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Propositions for standardized measuring and description of lorises and pottos
Some
general remarks concerning measuring, description and
labelling
Labelling: see
field methods and necropsy chapter: record-keeping,
labelling,
catalogues, field notes
Measuring equipment
recommended:
measurements down to 1 mm by
direct reading with a ruler or with dividers, measurements down
to 0.1 mm with vernier or dial calipers (Ansell, 1965).
Humane examination:
For wild animals, capture and handling for scientific examination
is certainly a traumatic experience which may well endanger the
animalsīs health, cause stillbirths in pregnant females or
increase the threat to fall victim to predators after release.
Groves (2002 in press) recommends to anesthetize animals before
measuring. For information about anesthesia in lorises see anesthesia
chapter
in the disease database; here, the short information may be
sufficient that, while anesthesia suppresses sensory stimuli and
tranquilizers at least calm down the animals, paralytic drugs
(muscle relaxants) only paralyze tha animal. Ryder, 1978, after
trying the effects of such drugs on himself; regards
muscle-relaxing drugs paralyzing without diminishing consciousness
as inhumane, causing terror and trauma in the animal.
Recommendation to measure
both sides of an animal:
Lateral differences for
instance of limb measurements have been found (B. Meier, pers.
comm.; Seth 1969). In forms in which only few animals are
available for examination, it might therefore be good to
increase sample size by measuring both left and right limbs and
other bilaterally occurring parts of the body in each animal
(according to Swindler, 1976, in teeth there is no noticeable
difference between right and left side; Schwartz and Beutel,
1995, however, recorded bilaterally different tooth
measurements). In addition, comparison of individual size and
asymmetry with the average values of the population may allow
some conclusions concerning heterozygosity: in a diversity of
species, relatively heterozygous individuals were found to have
reduced fluctuating asymmetry and reduced morphological
variation, suggesting a relationship beween heterozygosity and
developmental stability. Individuals with extreme values for a
morphological character whose variation is largely due to
additive genetic variation will tend to be homozygous at the
loci that influence the trait; they are also expected to be more
asymmetric than those with central values. Relationship between
extremity of measurements and asymmetry is highly dependant on
how strongly variation of the morphological character in
question is controlled by additive genetic variation and how
many loci are involved. If the number of loci is large, then
extremeness may provide a good estimate of genomic
heterozygosity (Allendorf, Leary 1986).
See also information about asymmetry and variation
within populations.
Comparability of
measurements:
Comparability of measurements
is usually limited by the following problems:
Recommended accuracy:
in general to 1 mm; in very
small mammals, an accuracy to 0.1 mm would be necessary for
instance for hindfoot length, but usually such exactness cannot
be achieved when different or unexperienced observers are
involved (Ansell, 1965).
Necessary additional data concerning described animals, labelling of collected samples:
Dates ought to be
unmistakeable (confusion of months and days impossible, include
the century). The following dates ought to be noted:
date of death of the animal,
in case of captive care of
wildcaught animals: in addition the date of capture / removal
from natural habitat;
when necessary: date of
preparation (for instance skin made up from an alcohol or
formalin specimen).
2) Origin: locality traceable on maps: latitude and longitude; in addition place name (not only names of minor features unlikely to be on published maps)
Loris and
potto database in http://www.species.net
Draft for a
measuring standard Last amendment: 9 May 2001