Data from: Lack of genetic introgression between wild and selectively bred Sydney rock oysters Saccostrea glomerata

Sydney rock oysters Saccostrea glomerata are among the most important estuarine species on the eastern coast of Australia and also the basis of a major aquaculture industry. The industry now largely relies on Sydney rock oysters that have been selectively bred for fast growth and disease resistance. Selectively bred S. glomerata are currently farmed in estuaries that also sustain wild populations of Sydney rock oysters, providing the opportunity for interbreeding. This has led to concern that gene flow from farmed, selectively bred oysters could alter the genetic variability of wild oyster populations. Here, we use next-generation genotype-by-sequencing to test for genetic introgression between wild and farmed, selectively bred (B2 line) Sydney rock oysters from 2 sites in the Georges River, NSW. Strong genetic partitioning was identified between the wild and selectively bred populations. There was no evidence of gene flow in the form of introgression, even though selectively bred B2 oysters have been farmed in the Georges River since the early 1990s. Contrary to our expectations, we also found significantly higher levels of genetic diversity and heterozygosity in the selectively bred population relative to the wild population. The relatively low level of genetic diversity that we detected in wild oysters may be particularly relevant to the adaptive capacity of this species in the wild.

悉尼岩牡蛎（Saccostrea glomerata）是澳大利亚东海岸最重要的河口物种之一，同时也是当地核心水产养殖产业的重要支撑。当前该产业主要依赖经选育获得快速生长与抗病特性的悉尼岩牡蛎。经选育的S. glomerata目前养殖在同时栖息有野生悉尼岩牡蛎种群的河口区域，这为两类种群间的杂交提供了可能。这一情况引发了学界担忧：养殖选育型牡蛎的基因流可能会改变野生牡蛎种群的遗传变异水平。本研究采用新一代分型测序（next-generation genotype-by-sequencing）技术，针对新南威尔士州（NSW）乔治河两处采样点的野生悉尼岩牡蛎与养殖选育型（B2品系，B2 line）悉尼岩牡蛎之间的遗传渐渗现象进行检测。研究在野生种群与选育种群之间检测到显著的遗传分化。尽管自20世纪90年代初以来，选育型B2牡蛎就已在乔治河开展养殖，但并未发现任何以遗传渐渗为形式的基因流证据。与研究预期相悖的是，本研究还发现选育种群的遗传多样性与杂合性水平显著高于野生种群。本研究在野生牡蛎中检测到的较低遗传多样性水平，或与该物种在野外环境中的适应能力密切相关。