Here you go on hybrids and fertility.
Dave Willis
Lunker
Member # 267
Member Rated:
posted November 08, 2005 11:18 PMNovember 08, 2005 11:18 PM
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Ewest -- thanks ever so much for pointing me back to this thread. It's been a little hectic lately (i.e., pheasant season and guests). :-) I honestly have little background in genetics, and so am learning here, rather than being able to contribute. As Bruce said, I might be able to track down a little background on this sunfish chromosome number from one of our famous fish geneticists. No promises, though!
I am uncertain about some of the other hybrids mentioned. For example, we know that saugeyes can produce an F2 generation, and can also backcross with both parental species. However, I don't think we know if that's true for both crosses (e.g., male sauger or female sauger used). Similarly, I've always believed that HSB simply have a functional sterility (eggs are too heavy to act like striped bass egss, and too light and not sufficiently sticky to act like white bass eggs). However, they can backcross with the parent species. Again, I wonder if we know if that is true for both "directions" of crosses.
This long-hair stuff is good.
Actually masterbasser, it's even worse than the state biologist told you. Hybrid striped bass are "functionally" sterile. The 1:200,000 probably applies to hybrids spawning with hybrids. However, the males of both species commonly run with either striped bass or white bass, and they certainly can produce a back-crossed generation with either. For example, hybrid males running with striped bass females will produce offspring that are 3/4 striper and 1/4 white bass genes.
The "functional" sterility comes from the difference in egg types for the two parentals. Striped bass have eggs that are nearly neutral buoyancy, and along the east coast they spawn in rivers that carry the eggs while they develop and hatch. If the eggs settle to the bottom, they typically smother and die in the organic/silt layer on the river bottom. Eggs need some oxygen, which crosses the membrane. White bass have heavy, sticky eggs. In rivers, they spawn on gravel riffles. The sticky, heavy eggs attach to the bottom and the current keeps them clean and oxygenated. Hybrid striped bass eggs are halfway in-between. They are too heavy to float with the striped bass eggs, settle to the bottom, and generally die. They are too light and not sticky enough to stay on the gravel if spawned in a riffle. They wash off, into a pool below, settle on the organic mud that usually has low or no dissolved oxygen, and die.
http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=256137#Post256137http://forums.pondboss.com/ubbthreads.ph...=true#Post84636
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