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Known Pumpkinseed Hybrids

Started by Guest_centrarchid_* , Jul 08 2008 02:48 PM

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#1 Guest_centrarchid_*

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Posted 08 July 2008 - 02:48 PM

For those interested or not inclined to accept the existance of hybrids.

My student, while trying to build a photography tank made these images of hybrids involving a female pumpkinseed sunfish. Fish are half-siblings (dam / mother) generated from the same batch of eggs.

All specimans photographed are male. Interesting that some characters of pumpkinseed are obvious in some crosses but not others. Still trying to standardize background and lighting. Hybrid with redear typical in that head profile more similar to redear even among large animals. In contrast with allotetraploid version of pumpkinseed x redear (shown in earlier thread), the diploid shown here does acquire ther black ventral coloration of redear when on the nest.

x northern bluegill

Pumpkinseed_x_Bluegill_1_Male.JPG 516.67KB 21 downloads
x central longear

Pumpkinseed_x_Central_Longear_male.JPG 448.99KB 14 downloads
x redear

Pumpkinseed_x_Redear_male.JPG 506.36KB 15 downloads
x green sunfish

Pumpkinseed_x_Green_Sunfish_male.JPG 589.94KB 11 downloads
x redspotted sunfish

Pumpkinseed_x_Redspotted_male.JPG 487.85KB 11 downloads

Attached Files

Pumpkinseed_x_Green_Sunfish_male.JPG 589.94KB 7 downloads

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#2 Guest_Gambusia_*

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Posted 08 July 2008 - 09:00 PM

Are these artificially spawned crosses?

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#3 Guest_sandtiger_*

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Posted 08 July 2008 - 09:17 PM

Interesting stuff, though those pictures put a hurtin on my dial up connection.

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#4 Guest_centrarchid_*

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Posted 08 July 2008 - 09:17 PM

Are these artificially spawned crosses?

Yes, we squeezed out the eggs and placed them into six dishes before each dish had semen added from bluegill, central longear, greensunfish, redear, redspotted orwarmouth sunfishes. Products were incubated separately until they were large enough to fin clip. Fin clips thought needed only for warmouth and green hybrids thinking they might be hard to distinguish but results were easy to tell apart.

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#5 Guest_fundulus_*

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Posted 08 July 2008 - 09:27 PM

Sure, hybrids exist in nature. It's a question of how important or common (or viable/fit) they are outside of specific transition zones for some species. There's also a large amount of variation in natural populations, and these are not nearly always the same phenomena. Therein lies the rub, to coin a phrase.

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#6 Guest_Gambusia_*

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Posted 08 July 2008 - 09:30 PM

Interesting

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#7 Guest_centrarchid_*

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Posted 08 July 2008 - 10:09 PM

Most of my hybrids do not appear to be important. Some do not occur because presently parental species do not have overlapping ranges, one or both genders are sterile (usually male is sterile) or resultant offspring of some are triploid and unlike some similarly derived triploid minnows, the triploid sunfish are sterile. Two of the hybrids could potentially be important are those involving redear and the redspotted. The both exhibit 50:50 sex ratios and the former is demonstrated to be very fertile and readily backcrosses with redear. The former I suspect could play a role in the interactions between pumpkinseed and redear where the latter is being moved about by pond manager stocking.

I am running a medium term experiment at this time looking at redear and pumpkinseed in a quarry without other sunfishes except warmouth which is to serve as the predator. So far the redear have spawned as a tight group on one side of the quarry in relatively deep water while the pumpkinseed disperse their nest (~ 30' apart) in much shallower water on the opposite side. Next year when the breeding sites become saturated and prey becomes limiting it will be interesting to see how nest sites are divied up and who shifts into the zooplankton specialist feeding guild or is eliminated. So far I have not been able to get these two species to cross voluntarily even when no other options available. Cuckholders were not involved at that time but in the years to come they likley will be. Will the cuckholders blurr the species lines or will intergrety be maintained.

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#8 Guest_Irate Mormon_*

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Posted 08 July 2008 - 10:46 PM

The question, as Bruce said, is not whether hybrids exist, but whether the frequency of CLAIMS of hybrids coincides with the actual frequency of their existence. One would think our lakes and streams were chock full of the things, going by the talk one hears.

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#9 Guest_centrarchid_*

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Posted 08 July 2008 - 11:07 PM

The question, as Bruce said, is not whether hybrids exist, but whether the frequency of CLAIMS of hybrids coincides with the actual frequency of their existence. One would think our lakes and streams were chock full of the things, going by the talk one hears.

I think I understand the point being made which did not jive with my points.

What I have seen is that hybrids of natural origin (human interventtion not direct) are not rare between some species and human mediated environmental changes often not needed for their formation, plus they are not the end of the world but a natural probability when complete isolation mechanisms have not had time to develop. The claims simply need to be substantiated better, otherwise they are just claims that are like "crying wolf" which can be problem if the wolves are in fact taking out your stock but you fail to provide adequate evidence to rule out typically more accepted dogs (domesticated wolves) or coyotes.

This is where the availability of knowns can be helpful for morphology at least. If putative hybrids (based on morphology) identified, then if considered worth effort, more definitive genetic analysis can be used.

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#10 Guest_farmertodd_*

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Posted 08 July 2008 - 11:31 PM

One would think our lakes and streams were chock full of the things, going by the talk one hears.

Again, you have no record of the "misses" that were NOT hybrids, that were never photographed, documented or asked about. You only have record of the "hits" where someone saw something different, which precipitated taking a picture, asking about it, and amounts to what...? Maybe 100 different individuals brought to our attention over the full term of this website? (I think that's a generous number)

I can tell you that I identified 10, maybe 20 times the "Forum Hybrid Frequency" (now known as FHF

) as true species in May 2008 alone. That was a single person's foray, and one that sadly wasn't in the field that often during that month. I also only found a single individual that was definately a green x bluegill hybrid, and that was in a very anthropogenically disturbed riverine area. Now we're at 1 in 1000-2000, with my locations during that month favoring severely disturbed, seasonally-lotic habitats.

You're drawing a spurious conclusion that the frequency of posts about hybrids on the NANFA Forum is representative of some sort of normal distribution in the wild.

Todd

Edited by farmertodd, 08 July 2008 - 11:34 PM.

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#11 Guest_centrarchid_*

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Posted 09 July 2008 - 06:30 AM

[/quote]

[quote name='farmertodd' post='41264' date='Jul 9 2008, 04:31 AM']Now we're at 1 in 1000-2000, with my locations during that month favoring severely disturbed, seasonally-lotic habitats.

You're drawing a spurious conclusion that the frequency of posts about hybrids on the NANFA Forum is representative of some sort of normal distribution in the wild.

Todd[/quote]

My experience largely with the sunfishes but as I understand minnows and their breeding habits, same is likely true for those as well.

1 in 1000-2000 is not rare, just infrequent when this number of individuals can be encountered in just acouple hours at many locations. My brain quickly picks out those unusual individuals and over processes. Aids in detection / use of potential new resources. Also when someone encounters something they were previously not familiar with, the "chimera thing" of combining similar knowns (parental species) is a simple short term way to make sense of world. This is how my brain works and may explain the over repressentation. Also few report on what they are confident about hence the misses not apt to be recorded.

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#12 Guest_farmertodd_*

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Posted 09 July 2008 - 09:12 AM

My experience largely with the sunfishes but as I understand minnows and their breeding habits, same is likely true for those as well.

We don't find many minnows here that suggest hybridization. But when I get into the Central Highlands diversity that's spawning on chub nests, the frequency is apparent. I've got video of a beautiful Nocomis x Luxilus from MO last year. I need to rip that up to the web.

Todd

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#13 Guest_centrarchid_*

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Posted 09 July 2008 - 09:41 AM

We don't find many minnows here that suggest hybridization. But when I get into the Central Highlands diversity that's spawning on chub nests, the frequency is apparent. I've got video of a beautiful Nocomis x Luxilus from MO last year. I need to rip that up to the web.

Todd

Correct me if I am wrong, but some hybrids produced over chub nest are frequent enough that on ocassion they were described as a species. The similar situations promoted by cuckholders among the sunfishes maybe as important as turbidity in densely packed multi-species breeding colonies. How picky are sneakers when they burst in and deposit a blast of sperm? Central longear sneakers seem to have a problem getting over the nest bowl when they seem concerned about attacks from nesting males and roving spotted bass.

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#14 Guest_farmertodd_*

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Posted 09 July 2008 - 10:49 AM

Correct me if I am wrong, but some hybrids produced over chub nest are frequent enough that on ocassion they were described as a species.

I would believe it. I have seen enough variation in conditions and community to support it beyond local variation (this is local varience, not regional varience) and continually to find individuals maintaining both parent species characteristics (and not just color patterns).

Temperature would be the hypothetical partition for the nest parastitizing minnow species, but after sticking my head into some of these congregations and watching what I saw in my own tank this spring, it's impossible for that to work all the time, esp when non-ideal conditions (such as a huge storm) prevent spawning at "the right time". They're still going to spawn and that might be the heterogenity in environmental conditions that produce the hybrids.

I've also seen enough under the water of centrarchid nest colonies in lotic systems that the probability of stray gametes is high. The partition was of space, perhaps by depth or substrate, where cyanellus have the marginalized nesting area, but the water still connects. Go figure who you continually see in the usual suspect matrix of hybrids.

And then there's that whole sneaker thing shooting sperm everywhere. Again, you have mobilization in a stream. In a eutrophied lake or pond, yeah, there's all sorts of stuff that will eat it before it gets anywhere. But in super low productivity stream (like a highland, spring fed stream in MO or NC), those gametes hypothetically will persist long enough to get to the next nest.

Todd

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#15 Guest_fundulus_*

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Posted 09 July 2008 - 11:20 AM

These hybrids may be produced, but how fit are these hybrids or their descendants? This kind of gene exchange may have minimal long term impact. That's my whole schtick, otherwise we're back the "species have no meaning" scenario.

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#16 Guest_centrarchid_*

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Posted 09 July 2008 - 11:50 AM

These hybrids may be produced, but how fit are these hybrids or their descendants? This kind of gene exchange may have minimal long term impact. That's my whole schtick, otherwise we're back the "species have no meaning" scenario.

Sometimes the hybrids are the conduit for gene exchange, sometimes not even and the yes or no may be a function conditions that prevail locally. This would be a case by case assessement and will have to be followed by the usual concerns for dilution / disruption of locally adapted gene complexes. In rare instance the receiving population may benefit. May not be so rare of longer than human lifetime scales.

The production of hybrids by some species could dilute one of the parental stocks gamete reserves since in reality the number of gametes that can be produced (even sperm) is limited. Also futile reproductive effort, just as with nominal within species / population reproduction, may shorten life of parentals when reproductive investment conflicts with longevity. A couple at least of the triploid hybrids that are sustained by subsequent cloning / parthenogenesis could under some conditions outcompete one or both parental taxa. Thinking here of the amazon mollie and northern dace hybrid.

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#17 Guest_mdwalt1_*

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Posted 09 July 2008 - 12:16 PM

centrarchid - Your experimentation/study is absolutely fascinating. You allude to the potential eventual degredation of the original species from which the hybrids are derived, due to sterilization, etc. Do you think there's also the possibility of a more robust, best of both worlds kind of hybrid resulting in a more hardy, fertile and dominant species?
BTW - Your hybrid program would make a fabulous topic at this year's convention. Do you plan to present it?

Edited by mdwalt1, 09 July 2008 - 12:17 PM.

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#18 Guest_farmertodd_*

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Posted 09 July 2008 - 12:45 PM

These hybrids may be produced, but how fit are these hybrids or their descendants? This kind of gene exchange may have minimal long term impact. That's my whole schtick, otherwise we're back the "species have no meaning" scenario.

I really like Centrarchid's point about scale.

Furthermore... Why would it have to have any impact on populations? Maybe it's just a biproduct? It just "is".

Todd

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#19 Guest_mikez_*

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Posted 09 July 2008 - 03:06 PM

I'm intrigued by the pumpkinseed x northern bluegill. That looks exactly like so many of the sunnies around here, I would have sworn it was a pumpkinseed. I don't see any bluegill in that.
I could be catching more hybrids than I realize. Bluegills and pumpkinseeds share waters all over the state.
How does that cross do? Can they reproduce? Would they cross back to pumpkinseeds?

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#20 Guest_fundulus_*

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Posted 09 July 2008 - 03:22 PM

I really like Centrarchid's point about scale.

Furthermore... Why would it have to have any impact on populations? Maybe it's just a biproduct? It just "is".

Todd

Exactly, typically it just "is" and is the gene flow version of white noise. Hybrids appear, they live and die, and not much happens; kind of like the Seinfeld show.