Kidwell M G
Department of Ecology and Evolutionary Biology, University of Arizona, Tucson 85721.
Annu Rev Genet. 1993;27:235-56. doi: 10.1146/annurev.ge.27.120193.001315.
Although there are several likely instances of trans-kingdom lateral transfer of genomic sequences involving eukaryotes and prokaryotes, almost all well-documented cases of eukaryote to eukaryote transfer seem to involve mobile elements or other parasitic sequences. Consistent with general observations of phylogenetic regularity, the limited molecular evidence suggests that lateral transfer of eukaryotic genomic sequences is at best very rare. However, due to limited data, the possibility of rare transfers that could have considerable evolutionary significance cannot be ruled out. A possible propensity for lateral transfer by mobile elements may reflect their innate capacity for genomic wandering. In addition, occasional cross-species mobility may play a critical role in the long-term evolutionary survival of these elements and have been subject to natural selection. Much work is needed to fully understand the dynamics of TEs and other multigene families. Problems of paralogy, recombination, and variation in evolutionary rates currently present important difficulties in distinguishing conclusively between occasional lateral transfer and strictly vertical transfer. The importance of lateral transfers for host organisms must await answers to more general questions about the long-term evolutionary significance of mobile elements and the extent to which they can act as vectors for host genomic sequences.
尽管存在一些涉及真核生物和原核生物的跨王国基因组序列横向转移的可能实例，但几乎所有有充分记录的真核生物到真核生物转移的案例似乎都涉及移动元件或其他寄生序列。与系统发育规律性的一般观察结果一致，有限的分子证据表明，真核生物基因组序列的横向转移充其量非常罕见。然而，由于数据有限，具有相当大进化意义的罕见转移的可能性不能排除。移动元件横向转移的一种可能倾向可能反映了它们固有的基因组游动能力。此外，偶尔的跨物种移动可能在这些元件的长期进化生存中起关键作用，并已受到自然选择。要全面了解转座元件和其他多基因家族的动态，还需要做很多工作。目前，旁系同源性、重组和进化速率变化的问题在确凿区分偶尔的横向转移和严格的垂直转移方面存在重要困难。横向转移对宿主生物体的重要性必须等待关于移动元件的长期进化意义以及它们作为宿主基因组序列载体的作用程度等更普遍问题的答案。
