New Zealand Journal of Zoology abstracts
Loss of negative eye-size allometry in a population of Aplochiton
zebra (Teleostei: Galaxiidae) from the Falkland Islands
R. M. McDowall
National Institute of Water and Atmospheric Research Limited
P.O. Box 8602
Christchurch, New Zealand
email: r.mcdowall@niwa.co.nz
N. W. Pankhurst
Faculty of Science, Engineering and IT
James Cook University
Townsville
Qld 4811, Australia
Abstract The population of zebra trout (Aplochiton
zebra – Galaxiidae) in Red Pond, Falkland Islands, lacks the
negative eye size allometry that is typical of the species elsewhere.
Eye size retains a near constant relationship to head length throughout
growth in Red Pond. In addition, the bold, narrow, vertical,
zebra-like, dark bands typically found on the body of this species are
lacking, or are present in the Red Pond population only as broader
dusky blotches. Absence of negative allometry is probably due to lack
of coupling of eye and somatic growth, probably owing to slow growth of
the fish living in the challenging dietary environment of a turbid
lake. Observations of diet show that the species is a generalised
invertebrate carnivore, but that food intake may be low, suggesting
that the modified coupling of eye growth to somatic growth is a likely
explanation of the loss of negative allometry.
Keywords growth; vision; eye size; turbidity;
Aplochiton; Falkland Islands
Z04017; Received 27 May 2004; accepted 1 November 2004; Online
publication date 2 March 2005
New Zealand Journal of Zoology, 2005, Vol. 32: 17–22
0301–4223/05/3201–0017
© The Royal Society of New Zealand 2005
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