Genetic diversity in two barnacle species, Chthamalus stellatus and Tesseropora atlantica (Crustacea, Cirripedia), with
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ORIGINAL PAPER
Genetic diversity in two barnacle species, Chthamalus stellatus and Tesseropora atlantica (Crustacea, Cirripedia), with diVerent larval dispersal modes in the archipelago of the Azores Federica Gabriella Pannacciulli · Georgia Manetti · Ferruccio Maltagliati
Received: 8 April 2009 / Accepted: 21 July 2009 / Published online: 16 September 2009 © Springer-Verlag 2009
Abstract ISSRs (Inter Simple Sequence Repeats) were employed to compare the genetic structure of Chthamalus stellatus and Tesseropora atlantica in the Azores. The two barnacles diVer as regards life cycle: the former conducting pelagic life for about 22 days, the latter for only 24 h. Thirty individuals of each species were analysed from four locations of three Azorean islands. Five ISSR primers produced, respectively, 117 and 79 polymorphic bands in C. stellatus and T. atlantica. Estimates of among-samples genetic diversity suggested extensive connectivity in the former species and isolation in the latter. AMOVA further supported these results by attributing 2% of genetic variance to the among-islands component of C. stellatus and 30% to T. atlantica. Results are consistent with expectations based on species life history and corroborate the importance of pelagic stages in determining the degree of genetic structuring in benthic marine invertebrates.
Introduction The majority of benthic marine invertebrates has a twophase life cycle in which sessile or sedentary adults This article is dedicated to the late Prof Alan J. Southward who raised the questions that motivated this study and provided information, advice and continuous support during the work. Communicated by S. Uthicke. F. G. Pannacciulli (&) · G. Manetti Marine Environment Research Centre, ENEA, PO Box 224, 19100 La Spezia, Italy e-mail: [email protected] G. Manetti · F. Maltagliati Dipartimento di Biologia, Università di Pisa, Via Derna 1, 56126 Pisa, Italy
produce long-life planktotrophic larvae, allowing species’ dispersal. Moreover, gametes may also give a contribution to dispersal when fertilisation is external and they are released in the water. Although in certain species, sessile or sedentary adults can also disperse through rafting on Xoating substrata or attached to boat and ship keels, pelagic larvae are generally considered the more eVective dispersal mechanism for marine invertebrates (Johannesson 1988). However, instances of internal fertilisation and brooding with reduction or even absence of pelagic stages are not uncommon across virtually all taxa. These exceptions to general rules raised the question on the evolutionary/adaptive signiWcance of pelagic larvae (Scheltema 1968; Hedgecock 1986; Todd et al. 1998; Bohonak 1999; Hellberg et al. 2002; Marko 2004; Levin 2006). Within this context, since the advent and spread of allozyme electrophoresis in the 60s, a number of experimental studies have been carried out for investigating how dispersal stages might aVect species’ genetic structure in terms of connectivity among populations. As a matter of f
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