Cotton James A, Page Roderic D M
Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
BMC Evol Biol. 2006 Aug 29;6:66. doi: 10.1186/1471-2148-6-66.
The shape of phylogenetic trees has been used to make inferences about the evolutionary process by comparing the shapes of actual phylogenies with those expected under simple models of the speciation process. Previous studies have focused on speciation events, but gene duplication is another lineage splitting event, analogous to speciation, and gene loss or deletion is analogous to extinction. Measures of the shape of gene family phylogenies can thus be used to investigate the processes of gene duplication and loss. We make the first systematic attempt to use tree shape to study gene duplication using human gene phylogenies.
We find that gene duplication has produced gene family trees significantly less balanced than expected from a simple model of the process, and less balanced than species phylogenies: the opposite to what might be expected under the 2R hypothesis.
While other explanations are plausible, we suggest that the greater imbalance of gene family trees than species trees is due to the prevalence of tandem duplications over regional duplications during the evolution of the human genome.
系统发育树的形状已被用于通过将实际系统发育的形状与物种形成过程的简单模型下预期的形状进行比较，来推断进化过程。先前的研究集中在物种形成事件上，但基因复制是另一种类似于物种形成的谱系分裂事件，而基因丢失或缺失类似于灭绝。因此，基因家族系统发育树形状的度量可用于研究基因复制和丢失的过程。我们首次系统地尝试利用树的形状，通过人类基因系统发育来研究基因复制。
我们发现，基因复制产生的基因家族树的平衡性明显低于该过程简单模型的预期，且低于物种系统发育树：这与2R假说下的预期相反。
虽然其他解释也有道理，但我们认为基因家族树比物种树的不平衡性更大，是由于在人类基因组进化过程中串联重复比区域重复更为普遍。
