Diverging patterns of mitochondrial and nuclear DNA diversity in subarctic black spruce: imprint of a founder effect associated with postglacial colonization
Diverging patterns of mitochondrial and nuclear DNA diversity in subarctic black spruce: imprint of a founder effect associated with postglacial colonization
复制标题
DOI：
10.1046/j.1365-294x.2003.01800.x
复制
发表时间：
2003-04-01
影响因子：
4.9
通讯作者：
Bousquet, J
中科院分区：
文献类型：
--
作者：
Gamache, I;Jaramillo-Correa, JP;Bousquet, J
物种边缘的高纬度生态种群可能表现出遗传多样性模式的改变，这是由于或多或少最近的奠基事件以及对气候波动的瓶颈效应造成的。使用种子分散的线粒体 (mt) DNA 和核 (nc) DNA 对加拿大魁北克西北部的九个针叶树黑云杉 (Picea mariana [Mill.] BSP.) 种群的遗传多样性模式进行了研究。在三个位点评估 mtDNA 多样性（有丝分裂型），并评估九个表达序列标签多态性 (ESTP) 位点的 ncDNA 多样性。采样对象包括来自北方森林以及亚北极森林苔原（一个火灾生态交错带）南部和北部分区的种群。对于 ncDNA，来自所有三个植被带的种群都高度多样化，种群差异很小 (theta(N) = 0.014）；即使是最北端的种群也没有表现出稀有等位基因的损失。线粒体型多样性的模式显着不同：北方森林种群的种群内多样性和种群分化很高[每个位点的预期杂合度（H（E））= 0.58和theta（M）= 0.529]，但所有亚北极种群都固定为单一线粒体型（H（E）= 0）。这种变异的缺乏表明了由冰河后殖民期间长距离种子建立引起的奠基事件，这与古生态学数据一致。与核变体的估计相比，仅种子的估计运动（每代有效迁移数量，Nm (M) < 2）受到很大限制，其中包括花粉运动（Nm (N) > 17）。这可以解释亚北极黑云杉线粒体 DNA 中创始人印记的保存。在减少之后，大概是在全新世早期，ncDNA 的多样性将通过花粉介导的基因流迅速补充，并随后在当前覆盖过去 3000 年的较冷时期通过营养分层得以维持。
High-latitude ecotonal populations at the species margins may exhibit altered patterns of genetic diversity, resulting from more or less recent founder events and from bottleneck effects in response to climate oscillations. Patterns of genetic diversity were investigated in nine populations of the conifer black spruce (Picea mariana [Mill.] BSP.) in northwestern Quebec, Canada, using seed-dispersed mitochondrial (mt) DNA and nuclear (nc) DNA. mtDNA diversity (mitotypes) was assessed at three loci, and ncDNA diversity was estimated for nine expressed sequence tag polymorphism (ESTP) loci. Sampling included populations from the boreal forest and the southern and northern subzones of the subarctic forest-tundra, a fire-born ecotone. For ncDNA, populations from all three vegetation zones were highly diverse with little population differentiation (theta(N) = 0.014); even the northernmost populations showed no loss of rare alleles. Patterns of mitotype diversity were strikingly different: within-population diversity and population differentiation were high for boreal forest populations [expected heterozygosity per locus (H (E) ) = 0.58 and theta(M) = 0.529], but all subarctic populations were fixed for a single mitotype (H (E) = 0). This lack of variation suggests a founder event caused by long-distance seed establishment during postglacial colonization, consistent with palaeoecological data. The estimated movement of seeds alone (effective number of migrants per generation, Nm (M) < 2) was much restricted compared to that estimated from nuclear variants, which including pollen movement (Nm (N) > 17). This could account for the conservation of a founder imprint in the mtDNA of subarctic black spruce. After reduction, presumably in the early Holocene, the diversity in ncDNA would have been replenished rapidly by pollen-mediated gene flow, and maintained subsequently through vegetative layering during the current cooler period covering the last 3000 years.