I recently found an article detailing the freshwater origins of saltwater fish. http://www.livescien...extinction.html

It really makes me wonder if a close relative to the ancestor exists (doubtful as the split started around the end carboniferous and the saltwater diversification really got up to speed in the creataceous meaning several massive extinctions occured between then and now) and also had me wondering which freshwater fish alive today could end up repopulating the oceans in the future if this were to happen again.

... had me wondering which freshwater fish alive today could end up repopulating the oceans in the future if this were to happen again.

The obvious candidates are estuary fish, fish who spend their life on the borders of fresh and salt water. There are also fish like American eels and salmon which migrate from salt to fresh or vice versa during the normal progression of their life span. Then there are surprising fish, who you wouldn't think of as being capable of living in salt water but who totally can. My favorite surprise fish is the common guppy, which can actually be acclimated to live in full salt water. Here's a forum topic with a neat picture of a guppy with coral in the background: http://forum.marined...c83121-4-1.aspx
The second poster gets trounced.

My vote is for gobies. Gobies already have colonized a large portion of the world. They're famous for being the only freshwater fish native to remote islands because the saltwater goby species from around the island crept up the streams and over time became adapted to the freshwater niche.

The article is oddly written. It implies that the relatively equal species diversity of fresh- and saltwater fishes is driven by a freshwater origin of Percomorpha, which is nonsense; 300 million years is more than long enough for speciation to "top out". The difference is driven by the difference in possibilities for vicariance and dispersal. Oceanic habitats are relatively contiguous- the only major barriers to dispersal are the two north-south continental masses (the Americas and Eurasia + Africa); thanks to the planktonic larvae of most marine fishes and extensive current systems, the open ocean is not a major barrier, even for inshore species. There is only one ocean, but there are thousands or millions of separate freshwater systems, separated by land or salt water. Endemism is the rule in freshwater, not the exception; besides anthropogenically spread species, there are only a few transcontinental freshwater species- northern pike, burbot, longnose sucker, some of the sticklebacks, etc.- and a few more transcontinental anadromous types- galaxiids, eels, and so on.

Yes, and the paper that the article is referencing may be equally odd. I've only read the abstract, but the paper does suggest that the low diversity of marine fishes stems from the freshwater origin of Percomorpha. Let us hope they suggest it is one reason among many others, and don't make overarching claims and igonore millions of years of geology and evolutionary history like the article did. I think the disparity in diversity comes from the very processes/reasons you mentioned.

http://rspb.royalsoc.../rspb.2012.0075

I am surprised it took so long for percimorpha to take over the seas. They survived several major niche opening extinctions including one that almost wiped out everything.

Thinking of extinctions I found their reference to mass extinctions hitting freshwater environments harder than marine to be interesting as I heard that mentioned in other cases such as K-T extinction survival rates. Is it mere coincidence or are freshwaters more resistant to mass extinctions?

First let me lament how underrecognized freshwater aquatic systems are as a means for controling dispersal among ecologists, in particular, community ecologists (a bunch of frickin' botanists and birders lol). We're all familiar with the two-directional pattern of rivers, esp among "darterologists" because we see it every time we go out (or have to walk it to get to the next "patch"). This is why I work with benthic riffle communities... I don't have to nuke an island to do community level research, I can just change riffles.

That said, as an academic "grandson" of Wiens, and without access to actual article (I tried, I can't get the paper myself), they do mention the fact you're clamoring about in the news piece. There's a whole paragraph stating that a related element may be dispersal, and we have no means of determing the level of treatment it recieved in the original. So don't get completely hung up on it... In knowing Wiens work, there's no way he left that stone unturned in the actual work. And I'm glad to see that he's continuing to work with fish. It's going to provide evidence he desires toward questions he's asked for a long long time (and pissed everyone off by asking them .

If anyone can get to the actual article, I would enjoy reading it. I may even bug them and see if they have author's copies available.

Todd

It was the FLOOD folks! When it topped Mt. Ararat the sea was no saltier than you'd use to treat a case of ich, so obviously most of the marine spp died and they've only had a few thousand years to re-diverisfy.

Gerald
- - a few blocks from Southeastern Baptist Theological Seminary

So don't get completely hung up on it... In knowing Wiens work, there's no way he left that stone unturned in the actual work. And I'm glad to see that he's continuing to work with fish. It's going to provide evidence he desires toward questions he's asked for a long long time (and pissed everyone off by asking them .

If anyone can get to the actual article, I would enjoy reading it. I may even bug them and see if they have author's copies available.

Todd

Yeah, I knew something had to be missing as soon as I noticed that Wiens was one of the authors. He's a well-respected herpetologist and I've always enjoyed the research out of his lab. I would love to read the full article as well, but I still get hung up when I read the title of the paper and the subsequent abstract. I'm glad to see a herp lab sticking their foot in fish stuff too (fresh perspectives!). Besides, a love for amphibians and fishes is a more natural grouping than amphibians and reptiles (although I love them too -- espically the non-avian ones!).

My bad, this is JJ Wiens! My line goes back to JA Wiens, the birder at CSU, I guess I should read all the details lol! Hillarious. Birds, reptiles, they're all the same right?