[Taxacom] an interesting paper on Long Distance Dispersal

John Grehan calabar.john at gmail.com
Wed Jul 4 20:35:44 CDT 2018


Oops, hit the send too quickly. Just want to add that for examples not
being explained by panbiogeography, also need to know why you think they
are not explained.

On Wed, Jul 4, 2018 at 9:34 PM, John Grehan <calabar.john at gmail.com> wrote:

> Les,
>
>
> 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
> archipelago?
>
> “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.”
>
> Or their ancestors never occupied landscapes that previously existed in
> the Pacific.
>
> “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?”
>
> 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 some patterns.”
>
> I would be interested to know what patterns you see as not being
> ‘explained’ by panbiogeography. That could be interesting.
>
> Cheers,
>
> John Grehan
>
>
> 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
>> tardigrade.
>>
>> https://peerj.com/articles/5035/
>>
>> 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.
>>
>> Best,
>> Les
>>
>>
>>
>>
>>
>>
>> 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
>> _______________________________________________
>> Taxacom Mailing List
>> Send Taxacom mailing list submissions to: Taxacom at mailman.nhm.ku.edu
>>
>> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
>> The Taxacom Archive back to 1992 may be searched at:
>> http://taxacom.markmail.org
>> To subscribe or unsubscribe via the Web, visit:
>> http://mailman.nhm.ku.edu/cgi-bin/mailman/listinfo/taxacom
>> You can reach the person managing the list at:
>> taxacom-owner at mailman.nhm.ku.edu
>>
>> Nurturing Nuance while Assaulting Ambiguity for 31 Some Years, 1987-2018.
>>
>
>


More information about the Taxacom mailing list