Department of Life Science, Pingtung University of Science and Technology, Pingtung, Taiwan.
BMC Evol Biol. 2010 Apr 30;10:124. doi: 10.1186/1471-2148-10-124.
Species in the varied geographic topology of Taiwan underwent obvious demographic changes during glacial periods. Cinnamomum kanehirae has been exploited for timber and to obtain medicinal fungi for the past 100 years. Understanding anthropogenic factors influencing the demography of this species after the last glacial maximum (LGM) is critically important for the conservation of this species.
Populations of C. kanehirae were classified into four geographic regions: northwestern (NW), west-central (WC), southwestern (SW), and southeastern (SE). In total, 113 individuals from 19 localities were sampled, and variations in the chalcone synthase gene (Chs) intron and leafy (Lfy) intron-2 sequences of nuclear DNA were examined in order to assess phylogeographic patterns, the timescales of demographic and evolutionary events, and recent anthropogenic effects. In total, 210 Chs and 170 Lfy sequences, which respectively constituted 36 and 35 haplotypes, were used for the analyses. Estimates of the migration rate (M) through time revealed a pattern of frequent gene flow during previous and the present interglacials. The isolation-by-distance test showed that there generally was no significant correlation between genetic and geographic distances. The level of among-region genetic differentiation was significant when comparing eastern to western populations. However, no significant among-region genetic differentiation was found in comparisons among the four geographic regions. Moreover, essentially no genetic structuring was found for the three regions west of the CMR. A fit of spatial range expansion was found for pooled and regional samples according to the non-significant values of the sum of squared deviations. Using the Bayesian skyline plot (BSP) method, a recent bottleneck after the LGM expansion was detected in both regional and pooled samples.
Common haplotype distributions among geographic regions and the relatively shallow genetic structuring displayed are the result of historical gene flows. Southward dispersals in an earlier time frame from the NW region and in a later time frame from the SE region were inferred. The BSP analysis suggested a postglacial expansion event. Recent trends, however, refer to a bottleneck due to human interventions observed for both pooled and regional C. kanehirae samples.
台湾多样的地理拓扑结构中的物种在冰期经历了明显的人口变化。肉桂在过去的 100 年里一直被用于木材和药用真菌的获取。了解末次冰期后影响该物种人口动态的人为因素对于该物种的保护至关重要。
我们将肉桂种群分为四个地理区域：西北（NW）、中西部（WC）、西南（SW）和东南（SE）。总共从 19 个地点采样了 113 个人，检查了查尔酮合酶基因（Chs）内含子和核 DNA 的叶状（Lfy）内含子-2 序列的变异，以评估系统地理格局、人口和进化事件的时间尺度以及最近的人为影响。总共使用了 210 个 Chs 和 170 个 Lfy 序列，分别构成 36 个和 35 个单倍型。通过时间估计的迁移率（M）揭示了在以前和现在的间冰期频繁基因流的模式。隔离距离测试表明，遗传距离和地理距离之间通常没有显著相关性。与东部种群相比，西部种群之间的区域间遗传分化水平显著。然而，在四个地理区域之间的比较中没有发现显著的区域间遗传分化。此外，CMR 以西的三个地区几乎没有发现遗传结构。根据平方和偏差的非显著值，发现了汇集和区域样本的空间范围扩张拟合。使用贝叶斯天际线图（BSP）方法，在区域和汇集样本中都检测到了末次冰期扩张后的近期瓶颈。
地理区域之间常见的单倍型分布和相对较浅的遗传结构是历史基因流的结果。推断在较早的时间框架内从西北区向南扩散，在较晚的时间框架内从东南区向南扩散。BSP 分析表明存在冰后期扩张事件。然而，最近的趋势是由于人为干预，无论是在汇集还是区域肉桂中都观察到瓶颈。
