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creek chub hybridization?

Started by Guest_FirstChAoS_* , Oct 13 2009 01:07 AM

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#1 Guest_FirstChAoS_*

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Posted 13 October 2009 - 01:07 AM

An odd question crossed my mind.

I noticed for a while that New Hampshire creek chubs look very different from New York ones, they are much more silvery and streamlined.

It made me wonder if creek chubs settling in the north east after the ice age ended hybridized with fallfish? if you ask me New England Creek Chubs seem to have more in common appearance wise to fallfish than creek chubs west of here.

I couldn't find a picture of the new york creek chubs we caught in the scholaire, but moxistomas picture of a minnesota creek chub here looks just like one. Note the browner color, pink accents, and stockier body. http://www.d.umn.edu.../dcreekchub.png

Here is a picture of a creek chub looking very similar to ones in new hampshire including the one in my tank. The one in my minnow tank (and many of the ones I catch in NH) are even skinnier bodied and when caught on hook and line they lose the brownish colorations and dark spots making them look more like fallfish. http://www.cnr.vt.ed...s/creekchub.jpg

And finally here is a picture of a fallfish for comparison http://www.nae.usace...nhlfallfish.jpg

Could creek chubs have hybridized with fallfish when settling new england leading to a more fallfish like population?

(EDIT: just noticed that creek chub pic i posted was from virginia, that complicates things a bit, I assumed vt.edu ion the address was vermont but it is virginia tech. still, maybe east of the applalacian populations hybridized then expanded in range)

Edited by FirstChAoS, 13 October 2009 - 01:13 AM.

#2 Guest_FirstChAoS_*

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Posted 13 October 2009 - 01:37 AM

ok, comparing these pictures to the creek chub in my tank now has me totally confused. It has a creekchub coloration like the brown tinted silvery of the eastern one in the pic posted but like this one http://www.fcps.edu/...romaculatus.jpg has a dark side stripe A(but a much fainter one than this), but with a very very forked tail like a fallfish not a square tail like these creek chubs in the pics I posted. Now instead of making a point I got myself all confused.

Edited by FirstChAoS, 13 October 2009 - 01:42 AM.

#3 Guest_darter1_*

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Posted 13 October 2009 - 09:28 AM

To start, I love the hybrid questions... I am always wondering the same thing with many similar fish species.
But... The first thing that should be looked at is morphometrics and meristics, as opposed to coloration. Nutrient supply, water quality, seasonal variation, and geographic varibility can all be factors causing one population to "look" slightly different. Looking at individuals in pictures is not a true sample of the population. It is a tough row to hoe.
I admire your eye for seeing a difference in these fish... it may be a clue to the ontogeny of that population. Just for the sake of comparison... do a work-up on a sample of fish. Count LL scales and look for the black dot at the front of dorsal fin. Small creek chubs will also have a prominent "mustache" on upper lip.
See where this takes you... put weight on LL scales. If they are intermediate between the two you may be on to something. But this would still be hard to prove, unless you have a geneticist at your disposal.
Good luck and keep asking questions on population dynamics, very interesting.

#4 Guest_FirstChAoS_*

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Posted 13 October 2009 - 12:26 PM

You make a very good point darter. I just find it odd that some parts of a fish population can look more like a related species than they could members of their own species.

#5 Guest_fundulus_*

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Posted 13 October 2009 - 12:44 PM

What you see could also be similar responses to the same environment over time, with microevolutionary processes selecting for the same general traits in two different (but related) species. There's always variation within a species which is the raw material for any future changes.

#6 Guest_darter1_*

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Posted 13 October 2009 - 01:19 PM

HAHAHA... sounds exactly like the conversation between me and my co-workers.
They just tell me to "prove it...then publish it"

#7 Guest_fundulus_*

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Posted 13 October 2009 - 04:54 PM

HAHAHA... sounds exactly like the conversation between me and my co-workers.
They just tell me to "prove it...then publish it"

I think we'd be late entries to such work. This quote by Mary Jane West-Eberhard of the Smithsonian Tropical Research Institute kind of captures the moment:
“The origin of a new direction of adaptive evolution starts with a population of variably responsive, developmentally plastic organisms. That is, before the advent of a novel trait, there is a population of individuals that are already variable, and differentially responsive, or capable of producing phenotypic variants under the influence of new inputs from the genome and the environment. Variability in responsiveness is due partly to genetic variation and partly to variations in the developmental plasticity of phenotype structure, physiology, and behavior that arise during development….”
--Mary Jane West-Eberhard

And no, I'm not a genius of factoid retrieval, I was just reading an article for one of the classes I teach that had this quote in it.

#8 Guest_darter1_*

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Posted 15 October 2009 - 07:39 AM

Heck of a good quote... Sure helps explain some of those tough populations, like those dang cottus. Sounds like an interesting article... was there more to it? I wouldn't mind reading it if you have some more info on it.

#9 Guest_bpkeck_*

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Posted 17 October 2009 - 08:35 PM

Heck of a good quote... Sure helps explain some of those tough populations, like those dang cottus. Sounds like an interesting article... was there more to it? I wouldn't mind reading it if you have some more info on it.

There are two good books that fit in with this.

M.J. West-Eberhard Developmental Plasticity and Evolution -- long and verbose, but some really good stuff.

J.N. Thompson The Geographic Mosaic of Coevolution -- I found it helpful to think about this in context of punctuated equilibrium/evolutionary stasis a la Eldredge and Gould

Ben

#10 Guest_fundulus_*

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Posted 17 October 2009 - 09:21 PM

I've attached a generally readable (for experienced aquarists) article by Sean Lema that's a review he wrote for the 'zine American Scientist about his work with Death Valley pupfishes. It's a fascinating body of work showing how closely related species have diverged in only 4000 years, with different levels of male aggressiveness related to features of brain structure that are plastic in response to environmental conditions. And who doesn't like desert fish?