Following the Antarctic Circumpolar Current: patterns and processes in the biogeography of the limpetNacella(Mollusca: Patellogastropoda) across the Southern Ocean

Abstract

Aim We use an integrative biogeographical approach to further understand the evolution of an important Southern Ocean marine benthic element, the limpet genus Nacella (Mollusca: Patellogastropoda). Location Southern Ocean.Methods We used multi-locus time-calibrated phylogeny of Nacella at the scale of the whole Southern Ocean to elucidate the underlying processes involved in the origin and diversification of the genus.Results Divergence-time estimates suggest that soon after its origin during the mid-Miocene (c. 12.5 Ma), Nacella separated into two main lineages currently distributed in (1) South America and (2) Antarctica and the sub-Antarctic islands. We identified two pulses of diversification, during the late Miocene (8 to 5.5 Ma) and the Pleistocene (< 1 Ma).Main conclusions Major periods of climatic and oceanographical change strongly affected the biogeography of Nacella and demonstrate both the longand short-term influence of the Antarctic Circumpolar Current across the Southern Ocean. Our analyses support the validity of all currently recognized Nacella species and reveal a new South-American lineage. This work constitutes the most detailed molecular-based study of an ecologically important, nearshore invertebrate Southern Ocean group and in so doing contributes to the improved understanding of the underlying patterns and processes in the origin and diversification of marine benthic fauna across this globally important region.

Unexpected absence of island endemics: Long‐distance dispersal in higher latitude sub‐Antarctic Siphonaria (Gastropoda: Euthyneura) species

“…We provide a clear picture of (1) the evolutionary relationships among the sub‐Antarctic Siphonaria species and (2) the geographical distribution of each taxon, to depict biogeographical patterns of the genus at high latitudes. As a consequence of direct development in these higher latitude pulmonates, the main biogeographical patterns in Siphonaria across the Indo‐West Pacific (Dayrat et al., ), and patterns recorded in Southern Ocean near‐shore marine molluscs including Nacella (Gonzalez‐Wevar et al., ) and Doris (Wilson et al., ), we expected to find closely related cryptic species, endemic to each island group. Alternatively, long‐distance dispersal mediated by rafting could play a key role in the biogeography of direct developers like Siphonaria permitting a broad distribution of its representatives across the sub‐Antarctic.…”

“…Biogeographical mechanisms explaining the distribution of southern temperate taxa have been debated for more than a century (Crame, ; Darwin, ; Dell, ; Knox, ; Strugnell, Rogers, Prodöhl, Collins, & Allcock, ). Recently, the literature has been characterized by disagreement over the relative importance of vicariance versus dispersal in the biogeography of the Southern Ocean biota but consensus has emerged about the combined significance of these processes (Clarke, Barnes, & Hodgson, ; Fraser, Nikula, Spencer, & Waters, ; González‐Wevar, Nakano, Cañete, & Poulin, ; Gonzalez‐Wevar et al., ; Moon, Chown, & Fraser, ; Nikula, Fraser, Spencer, & Waters, ; Nikula, Spencer, & Waters, ; Poulin, Gonzalez‐Wevar, Díaz, Gérard, & Hüne, ; Saucède, Pierrat, Danis, & David, ; Waters, ).…”

“…The role of long‐distance dispersal by rafting has been especially controversial (Gillespie et al., ; Thiel & Haye, ), with its rarity and unpredictability often hindering the development of testable hypotheses (Cowie & Holland, ; Crisp, Trewick, & Cook, ). In the sub‐Antarctic, rafting events are mainly associated with buoyant kelps, which facilitate dispersal of different groups from invertebrates (Cumming et al., ; Gonzalez‐Wevar et al., ; Helmuth et al., ; Nikula et al., ) to non‐buoyant kelps (Fraser et al., ).…”

Distributional Patterns of Polychaetes Across the West Antarctic Based on DNA Barcoding and Particle Tracking Analyses

“…For example Matschiner et al (2009) concluded that the lack of genetic structuring between populations of the notothenioid, Gobionotothen gibberifrons, throughout the Scotia Sea could be assigned to the passive transport of their larvae during the pelagic development phase by the ACC as indicated by surface drifter trajectories. The geographic distribution of marine taxa within the Southern Ocean reflects the species life-history traits (including bathymetric ranges, developmental modes and larval lifespans) and the influence of circum-Antarctic current systems (Young et al, 2015;González-Wevar et al, 2017;Moreau et al, 2017).…”

Biogeography in Cellana (Patellogastropoda, Nacellidae) with Special Emphasis on the Relationships of Southern Hemisphere Oceanic Island Species

“…For this, we used a specific mutation rate (0.85%– 1.15%) previously estimated for nacellid limpets [28]. An age prior with a normal distribution was applied to the most recent common ancestor (tmrca) of Nacellidae (mean, 38; SD, 3.8), an Upper Eocene fossil of Cellana ampla [29].…”