Interestingly the text of the White et al. paper gives a time of the
divergence of the two subgenera as 10.1 Ma while their Figure 2 gives it
as 15.2 Ma. It isn't obvious from the text why this discrepancy occurs
- perhaps their supplementary data may help but I don't currently have
that available to check. The amount of time that has passed since two
taxa diverged is not in itself a basis of degree of separation - whether
it be species, subgenus, genus or family. It is the degree of generic
difference that is the key factor. Some taxa can rapidly diverge from
each other while others can remain little changed after the initial
divergence. To my mind the divergence of species within the
traditional Calyptorrhynchus is pretty small given it occurred at least
10 M if not 15 Ma. ago.
If del Hoyo & Collar want to elevate Zanda to full genus status I think
they have to be a bit more expansive in why than just saying than "DNA
study indicates that recognition is warranted", especially when the ones
doing that DNA work were happy to have it as a subgenus of
Calyptorhynchus. My suspicion would be that they misinterpreted the
comments in White et al.
cheers,
Mike Owen
on Jan-16 10:30 AM, Perkins, Harvey wrote:
> The depth of the fork between the Calyptorhynchus and Zanda subgenera (15.2
> MY) in the White et al paper is deeper than that between Eolophus (galah) and
> Callocepahalon (gang-gang) (12.4 MY), and that between those two and the
> Cacatuine/Lophochroa lineage (14.6MY). I suspect that del Hoyo and Collar
> interpreted this to mean that Calyptorhynchus should therefore be split.
>
> Harvey
>
> Dr Harvey Perkins
> A/g Assistant Manager
> CRC Contracts, DFCTC & Legacy Programmes
> AusIndustry - Business Services
>
> Phone +61 2 6213 7472
> Internet: business.gov.au
>
>
>
>
> -
<HR>
<BR> Birding-Aus mailing list
<BR>
<BR> To change settings or unsubscribe visit:
<BR> http://birding-aus.org/mailman/listinfo/birding-aus_birding-aus.org
</HR>
|
