Contrasting patterns of genetic structure and disequilibrium in populations of a stone-cased caddisfly (Tasimiidae) from northern and southern Australia
Alicia Slater Schultheis A D , Richard Marchant B and Jane Margaret Hughes CA Biology Department, Stetson University, 421 N. Woodland Blvd. Unit 8264, DeLand, FL 32723, USA.
B Museum of Victoria, GPO Box 666, Melbourne, Victoria 3001, Australia.
C Griffith School of Environment, Griffith University, Nathan, Queensland 4111, Australia.
D Corresponding author. Email: aschulth@stetson.edu
Marine and Freshwater Research 59(3) 235-245 https://doi.org/10.1071/MF07104
Submitted: 22 May 2007 Accepted: 26 February 2008 Published: 30 April 2008
Abstract
In marine and freshwater invertebrate populations, microscale genetic differentiation or ‘genetic patchiness’ is thought to result from variation in the abundance and genetic composition of new recruits at a particular location. In the present study, the role of the adult emergence patterns in genetic patchiness was examined using mtDNA and two microsatellite loci to compare patterns of genetic differentiation in asynchronously (subtropical) and synchronously emerging (temperate) populations of the stone-cased caddisfly Tasimia palpata. A 550 base pair region of the mitochondrial cytochrome c oxidase subunit I gene (COI) was sequenced in at least 14 individuals from each population. Genetic structure was detected only at the reach scale in the subtropical populations and no genetic differentiation was detected in temperate populations. There were more deviations from Hardy–Weinberg equilibrium (HWE) in subtropical populations than in temperate populations where 44% and 12.5%, respectively, of tests for deviations from HWE were significant. Although distinct patterns of genetic structure and deviations from HWE were observed in the subtropical and temperate populations of T. palpata, no conclusive evidence was found to suggest that the differences are caused by differences in emergence patterns. We hypothesise that genetic patchiness must be caused by post-recruitment processes, most likely the preservation of oviposition ‘hotspots’ in subtropical streams.
Additional keywords: dispersal, microsatellites, mtDNA, recruitment, Trichoptera.
Acknowledgements
We thank Mia Hillyer and David Hurwood for their assistance in collecting samples and Melissa Gibbs for assistance with the illustrations. This work was supported by NSF grant INT-0076202 to A. Schultheis and a grant from the Australian Research Council to J. Hughes, S. Bunn, and R. Marchant.
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