Global invasion genetics of two parasitic copepods infecting marine bivalves

Abstract

Invasive species, and especially invasive parasites, represent excellent models to study ecological and evolutionary mechanisms in the wild. To understand these processes, it is crucial to obtain more knowledge on the native range, invasion routes and invasion history of invasive parasites. We investigated the consecutive invasions of two parasitic copepods ( Mytilicola intestinalis and Mytilicola orientalis ) by combining an extensive literature survey covering the reported putative native regions and the present-day invaded regions with a global phylogeography of both species. The population genetic analyses based on partial COI sequences revealed significant population differentiation for M . orientalis within the native region in Japan, while introduced populations in North America and Europe could not be distinguished from the native ones. Thus, M . orientalis ’ invasion history resembles the genetic structure and recent spread of its principal host, the Pacific oyster, Crassostrea gigas , while M. intestinalis lacks population genetic structure and has an overall low genetic diversity. Therefore, the native origin of M . intestinalis remains unclear. With this study, we demonstrate that even highly related and biologically similar invasive species can differ in their invasion genetics. From this, we conclude that extrapolating invasion genetics dynamics from related invasive taxa may not always be possible.

Spread of the invasive shell-boring annelid Polydora websteri (Polychaeta, Spionidae) into naturalised oyster reefs in the European Wadden Sea

“…Some species, such as the Pacific oyster Crassostrea (Magallana) gigas (Thunberg, 1793), have been repeatedly translocated into new environments and are nowadays traded and cultured globally (Ruesink et al 2005;Lucas 2019). Consequently, associated organisms that live in or on the oysters, such as sessile and boring species or parasites, have also unintentionally been introduced outside their native range (Elton, 1958;Goedknegt et al 2016;Feis et al 2019). One group of organisms that is likely to be co-introduced with commercial molluscs are shell-boring polychaetes, of which polydorins are the most common group (Blake 1969; Communicated by P. Lana Boonzaaier et al 2014).…”

The Importance of Marine Bivalves in Invasive Host–Parasite Introductions

“…For example, a recent study combined genetic sequencing of the two parasitic copepods, Mytilicola intestinalis and Mytilicola orientalis, with an in-depth literature review to identify native and invaded ranges. In the case of M. orientalis there was strong overall population differentiation between the native Japanese range and the invaded North American and European ranges, with the invasion history of this copepod species reflecting the movement of its principle host, C. gigas (Feis et al, 2019). However, although population sequencing proved effective for M. orientalis, the native range of M. intestinalis remained unclear due to a lack of population genetic structure, suggesting that for some species extrapolation of the invasion history using genetic analyses is not feasible.…”

Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia

“…On the other hand, the lack of reports of R. dubia on farmed M. gigas might also be derived from the lack of research on fauna associated with Pacific oysters, particularly in the Mediterranean Sea. There are only three papers reporting species associated with farmed M. gigas in the Mediterranean Sea [43][44][45], while no papers refer to the fauna associated with natural populations of Pacific oysters (Mikac et al, in prep.). Moreover, comprehensive investigation of the literature dealing with fauna associated with farmed Pacific oysters outside the Mediterranean (Mikac et al, in prep.…”