Genetic structure and effective population size of Sydney rock oysters in eastern Australia

Jessica O'Hare*, Paolo Momigliano, David Raftos, Adam Stow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Oyster reef habitats are critical to coastal biodiversity and their decline has prompted restoration efforts in Australia. Knowledge gaps exist regarding the population structure and diversity of key species in these habitats. This may be critical information for the design of effective restoration programs. Sydney rock oysters (Saccostrea glomerata) are the dominant reef-forming bivalve in eastern Australia. Wild populations of S. glomerata have declined due to overharvesting, disease outbreaks, coastal development and reduced water quality. Here, we use genetic markers identified by genome-wide sequencing to investigate the genetic structure and diversity of wild Sydney rock oysters throughout their distribution in eastern Australia. We examine evidence for past population bottlenecks and spatial genetic structure associated with the East Australian Current. Analysis of 3, 400 neutral single-nucleotide polymorphisms (SNPs) revealed a single population, and an overlap with two other Saccostrea sp. at the northernmost boundary of the distribution. We detected signals of asymmetric gene flow consistent with the direction of the East Australian Current, and spatial structure patterns of limited genetic isolation by distance and spatial autocorrelation in the northern region (which experiences stronger effects of the East Australian Current) but not in the southern region of the distribution. We found no evidence of significant recent bottlenecks, with high effective population size throughout the species’ range. This information will provide a baseline against which to assess the impact of restoration projects, and guide strategies for sourcing stock for the enhancement of wild oyster populations. Our results provide a positive outlook for the resilience and adaptive capacity of Sydney rock oysters, and highlight wild populations as valuable resources for aquaculture and restoration initiatives.
Original languageEnglish
Pages (from-to)427-442
Number of pages16
JournalConservation Genetics
Volume22
Issue number3
Early online date12 Mar 2021
DOIs
Publication statusPublished - Jun 2021

Keywords

  • Demographic modelling
  • Genetic diversity
  • Population genetics
  • Stock structure

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