[Taxacom] Dispersal clarifications: frogs on an oceanic islands

[John Grehan]

These generalities may be true, but the point is that the ecological
ability of organisms to survive inhospitable environment has not proved
to be predictive in understanding biogeographic patterns, and that the
absence of mammals in certain locations may be just as much a result of
survival (or its lack) as anything else. It is the latter that has
proved to be more informative about the former when it comes to
understanding where and how species have differentiated.

John Grehan 

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of David Campbell
Sent: Monday, June 13, 2011 12:44 PM
To: Taxacom
Subject: Re: [Taxacom] Dispersal clarifications: frogs on an oceanic
islands

> The delineation of 'oceanic' island (as opposed to 'non-oceanic') is
> another one of those prejudicial categories so often used in
> dispersalist biogeography. As Heads has pointed out in the list and in
> publications, supposedly oceanic islands can have non-oceanic life.
The
> lack of mammals and other "poor" dispersers may be a function of their
> really being poor survivors in regions of highly unstable terrestrial
> landscapes.

"Dispersal" involves multiple factors.  Most mammals are fairly good
locomotors, but many are somewhat large for riding on the average
floating or flying object and the high metabolism limits how long they
can float or swim without food.  Non-swimming mollusks are generally
slow but good at riding and at estivating. Of course, ability to
survive upon arrival is also an issue.

Organisms disperse and they experience vicariant events.  Different
species will have a different balance.

-- 
Dr. David Campbell
The Paleontological Research Institution
1259 Trumansburg Road
Ithaca NY 14850

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