Genetics of the early stages of invasion of the Lessepsian rabbitfish Siganus luridus

Information on the initial stages of dispersal and settlement are of great interest in understanding the dynamics of biological invasions and in designing management responses. A newly settled population of the Lessepsian rabbitfish migrant Siganus luridus, that arrived in Linosa Island (Sicily Strait) in 2000, offered a unique opportunity to examine the genetic variability of the early phase of invasion and the starting point to test genetic variation within and between colonist and source populations. Demographics and dynamic aspects of S. luridus in the Mediterranean were evaluated by using phylogeographic and demographic (coalescent) methods based on DNA sequences of the mitochondrial control region. Sequences from 95 S. luridus, 25 Siganus rivulatus, and one of Siganus (Lo) vulpinus and S. doliatus were used. Samples were collected in one locality in the Red Sea (Eilat) and three localities in the Mediterranean (Israel, Greece and Linosa, Italy). Data showed (for the first time in a Lessepsian migrant) a lowering of the genetic diversity of the invading population (Mediterranean) (haplotype diversity 0.879, nucleotide diversity 0.592) compared to the parental one (Red Sea) (haplotype diversity 0.978, nucleotide diversity 0.958). Within the Mediterranean populations, there was no pattern of regional separation and mitochondrial diversity appeared to be preserved during the Linosa colonization, with no traces of founder events. Such evidence agrees with the idea that Lessepsian migration involves many individuals from its earliest stages. © 2005 Elsevier B.V. All rights reserved.