Pie Marcio R, Torres Rodrigo A, Brito Diego M A
Laboratório de Parasitologia Evolutiva, Departamento de Zoologia, Setor de Ciências Biológicas, Universidade Federal do Paraná, C.P. 19020, Curitiba PR 81531-980, Brazil.
Genetica. 2007 Sep;131(1):51-8. doi: 10.1007/s10709-006-9112-7. Epub 2006 Oct 25.
Despite remarkable advances in genomic studies over the past few decades, surprisingly little is known about the processes governing genome evolution at macroevolutionary timescales. In a seminal paper, Hinegardner and Rosen (Am Nat 106:621-644, 1972) suggested that taxa characterized by larger genomes should also display disproportionately stronger fluctuations in genome size. Therefore, according to the Hinegardner and Rosen (HR) hypothesis, there should be a negative correlation between average within-family genome size and its corresponding coefficient of variation (CV), a prediction that was supported by their analysis of the genomes of 275 species of fish. In this study we reevaluate the HR hypothesis using an expanded dataset (2050 genome size records). Moreover, in addition to the use of standard linear regression techniques, we also conducted modern comparative analyses that take into account phylogenetic non-independence. Our analyses failed to confirm the negative relationship detected in the original study, suggesting that the evolution of genome size in fishes might be more complex than envisioned by the HR hypothesis. Interestingly, the frequency distribution of fish genome sizes was strongly skewed, even on a logarithmic scale, suggesting that the dynamics underlying genome size evolution are driven by multiplicative phenomena, which might include chromosomal rearrangements and the expansion of transposable elements.
尽管在过去几十年里基因组研究取得了显著进展，但令人惊讶的是，在宏观进化时间尺度上，我们对基因组进化过程的了解却少之又少。在一篇具有开创性的论文中，海因加德纳和罗森（《美国博物学家》106:621 - 644，1972年）提出，基因组较大的分类群在基因组大小上也应该表现出不成比例的更强波动。因此，根据海因加德纳和罗森（HR）假说，家族内平均基因组大小与其相应的变异系数（CV）之间应该存在负相关，他们对275种鱼类基因组的分析支持了这一预测。在本研究中，我们使用一个扩展数据集（2050个基因组大小记录）重新评估了HR假说。此外，除了使用标准线性回归技术外，我们还进行了考虑系统发育非独立性的现代比较分析。我们的分析未能证实原研究中检测到的负相关关系，这表明鱼类基因组大小的进化可能比HR假说所设想的更为复杂。有趣的是，即使在对数尺度上，鱼类基因组大小的频率分布也严重偏斜，这表明基因组大小进化背后的动力学是由乘法现象驱动的，这可能包括染色体重排和转座元件的扩增。
