I need support for calculation of covariance for half-siblings and full-siblings in a line x tester mating design applied to replicated multi-environment trial (MET) data for self-pollinated crops.
Specifically, I am interested in finding formulas or a step-by-step approach to compute the covariance between:
- Half-siblings
- Full-siblings
Additionally, I would appreciate any recommendations for relevant manuscripts that could provide further support and details on this topic.
Thank you for your time and assistance.
Sincerely,
Adane
First, full-siblings share both parents, but half-siblings share only one parent.
Second, σ2A = additive genetic variance, σ2D = dominance genetic variance, and σ2E = environmental variance.
Third, half-siblings share one parent, so their covariance is based on half the additive genetic variance. Cov 𝐻𝑆 = 1/4 𝜎2𝐴. For full-siblings sharing both parents, their covariance includes additive and dominance genetic variance.
Cov 𝐹𝑆 = 1/2 𝜎2A + 1/4 𝜎2D.
The total phenotypic variance can be expressed as:
𝜎2𝑃 = 𝜎2A+𝜎2D +𝜎2E
Look at the slide 37: https://www.zoology.ubc.ca/~whitlock/bio434/overheads/09_Quantitative_genetics.pdf
Thank you Nicole Frantavá for interesting response and reading material you shared.
How can I compute the half and full sib covariances from ANOVA of the line x tester analysis for multi-location experiment? How could I incorporate the location effect while computing the above covariances?
Is there anyone who could share a published journal in this regard for MET data? I have too much journals for single environment.
Thank you for your time and understanding.
Adane
You will run an ANOVA for your line x tester experiment. This will help you break down the total variation in your data into components due to lines, testers, their interaction, and location.
More info for your example: https://iastate.pressbooks.pub/quantitativegenetics/chapter/estimates-of-variance/
Thank you @ Nicole Frantva for kind assistance and sharing the book.
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