[Taxacom] more ant discussion

[John Grehan]

Hi Brendon,

Thank you for taking the time to address the various points. This is what I
consider reasoned and worthwhile discussion involving empirical data (i.e.
not just assertions of belief). Comments below:

BB “Remarkably, *Lasiophanes *would be the only genus that may have
dispersed from Australia to South America—and it is a cold-adapted clade.”

Why even consider such directional dispersal?

BB “All other known instances of apparent interchange among these
continents are for warm-adapted clades from South America to Australia”

What do you cite as “apparent instances” as I am not aware of any.

BB “I am still struck by the asymmetry of E-W, W-E patterns in Austral
ants.”

Not sure what you mean by that. Please clarify.

BB “you might enjoy perusing AntMaps.”

I'll take a look.

BB “Thank you. Out of curiosity, how old would you infer *Syscia *to be if
it were to have had such an ancestral distribution?”

Early Cretaceous

BB “Also, what would you predict the phylogenetic pattern for *Syscia *to
be? Would the clade be split evenly between E and W species groups, would
there be asymmetry, and what about the rate of molecular evolution among
the various lineages? To reiterate, I ask this non-combatively, but in the
spirit of discussion.”

I have no necessary predictions as some differentiation may have already
occurred before Pacific vicariance. Will be interesting to see what is
discovered on that. Please explain the 'asymmetry'

BB “Neither of us disagree that we are effectively talking about minimum
ages, and that the couching of statements is important. In the
specific casecited,
the authors did address their estimates from the statistical point of view;
whether the specific phrasing could be altered is another subject.

But it is important. If ages are minimums then one should not say “about”.
This happens all too often. And it's not just phrasing when researchers use
such 'minimum' ages to posit an actual age for a biogeographic senario.

BB “ The fossil record of crown angiosperms is better than that of ants and
shows a nice transition in the Cretaceous from stem to crown Angiospermae,
and to crown eudicots.”

It shows what it shows, a series of minimum fossil ages for various taxa.
These do not preclude earlier origins where predicted by other measures
(such as tectonic correlations), although sometimes there is a good match
as with Nothofagus for example.

Cheers, John