New Zealand Journal of Marine and Freshwater Research abstracts
Movement of male Heterozius rotundifrons (Crustacea: Decapoda:
Brachyura) depends upon local sex ratio
B. A. Hazlett
Department of Ecology and Evolutionary Biology
University of Michigan
Ann Arbor
MI 48109, United States
C. E. Bach
Department of Biology
Eastern Michigan University
Ypsilanti
MI 48197, United States
G. A. Thompson
C. L. McLay
School of Biological Sciences
University of Canterbury
Private Bag 4800
Christchurch, New Zealand
email: colin.mclay@canterbury.ac.nz
Abstract Heterozius rotundifrons is a New Zealand
endemic crab that lives in the intertidal zone and is found under rocks during
low tides. We investigated the role of the local sex ratio (= under rock)
in affecting movement patterns of this crab. In the laboratory, male crabs
moved more when the sex ratio was male biased. Field surveys suggested that
there is an upper limit to the number of males found under rocks, even as
the number of females increases. Field manipulations demonstrated that when
the sex ratio under a rock is female biased there is no effect on female
movement but when the ratio is male biased, males move away more frequently
and move further. This increased movement by males is probably related to
avoidance of male-male competition for females.
Keywords Heterozius; intertidal; male-male competition;
movement patterns; sex ratio
M04094; Online publication date 18 February 2005
Received 28 April 2004; accepted 27 September 2004
New Zealand Journal of Marine and Freshwater Research, 2005, Vol. 39:
157–163
0028-8330/01/3901-0157 © The Royal Society of New Zealand 2005
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