Table 1. Characteristics of sampling sites, including geographic information and genetic diversity indices per geographic sample.

N: number of individuals sampled in each site; N_pa: number of private alleles; A_r: allelic richness per geographic sample; H_e and H_o indicate expected and observed heterozygosity respectively; F_IS is the inbreeding coefficient calculated in each population sample. In italics values after correction for null alleles.

Region	Geographicsample	Code	Coordinates	N	Npa	Ar	He	Ho	FIS
Atlantic Ocean	Portugal,Ria Formosa	PTG	36°49’16.76”N7°53’7.73” O	25	23	8.115 ± 0.4368.738 ±0.227	0.6670.693	0.5010.655	0.271***0.055*
Mediterranean(Balearic Sea)	Spain,Balearic Sea	SPN	39°02’59.43” N0°10’27.54” E	26	4	7.846 ± 0.2358.154 ± 0.235	0.6780.690	0.4980.654	0.278***0.054*
Mediterranean(Sea of Sardinia)	Italy,Gulf of Oristano	ORI	39°48’46.72” N8°28’37.47” E	25	5	7.715 ± 0.1858.008 ± 0.172	0.6830.699	0.4590.637	0.341***0.090***
Mediterranean(Tyrrhenian Sea)	Italy,Gulf of Naples	NA1	40°47’8.31” N14°10’54.14” E	25	6	7.846 ± 0.1408.123 ± 0.236	0.6420.665	0.5230.628	0.204***0.058*
Mediterranean(Tyrrhenian Sea)	Italy,Gulf of Naples	NA2	40°49’22.10” N14°15’0.86” E	25	7	8.100 ± 0.1788.492 ± 0.259	0.6490.682	0.5170.640	0.223***0.062*
Mediterranean Sea	Italy,Strait of Messina	STM	38°14’51.81” N15°38’19.90” E	17	2	5.615 ± 0.0006.462 ± 0.000	0.6000.633	0.4930.615	0.207**0.029ns
Mediterranean(Ionian Sea)	Italy,Porto Cesareo	PCS	40°14’42.51” N17°52’20.49” E	25	5	7.092 ± 0.2327.669 ± 0.274	0.6340.662	0.4920.615	0.241***0.071**
Mediterranean(Adriatic Sea)	Croatia,Split	CRZ	43°23’58.25” N16°24’54.48” E	25	3	7.300 ± 0.3197.715 ± 0.438	0.6600.681	0.5480.631	0.190***0.075**

Asterisks indicate the p value of each pair-wise comparison:

* p < 0.05;

** p < 0.01;

*** p < 0.001; ns = not significant.