Outbreeding Depression

L

Lekhaka

Registered Member
What are the best examples of outbreeding depression that is caused by incompatible biochemical or physiological systems caused by the hybrid genes as opposed to having an intermediate trait that is not beneficial due to lack of specialization?

Real examples are a priority of course, but speculative examples would be interesting as well.
 
Nope, fiction writing actually.

I try to make my speculative evolution as plausible as possible.
 
Intercrossing of French and Turkish storks. Both migrate, but the F1 hybrids chose an intermediate path and concluded migration over the sea.

Edit: not actually over the sea. Just a bad nesting area in central North Africa, I think. Can't remember.
 
Thank you for the link, GeoffP.

I have a couple of related, perhaps more specific, questions:

1. What are some notable cases of deformity in hybrids?

2. And also so far I have read that in the speciation process, hybrids first become all sterile before becoming inviable. Haldane's Rule observes that the heterogametic sex is usually the first to become sterile or inviable, if it is preferential at all. I wonder just how different two hybrid sexes could become (in terms of fertility and viability). One of the first sites I found on Google shows first the heterogametic sex becoming sterile, then all hybrids being sterile, then all hybrids being inviable (as incremental stages of speciation).

Then is it possible to have a stage where one sex is inviable while the other is sterile, or where one sex is inviable and the other is fertile? Are there any documented cases of these? Are they theoretically possible?
 
As far as deformity goes, that's relatively rare for hybrids. Hybrids actually tend to have trait advantages, usually ascribed to elimination of residual or general inbreeding ('heterosis'/'hybrid advantage') (check out Lerner 1977 for a review); larger size, for one. But their problem is as you say - inviability among some hybrids depending on genetic distance between the progenitors.

As for your specific question on stages where one sex is viable/sterile and the other not....yeeeees, I think so. Some species of snails do this, as I very vaguely recall. There's also a Rana (frog) complex that does this; a Baltic case of two species introgressing. I would argue a fourth stage, naturally: where hybrids of one sex is less fit than the other. This would probably occur in any case where, say, female phenotype is adapted to local environment while males roam, experiencing environment as fine-scale. I think this goes on in salmonids, and I'm sure I recall an article about female trout intraspecific hybrids having poor survivorship compared to male hybrids. Danish group as I recall. Anyway, it's definitely possible if you had Y genes (Z in ZW systems) that were incompatible with the autosomal (or sex chromosomal) genome of the other parent.
 
Mod note: Quotation from a post that was moved here.

I breed Serval cats, i also cross them with tabby cats, which creates a new hybrid species called the savannah cat.
male savannah cats f1-f4 cannot re produce what so ever, this is the case with almost all animal hybrids, including horse / zebra mixes, and my personal fav, the wolphin, a dolphin killer whale mix
Click to expand...

Yes, I think it is generally known that interspecific hybrids can be sterile, since this is the semi-circular consequence from the definition of species... but what I asked was about differences in the viability/fertility of different sexes of the same hybrid type.

Maybe I didn't phrase my specific question too well, so let me try again:

When one sex of hybrid is inviable while the other is viable (as frequently observed with Haldane's Rule), would the viable sex be sterile or fertile? I suspect that both cases are possible, though sterility would be more likely, since genetic distance is already great enough to make the other sex inviable. But that's what I asked for help with: known cases or theories on the subject to support or oppose my conjecture.

In short, how scientifically plausible are these cases?
1. In a hybrid, one sex is inviable while the other is viable but sterile
2. In a hybrid, one sex is inviable while the other is both viable and fertile
 
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Very plausible. Y-autosomal cross-species incompatibility. Why don't you do a search on Web of Science?
 
Forget WoS, you likely don't have a subscription. Just google those terms and see what comes up. There's a few high-end free genetics journals also, and you might get lucky.
 
Mod note: TheTruth101’s posts, and associated replies, have been moved to another thread here. This thread can now return to the discussion that was intended.
 
I think you're right about the first point.

Silence of the Lambs was a monstrous misrepresentation of biology. Liver simply does not go with Chianti.
 
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