Population genetics meets phylogenetics: new insights into the relationships among members of the genus Euthynnus (family Scombridae)

Abstract

Euthynnus (family Scombridae) is a genus of marine pelagic fish species with a worldwide distribution that comprises three allopatric species: E. alletteratus, E. affinis and E. lineatus. All of them targeted by artisanal and commercial fisheries. We analyzed 263 individuals from Atlantic and Pacific Oceans using two genetic markers, the mtDNA Control Region (350 bp) and nuclear calmodulin (341 bp). The results obtained challenge the phylogeny of this group. We found a deep genetic divergence, probably at species level, within E. alletteratus, between the North Atlantic-Mediterranean and the Tropical East Atlantic. This deep genetic divergence was tested with several species delimitation methods. This complete phylogeographic association between the North Atlantic and the Tropical East Atlantic support the hypothesis of two cryptic species. In addition, population genetic heterogeneity was detected between the North East Atlantic–Mediterranean and North West Atlantic regions. Our results indicate two scales of differentiation in what is currently considered a single population. Accordingly, for management purposes, the populations of E. alletteratus, should be divided into a minimum of three management units. On the other hand, the high level of differentiation found in E. alletteratus contrasts with the shallow genetic divergence of E. affinis and E. lineatus.

Differentiation of Spatial Units of Genus Euthynnus from the Eastern Atlantic and the Mediterranean Using Otolith Shape Analysis

“…Otolith shape analysis complements the genetics study already published on stock structure of this species [65]. The findings from our research on little tunny in the Eastern Atlantic have unveiled a new perspective.…”

“…Biological differences between both areas analyzed in this work have been poorly documented. In the genetic aspect, differentiating results could indicate the presence of separate species [65,66]. Olle et al (2022) observed that the mtDNA CR divergence between the two areas studied of E. alletteratus was nearly 20 times larger than the CR divergence between E. lineatus (Pacific Ocean) and E. affinis (Indian Ocean), and similar to the distance that separates E. alletteratus respectively from E. affinis and from E. lineatus [65].…”

“…In the genetic aspect, differentiating results could indicate the presence of separate species [65,66]. Olle et al (2022) observed that the mtDNA CR divergence between the two areas studied of E. alletteratus was nearly 20 times larger than the CR divergence between E. lineatus (Pacific Ocean) and E. affinis (Indian Ocean), and similar to the distance that separates E. alletteratus respectively from E. affinis and from E. lineatus [65]. Regarding growth, almost all the works published so far come from very specific areas and mostly from the Mediterranean [39,40,42,43].…”

Resolved and Redeemed: A New Fleck to the Evolutionary Divergence in the Genus Scomberomorus Lacepède, 1801 (Scombridae) With Cryptic Speciation

“…(Som, 2015). M t D N A i n t r o g r e s s i o n o c c u r s b e t w e e n s p e c i e s i n Scomberomorus (e.g., Morgan et al, 2013), and the possibility of incomplete lineage sorting in the youngest lineages in Scombridae has been suggested (Olléet al, 2022). Collette and Russo (1984), based on a cladistic analysis of 58 characters, identified six species groups in Scomberomorus, viz., the "sinensis group," which contains only S. sinensis; the "commerson species group" with S. commerson, S. niphonius, S. queenslandicus, and S. cavalla; the monotypic "munroi species group"; the "semifasciatus species group" with S. semifasciatus, S. plurilineatus, and S. lineolatus; the "guttatus species group" with S. guttatus, S. multiradiatus, and S. koreanus; and the "regalis species group" with S. regalis, S. tritor, S. maculatus, S. concolor, S. sierra, and S. brasiliensis.…”

Larval Retention and Homing Behaviour Shape the Genetic Structure of the Bullet Tuna (Auxis rochei) in the Mediterranean Sea

“…Additionally, a collection of 41 new sequences was added to the dataset and is available online under accession numbers MW574141-MW574181. All sequences of the dataset were generated following the procedures of Alvarado [31] and Ollé [32] and aligned with ClustalW [33] implemented in Geneious v7.1.9 [34]. Haplotypes were collapsed using DNAsp 6.12.03 [35] and assigned to the previously mentioned mitotype I and mitotype II based on reference sequences AB103467 and AB103468, respectively.…”