New Zealand Journal of Zoology abstracts
*Author for correspondence.
Z00003Received 18 April
2000; accepted 12 October 2000
Variation in size of male weaponry in a harem-defence polygynous insect, the
mountain stone weta Hemideina maori (Orthoptera: Anostostomatidae)
J. WILL KONING
IAN G. JAMIESON*
Department of Zoology
University of Otago
P. O. Box 56
Dunedin, New Zealand
email: ian.jamieson@stonebow.otago.ac.nz
Abstract This study examined intrasexual size variation in
the sexually dimorphic mountain stone weta
Hemideina maori. We were
unable to determine the proportion of weta maturing at different instars,
because linear variation in adult head sizes was continuous and not discrete.
However, by measuring the growth increment from subadult to adult of weta
raised in the laboratory, we estimated that 11% of the males in our main study
site were maturing two instars earlier than the largest male. Similar variation
in size at maturation has been observed in male Wellington tree weta
Hemideina crassidens, which are known to mature at three different
instars, but is unusual for insects in general. The variation in head and femur
sizes of
H. maori was greater between sites (= isolated populations)
than within sites, corresponding to an altitude gradient. Females showed a
similar altitude gradient, although they showed less variation in body size
than males. These data suggest that at any given local environmental
temperature, there may be selection for an optimum body size. Whether there is
further selection on the smallest males within each site to exhibit alternative
mating tactics, as part of a conditional reproductive strategy, remains to be
determined.
Keywords instars; New Zealand; sexual size dimorphism; size
at maturity; Stenopelmatidae; wetas
New Zealand Journal of Zoology, 2001, Vol. 28: 109-117
0301-4223/00/2801-0109 $7.00/0 (c) The Royal Society of New
Zealand 2001
PDF file of entire paper: medium quality (964K); (scanned from paper original: notes about this process)
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