mating systems Flashcards
reasons for choosing mating system
1 increase genetic gain
2 make use of complimentarity
3 heterosis
prerequisite for choosing mating combination system
traits of interest
inheritance pattern
**expression pattern
**parental genotype
random mating
panmixia
each individual has equal chnce to mate the other individual
non random mating
decided by breeder
based on ARTIFICIAL SELECTION
RANDOM MATING
selected at random
when no genetic records available
easy
non randing mating
2 types
- based on genotypic resemblance
* based on phenotypic resemblance
phenotypic resemblance mating 2 types
positive assortative mating
negative assortative mating
positive assortative mating
phenotypically similiar individuals mate together
- *more variation
- *more homozygosity
outbreeding
- unrelated individuals
- *increase heterozygosity
- *increase variability
different types of inbreeding
- *close inbreeding
- *line inbreeding
- *strain formation
- *pure breeding
close inbreeeding?
- *mating btw siblings
- *mating btw progeny parent
- it is for increasing homozygosity
- *undesirable genes are found out
most common method of close inbreeding is
**full sib followed by backcross followed by half sib mating
line breeding
- mating btw cousins
* *maintaining a connection with outstanding ancestor while keeping inbreeding low
strain formation
a population is mated for 3 to 5 generations
**without entry of any other one
inbred line?
***after 2 generation of full sib mating,
inbreeding coefficient becomes 0.375,it is called inbred line
pure breeding
- *mating btw purebreds of the same breeds
- -planned matings practised to lower the level of inbreeding
uses of inbreeding
- *inbred lines
- *genetic worth calculation
- *recessive gene elimination
- *form distinct lines from breeding stock
prepotency
inbreeding increases prepotency
that is ablity to
**produce offsprings with uniform performance without variation
inbreeding depression
- *decrease in inbred performance
* *low heritability traits are affected
**1%increase in inbreeding
0.14%reduction in mean value of trait
introgression or repeated backcrossing
**incorporate an allele to another population
**initial crossing and successive backcrossing
grading up or topcrossing
- **to create a purebred population
- *non purebred females X purebred sires
- ***no selection involved
- **repeated backcrossing involved
