[Taxacom] Just one species of Bromeliales in Africa

[John Grehan]

From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman



 

 Hi John, 

>        The damselfly genera Rimanella and Pentaphlebia

> seem to be a pretty clear case of vicariance, supposedly having
diverged

 

There is nothing presented here that is any more 'clear cut' with the
damselflies than with Pitcairnia. 

 

> Getting back to Pitcairnia feliciana, it supposedly
> dispersed to Africa about 9-12 million years (far more recently than
the

 

Yeah - 'supposedly'

 

> And yes, that is based on sequences,

 

No it is not, it is based on a misrepresentation of sequence divergence
theory.

 

> but bromeliads have such a poor fossil record, molecular data is by
far
> our best source of information (even if the dates can only be rough
> estimates).  

 

They are not only 'rough' they are minimal - something that too many
people continue to be in denial about.

     

> Anyway, I've been thinking more about the reasons
> Pitcairnia feliciana might not have dispersed further into Africa.
Could

 

Having invented a dispersal event, now invent why it did not disperse
further.

                         

> .S.   I just found that genus Maschalocephalus (of Family Rapateaceae,
> closely related to bromeliads) has a very similar origin to that of
> Pitcairnia feliciana, and Givnish et al. concluded that it was also
the
> result of almost the same transoceanic dispersal, but perhaps
happening
> even later (about 7 million years ago).  

 

I am betting that their 'conclusion' is based on the usual
misrepresentation of divergence dating.

 

> So it seems that the Pitcairnia case is not unique, unless both
actually 
> occurred in a single dispersal event (perhaps about 8 million years
ago?).  

Inventing dispersal events is certainly not unique to Pitcairnia.

John Grehan