John's ponderings on doing the chalcids - a more radical view

[Donald Quicke]

hi all

I too have been pondering on doing a large group - in my case the
Ichneumonoidea. probably not as speciose as the Chalcidoidea, but certainly
35,000 described and roughly 3 to 5 times as many awaiting description
(i.e. not quite so tropicocentric as chalcidoids).

John considers the preoblem purely from a morpho-taxonomic point of view
and I would propose taht in the 21st century we may be obliged to combine
this or even to substitute this for a molecular approach.

My reasons are as follows -

Firstly, we have very little idea (at least among parasitic wasps) about
how our traditional morpho-species correlate to actual biological species
(don't let's argue about definitions - things which are interbreeding ...).
Recent studies, e.g. by Gokhman et al., have for example, shown taht two
parasitic wasps (Anisopteromalus in his case) can look to all intent and
purpose identical, yet be clearcut species with totally different
biologies. Such cryptic species seem to occur very frequently in any
applied (i.e. biocontrol) situations, and i personally would guess that it
could be anything between 5 and 50%. It would seem to me impotant to know
the magnitude of this cryptic species problem first - before assuming that
we must follow a morphology-based path - when in fact we have so far done
rather less than half the work. Molecular approaches will be the easiest
way of solving this , and can be applied to a random sample of putative
species based on traditional morphological defnition.

Secondly, it takes a long time to train morphologists to any competance.
Some would say that they are born rather than trained - i would concur. It
is far easier to train people to sequence things, and a lot can be
automated.

Thirdly, John points out that there could well be a duplication of effort
in even a well-run scenario as he describes. It is hard to check what
others are describing before they have described them. True too of
sequences, but you can get several sequences done in a few days, and place
them on a readily searchable data base. Certainly, taxonomic expertise will
be needed to give some sort of identification to taxa - but it may not be
necessary or advisable to describe and name each morpho-species.

I am not saying do away with morphology, or don't bother about voucher
specimens. Rather that molecular approaches will have to be brought to bear
too. Obtaining the material, setting up large international networks of
traps, arranging one or more dedicated sequencing centres and housing the
collections are of course necessary costs here. But I envisage a time when
it will be easier and cheaper to do research on biology/ecology/behaviour
of organisms such as insects in the tropics by saying that you are working
on the species of X whose DNA sequence is "ATGGTCGAT...." rather than on
Aus bus.

With an appropriate choice of two or three gene fragments it should be
possible to provide a full species-specific identification. And once that
sequence is archived, it won't matter if the world expert on the group has
long-since retired or succumbed to drink - the species will always be
recognisable


Donald

________________________________________________________

Dr Donald Quicke,
Senior Lecturer, Department of Biology
Imperial College at Silwood Park, Ascot
Berkshire SL5 7PY, UK

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