How does gene selection work in honeybees?

September 5, 2013 7:17 AM

This question has several parts, so please bear with me while I suss it all out. I have a specific question about inbreeding, and an open ended one about selecting traits in animals in general and honeybees in specific, though anyone familiar with genetics and animal husbandry can help me here.

First, what exactly is inbreeding? I know what when genetically similar animals create offspring, the result may be inbred. In terms of the genetics of this animal, why is it inbred? Also, how many generations of out-breeding until you get a vigorous animal? I am aware of hybrid vigor, but is this hybrid animal considered a a little inbred? In other words, if I have an inbred queen bee, and she out-crosses with an unrelated drone, are her daughters 'normal' bees, or do I have to out-breed for several generations in order to get back to 'normal' or not inbred?

Next, lets say I want to set up a beeyard in order to select for certain traits. Given that any given Queen bee will mate on the wing (thus you cannot really control the source of the other chromosomes) and given that she will mate with several individuals (thus in any given hive you have a collection of half-sisters and a varied gene-pool) approximately how many hives would I need in order to effectively select for any given trait? Is it even possible to answer this question? Thanks for your help!

posted by TheTingTangTong to Science & Nature (2 answers total)

Inbreeding isn't necessarily bad for a species, though it can often be very bad for individuals. Remember that Evolution is a process that applies to populations, and that it often involves tragedy for individuals.

"inbreeding" means mating with a close relative, who has many genes in common.

how many generations of out-breeding until you get a vigorous animal? Inbreeding can create a vigorous animal. You're making some deep -- and incorrect -- assumptions about it.

If the individual carries a bad recessive gene, then inbreeding has a better chance of expressing it. The assumption is that such an offspring will die. But not all offspring of inbreeding will get the gene, and offspring which don't could be stronger than the parent.

In a lot of species, inbreeding is the norm. For many, many plants self-fertilization is usual, for instance. A flowering tree? Bees buzz from flower to flower on the same tree fertilizing as they go. The only time outbreeding takes place is if there are two or more trees, and a bee moves from one to another, carrying pollen with it. Bees don't usually do that, so outbreeding is actually quite rare.

And even if there are multiple trees! In the wild, when you find several trees of a given type near one another, there's a good chance they're all descended from the same parent tree, so even crossbreeding among them is inbreeding.
posted by Chocolate Pickle at 9:30 AM on September 5, 2013 [2 favorites]

I would expect that bees are particularly unlikely to suffer from small-scale inbreeding, since the drones are haploid. If a recessive gene is particularly disabling, drones carrying that gene will probably not be able to reproduce, so it won't spread in the population. Of course, some such genes could manifest only in workers and queens, in which case inbreeding could still be a problem.
posted by vasi at 9:38 AM on September 5, 2013 [1 favorite]