DOI: 10.5061/dryad.brv15dvc4
title: Assessment of connectivity patterns of the marbled crab Pachygrapsus marmoratus in the Adriatic and Ionian seas through combination of genetic data and Lagrangian simulations

description: Seascape connectivity studies, informing the level of exchange of
 individuals between populations, can provide extremely valuable data for
 marine population biology and conservation strategy definition. Here we
 used a multidisciplinary approach to investigate the connectivity of the
 marbled crab (Pachygrapsus marmoratus), a high dispersal species, in the
 Adriatic and Ionian basins. A combination of genetic analyses (based on 15
 microsatellites screened in 314 specimens), Lagrangian simulations
 (obtained with a biophysical model of larval dispersal) and
 individual-based forward-time simulations (incorporating species-specific
 fecundity and a wide range of population sizes) disclosed the realized and
 potential connectivity among eight different locations, including existing
 or planned Marine Protected Areas (MPAs). Overall, data indicated a
 general genetic homogeneity, after removing a single outlier locus
 potentially under directional selection. Lagrangian simulations showed
 that direct connections potentially exist between several sites, but most
 sites did not exchange larvae. Forward-time simulations indicated that a
 few generations of drift would produce detectable genetic differentiation
 in case of complete isolation as well as when considering the direct
 connections predicted by Lagrangian simulations.Overall, our results
 suggest that the observed genetic homogeneity reflects a high level of
 realized connectivity among sites, which might result from a regional
 metapopulation dynamics, rather than from direct exchange among
 populations of the existing or planned MPAs. Thus, in the Adriatic and
 Ionian basins, connectivity might be critically dependent on unsampled,
 unprotected, populations, even in species with very high dispersal
 potential like the marbled crab. Our study pointed out the pitfalls of
 using wide-dispersing species with broad habitat availability when
 assessing genetic connectivity among MPAs or areas deserving protection
 and prompts for the careful consideration of appropriate dispersing
 features, habitat suitability, reproductive timing and duration in the
 selection of informative species.
description: 314 samples of
 <em>Pachygrapsus marmoratus</em> were collected in the
 Adriatic and Ionian seas. Genomic DNA was extracted using a standard
 salting out protocol. 15 Fifteen polymorphic microsatellite loci specific
 for <em>P. marmoratus</em> were used for genetic
 analysis. Refer to the full article for details at https://doi.org/10.3389/fmars.2022.944851
description: The "Pachygrapsus marmoratus_rawdata.txt" and
 "Pachygrapsus marmoratus_genotypes.txt" files contain
 information on 15 microsatellite loci. Eight population samples are
 reported for a total of 314 individuals. Please note that locus pm108 was
 identifed as an outlier using LOSITAN (Amos et al. 2008) and DETSEL
 (Vitalis et al. 2012). The file "Pachygrapsus
 marmoratus_rawdata.txt" is a tab separated text file, organized with
 a first header row identifying columns for population ID, individual ID
 and names of the loci (two alleles per locus). The following 314 rows
 report for each individual population ID, individual ID, followed by
 genotypes information for each locus. For each locus, the two
 corresponding columns report raw size in base pairs of each of the two
 alleles.  The file "Pachygrapsus
 marmoratus_genotypes.txt" is a tab separated text file, organized
 with a first header row identifying columns for population ID, individual
 ID and names of the loci. The following 314 rows report for each
 individual population ID, individual ID, followed by genotypes information
 for each locus. Alleles are given in repeat numbers, after that binning
 was performed automatically with the software FlexiBin version 2 (Amos et
 al. 2007). Missing data are represented by '000'.