Fish Quiz

Time for a good fish quiz. Any guesses?

It's geographically isolated (the locality info would give it away), so let's see if folks can get it without locality info.

Some sort of dace? I'm horrible at minnows.

little Colorado spinedace?

Nope. Scales on spinedace are so embedded as to be nearly invisible, and they're more silvery....

Hrrmmrmrmmm.... Maybe one of the longfin dace (Agosia)?

Nope.

Hmm. Hardhead, maybe? Wild-ass guess.

Splittail?

A Gila species. Maybe brevicausa? Maybe minacae?

Chris Scharpf
Baltimore

Irate - nope.
Skipjack - nope.
Chris, you're the closest so far, if I were guessing that's what I would have thought, and that's part of the reason I posted it.

I guess it really wasn't fair. It's Oreoleuciscus humilis.

...so the real reason I posted this is to point out how superficially similar some members of the Eurasian fauna are to some of our western North American species. This genus, Oreoleuciscus, is restricted to a series of large endorheic basins in western Mongolia and a small portion of adjacent Russia. At first glance you wouldn't think twice about calling this a Gila, but they supposedly aren't closely related (though we'll see about that!)...

Is this environment-driven? Are the shared features among western spring-dwelling cyprinids like Moapa, Iotichthys, Relictus, Eremichthys, etc. (small mouths, small scales, stubby body) all driven by environmental factors? All of these species are interspersed with larger, coarser-scaled things that are more widespread. What's driving this convergence?

I spent a month sampling fishes in Mongolia earlier this fall. Incredible trip, and awesome fishes. Even though it's a bit OT, I'll drop some of the cooler pics in below...

Oreoleuciscus dsachypensis
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Me with a larger Oreoleuciscus angusticephalus
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Triplophysa sp. (if you have any ideas on this one I'm all ears)
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Barbatula sp. (as above)
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Thymallus brevirostris
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main highway across the country (Dan Mulcahy photo)
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Deep in the Altai mountains
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channel between Khar-Us and Khar lakes (with camel skull)
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Off topic, puhleaaaase! This is one of the coolest post I've ever viewed!

What are the time wise relationships between the smallscale and large scale stuff?

One idea... The small scaling may have been an extremely successful body type in the Laurasian climates pre-Chicxulub asteroid strike, and only persist in localized spring situations where their water conditions were maintained. The big scale stuff, is basically filling the available niches in the newly detritus and sediment-rich systems post strike, with its new climate.

This body type may have been distributed all over the Laurasian masses prior to strike, and we're basically looking at a relict of that time.

In Asia, the cyprinids have come to have been the dominanting large scale species. We've seen that in North America with the addition of catostomids. Ganoid fishes persist everywhere.

We may have had fishes like this all over the northern hemisphere, but they're now mostly gone due to the Laurentide advances. The relicts in the east are blacknose, longnose, redside, rosyside, pearl dace. And we've caught Phoxinus taking advantage of the recent stability with an insane radiation among the erythrogaster complex.

Of course, it falls flat on its face if the widely distributed larger scaled species are older than these dace-like dudes.

So that's my 2 cent speculation

Todd

I take it by the DAN coding (I'm guessing this is a museum tag) that these particular specimens are being used as holotype/paratypes in a soon to come paper? New species to come?

Todd, I have to ask: you see that on this side of the K/T boundary that global (or semi-global) climate changed as a result of the impact, and this altered stream conditions in the direction of a sediment-rich (eutrophic?) bias in streams? It could well be but I hadn't encountered that exact line of reasoning. Maybe an easier explanation is for convergent evolutionary processes in similar habitats over the next 65 million years? My guess for Dave's photo was some kind of Gila species, the same as Chris. But some of those other photos look way different from the NA fauna.

Dave, how do you like your Tilley? Now I suppose everybody will want one.

Todd, the idea is interesting, but application of molecular clocks to the North American stuff (Smith & Dowling & others I can't remember in my pre-coffee stupor) suggests that at least within North America, these things have shared a common ancestor way more recently than that. Heck, the earliest fossil cyprinids only date back to the Miocene, right? That said, I think there's more groups shared between NA and Asia than what we currently think; Tribolodon is a dead ringer for Mylocheilus (which, coincidentally, are both semi-saltwater tolerant). There are others, too.

Bruce's reasoning seems more in line, but we had all sorts of other crazy geological things going on out this way fairly recently; volcanoes erupting all over the place, giant lakes filling and drying and filling again, massive quakes, etc. etc. The thing I don't get about the Chicxulub strike hypothesis is that if North America was so devastated, how did we retain so many basal telosts (hiodontids, gars, bowfin) that blinked out elsewhere?

Some folks have speculated that (in both Oreoleusciscus and Gila) one thing you see is repeated colonization of large lakes during the wet cycles (so you get large-bodied species and trophic specialization/ecological speciation from these types of habitats being available), then crashes when they dry...

There's only supposed to be four species in the genus. I only put a couple of pics up here, but there's a much broader range of variation in mouth shape, orientation and size, body size, gill raker development, etc. that what you would expect for four species...

Seedy - the numbers correspond to field notes that I take at every site I sample, the decimal at the end refers to tissue samples (I took fin clips from all of these prior to formalin fixing them and taking the photos, so I can easily go back and tie a DNA sequence to an individual specimen; each specimen also now has a small labeled tag securely tied to them). They'll eventually get museum accession numbers at the California Academy of Sciences (who funded the trip), and yeah, some will likely get described as new species, but that will take a while...

Irate - I love it. While it's certainly not a fashion statement, I spend too much time on the water to keep burning the heck out of myself.

Very Cool. Sounds like a very interesting trip. Your non-fish photos are quite spectacular as well.

> The thing I don't get about the Chicxulub strike hypothesis is that if North America was so devastated,
> how did we retain so many basal telosts (hiodontids, gars, bowfin) that blinked out elsewhere?

Tim Flannery asked a similar question in his book THE ETERNAL FRONTIER: AN ECOLOGICAL HISTORY OF NORTH AMERICA AND ITS PEOPLE (2001):

So why did gars, sturgeons, paddlefish, bowfin, and other aquatic creatures such as turtles and hellbenders survive the catastrophic asteroid that
struck the Gulf of Mexico 65 millions years ago, whereas dinosaurs and many other terrestrials creatures did not?

According to Dr. Flannery, the answer lies partly in the fact that freshwater aquatic environments are somewhat independent of plants and
photosynthesis; their chain of life is in part detritus-fed. When the immense dust cloud from the asteroid’s impact blocked the sun and halted
photosynthesis, plant-based marine and terrestrial ecosystems crashed. Dead leaves and other plant matter, however, continued to flood into ancient
rivers and lakes, feeding the bacteria that formed the foundation of a still-functioning food web. In addition, water absorbs heat, and creatures
living in deep pools may have been shielded from the intense temperature of the initial impact.

Chris Scharpf
Baltimore

Sounds good to me!

Hmmm.... what do you guys think will happen when Yellowstone blows in a few years?

It didn't necessarily have to happen at the KT boundary, that's why I was asking how old the different lineages are. That was more a speculative illustration of my point, more than anything I was "factualizing" As you say Dave, there were all sorts of other things going on in the meantime that would severely modify climate. And that was really all that I was pointing out, and something that to me, is miraculously understated in the phylogeographic literature.

I guess my point is... It seems MORE likely to me that we're observing an artifact of a successful set of genes shared all over Laurasia in what now seems similar habitat, rather than having these hundreds of random acts of evolution converging on one another???

I mean, why haven't bowfin changed in all these years? Because they didn't need to. Maybe its a similar thing in all these habitats. A more true process of convergence would be the snakehead, as an example.

If I remember right, Inner Mongolia was unglaciated besides very localized formations in the Pleistocene, much like the North American west south of the Cordilleran Glacier. It would be interesting to see where these fishes made their way back into glaciated regions on outwash and etc. in Asia. Or is this your field question?

Neat stuff. I could sit around all day and wildly speculate on this kind of stuff lol. Philosophy is boring to me, now that I am somewhat familiar glacial geology and zoogeography. The speculation is just as wild, with the added benefit of testable outcomes lol.

Todd

Oh, and the asteriod...

Scientific American had an article a few years back. While the effects of seawater were much more pronounced on the western hemisphere... The real trouble happened in the fall out in the eastern hemisphere. Huge firestorms started on the opposite side of the globe, which was minimized in the western because of the innundation from the waves. It'd be interesting to get some primary lit on this.

Again, second hand info and wild speculation

Todd