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chub nest spawners

Started by Guest_FirstChAoS_* , Feb 14 2012 03:56 AM

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#1 Guest_FirstChAoS_*

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Posted 14 February 2012 - 03:56 AM

After finding this lovely picture of colorful shiners spawning on a chub nest

http://www.flickr.co...in/photostream/

I became curious on fish that spawn on chub nests. And noting how one of my local minnows the fallfish makes among the largest nests of minnows I wondered if anything used their nest.

This very informative page on fishes of candas capital region gave an interesting snippet of info on the fallfish

http://www.briancoad...ContentsNCR.htm

Apparently the Common Shiner will not only NEST in fallfish nests, they will also hybridize.

Has anyone seen one of these hybrids?

Do common shiners grow large for shiners as a way to evolve approaching a fallfish nest without being eaten, growing along with their co-nester as they coevolved?

Are the hybrids sterile? I'd almost assume they were as the species haven't intergraded into one.

Do you know how annoying this possibility is when I have trouble identifying silvery minnows under 3 inches as it is?

Exactly what WOULD you call such a hybrid? A fall shiner? a common fish? a commish? I like common fish as it is confusingly nondescript.

#2 Guest_EricaWieser_*

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Posted 14 February 2012 - 09:09 AM

Are the hybrids sterile? I'd almost assume they were as the species haven't intergraded into one.

That's a logical conclusion. But if it's true then that means there are a lot of sterile hybrids swimming around. It's a little scary to think about. You'd see a stream full of fish but if 10%, 20%, or 70% of those fish were sterile, the stream full of fish would be much more empty come next year than it should be. I wonder if the people who classify endangered species think about that.

#3 Guest_fundulus_*

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Posted 14 February 2012 - 09:30 AM

Such hybrids may not be sterile but likely have reduced fitness in subtle ways like not being reproductively competent in the right place at the right time, and other behavioral issues. This has been going on for a long time, so it's not a glaring problem. The lineages involved have pretty well sorted themselves out but obviously it's not a perfect separation.

#4 Michael Wolfe

Board of Directors

North Georgia, Oconee River Drainage

Posted 14 February 2012 - 11:53 AM

It's a little scary to think about. You'd see a stream full of fish but if 10%, 20%, or 70% of those fish were sterile, the stream full of fish would be much more empty come next year than it should be.

Interesting point, but be careful there with the "next year" part of that statement... these fish are not annuals... these are big fish that live for years...

Either write something worth reading or do something worth writing. - Benjamin Franklin

#5 Guest_gerald_*

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Posted 14 February 2012 - 12:23 PM

Apparent hybrids I have caught (probably conceived on chub nests) include:

bluehead chub x white shiner (Wake County NC, Neuse River basin)
rosyside dace x mtn redbelly dace (Allegheny County NC, New-Kanawha River basin)
rosyside dace x greenhead shiner (Catawba County NC, Catawba River basin) - I still have this guy.

#6 Guest_farmertodd_*

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Posted 14 February 2012 - 01:10 PM

Interesting point, but be careful there with the "next year" part of that statement... these fish are not annuals... these are big fish that live for years...

Nor do hybrids ever account, all other things being equal, for more than a fraction of a percent of any population, or would be selected as mates. These spawning congregations look random, but they are far from it once you lay in the water next to one and watch species-specific interactions. The hybrids are the result of chance occurences, there are partitions in timing and behavior that keep the species separate - in particular, the timing of when the females rush in to actually spawn.

In environmental disturbance, however, the frequency rises. And at longer time scales this becomes more apparent (Keck & Near 2009 for example). Still, I have yet to see 10% hybrids of any given population swimming around anywhere, even in some of these so called Lepomis hybrid hot spots.

Todd

#7 Guest_gerald_*

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Posted 14 February 2012 - 05:58 PM

I can think of only one place where hybrid minnows were really abundant, more than 20% of fish. South Stanley Creek in eastern Gaston Co NC, where redlip shiners were introduced into native greenhead shiner habitat. I recall lots of redlips and hybrids, and very few pure-looking greenheads. That was 15 yrs ago. I oughta go back and see whats there now. It was an agricultural watershed beginning to urbanize back then (i was surveying for a new sewerline) so it may now be shiner-less. (Redlips, greenheads and yellowfins are all closely related and I'd guess their hybrids are pretty "fit" and fecund).

Edited by gerald, 14 February 2012 - 06:01 PM.

#8 Guest_blakemarkwell_*

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Posted 14 February 2012 - 06:33 PM

I agree with what is being said, but there is still some funky stuff going on that makes for interesting biology. Look at Chrosomus eos-neogaeus hybridogenic unisexuals that extend across most of the northern U.S. and southern Canada (east of the Rockies). While the diploid hybrids are genuine gynogenetic lineages, there are also triploids that are not (which can sometimes comprise ~50% of unisexual Chrosomus at certain locales). The triploids arise de novo each generation, are typically fertile, and apparently reproduce sexually (not clonally like the unisexual diploid gynogens).

Anybody have any info on Pararhinichthys bowersi? Seeing as how they come from two different genera I can't see how they'd be fertile. I imagine they arise de novo each generation, but I'm still waiting for some literature to pop up on that enigma. I think we need more biologists like Carl Hubbs....

#9 Guest_fundulus_*

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Posted 14 February 2012 - 07:59 PM

Carl Hubbs? We all bow and point!

#10 Guest_farmertodd_*

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Posted 14 February 2012 - 11:32 PM

Introductions of sister species are not all things being equal

Todd

#11 Guest_blakemarkwell_*

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Posted 15 February 2012 - 12:23 AM

Introductions of sister species are not all things being equal

Todd

Yeah, I hope introductions like that are not commonplace. Are those Hydrophlox introductions restricted to the Catawaba, or do I need to worry about them in other places too? I remember hearing about some weird chlorocephalus as well, maybe from the Yadkin? I need to get my head around this stuff because one of my good friends just moved to Chapel Hill, and I need to exploit that this coming spring and summer (luckily, he likes fishes too)!

#12 Guest_farmertodd_*

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Posted 15 February 2012 - 09:07 AM

The Broad is a frickin' mess, which is where the wierd greenhead is at. So yeah, stuff has been moved all around... but I doubt that's cause to not go looking.

#13 Guest_gerald_*

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Posted 15 February 2012 - 10:03 AM

Blake, Are these triploid dace all-females too? If they are reproducing sexually (I assume with diploid males) then why are they "de novo each generation" ? Are their eggs (pre-fert) haploid or diploid?

Look at Chrosomus eos-neogaeus hybridogenic unisexuals that extend across most of the northern U.S. and southern Canada (east of the Rockies). While the diploid hybrids are genuine gynogenetic lineages, there are also triploids that are not (which can sometimes comprise ~50% of unisexual Chrosomus at certain locales). The triploids arise de novo each generation, are typically fertile, and apparently reproduce sexually (not clonally like the unisexual diploid gynogens).

Redlips (N. chiliticus) are native in the Yadkin and introdoced in the Catawba (greenhead native range) and (probably intro) in the New-Kanawha basin. Saffron (rubricroceus) and Tennessee (leuciodus) are introduced in the New-Kanawha and Catawba headwaters. So far I have not seen anything that looks like an obvious Hydrophlox hybrid except for those chili x chloro in the Catawba tribs (Gaston County). You might want to look for possible rubri x chloro and/or leuci x chloro in the Catawba headwaters northwest of Morganton, and possible rubri x chili and/or leuci x chili in the New River. I'm guessing rubri x leuci is less likely since these two spp have a shared native range. I'm not even gonna mention yellowfins (lutipinnis).

#14 Guest_farmertodd_*

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Posted 15 February 2012 - 01:03 PM

That paragraph will be printed and placed in the NC, VA and TN books. Thanks for typing it up Gerald!

Todd

#15 Guest_blakemarkwell_*

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Posted 15 February 2012 - 01:33 PM

Thanks for the indispensible information, Gerlad (why I love this forum). In regards to your questions -- yes, the triploid dace are all females. We've got two amazing things going on here at once, so it can get a little confusing. On one hand, we have all female C. eos-neogaeus diploid hybrids that are gynogenetic; so these all female, diploid gynogentic C. eos-neogaeus will spawn with male C. eos. Now, since they're supposed to be true gynogens, they just use the sperm to activate (and not incorporate) their reproduction, so they can clonally pass on their C. eos-neogaeus diploid genomes to produce identical all female, diploid C. eos-neogaeus. However, that sperm often gets incorporated (snygamy) so you have haploid C. eos sperm fusing with the C. eos-neogaus diploid ova that the females are 'trying' to pass on clonally. This is the only way to get triploids, and it is de novo each generation.

On the other hand, the triploids created from this process can go off to reproduce sexually. The all female, triploid C. eos-eos-neogaus will do two reductional divisions so her eggs have one genome (EEN ----> EE ----> E). So at the end of these reductional divisions, even though the female is a triploid, she is gametically no different than a diploid, bisexual C. eos. These triploid females then mate with male C. eos and the females E meets up with the males haploid sperm (the other E) to restore the diploid condition (EE) -- a normal C. eos (EE); so from this you have triploids (C. eos-eos-neogaues) giving rise to fully normal bisexual and diploid C. eos. Since the all female, gynogenetic hybrids (C. eos-neogaeus) often incorporate genetic matieral from sperm, their reproductive mode might be best termed 'kleptogenesis' instead of 'gynogenesis'. The triploid Ambystoma (mole salamanders) do something very similar -- ocassionally incorpating genetic material. This might be the very reason these evolutionary dead ends (the antithesis of sex) have been around for millions of years.

Edited by blakemarkwell, 15 February 2012 - 01:37 PM.

#16 Guest_fundulus_*

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Posted 15 February 2012 - 01:45 PM

Hey Blake, do you know of any literature on the Chrosomus systems you describe?

#17 Guest_blakemarkwell_*

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Posted 15 February 2012 - 01:52 PM

Yep. This is all coming from the attached paper. The first figure and introduction are especially nice. I just realized I spelled neogaeus three different ways in the above post. Go me!

Attached Files

cyprinidae - chrosomus eos-neogaeus - gynogenesis - goddard 01.pdf 243.59KB 50 downloads

Edited by blakemarkwell, 15 February 2012 - 01:56 PM.

#18 Guest_gerald_*

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Posted 15 February 2012 - 03:07 PM

I had always thought sperm was "wasted" when mating with a gynogenetic female (not that males seem terribly bothered by that), but from what you're saying they actually can pass on some genes. Does this happen in "Amazon" mollies too?

#19 Guest_fundulus_*

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Posted 15 February 2012 - 03:26 PM

The various Amazon mollies vary in similar ways to the dace, which is the fascinating part of the story. But I guess there are only so many ways that gametes can be produced and combined or not combined.

#20 Guest_blakemarkwell_*

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Posted 15 February 2012 - 03:41 PM

Yes, some paternal genomic material ocassionally leaks into the gynogenetic molly lineages, but from what I understand it is quite rare. The Amazon molly appears to be a good gynogen, unlike Chrosomus eos-neogaeus and some of the unisexual triploid Ambystoma that can have a comparatively high rate of sperm incorporation. It seems almost all gynogenetic lineages have some level of sperm incorporation, probably because the egg requires a physial poking/pricking by a sperm in order to begin dividing. The Chrosomus example is just too cool because it invovles gynogenesis, kleptogenesis, and hybridogenesis.

If you, or anyone else is interested in this stuff, John Advise's Clonality: The Genetics, Ecology, and Evolution of Sexual Abstinence in Vertebrate Animals has been a good introduction and really helped answer a lot of my questions.