英语翻译This approach reveals that C-value data are already available for 152 out of the approx.500 families currently recognized covering all four major subdivisions and 15 out of the 20 higher level groups.However,it is clear that more work is
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英语翻译This approach reveals that C-value data are already available for 152 out of the approx.500 families currently recognized covering all four major subdivisions and 15 out of the 20 higher level groups.However,it is clear that more work is
英语翻译
This approach reveals that C-value data are already available for 152 out of the approx.500 families currently recognized covering all four major subdivisions and 15 out of the 20 higher level groups.However,it is clear that more work is needed for full phylogenetic representation.Thus,no C-value data exist for many families with large numbers of genera (e.g.Melasto-mataceae,| nI-1 --r r higher eudicots-rosids; and Gesneriaceae,higher eudicots-asterids).Moreover the data are still largely concentrated in a few families predominantly in the higher eudicots and monocots.Thus just three families,the Fabaceae (higher eudicots-rosids),Poaceae (monocots-commelinoids),and Asteraceae (higher eudicots-asterids) account for more than 34% of the total number of C-values,and the addition of just four further families,Alliaceae (monocots-Asparagales),Solanaceae (higher eudicots-asterids),Ranunculaceae (lower eudicots-Ranunculales) and Commelinaceae (monocots-comme-linoids) account for more than 525 % of the data.Only 47 families have ten or more C-values whereas 51 families are represented by just one C-value.
EVIDENCE FOR A SMALL ANCESTRAL GENOME SIZE IN THE ANGIOSPERMS
The best explanation for this phylogenetic distribution of C-values is that ancestral angiosperms,like most extant species,almost certainly had small C-values,whereas the possession of very large C-values represents a derived condition that has arisen independently at least twice during angiosperm evolution.Even if significant portions of the phylogenetic patterns at the deepest levels were inaccurate,it would not change the conclusion that the ancestral angiosperm genomes were small.The recent proposal by Bennetzen and Kellogg (1997) that plants may have a 'one way ticket to genomic obesity' through amplification of retrotransposons agrees with this.
英语翻译This approach reveals that C-value data are already available for 152 out of the approx.500 families currently recognized covering all four major subdivisions and 15 out of the 20 higher level groups.However,it is clear that more work is
这种做法表明,C值数据已可供152位的约.500个家庭目前公认的,涵盖所有四个主要区分单位和15个列在20个较高水平的群体.不过,很显然,需要做更多的工作,为全面系统发育的代表性.因此,没有C值数据存在许多家庭同大批属(如melasto - mataceae ,|镍- 1 -为高e udicots-蔷薇分支;苦苣苔科,更高e udicots-菊分支) .而且这些数据在很大程度上仍然集中在少数几个家庭为主,而在较高eudicots和monocots .因此,只有三个家庭,豆科(高eudicots -蔷薇分支) ,而且这些数据在很大程度上仍然集中在少数几个家庭为主,而在较高eudicots和monocots .因此,只有三个家庭,豆科(高eudicots -蔷薇分支) ,禾本科( monocots - commelinoids ) ,菊科(高eudicots -菊分支)的帐户超过34个,占总人数的C值,并增设短短的4进一步家人,葱( monocots -天门冬目) ,茄科(高eudicots -菊分支) ,毛茛科(下eudicots - ranunculales )和commelinaceae ( monocots - comme - linoids )占多525 %的数据.只有47个家庭有10个或更多的C -值,而51个家庭的代表只有一个C值.
证据显示,一个小型祖先基因组大小在被子植物
最好的解释这个亲缘分布的C值是被子植物的祖先一样,大多数现存物种,几乎可以肯定了小型的C -价值观,而藏有很大的C -价值观,代表着一种衍生的条件下,出现了独立至少两次在被子植物的进化.即使相当大一部分的系统发育模式在最深层次是不准确的,它不会改变的结论,即祖被子植物基因组小.最近提案bennetzen和Kellogg ( 1997 ) ,植物可能有'一个单程票,以肥胖基因通过扩增反转录转座子赞同这一点.差不多吧?