Scalloped Hammerhead microsatellite genotypes (eight loci) representing five regions on Australia's east coast and one location in central Indonesia.

Biodiversity of sharks in the tropical Indo-Pacific is high, but species-specific information to assist sustainable resource exploitation is scarce. The null hypothesis of population genetic homogeneity was tested for scalloped hammerhead shark (Sphyrna lewini, n=244) and the milkshark (Rhizoprionodon acutus, n=209) from northern and eastern Australia, using nuclear (S. lewini, eight microsatellite loci; R. acutus, six loci) and mitochondrial gene markers (873 base pairs of NADH dehydrogenase subunit 4). We were unable to reject genetic homogeneity for S. lewini, which was as expected based on previous studies of this species. Less expected were similar results for R. acutus, which is more benthic and less vagile than S. lewini. These features are probably driving the genetic break found between Australian and central Indonesian R. acutus (F-statistics; mtDNA, 0.751 to 0.903; microsatellite loci, 0.038 to 0.047). Our results support the spatially-homogeneous management plan for shark species in Queensland, but caution is advised for species yet to be studied.

热带印度洋-太平洋海域的鲨鱼物种多样性极高，但可支撑可持续资源开发的物种特异性信息却十分匮乏。本研究以澳大利亚北部及东部海域的锤头双髻鲨（scalloped hammerhead shark, *Sphyrna lewini*，样本量n=244）与尖吻露齿鲨（milkshark, *Rhizoprionodon acutus*，样本量n=209）为研究对象，利用核基因标记（锤头双髻鲨采用8个微卫星位点（microsatellite loci），尖吻露齿鲨采用6个微卫星位点）及线粒体基因标记（mitochondrial gene markers，包含长度为873碱基对的烟酰胺腺嘌呤二核苷酸脱氢酶亚基4（NADH dehydrogenase subunit 4）序列），对种群遗传同质性（population genetic homogeneity）的零假设（null hypothesis）进行了检验。针对锤头双髻鲨，本研究无法拒绝其种群遗传同质性的零假设，这一结果与此前针对该物种的研究结论一致。而更为意外的是，尖吻露齿鲨也得到了相似的结果——相较于锤头双髻鲨，尖吻露齿鲨更多营底栖（benthic）生活，活动能力（vagile）更弱。上述特征或许正是造成澳大利亚与印度尼西亚中部海域尖吻露齿鲨种群间遗传分化（genetic break）的关键因素，相关F统计量（F-statistics）结果显示：线粒体DNA的分化系数为0.751至0.903，微卫星位点的分化系数为0.038至0.047。本研究结果支持昆士兰州针对鲨鱼物种制定的空间均质化管理方案（spatially-homogeneous management plan），但对于尚未开展相关研究的鲨鱼物种，仍需保持审慎态度。