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New Zealand Journal of Marine and Freshwater Research abstracts

Population genetic structures of two New Zealand stream insects: Archichauliodes diversus (Megaloptera) and Coloburiscus humeralis (Ephemeroptera)

Ian D. Hogg
Pia Willmann-Huerner
Mark I. Stevens

Centre for Biodiversity and Ecology Research
Department of Biological Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: hogg@waikato.ac.nz

Abstract   We examined the population genetic structure (allozyme variation) of two New Zealand aquatic insects: Archichauliodes diversus (Walker) (Megaloptera) and Coloburiscus humeralis (Walker) (Ephemeroptera); and tested the hypothesis that species with limited adult dispersal abilities would show high levels of genetic differentiation among hydrologically isolated habitats. Both species were characterised by low levels of within-population genetic variability (e.g., Hexp = 0.06 and 0.04 for A. diversus and C. humeralis, respectively). However, genetic differentiation among sites was considerably greater for A. diversus relative to C. humeralis (FST = 0.57 and 0.03, respectively). A. diversus consisted of two genetically distinct groups in the North Island (I = 0.96), and a third group from the South Island (I = 0.67). By contrast, allelic differences among C. humeralis were minimal (I > 0.99, in all cases), and appeared unrelated to geographic proximity or habitat type. We suggest that a combination of historic range changes and reproductive mechanisms, as well as contemporary dispersal capabilities, may be responsible for the observed population genetic structures of A. diversus and C. humeralis. Accordingly, generalisations based on present-day dispersal abilities alone may be misleading particularly for island habitats such as New Zealand where gene pools may already be restricted.

Keywords   gene flow; allozymes; Ephemeroptera; Megaloptera; biodiversity; dispersal

M01069 Received 26 July 2001; accepted 19 March 2002; published 17 September 2002
New Zealand Journal of Marine and Freshwater Research, 2002, Vol. 36: 491-501 0028-8330/02/3603-0491 $7.00 © The Royal Society of New Zealand 2002

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