Hi all
I will try to straighten out things by describing in general terms how
Morphometry can be used and the accuracy that can be expected.
First of all,
Morphometry is the precise study of anatomical characters by measurement.
Morphology is merely the study of form and structure, although the word
is often wrongly used to imply morphometry.
If our objective is to sort unknown colonies of bees into racial types,
there are various characters that can be measured that we already have
databases for. (many of these characters can be viewed on...
http://www.dave-cushman.net/bee/morphometry.html
tools that are helpful are on...
http://www.dave-cushman.net/bee/morphometrytools.html
If your objective is to discriminate AHB from EHB, then the basic
database is not enough, because the small body size of AHB overlaps the
lower region of sizes that is also common to Ligustica, the genes of
which are prevalent in US bee populations.
Some very detailed studies have been done of island populations of AHB,
to the extent that they can tell which village the colony came from, but
a database of this type is only of any use on the island concerned.
When two populations have portions of data that overlap we need to
extend the database to include more characters in the measurements
(things like inter-joint distances on legs, relationships of all wing
veins) so that we can build an additional portion to the database. I say
this glibly, because the amount of work involved is enormous and each
finding has to be checked back to the original populations to make sure
that it is valid.
I believe that such morphometric databases do exist in US research labs
(I would love to get my hands on them), but the information is very
extensive... To check all possibilities for a 50 bee sample runs into
hundreds of hours of lab time, so in practice the full ID job is rarely
done.
Then we come to FABIS
If we have reasons to suspect AHB, our suspicions are first aroused by
the behaviour of the bees and the colony in general, because the number
of cases where AHB is suspected is quite high, and the government
establishments are unwilling to invest the full effort required to make
a positive identification, a streamlined identification system (fabis)
is used which picks a limited number of characters, but because of the
limitation an ID can only be made on a probability basis rather than
certainty.
I believe that cases identified as likely to be AHB were originally
intended to be followed up with a full detailed analysis, but in
practice, I do not think this happens.
Closed or limited populations
If we have adequate records of colony data that goes back many
generations (of bees) for a limited population that we are already
convinced of the racial type. Then we can look at this population to
establish other things. Natural selection works right down to a village
by village basis, but what can we expect to change in a bee over such
short distances ? There are climate, geography, geology, forage that can
all vary over short distances and we can map those changes and not on
the map the locations of the colonies in our study. We can do a large
number of dissections of bees measuring each part as we go. This data in
turn can be compared to the map information of climate, geography,
geology and forage to see if we can identify changes that match. If such
a match is found we can then mount a study to examine that feature in
yet more detail.
To sum up...
If you have a colony with well recorded behaviour, backed up by
morphometry using the right database, you can have good confidence in
your conclusions.
One or the other on their own is not enough.
I have not brought in to any of the discussion the use of DNA evidence
(because we were talking about Morphometry). In recent years DNA has
proved incredibly useful in confirming the high standards that
morphometry and behaviour analysis can achieve.
The automatic identification of wing vein junctions, coupled with
extensive computer calculations can now give good results with much less
tedium to the operator, but we should be wary that we do not believe a
result just because it has been generated by the computer, everything
still needs to be capable of being tracked back to a database that was
generated from bee colonies.
Regards & Best 73s, Dave Cushman, G8MZY
http://website.lineone.net/~dave.cushman or http://www.dave-cushman.net
Short FallBack M/c, Build 6.02/3.1 (stable)
-- Visit www.honeybeeworld.com/bee-l for rules, FAQ and other info ---
|