Beltrán Margarita, Jiggins Chris D, Bull Vanessa, Linares Mauricio, Mallet James, McMillan W Owen, Bermingham Eldredge
Smithsonian Tropical Research Institute, AA2072 Balboa, Panama.
Mol Biol Evol. 2002 Dec;19(12):2176-90. doi: 10.1093/oxfordjournals.molbev.a004042.
Recent adaptive radiations provide excellent model systems for understanding speciation, but rapid diversification can cause problems for phylogenetic inference. Here we use gene genealogies to investigate the phylogeny of recent speciation in the heliconiine butterflies. We sequenced three gene regions, intron 3 ( approximately 550 bp) of sex-linked triose-phosphate isomerase (Tpi), intron 3 ( approximately 450 bp) of autosomal mannose-phosphate isomerase (Mpi), and 1,603 bp of mitochondrial cytochrome oxidase subunits I and II (COI and COII), for 37 individuals from 25 species of Heliconius and related genera. The nuclear intron sequences evolved at rates similar to those of mitochondrial coding sequences, but the phylogenetic utility of introns was restricted to closely related geographic populations and species due to high levels of indel variation. For two sister species pairs, Heliconius erato-Heliconius himera and Heliconius melpomene-Heliconius cydno, there was highly significant discordance between the three genes. At mtDNA and Tpi, the hypotheses of reciprocal monophyly and paraphyly of at least one species with respect to its sister could not be distinguished. In contrast alleles sampled from the third locus, Mpi, showed polyphyletic relationships between both species pairs. In all cases, recent coalescence of mtDNA lineages within species suggests that polyphyly of nuclear genes is not unexpected. In addition, very similar alleles were shared between melpomene and cydno, implying recent gene flow. Our finding of discordant genealogies between genes is consistent with models of adaptive speciation with ongoing gene flow and highlights the need for multiple locus comparisons to resolve phylogeny among closely related species.
近期的适应性辐射为理解物种形成提供了绝佳的模型系统，但快速的多样化会给系统发育推断带来问题。在此，我们利用基因谱系来研究长翅蝶亚科蝴蝶近期物种形成的系统发育。我们对来自25个物种（包括光明女神闪蝶属及相关属）的37个个体的三个基因区域进行了测序，即性连锁磷酸丙糖异构酶（Tpi）的内含子3（约550 bp）、常染色体磷酸甘露糖异构酶（Mpi）的内含子3（约450 bp）以及线粒体细胞色素氧化酶亚基I和II（COI和COII）的1603 bp。核内含子序列的进化速率与线粒体编码序列相似，但由于插入缺失变异水平较高，内含子的系统发育效用仅限于亲缘关系较近的地理种群和物种。对于两对姐妹物种，光明女神闪蝶 - 希默拉长翅蝶和黑脉金斑蝶 - 塞德诺长翅蝶，这三个基因之间存在高度显著的不一致。在mtDNA和Tpi上，至少一个物种相对于其姐妹物种的相互单系和并系假设无法区分。相比之下，从第三个位点Mpi采样的等位基因在这两对物种之间显示出多系关系。在所有情况下，物种内mtDNA谱系的近期合并表明核基因的多系性并不意外。此外，黑脉金斑蝶和塞德诺长翅蝶之间共享了非常相似的等位基因，这意味着近期存在基因流动。我们发现基因之间的谱系不一致与正在进行基因流动的适应性物种形成模型一致，并强调需要进行多位点比较以解决亲缘关系较近物种之间的系统发育问题。
