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During the postgenomics era the information about genomic sequence and gene functions provides a new foundation for evolutionary biology and ecology As the first whole-genome sequenced plant Arabidopsis thaliana and its wild relatives have played a critical role in understanding the evolution of genomics and speciation Both A halleri and A lyrata are closely related to the model species A thaliana A halleri ssp gemmifera occurs in northeastern China Japan and Taiwan; while its sister A halleri ssp halleri is mainly distributed in Europe Geographical barriers such as Tienshan Mountain Range isolate these intraspecific sisters Likewise A lyrata ssp kamchatica and ssp lyrata occur in East Asia and North America respectively Such distribution patterns seem to be consistent with allopartic speciation The comparison between ancestral and extant polymorphism by multilocus can be informative about the population genetics of speciation In this study we collected and analyzed DNA sequences of 98 genes from four wild relatives of A thaliana A halleri ssp gemmifera A halleri ssp halleri A lyrata ssp kamchatica and A lyrata ssp lyrata The ancestral states of these four species were compared to each other in terms of level of genetic variation However the ancestral species at the time of speciation were substantially more polymorphic than the extant geographical populations The observations are not fully compatible with speciation by strict allopatry At some species pairs parapatric speciation seems more reasonable in speciation of Arabidopsis The 98 gene sequences are also used for the congruence test between gene genealogy and species phylogeny Only 28 genes support the species phylogeny but there are 23 genes supports another major genealogy { lyrata} thaliana Based on the phylogenetic position change of A lyrata ssp kamchatica and Ks value for each species pair suggested the recent directional gene flow between A halleri ssp gemmifera and A lyrata ssp kamchatica

阿拉伯芥是第一个完成基因体定序的开花植物，其基因体资讯提供植物学研究的重要依据；在解析阿拉伯芥属物种的亲缘关系以及种化机制等重要的演化议题时，阿拉伯芥近缘的野生物种自然成了不可或缺的关键；跟阿拉伯芥近缘的物种包括A halleri及A lyrata，其中A halleri ssp gemmifera主要分布於中国东北、日本以及台湾，与近缘的A halleri ssp halleri其分布於欧洲隔著天山及大陆的障蔽，而A lyrata ssp kamchatica主要分布於东北亚及台湾，与分布於北美五大湖的A lyrata ssp lyrata被北极圈所分隔，这样的分布模式暗示异域种化的可能。藉由多基因分析比较祖先物种与现生物种遗传歧异度的相关可提供讯息探讨种化时期的族群遗传结构，本研究针对A halleri ssp gemmifera、A halleri ssp halleri及A lyrata ssp kamchatica、A lyrata ssp lyrata四个物种，两对互为亚种的姊妹群，以阿拉伯芥为外群进行研究，在四个物种完成98个同源基因的分子序列，利用套装软体MCMCcoal来估算祖先物种的遗传变异，亦估算现生物种的核苷酸歧异度，观察到？多物种配对中祖先物种遗传多型性大於现生物种DNA歧异度，显示异域种化模型并无法完全解释阿拉伯芥属物种的种化模式，在某些物种配对间邻域种化模式应比异域种化更为可能；在基因树与物种树的比较，98个基因片段的亲缘模式只有28个是与已知物种树一致的，有23个基因其树状图支持{ lyrata} thaliana的型式，藉由kamchatica位置的变化以及估算各物种配对间的平均同义置换率，推测在A halleri ssp gemmifera与A lyrata ssp kamchatica间具有近代的单方向基因交流。

Recent studies indicate that extensive genetic and epigenetic changes often occur at the early stage of allopolyploid\'s genome formation,these changes have played a significant role in stabilization of newly formed genome of species.

研究表明，异源多倍体在形成的早期会出现广泛的基因组遗传和表观遗传变化，这些变化直接关系到物种的形成和稳定。

Based on the above results, we suggest that selective changes of low-copy sequences occur rapidly after polyploid formation, which may contribute to the differentiation of chromosomes in newly formed allopolyploid wheats.

认为这些低拷贝的染色体专化序列对于多倍体形成后部分同源染色体之间的进一步分化起着重要作用。

Almost all of this increase will occur in the developing countries.

几乎所有的人口增加将发生在开发中国家。

Things occur in with friends , like jealousy , aloofness , diffidation, are not not fresh .

哥们间除了的事，像妒忌、疏远、绝交，并不新鲜。

Things occur between friends, like jealousy, aloofness, diffidation, are not fresh.

朋友间发生的事，像嫉妒，疏远，绝交，并不新鲜。

Things occur between friends, like jealousy, aloofness, deification, is not fresh.

朋友间发生的事，像妒忌、疏远、绝交，并不新鲜。

Alopecia universalis can occur at any age, and is currently believed to be an autoimmune disorder .

泛脱发，就可能发生在任何年龄，目前认为是一种自身免疫性疾病。

Alpha decay commonly occurs in elements with atomic numbers greater than 83, but can occur in some rare-earth elements in the atomic-number range of 60 to 71.

发射α粒子的主要是重于铋(lutetium，原子序数83)和从钕(neodymium，原子序数60)到镏(Iutetium，原子序数71)的稀土元素，α衰变的半衰期，从1微秒(10-6秒)到约1017秒。

And since the damage can occur without signs of altitude sickness, we can only assume that the worse you feel, the more at risk you are.

同时由于这种损害的发生时并没有高山病症状的出现，所以我们只能假设，登山者的感受越糟，登山者面临的风险越大。

Do you know, i need you to come back

你知道吗，我需要你回来

Yang yinshu、Wang xiangsheng、Li decang,The first discovery of haemaphysalis conicinna.

1〕 杨银书，王祥生，李德昌。安徽省首次发现嗜群血蜱。