Hardie David C, Hebert Paul D N
Department of Zoology, University of Guelph, Guelph, ON, Canada.
Genome. 2003 Aug;46(4):683-706. doi: 10.1139/g03-040.
Cytological and organismal characteristics associated with cellular DNA content underpin most adaptionist interpretations of genome size variation. Since fishes are the only group of vertebrate for which relationships between genome size and key cellular parameters are uncertain, the cytological correlates of genome size were examined in this group. The cell and nuclear areas of erythrocytes showed a highly significant positive correlation with each other and with genome size across 22 cartilaginous and 201 ray-finned fishes. Regressions remained significant at all taxonomic levels, as well as among different fish lineages. However, the results revealed that cartilaginous fishes possess higher cytogenomic ratios than ray-finned fishes, as do cold-water fishes relative to their warm-water counterparts. Increases in genome size owing to ploidy shifts were found to influence cell and nucleus size in an immediate and causative manner, an effect that persists in ancient polyploid lineages. These correlations with cytological parameters known to have important influences on organismal phenotypes support an adaptive interpretation for genome size variation in fishes.
与细胞DNA含量相关的细胞学和机体特征是大多数关于基因组大小变异的适应主义解释的基础。由于鱼类是唯一一组基因组大小与关键细胞参数之间关系不确定的脊椎动物，因此在该类群中研究了基因组大小的细胞学相关性。在22种软骨鱼和201种硬骨鱼中，红细胞的细胞和核面积彼此之间以及与基因组大小均呈现出高度显著的正相关。在所有分类水平以及不同鱼类谱系中，回归分析均具有显著性。然而，结果显示软骨鱼比硬骨鱼具有更高的细胞基因组比率，冷水鱼相对于其温水同类也是如此。发现由于倍性变化导致的基因组大小增加会以直接且因果的方式影响细胞和细胞核大小，这种效应在古老的多倍体系谱中持续存在。这些与已知对机体表型有重要影响的细胞学参数的相关性支持了对鱼类基因组大小变异的适应性解释。
