breeding final exam

inbreeding

inbreeding

mating of relatives more closely related than the average of the population

what is a common misconception about inbreeding

that it creates genetic defects

effects of inbreeding

increase homozygousity, prepotency in inbreds, expression of deleterious recessiveness, inbreeding depression

increase homozygousity in inbreeding

the more common ancestors the more inbred, the closer the commone ancestor is to the individual the more inbred, reffered to ancestor common to parents of inbred individuals

prepotency in inbreds

produce more copies of good genes whose performance is the same as its own or is uniform, decreases heterozygousity, cant produce as many different gametes

expression of deleterious recessiveness in inbreeding

gives inbreeding bad reputation, increases homozygousity so if gene is present its more likely to occur, doesn’t create genetic defects, increases likelihood of deleterious recessiveness alleles becoming homozygous

inbreeding depresssion

reverse of hybrid vigor, poor gene combination value, plateau out then decrease because no more GCV- direct result of increased homozygous, works on fitness traits first

for fitness traits what percent inbreeding will there be

10%

what percent inbreeding will production traits have

20%

increase in inbreeding leads to increase and decrease in what

increase homozygousity and decrease heterozygousity

inbreeding coefficent

measure level of inbreeding in an individual, probability that both genes of a pair in an individual are identical by descent, range 0-100%

what is the inbreeding formula

Fx= ∑ [ (1/2)^n1+n2+1 * (1 + Fca)

what is the relationship coefficent of inbreeding

Rxy= ∑ [ (1/2)^n1+n2 (1 + Fca)] / sqrt(1+Fx) * sqrt (1+Fy)

steps for solving inbreeding coefficent

1. convert the pedigree to arrow diagram where each individual shows up once

2. locate common ancestors for inbreeding they will be to both sire and dam

3. locate inbred CA and calculate the inbreeding coefficent for each CA

4. create the table

5. add together all values in the last column of the table to calculate the Fx or the numerator to Rxy

   1. for Rxy calculation only divide the sum by the sqr(1+Fx)*sqr(1+Fy)

what are three really important aspects in solving for the inbreeding coefficient

you will never go past the sire and dam, never go against the arrow, the arrow diagram will not go through the same individual twice

for projenuy of a sire daughter mating what is the Rxy

25%

what does the relationship coefficient of inbreeding tell us

at any given locus that the individuals are a similar gene

line breeding

mating of individuals with in a particular line, mild inbreeding, maintain a substantial degree of relation to highly regarded ancestor without causing high levels of inbreeding

what are some reasons to inbreed

increase uniformity, creates opportunity for hybrid vigor- inbred line crossed with inbred line

outbreeding or outcrossing

opposite of inbreeding, mate unrelated individuals, more different is more heterozygous, increase heterozygousity, low heritable traits respond better

effects of outbreeding

masks deleterious alleles, hybrid vigor- or heterosis increases GCV and increase fitness traits, breed complementarity

heterosis and hybrid vigor

an increase in the performance of hybrids that of purebred, most noticeably in traits like fertility and survivability

measuring hybrid vigor

difference between average performance of crossbreds and their average performance of their parental lines of breeds

F1 hybrid vigor

the amount of hybrid vigor attainable in first cross individuals aka max hybrid vigor

percent hybrid vigor equation

PF1-Pp/Pp *100

hybrid vigor equation

PF1-Pp

what traits have more HV

low heritable traits

measuring heterosis

matching of unlike genes or measuring the amount of unlikeness

retained hybrid vigor

the HV that will remain in later generations of hybrids

general rules of retained HV

always expressed as proportion of F1 vigor, HV displayed by two breed F1crossesis halved in the corresponding F2’s, mating of F2’s to produce F3’s will not diminish HV because of HWE

difference between what HV and heterosis measures

heterosis measures genes and hybrid vigor measure performance

hybrid vigor estimates

individual or direct component, maternal, paternal

what is the criteria for evaluating crossbreeding systems

merit of component breeds, HV, breed complementarity, consistency of performance, replacement considerations, simplicity, accuracy of genetic predictions

two breed terminal mating system

breeds A and B, projeny 100% HV if possible (all would be sold)

three breed terminal mating system

breeds A, B, and C, sire A on BxC F1 female, females 100% HV if possible, projeny 100% HV if possible to be sold

what is the only crossbreeding system where you will get the maximum HV in females and projeny

three breed terminal mating system

two breed rotational mating system

breeds A and B, projeny 67% HV possible after 7 generations, males sold and females as replacements

three breeed rotational mating system

breeds A, B, and C, projeny 86% HV after 7 generations, males sold and females replace

two breed rotational and terminal

breeds A, B, and C, rotate A and B, projeny 67% Hv after 7 generations, males sold and females replace, terminal C breed with projeny have 100% HV

three breed rotational and terminal

breeds A, B, C, and D, rotate A B and C, projeny will have 86% HV with males sold and females replace, terminal D breed with older females used in unit and porjeny with 100% HV

four breed rotational system

breeds A B C and D, porjeny 93% possible HV

what are the four types of biotechnology

MOET, cloning, sexed semen, split embryos

MOET

multiple ovulation emrbyonic transfer, used to increase number of offspring per female, not genetically identically just full sibs

cloning

somatic tissue is taken from a cow and cells are grown, then transferred to receipents and get exact copies of cloned individual, not used often because expensive

sexed semen

separate sperm cells, not as good conception rates, mainly in dairy industry

split embryo

16 cell embryo into two 8 cell embryos both placed in a recipient, will produce multiple copies of the same cross

what are the three kinds of DNA technology

finger printing, genetic markers, gene transfer

finger printing

occurence of fragment to determine parents

genetic markers

paired genes might have major or minor effects, genes may control a trait or influence genes that do control, profiles created, select and DNA level, polygenic and mutation

marker assisted selection

use genetic markers to select animal for quantitative traits, improve accuracy but not 100%, never select just off this

gene transfer

transfer of one gene to another, multiple copies of a gene transferreed to one of two pro-nuclei of a fertilized egg, if one of the genes becomes integrated into DNA the genes may be influenced on function

what should be used with marker assisted selection

quantitiative measures

what are QTLs

qualtitative traits loci

what is the heterosis level for and A x AB

50%

what is the heterosis for A x B2C1D1

100%

what is the heterosis level for AB x BA

50%

what is the heterosis level for A x B

100%

what is the heterosis level for A x A2B1C1

50%

what is the heterosis level for AB x DE

100%

what does the relationship of inbreeding coefficent tell us

it is the probability at any given locus they share a gene