[Taxacom] Biodiversity questions: Classifications

[Richard Jensen]

Could it be that the apparent discrepancy in biodiversity, as we perceive
it, is that family Z has had just as many speciation events as family X,
but has experienced extremely high rates of extinction?  If so, then
knowing the age tells us nothing about biodiversity - the two clades, one
with 999 surviving species, and one with 1 surviving species, could be the
same age.

Dick J


On Thu, Oct 3, 2013 at 11:15 AM, Chris Thompson <xelaalex at cox.net> wrote:

> PAUL:
>
> The scientific question that we begin with was about biodiversity.
>
> And Hennig said to answer those kinds of questions, then groups based on
> time are the best.
>
> So, under the Hennig system, one could say that family X which now contains
> 999 species is more biodiversity, has more speciation, etc., than family Z
> which now contains only 1 species. BECAUSE the contents (species) of each
> family represents a clade that has evolved over the SAME time period.
>
> But as I indicated in my Diptera example, comparison of the number of
> species in Limoniidae versus Inbiomyiidae does not tell you anything about
> biodiversity, speciation, etc. because those groups are not equivalent, not
> comparable, etc.
>
> Oh, well ...
>
> Sincerely,
>
> Chris
>
> -----Original Message-----
> From: muscapaul
> Sent: Thursday, October 03, 2013 10:27 AM
> To: TAXACOM
> Subject: Re: [Taxacom] Biodiversity questions: Classifications
>
> Just out of interest: If actual age would (should?) be playing a role,
> where do we then account for differences between taxa with highly divergent
> generation time, like drosophilids with perhaps more than 10 generations
> per year under favourable conditions and panthophthalmids which probably
> take multiple years to develop? And then I am just considering taxa within
> the same order where one might give rise to new taxa on a much shorter
> absolute time scale than the other.
>
> Paul
>
> On 3 October 2013 12:59, Chris Thompson <xelaalex at cox.net> wrote:
>
> > So, for example, in Diptera, we now recognize a family which is a clade
> of
> > some 10 thousand species and of some 200 million years old (Limoniidae)
> > and
> > another family of less than a dozen species and probably less than 5
> > million
> > years old (Inbiomyiidae).
>
> ...
> >
> > So, if one wants to derived scientific hypotheses from classifications,
> > one
> > must go back to clades and their age.
> >
> > Sincerely,
> >
> > Chris
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-- 
Richard Jensen, Professor
Department of Biology
Saint Mary's College
Notre Dame, IN 46556