi­fic­ation system
FATHER OF ANIMAL BREEDING
Sir Robert Bakewell (18th century, 1725–1795)
Shire horses, Old Longhorn cattle, Leicester sheep
  
"like begets like" – superior parents are more likely to produce superior progeny than are inferior parents
therefore, "­breed the best to the best!"