Ocean currents influence the genetic structure of an intertidal mollusc in southeastern Australia – implications for predicting the movement of passive dispersers across a marine biogeographic barrier

Abstract

Major disjunctions among marine communities in southeastern Australia have been well documented, although explanations for biogeographic structuring remain uncertain. Converging ocean currents, environmental gradients, and habitat discontinuities have been hypothesized as likely drivers of structuring in many species, although the extent to which species are affected appears largely dependent on specific life histories and ecologies. Understanding these relationships is critical to the management of native and invasive species, and the preservation of evolutionary processes that shape biodiversity in this region. In this study we test the direct influence of ocean currents on the genetic structure of a passive disperser across a major biogeographic barrier. Donax deltoides (Veneroida: Donacidae) is an intertidal, soft-sediment mollusc and an ideal surrogate for testing this relationship, given its lack of habitat constraints in this region, and its immense dispersal potential driven by year-long spawning and long-lived planktonic larvae. We assessed allele frequencies at 10 polymorphic microsatellite loci across 11 sample locations spanning the barrier region and identified genetic structure consistent with the major ocean currents of southeastern Australia. Analysis of mitochondrial DNA sequence data indicated no evidence of genetic structuring, but signatures of a species range expansion corresponding with historical inundations of the Bassian Isthmus. Our results indicate that ocean currents are likely to be the most influential factor affecting the genetic structure of D. deltoides and a likely physical barrier for passive dispersing marine fauna generally in southeastern Australia.

Swept away: ocean currents and seascape features influence genetic structure across the 18,000 Km Indo-Pacific distribution of a marine invertebrate, the black-lip pearl oyster Pinctada margaritifera

“…However, ocean currents together with isolation by geographic distance are also likely to maintain sub-regional population structure (e.g. Miller et al [130] for the surf clam Donax deltoides ).…”

Boomeranging around Australia: Historical biogeography and population genomics of the anti‐equatorial fish Microcanthus strigatus (Teleostei: Microcanthidae)

“…To the south, conflicting oceanic currents and low surface temperatures of the Bass Strait act as a barrier to gene flow for many marine species along the southeastern Australian coast (Miller, Versace, Matthews, Montgomery, & Bowie, ). Warmer‐adapted species unable to withstand these lowered temperatures at the southern end of the strait during glacial maxima might show signatures of genetic isolation and divergence that persist into the present day (DiBattista, Randall, Newman, & Bowen, ).…”

Historical demography and colonization pathways of the widespread intertidal seaweed Hormosira banksii (Phaeophyceae) in southeastern Australia

“…The distribution of marine benthic species and patterns of connectivity among populations are driven by a combination of historic and contemporary oceanographic processes (Avise , Palumbi ) although the relative contribution varies between species due to differences in life‐history and biology (Avise , Miller et al. ). Moreover, while habitat availability and continuity enhance gene flow (Ayre et al.…”

“…A combination of complex hydrodynamic patterns, temperature gradients and historic and contemporary disjunctions delineate the boundaries between these biogeographic provinces (Miller et al. ) and help define biogeographic structures. Increasing evidence demonstrates that the location of major barrier systems and phylogenetic breaks corresponds to the prominent province boundaries (Waters and Roy ) and that genetic population structuring varies less within provinces than between provinces (Li et al.…”