Heterosis Genotype x Environment Interaction. Two General Methods of Assortative Matings / Breeding. 1. Close breeding, Inbreeding mating of two related individuals 2. Outbreeding * mating of unrelated individuals . * Today’s topic. Outbreeding Three categories:
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Two General Methods of Assortative Matings / Breeding
1. Close breeding, Inbreeding
mating of two related individuals
2. Outbreeding *
mating of unrelated individuals
LineCrossing - mating of unrelated animals within the same breed or 2 lines within the same breed. aka . Outcrossing
BreedCrossing - Mating of animals from different breeds aka . Crossbreeding
SpeciesCrossing - Breeding of different animal species e.g. dog and wolf
Phenotypic Effect of Outbreeding
progeny* usually but not always perform > than the parents.
Performance = hybrid vigor ; measurement = heterosis.
* Progeny could perform worse than the parents
Example Calculation of Heterosis
Lamb weaning weight
Purebred Hampshire mean = 58.3 lb
Suffolk = 73.3 lb
Mean of the 2 purebreds = 65.8 lb
Hampshire - Suffolk hybrid mean = 72.5 lb
heterosis = (mean of hybrids - mean of parents) x 100 mean of parents
= 72.5-65.8 x 100 = 10.2 % 65.8
Individual + Maternal
((AxB) x C)
Genotype-Environment (GxE) Interaction
GxE = a situation where the same genotype responds differently in dissimilar environments
-different phenotypic responses
- animal’s management protocol; - endemic pathogens (bacteria, viruses, mycoplasmas); - climate (temp., humidity, day-length; dist. to the ocean, etc.); - altitude, geography, etc.
Types of GxE Interaction
Example of GxE, Performance of Cattle in a Hot Environment
In which environment do youconduct genetic selection to improve the desired phenotypic trait?
(Examples - environment for disease resist., contaminated vs aseptic environment
- breed in Corvallis for an animal destined for E. OR)