[Taxacom] an interesting paper on Long Distance Dispersal
calabar.john at gmail.com
Wed Jul 4 20:34:43 CDT 2018
What the paper points to for me is that some species are more widespread
than others and some species have a ‘global’ span. It also shows the
potential for some other species to hitch rides on these widespread species
(in this case birds). Of course the question still remains as to whether
this was operational in the origin of allopatric taxa (such as might occur
between NAmerica and S America). It is often assumed that such allopatry is
connected to bird mediated dispersal in recent times. Possible, but it’s
only an assumption. They key here is comparative biogeographic analysis of
patterns. As the authors note for tadigrades, too little known about that
to assess at this time.
Some further comment:
“Primates probably could wander long distances, but why would they?
Especially if their needs are being met where they are. In which case
rafting on continental chunks might be what carries them around.”
But to have an ancestral range that was split up by continents moving does
imply that the common ancestor did wander ‘long’ distances in the first
place. But ‘long’ or ‘short’ is relative.
“In Hawaii, some animals, such as terrestrial amphipods have no likelihood
of dispersing over the sea on rafts or other floating objects because of
their osmotic intolerance to sea water.”
So the biogeographic question still is for such organisms, under what
spatio-temporal conditions did they come to be at what is now the Hawaiian
“On the other hand, we also know that certain marine taxa, such
as cumaceans, which are small benthic crustaceans with almost no
and no larvae, have not made it to Hawaii.”
Or their ancestors never occupied landscapes that previously existed in the
“So the deep sea species have made it, easily, but the shallow species have
not. Low dispersal capability in the latter, and long distance larvae in
Or the deep sea species survived in the Pacific basin and the shallow
species did not.
“And, from where I sit, I see both panbiogeography and LDD each explaining
I would be interested to know what patterns you see as not being
‘explained’ by panbiogeography. That could be interesting.
On Wed, Jul 4, 2018 at 1:41 PM, Les Watling <watling at hawaii.edu> wrote:
> Apropos the recent discussion re dispersal vs vicariance. As a recent paper
> in PeerJ makes clear, the size of the dispersing organism matters. As does
> mobility, and a host of other factors.
> In the case of tardigrades it was long assumed that wind was the major
> dispersion agent, but the authors demonstrate, as much as one likely can,
> that bird feathers are an effective agent for something as small as a
> Not a too-likely method for primates other than in sci-fi stories(!).
> Primates probably could wander long distances, but why would they?
> Especially if their needs are being met where they are. In which case
> rafting on continental chunks might be what carries them around.
> But I think bird feathers also work for seeds of some species, and
> something as unusual as terrestrial amphipods. In Hawaii, some animals,
> such as terrestrial amphipods have no likelihood of dispersing over the sea
> on rafts or other floating objects because of their osmotic intolerance to
> sea water. On the other hand, we also know that certain marine taxa, such
> as cumaceans, which are small benthic crustaceans with almost no swimming
> ability and no larvae, have not made it to Hawaii. Most likely that is
> because they could only get there by travelling along the bottom, meaning
> they would have to crawl through the abyss.... not going to happen,
> temperature and pressure. But 3 species of cumaceans have now made it, most
> likely in ship ballast water.
> As with cumaceans, shallow water octocorals, a regular feature of most
> tropical coral reefs, are essentially absent from Hawaii. There are a few
> (maybe 4?) species of very small soft corals that can be found in shallow
> pools or in water a few meters deep. But the normal reef habitat has no
> octocorals. However, at depths greater than about 350 m, octocorals become
> abundant and diverse, exceeding more than 100 species, and inhabiting
> depths to over 3000 m. So the deep sea species have made it, easily, but
> the shallow species have not. Low dispersal capability in the latter, and
> long distance larvae in the former?
> In the end, I think the debate needs to be more carefully circumscribed
> with respect to the organisms. And, from where I sit, I see both
> panbiogeography and LDD each explaining some patterns.
> Les Watling
> Professor, Dept. of Biology
> 216 Edmondson Hall
> University of Hawaii at Manoa
> Honolulu, HI 96822
> Ph. 808-956-8621
> Cell: 808-772-9563
> e-mail: watling at hawaii.edu
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