High genetic diversity and lack of structure underlie the invasion history of the non-indigenous oyster Dendostrea cf. crenulifera (Mollusca, Ostreida, Ostreidae) spreading in the eastern Mediterranean Sea

By

Delcour, Nathan
Garzia, Matt
Oliver, Graham
Berrilli, Emanuele
Toso, Andrea
Bariche, Michel
Albano, Paolo Giulio.
Mariottini, Paolo
Salvi, Daniele

Type

Article

Date of Publication

2025-10-3

Original Publication

Zoosystematics and evolution

Volume

101

Pages

277--302

Subjects

Alien , bivalve , cox1 , phylogenetics , phylogeography , systematics , true oyster

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia Pensoft

Identifiers

DOI: https://doi.org/10.3897/neobiota.101.154917

 

Abstract

Since the opening of the Suez Canal in 1869, hundreds of Indo-Pacific species have rapidly colonised the Mediterranean. Understanding the spatial and temporal patterns of this biological invasion is crucial for assessing its ecological impact. A notable example is the non-indigenous oyster Dendostrea sp., first discovered in Türkiye in 1998 and later found throughout the easternmost Mediterranean, though its identity remained uncertain. This study clarifies the taxonomic identity and the introduction pathways of Dendostrea sp. using molecular analyses. Over 100 specimens from 25 sites in the eastern Mediterranean, as well as Île d’Ambre and Rodrigues in the Mauritius Archipelago (the native range), were sequenced for mitochondrial DNA (COI) and compared to 422 sequences from GenBank. Phylogenetic and species delimitation analyses identified the Mediterranean oysters as D. cf. crenulifera, conspecific with oysters from Rodrigues. The Mediterranean populations exhibited high genetic diversity, lack of phylogeographic structure and showed no evidence of a founder effect. These findings suggest that D. cf. crenulifera entered the Mediterranean over two decades ago through multiple shipping-mediated introductions from its native range and successfully established, likely aided by the decline of native biodiversity. The observed genetic diversity pattern across the Mediterranean indicates high propagule pressure driving the species’ invasion history, which likely underpins its establishment success by reducing the deleterious consequences of population bottlenecks and overcoming the so-called genetic paradox. This study underscores the value of molecular surveys in identifying taxonomically challenging non-indigenous species and uncovering their invasion histories.