Understanding Inbreeding and Outcrossing Depression: Breeding and Genetics Part 2

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Greetings! This video follows up on the first genetics video (primarily on Mendelian genetics) and describes the dynamics of population genetics and how inbreeding and outbreeding depression can come into a population. This is especially important when trying to fix "type" in a livestock line, since it is far more difficult to breed for polygenic traits than simple Mendelian ones. The upcoming third video will begin to describe specific patterns of breeding, and how they relate to all of the concepts laid out in the first two videos of this series!
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Citations on the example of sheep genetic introgression:
Cao, Y. H., Xu, S. S., Shen, M., Chen, Z. H., Gao, L., Lv, F. H., ... & Li, M. H. (2021). Historical introgression from wild relatives enhanced climatic adaptation and resistance to pneumonia in sheep. Molecular Biology and Evolution, 38(3), 838-855.
Chen, Z. H., Xu, Y. X., Xie, X. L., Wang, D. F., Aguilar-Gómez, D., Liu, G. J., ... & Li, M. H. (2021). Whole-genome sequence analysis unveils different origins of European and Asiatic mouflon and domestication-related genes in sheep. Communications biology, 4(1), 1307.
Hu, X. J., Yang, J., Xie, X. L., Lv, F. H., Cao, Y. H., Li, W. R., ... & Li, M. H. (2019). The genome landscape of Tibetan sheep reveals adaptive introgression from argali and the history of early human settlements on the Qinghai-Tibetan Plateau. Molecular biology and evolution, 36(2), 283-303.
Zhao, Y. X., Yang, J., Lv, F. H., Hu, X. J., Xie, X. L., Zhang, M., ... & Li, M. H. (2017). Genomic reconstruction of the history of native sheep reveals the pepollygeneticopling patterns of nomads and the expansion of early pastoralism in East Asia. Molecular Biology and Evolution, 34(9), 2380-2395.
0:00 Why we need population genetics
5:04 Population genetics overview
12:55 Founder effect
20:03 Balance and nuance!
21:33 Understanding inbreeding
27:20 The 50:500 rule (of thumb)
30:45 Effective population
39:09 ...When there is relatedness....
48:13 Outcrossing
58:20 Outcross depresion

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Опубликовано:

3 авг 2024

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Комментарии : 9

@pseudopetrus 8 месяцев назад

Some good concepts here

@VonGontaHaus Год назад

Good content

@oldwaysrisingfarm Год назад

Thank you so much, glad it was useful for you!

@critthepoet9160 6 месяцев назад

😊

@user-yz6tu6ft7q 5 месяцев назад

Good video, lots of great and very useful information in here. Although, the idea that genetic drift is a "code word" for inbreeding is incorrect. While both processes can affect allele frequencies and genetic diversity, they are different mechanisms. Inbreeding specifically involves the breeding of genetically similar individuals, while genetic drift is about random changes in allele frequencies that can occur in any mating pattern. I am assuming you know this but you did say it in the video maybe just to make a certain point and I just wanted to add this detail. Also, inbreeding depression can occur without a significant loss of genetic diversity despit what you say in your video. It is the reduced fitness or performance that often accompanies inbreeding or random genetic drift, and it can result from the expression of deleterious recessive alleles due to increased homozygosity, rather than a substantial loss of genetic diversity.

@oldwaysrisingfarm 5 месяцев назад

Of course you are quite correct, these are the dangers of trying to simplify so much into so little time. Thanks for the kind comment!

@drtootsi Год назад

Have you heard what Allen Williams says about artificial insemination? In a recent webinar he said that after doing AI and studying it on the highest academic level for many years he would always prefer natural copulation because of the many experienced drawbacks otherwise. Your thoughts on that? Also, have you heard of mob breeding? I'd like to get your take on that as well :)

@oldwaysrisingfarm Год назад

Well, I don't know Allen Williams (any public lectures available to look him up?) but I have mixed feelings on AI. When used properly it has the potential to allow for crosses that no other agriculture process does. But when used incorrectly it has the potential to crush genetic diversity faster than any other process as well. like any technology it is a "double edged sword." My opinion of it, like my opinion of most technologies, is that we need to seek balance--use it occasionally where it can really help and keep enough males in our herds/flocks for routine breeding. It is a both/and situation, not an either/or. Now, mob breeding--you are referencing the practice of creating multiple male herds that develop natural herd structures, yes? I will be discussing that at length in the next breeding/genetics video! If you want a spoiler, look up the ancient white park cattle and the research that has been done on them in England. It is a breeding method that for sure works and has a place...as long as you can meet the 50/500 rule requirements, so it is not for small holdings. In short, all breeding methods work in SOME situation...the real task is to understand them all well enough that you can make a nuanced decision as to what method is most appropriate for your farm and goals for it! Anybody who comes at this preaching "this thing over here is the only thing" or "that thing over there never works" is way off from the get go.

@oldwaysrisingfarm Год назад

Hello! My third video in this series which talks about mob breeding specifically is up, in case you are interested!