GENOTYPIC DIVERSITY AND GENE FLOW IN BROODING AND SPAWNING CORALS ALONG THE GREAT BARRIER REEF, AUSTRALIA
GENOTYPIC DIVERSITY AND GENE FLOW IN BROODING AND SPAWNING CORALS ALONG THE GREAT BARRIER REEF, AUSTRALIA
复制标题
澳大利亚大堡礁沿线孵化和产卵珊瑚的基因型多样性和基因流
DOI：
--
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
T. Hughes
中科院分区：
文献类型：
--
作者：
D. Ayre;T. Hughes
摘要海洋生物在繁殖方式、幼虫类型和其他生活史特征上表现出很大的差异，这些特征可能会产生重大的进化后果。我们测量了澳大利亚大堡礁沿岸珊瑚遗传变异的地方和地区模式，以确定有性繁殖和无性繁殖对补充的相对贡献，并推断局部(相邻地点之间，相隔5公里)和区域(相距500-1200公里的珊瑚礁之间)的基因流动水平。我们选择了五种常见的孵化物种(楔形顶孢子虫、黑斑顶孢子虫、达米科氏轮虫、海鞘轮虫和柱头轮虫)和四种广播性产卵者(风信子顶孢子虫、天仙花顶孢子虫、米氏顶孢子虫和有效顶孢子虫)，它们涵盖了广泛的幼虫类型和潜在的传播能力。我们在9个物种中的6个物种(4个亲鱼，2个产卵者)中发现了相当大的地方规模的基因多样性。在这6个种群中，每个种群的多基因座遗传多样性(GO)水平与异交有性繁殖的预期水平大致相同(GO：GE平均值在0.85-1.02之间)，尽管一致的单基因座杂合性缺失表明近亲繁殖发生在整个珊瑚礁的规模上。其余3个物种，即海氏交配亲鱼和产卵者，在几个地点显示的多位点基因多样性(GO)显著低于异交有性繁殖(GE)的预期。Acropora valida和A.millepora表现出广泛的局部性无性复制的证据：(1)少数多位点(克隆)基因型在某些位点上数量占优势(Go：GE值低至0.17和0.20)：(2)单基因座基因型频率以杂合子(Cf)的过剩和缺失为特征。Hardy-Weinberg预期)，以及(3)发生了显著的连锁不平衡。4个地点的GE值也都很低(x̄=0.48)。然而，这一结果很可能反映了配子或幼虫的高度限制的传播，因为珊瑚礁内地点之间的遗传变异水平非常高(FSR=0.28)。对于所有物种，我们在每个珊瑚礁内的地点之间检测到相当大的遗传细分(高FSR值)，我们推断幼虫的传播出人意料地有限(即每代迁徙地点的NEM从0.6到3.3不等)，即使在浮游持续时间相对较长的物种中也是如此。然而，我们对珊瑚礁之间等位基因变异(FRT)的估计也表明，对于所有四个广播产卵物种和三个亲鱼来说，幼体的扩散足以维持整个大堡礁(即珊瑚礁之间的NEM为5到31)的中到高水平的基因流动。相比之下，广泛分布的海鱼和水鱼种群(剩下的两种鱼种)联系相对较弱(珊瑚礁之间的NEM分别为1.4和2.5)。我们的结论是，大多数珊瑚的补充都是非常地方性的，特别是在幼鱼中，但有足够的繁殖体被广泛分散，以确保广播产卵和孵化物种在大堡礁形成大量有效的全栖种群。通讯编辑：R.Burton
Abstract Marine organisms exhibit great variation in reproductive modes, larval types, and other life-history traits that may have major evolutionary consequences. We measured local and regional patterns of genetic variation in corals along Australia's Great Barrier Reef to determine the relative contributions of sexual and asexual reproduction to recruitment and to infer levels of gene flow both locally (among adjacent sites, < 5 km apart) and regionally (among reefs separated by 500–1200 km). We selected five common brooding species (Acropora cuneata, A. palifera, Pocillopora damicornis, Seriatopora hystrix, and Stylophora pistillata) and four broadcast spawners (Acropora hyacinthus, A. cytherea, A. millepora, and A. valida), which encompassed a wide range of larval types and potential dispersal capabilities. We found substantial genotypic diversity at local scales in six of the nine species (four brooders, two spawners). For these six, each local population displayed approximately the levels of multilocus genotypic diversity (Go) expected for outcrossed sexual reproduction (mean values of Go:Ge ranged from 0.85 to 1.02), although consistent single-locus heterozygous deficits indicate that inbreeding occurs at the scale of whole reefs. The remaining three species, the brooder S. hystrix and the spawners A. valida and A. millepora displayed significantly less multilocus genotypic diversity (Go) than was expected for outcrossed sexual reproduction (Ge) within each of several sites. Acropora valida and A. millepora showed evidence of extensive localized asexual replication: (1) a small number of multilocus (clonal) genotypes were numerically dominant within some sites (Go:Ge values were as low as 0.17 and 0.20): (2) single-locus genotype frequencies were characterized by both excesses and deficits of heterozygotes (cf. Hardy-Weinberg expectations), and (3) significant linkage disequilibria occurred. For the brooding S. hystrix Go:Ge values were also low within each of four sites (x̄ = 0.48). However, this result most likely reflects the highly restricted dispersal of gametes or larvae, because levels of genetic variation among sites within reefs were extremely high (FSR = 0.28). For all species, we detected considerable genetic subdivision among sites within each reef (high FSR-values), and we infer that larval dispersal is surprisingly limited (i.e., Nem among sites ranging from 0.6 to 3.3 migrants per generation), even in species that have relatively long planktonic durations. Nevertheless, our estimates of allelic variation among reefs (FRT) also imply that for all four broadcast spawning species and three of the brooders, larval dispersal is sufficient to maintain moderate to high levels of gene flow along the entire Great Barrier Reef (i.e., Nem among reefs ranged from 5 to 31). In contrast, widespread populations of S. hystrix and S. pistilata (the two remaining brooders) are relatively weakly connected (Nem among reefs was 1.4 and 2.5, respectively). We conclude that most recruitment by corals is very local, particularly in brooders, but that enough propagules are widely dispersed to ensure that both broadcast spawning and brooding species form vast effectively panmictic populations on the Great Barrier Reef. Corresponding Editor: R. Burton