Investigating the genetic structure of the parasites Anisakis pegreffii and A. berlandi (Nematoda: Anisakidae) in a sympatric area of the southern Pacific Ocean waters using a multilocus genotyping approach: first evidence of their interspecific hybridization

Eleonora Bello; Marialetizia Palomba; Stephen C Webb; Michela Paoletti; Paolo Cipriani; Giuseppe Nascetti; Simonetta Mattiucci

doi:10.1016/j.meegid.2021.104887

Investigating the genetic structure of the parasites Anisakis pegreffii and A. berlandi (Nematoda: Anisakidae) in a sympatric area of the southern Pacific Ocean waters using a multilocus genotyping approach: first evidence of their interspecific hybridization

Infect Genet Evol. 2021 Aug:92:104887. doi: 10.1016/j.meegid.2021.104887. Epub 2021 Apr 30.

Authors

Eleonora Bello¹, Marialetizia Palomba², Stephen C Webb³, Michela Paoletti⁴, Paolo Cipriani⁵, Giuseppe Nascetti⁴, Simonetta Mattiucci⁶

Affiliations

¹ Department of Biological and Ecological Sciences, Tuscia University, Viale dell'Università snc, 01100 Viterbo, Italy; Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy.
² Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy; Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121 Naples, Italy.
³ Cawthron Institute, Nelson, New Zealand.
⁴ Department of Biological and Ecological Sciences, Tuscia University, Viale dell'Università snc, 01100 Viterbo, Italy.
⁵ Institute of Marine Research (IMR), Bergen, Norway.
⁶ Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Laboratory affiliated to "Istituto Pasteur Italy - Fondazione Cenci-Bolognetti", P.le Aldo Moro 5, 00185 Rome, Italy. Electronic address: simonetta.mattiucci@uniroma1.it.

PMID: 33940197
DOI: 10.1016/j.meegid.2021.104887

Abstract

The southern Pacific Ocean, off the New Zealand coast, has been reported as one sympatric area of the two parasite species Anisakis pegreffii and A. berlandi. Here, a multilocus genotyping approach, based on a panel of eleven DNA microsatellite (SSR) loci plus the sequences analysis of the nuclear nas10 nDNA and the mitochondrial mtDNA cox2 gene loci, was applied to a total of N = 344 adults and larvae of Anisakis spp. from cetacean and fish species, respectively. Out of the newly scored SSR loci, Anisl 15 and Anisl 2 showed fixed alternative alleles between A. pegreffii and A. berlandi resulting as 100% diagnostic loci. Out of SSRs Anisl 00314 and Anisl 7 previously disclosed, two additional loci, i.e., Anisl 4 and Anisl 22, were found to be sex-linked. The Bayesian genotypes clustering approach (STRUCTURE) allowed identification, with a 100% of probability value, N = 208 specimens to the "pure parental" A. pegreffii, N = 133 to the "pure parental" A. berlandi, while one adult and two larval stages showed mixed ancestry between the two groups having, in all cases, a Q-value = 0.50. NEWHYBRIDS analysis assigned (100% of probability) those specimens to their F1 hybrid category. This represents the first evidence of contemporary hybridization between the two parasite species in a sympatric area. The pairwise F_ST values estimated at intraspecific and interspecific level, inferred from both SSR loci and mitochondrial mtDNA cox2 sequences, have also demonstrated the existence of two distinct panmictic units in this study area, corresponding respectively to A. pegreffii and A. berlandi. The results obtained support the useful application of a multilocus approach in the identification of sibling species and their hybrid categories in sympatric areas. The possible use of sex-linked SSR loci of the two species of the A. simplex (s. l.), for sex determination of their larval stages, is also suggested.

Keywords: Anisakis; Hybridization; New Zealand; SSR loci; Sex-linked loci; mtDNA cox2; nas10 nDNA.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Anisakis / genetics*
Female
Genetic Variation*
Genotype*
Hybridization, Genetic*
Male
Multilocus Sequence Typing
New Zealand
Pacific Ocean
Species Specificity
Sympatry