Freethought & Rationalism Archive

RufusAtticus · 08-01-2002, 07:10 PM

Quote:

Originally posted by theyeti:
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For an undergraduate project, I did some phylogenetic work on some deep-sea hydrothermal vent amphipods. One was a new species that apparently made its way several hundred/thousand miles to the next vent system, where it was isolated enough to speciate. Never got it publshed though.

Anyway, now it's known that there are deep-sea "rivers" with fast flowing water that could potentially enable these small crustaceans to travel large distances. At the time of my project, we had no clue how they got that far. (And no, we didn't consider the possiblity that they were created in situ!)

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Did someone go to Penn St?

NeilUnreal · 08-02-2002, 04:51 AM

Thanks, Coragyps and theyeti, I should be able to get ahold of the Science article. My off-the-cuff prediction would be that the vents would be similar to islands with respect to organisms that spread by non-planktonic means, but different from islands for organisms with a planktonic phase. I wonder whether the ecology is driven mainly by this oppourtunistic mechanism, or whether a true ecosystem has developed which is spreading from vent to vent?

-Neil

Coragyps · 08-02-2002, 05:56 AM

From the Science article I referenced above:

Quote:

Although it is difficult to assess directly the dispersal abilities of deep-sea invertebrates, estimates of gene flow provide a measure of rates and modes of dispersal. For example, genetic evidence reveals that Ventiella sulfuris, an amphipod that broods its young and has no larval stage, is limited in its ability to cross habitat gaps separating the East Pacific Rise and the Galapagos Spreading Center. In contrast, high rates of gene flow across thousands of kilometers occur among disjunct East Pacific Rise populations of species that have planktonic larval stages (e.g., vent mussels, clams, limpets, tubeworms, and polychaetes). Developmental arrest at cold temperatures has been implicated in extending the duration and dispersal capabilities of larval life; empirical evidence for arrested development is now available for a vent-endemic polychaete species. Mussels and clams exhibit no evidence for isolation by distance across thousands of kilometers. For these bivalve mollusks, larvae from distant source populations probably mix in the water column before they settle at hydrothermal sites. Tubeworm populations exhibit genetic signatures of stepping-stone dispersal between neighboring vent habitats, indicating that average dispersal distances of tubeworm larvae (< 100 km) may be considerably shorter than those of the bivalves.
Dispersal in open, turbulent systems seems trivial for marine species with large reproductive outputs and prolonged planktonic larval stages. More problematic is how dilution of larval propagules is kept low enough to account for large numbers of juvenile recruits found at extant vent habitats. One solution may be optimization of larval life-span to correspond with oscillatory deep-water circulation regimes, as proposed for the vestimentiferan tubeworm Riftia pachyptila. The likely average dispersal range of most vent larvae is 35 to 55 km, assuming larval durations of 2 to 3 weeks and average along-axis velocities of <3 cm [per]s.

(Footnotes omitted)

ps418 · 08-03-2002, 11:44 AM

Nice work Dr.GH.

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08-02-2002, 04:51 AM	#12
NeilUnreal Junior Member Join Date: Nov 2001 Location: USA Posts: 77	Thanks, Coragyps and theyeti, I should be able to get ahold of the Science article. My off-the-cuff prediction would be that the vents would be similar to islands with respect to organisms that spread by non-planktonic means, but different from islands for organisms with a planktonic phase. I wonder whether the ecology is driven mainly by this oppourtunistic mechanism, or whether a true ecosystem has developed which is spreading from vent to vent? -Neil

08-03-2002, 11:44 AM	#14
ps418 Veteran Member Join Date: Mar 2001 Location: Louisville, KY, USA Posts: 1,840	Nice work Dr.GH.

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