engleski

Morphometric characteristics and nuclear marker Me 15/16 analyses of mussel Mytilus galloprovincialis populations along the eastern Adriatic coast

Mussels Mytilus spp. belong to a group of key species in marine, coastal ecosystems. This work demonstrated the dominant presence and morphological variations (shell shape) of Mediterranean mussel M. galloprovincialis along eastern Adriatic coast (22 sites), from Limski kanal to Dubrovnik. Morphometric characteristics of sampled mussel specimens were inside normal values for M. galloprovincials: height/length 55.89±5.08 % and width/length 38.76±3.42 %. Different alleles coding an adhesive protein of the byssus were observed in the population of mussels in Croatian Adriatic Sea. Only 2 specimens among the 110 analysed were found that showed a heterozygote genotype: one with an E (edulis) allele and one with a T (trossulus) allele, all others were identified as homozygotes for the G (galloprovincialis) allele . The presence of the E allele at low frequency in M. galloprovincialis mussels can simply be explained by introgression, as M. edulis and M. galloprovincialis are known to hybridise and exchange genes in the European contact zone. The presence of the T allele is very surprising. According to the current distribution of the three species, a T allele would first need to introgress the edulis genetic background before to have the opportunity to introgress the galloprovincialis background, while this is not observed –the T allele has never been sampled in M. edulis to date. Shell height/length values of heterozygote mussels: GE (h/l 46.90 %, w/l 38.45 %) and MT (h/l 48.91 %, w/l 39.11 %) were closer to M. edulis (h/l 44.50±2.26 %, w/l 35.38±2.00 %), while the width/length values were typical for M. galloprovincialis. Further analyses using different genetic markers and detailed shell morphometric measurements on larger numbers of specimens are needed to clarify the processes underlying introgression in Mediterranean mussels.

M. galloprovincialis; Me 15/16; heterozygote; morphometric variation; Adriatic Sea

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