The success of invasive species in the Mediterranean basin: molecular tools to identify non indigenous benthic species

Abstract

Biogeographia vol. XXV - 2004 (Printed December, 30 'q 2004) Marine Biogeography of the Mediterranean Sea: patterns and dynamics of biodiversity The success of invasive species in the Mediterranean basin: molecular tools to identify non indigenous benthic species FRANCESCO PAOLO PATTI Lrzeomtorio di Ecologia del Benz‘/J05, Strzzizme Zaologiaz ii/l. Dobm ”, Pzmta S. Pietro 1, 80077 [st/7121, Nzzpoli (Italy) e-7mziZ' fivrzt2‘z'@.vz72. it Key words: invasive species, genetic drift, molecular biology, SNPs. SUMMARY The increase of non indigenous species (NIS) into the Mediterranean Sea in the last years, has had a significant effect on the economy and the ecology of the basin. The reasons that allow introduced species to become invasive are however still unclear. The classic ecological analyses, based on photometric methods and through direct observations are often unable to clarify the real taxonomic identity. The presence of cryptic species and of species with different dispersal capability, do not often give the possibility of identifying the origin of populations, the occurring of metainvasions and/or the genetic diversity (Geller, 1996). Witli the modern techniques of molecular biology it is however easier to give answers to the fundamental ecological questions of the bioinvasions phenomenon, producing at the same time usefiil data to develop models to prevent and to predict the invasive event. The use ofspecific molecular markers, like Microsatellites and SNPS has stressed that between the introduced populations there is a loss of genetic diversity, while the native populations are genetically more variable. Even if the reduction of the genetic diversity is usually considered disadvantageous at population level, the genetic reduction can lead to the ecological success of the invasive species (Lee, 2002). In this contest, through the analysis of the bio—ecology and genetic characteristics, the possibility to identify general models to discover and to study non indigenous species will be discussed. INTRODUCTION Marine ecosystems are populated by species that disperse between localities, sometimes sending propagules far away from their parental population, sometimes retaining eggs and larvae close to the point of origin. This potential dispersal, and its Variation, is one of the critical elements of marine life history dynamics, and influences the aspect of ecosystem functionality including stability of populations, resilience to extinction, and the degree to which species can adapt to local conditions, establishing the bases for new colonizations.