engleski

Solving the mystery of Alloteuthis distribution in the Eastern Adriatic Sea through morphometric and genetic approaches

Two Allotheuthis species have historically been recorded in the Mediterranean Sea and Adriatic basin: A. media and A. subulata. Their identification has largely been descriptive in nature and conducted using morphometric parameters that have proven insufficient and unreliable in the advent of genetic analyses. In this study we have collected samples of loliginids during two consecutive MEDITS expeditions in 2014 (n=32) and 2015 (n=21) covering entire eastern Adriatic Sea. Specimens were caught using the bottom trawl net and frozen immediately on board until laboratory inspection when nine morphological traits were measured for each specimen and samples taken for DNA processing. Using partial sequencing of cytochrome oxidase I (COI) mtDNA gene, 30 individuals were identified as A. media and 21 as A. subulata, with A. media distributed throughout the basin and A. subulata only in its central and southern parts. Alloteuthis media showed high genetic diversity (Hd = 0.88) and statistically significant genetic differentiation between Adriatic, Aegean and Ionian populations in respect to Atlantic haploytpes, as was inferred by the use of publicly available sequences. Alloteuthis subulata in the Eastern Adriatic shared a single haplotype. Analyses of morphometric data suggested that there was no single morphometric character with strong enough power to discriminate between the two species, however, when morphological traits were looked as a composite metric rather than in isolation, 87.5% of individuals were correctly classified as A. media males, A. media females or A. subulata.

Alloteuthis media, Alloteuthis subulata, COI, Adriatic

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