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MEPS 277:197-207 (2004)
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Abstract
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RAPD analysis of southern populations of Gammarus locusta: comparison with allozyme data and ecological inferences
Filipe O. Costa1,*, Teresa Neuparth1, Chris W. Theodorakis2, M. Helena Costa1, Lee R. Shugart 3
1IMAR-Centro de Modelação Ecológica, DCEA, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
2The Institute of Environmental and Human Health, Department of Environmental Toxicology, Texas Tech University, Lubbock, Texas 79409-1163, USA
3L.R. Shugart and Associates, PO Box 5564, Oak Ridge, Tennessee 37831, USA
*Email: fjc@fct.unl.pt
ABSTRACT: The genetic variability of southern European populations of the marine amphipod Gammarus locusta (L.) was analyzed using randomly amplified polymorphic DNA (PCR-RAPD). We analyzed 4 populations along the Portuguese coast with 10 arbitrary
primers, which produced a total of 114 interpretable bands. The average percentage of polymorphism was 77% and the within-population average similarity index was high (0.841). Between-population differentiation was low, as determined by Wright's fixation
index, FST (0.074), analysis of molecular variance (AMOVA) ΦST (0.048), and Nei's unbiased distances (mean 0.032). These results are consistent with those of previous allozyme analysis, which indicated that G.
locusta has low intra- and inter-population genetic variability. Low between-population differentiation indicates that G. locusta has efficient dispersal mechanisms for an organism lacking larval stages and that disperses passively. Despite the
low level of genetic differentiation it was still possible to detect some genetic subdivision. The Sado and Alvor populations clustered together consistently in dendograms based on several genetic distances, and AMOVA analysis indicated some level of
differentiation between populations located to the north (Aveiro and Foz do Arelho) versus southern populations (Sado and Alvor), albeit this was very low (<1.5%). Analysis of migration patterns suggested that dispersal is unbalanced, occurring
primarily from west coast populations to the south coast population of Alvor, with much less reciprocal dispersal. It would be worthwhile inspecting the significance of this unbalanced north-south flow, by determining whether populations located east of
Alvor also exibit such unbalanced dispersal relative to west coast populations.
KEY WORDS: Gammarus locusta · Amphipod · Genetic variability · Random amplified polymorphic DNA · Allozymes · Gene flow · Dispersal · Migration
Full text in pdf format
Published in MEPS Vol.
277
(2004) on August 16
Print ISSN: 0171-8630; Online ISSN: 1616-1599.
Copyright © Inter-Research, Oldendorf/Luhe, 2004
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