Deeply divergent lineages of the widespread New Zealand amphipod Paracalliope fluviatilis revealed using allozyme and mitochondrial DNA analyses

• Published in: Freshwater biology Vol. 51; no. 2; pp. 236 - 248
• Main Authors: HOGG, IAN D., STEVENS, MARK I., SCHNABEL, KAREEN E., ANN CHAPMAN, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01-02-2006; Blackwell Science; Wiley Subscription Services, Inc
• Subjects: allopatric isolation; Animal and plant ecology; Animal, plant and microbial ecology; biodiversity; Biological and medical sciences; Crustacea; cryptic species; dispersal; DNA barcoding; Fresh water ecosystems; Freshwater; Fundamental and applied biological sciences. Psychology; Gammarus; Hyalella; Invertebrates; Paracalliope fluviatilis; Synecology; New Zealand; Oceania; New Zealand, South I; North America; New Zealand, North I; Geographical isolation; DNA barcoding; dispersal; Mitochondrial DNA; Allozyme; Biodiversity; Dispersion; cryptic species; Amphipoda; Crustacea; Freshwater environment; Aquatic environment; Hydrobiology; Geographic distribution; Arthropoda; Sibling species; allopatric isolation; Invertebrata; Allopatry
• ISSN: 0046-5070; 1365-2427
• DOI: 10.1111/j.1365-2427.2005.01491.x

Summary
1. We evaluated the population genetic structure of the common New Zealand amphipod Paracalliope fluviatilis using eight allozyme loci, and the mitochondrial cytochrome oxidase c subunit I (COI) gene locus. Morphological analyses were also conducted to evaluate any phenotypic differences. Individuals belonging to P. fluviatilis were collected from a total of 14 freshwater fluvial habitats on the North and South Islands, New Zealand.
2. We found evidence for strong genetic differentiation among locations (Wright's FST > 0.25), and fixed differences (non‐shared alleles) at two of the eight allozyme loci indicating the possibility of previously unknown species. Analysis of a 545‐bp fragment of the COI locus was mostly congruent with the allozyme data and revealed the same deeply divergent lineages (sequence divergences up to 26%).
3. Clear genetic breaks were identified between North Island and South Island populations. North Island populations separated by <100 km also showed genetic differences between east and west draining watersheds (sequence divergence >12%). Accordingly, present‐day dispersal among hydrologically isolated habitats appears minimal for this taxon.
4. Although population differences were clearly shown by allozyme and mtDNA analyses, individuals were morphologically indistinguishable. This suggests that, as in North American and European taxa (e.g. Hyalella and Gammarus), morphological conservatism may be prevalent among New Zealand's freshwater amphipods. We conclude that molecular techniques, particularly the COI gene locus, may be powerful tools for resolving species that show no distinctive morphological differences.