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Range map strangeness


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#21 Guest_blakemarkwell_*

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Posted 11 March 2012 - 07:49 PM

Interesting, does the subspeciation of brook trout and arctic char in some areas reflect the headwater species differences?


I couldn't tell you in that specific case. But in general, species that inhabit headwaters become adapted to them, and that is usually associated with changes that do not serve them well when they try to disperse from headwater A to headwater B via big water (rivers, marshes, etc) that connects them. This headwater isolation leads to genetic isolation, and thus speciation, especially when allopatry is used as a major "character" to warrant species status. Of course, this period you're interested in involved rapid changes in base flows, which facilitated headwater captures and inter-basin exchanges that lead to some big head scratchers.

Allopatry is the reason there are so many species of darters, because as Todd has pointed out, you can think of riffles as islands and once that proto-Ammocrypta-Etheostoma-Nothonotus ancestor lost that swim bladder, it got really hard to disperse through big water connecting various riffle habitats. However, the basal Percina still have a swim bladder (to varying degrees) and other ancestral characters that still allow them to disperse through larger systems, and is likely the reason many big river Percina have such large distributions (compared to most Etheostoma). Of course, each species has differing dispersal capabilities, but you can draw some rough lines to help understand fish distributions.

#22 Guest_fundulus_*

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Posted 11 March 2012 - 08:29 PM

Wait a minute, a post glacial forest is preserved (lying horizontally) under the ocean. Then find the spots between the trees and find the rivers! The Atlantic refugium may have some degree of preservation assuming the trees were not moved too far out of place.

The channels of many drowned rivers are still fairly obvious approaching the former coastline, some of them drop off into canyons on the edge of the continental shelf like former parts of the Hudson River. Along the coast the same basic rivers have existed for a long time in about the same beds, unlike much of the Ohio drainage which has jumped around.

#23 Guest_nserrao_*

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Posted 09 February 2013 - 07:22 PM

Not necessarily. Look at Coregonids... Ets still does :)

I'd say pearl dace is another prime for investigation (you're telling me those fish in Maine are the same as what's in Alberta?). And failing to reject the null is even more interesting!

Redside dace are another. I have tissues from Ohio of those if anyone wants to sequence some to see how they compare to Berezden's sequences from WI and MN.

Todd

Hi Todd, I recently started a MSc at Trent university and am studying studying phylogeography of redside dace. I was wondering if by any chance you would still happen to have any tissue from the specimens mentioned above? thanks, N

#24 Guest_Skipjack_*

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Posted 09 February 2013 - 07:28 PM

Hi Todd, I recently started a MSc at Trent university and am studying studying phylogeography of redside dace. I was wondering if by any chance you would still happen to have any tissue from the specimens mentioned above? thanks, N


Since this is an old thread, you may get a better response from Todd if you send him a PM.



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