Natural History Museum and Institute, Chiba, 955-2 Aoba-cho, Chuo-ku, Chiba 260-8682, Japan.
BMC Evol Biol. 2010 Feb 23;10:58. doi: 10.1186/1471-2148-10-58.
The teleost order Lophiiformes, commonly known as the anglerfishes, contains a diverse array of marine fishes, ranging from benthic shallow-water dwellers to highly modified deep-sea midwater species. They comprise 321 living species placed in 68 genera, 18 families and 5 suborders, but approximately half of the species diversity is occupied by deep-sea ceratioids distributed among 11 families. The evolutionary origins of such remarkable habitat and species diversity, however, remain elusive because of the lack of fresh material for a majority of the deep-sea ceratioids and incompleteness of the fossil record across all of the Lophiiformes. To obtain a comprehensive picture of the phylogeny and evolutionary history of the anglerfishes, we assembled whole mitochondrial genome (mitogenome) sequences from 39 lophiiforms (33 newly determined during this study) representing all five suborders and 17 of the 18 families. Sequences of 77 higher teleosts including the 39 lophiiform sequences were unambiguously aligned and subjected to phylogenetic analysis and divergence time estimation.
Partitioned maximum likelihood analysis confidently recovered monophyly for all of the higher taxa (including the order itself) with the exception of the Thaumatichthyidae (Lasiognathus was deeply nested within the Oneirodidae). The mitogenomic trees strongly support the most basal and an apical position of the Lophioidei and a clade comprising Chaunacoidei + Ceratioidei, respectively, although alternative phylogenetic positions of the remaining two suborders (Antennarioidei and Ogcocephaloidei) with respect to the above two lineages are statistically indistinguishable. While morphology-based intra-subordinal relationships for relatively shallow, benthic dwellers (Lophioidei, Antennarioidei, Ogcocephaloidei, Chaunacoidei) are either congruent with or statistically indistinguishable from the present mitogenomic tree, those of the principally deep-sea midwater dwellers (Ceratioidei) cannot be reconciled with the molecular phylogeny. A relaxed molecular-clock Bayesian analysis of the divergence times suggests that all of the subordinal diversifications have occurred during a relatively short time period between 100 and 130 Myr ago (early to mid Cretaceous).
The mitogenomic analyses revealed previously unappreciated phylogenetic relationships among the lophiiform suborders and ceratioid familes. Although the latter relationships cannot be reconciled with the earlier hypotheses based on morphology, we found that simple exclusion of the reductive or simplified characters can alleviate some of the conflict. The acquisition of novel features, such as male dwarfism, bioluminescent lures, and unique reproductive modes allowed the deep-sea ceratioids to diversify rapidly in a largely unexploited, food-poor bathypelagic zone (200-2000 m depth) relative to the other lophiiforms occurring in shallow coastal areas.
硬骨鱼纲的鮟鱇目，通常被称为鮟鱇鱼，包含了各种各样的海洋鱼类，从底栖浅海生物到高度特化的深海中层生物。它们由 321 个现存物种组成，分为 68 属、18 科和 5 个亚目，但大约一半的物种多样性由分布在 11 个科中的深海鮟鱇鱼组成。然而，由于缺乏大多数深海鮟鱇鱼的新鲜材料，以及整个鮟鱇目化石记录的不完整，这些显著的栖息地和物种多样性的进化起源仍然难以捉摸。为了全面了解鮟鱇鱼的系统发育和进化历史，我们从 39 种鮟鱇鱼（本研究中确定了 33 种新物种）中组装了整个线粒体基因组（mitogenome）序列，代表了所有 5 个亚目和 18 科中的 17 个科。77 种高级硬骨鱼的序列（包括 39 种鮟鱇鱼序列）被明确对齐，并进行了系统发育分析和分歧时间估计。
分区最大似然分析自信地恢复了所有高等分类群（包括该目本身）的单系性，除了 Thaumatichthyidae 科（Oneirodidae 科中的 Lasiognathus 被深深嵌套）。线粒体基因组树强烈支持 Lophioidei 的最基部和顶端位置，以及包含 Chaunacoidei + Ceratioidei 的分支，尽管其他两个亚目（Antennarioidei 和 Ogcocephaloidei）相对于上述两个谱系的剩余两个分支的系统发育位置在统计学上是不可区分的。虽然基于形态的相对较浅、底栖生物的亚目内关系（Lophioidei、Antennarioidei、Ogcocephaloidei、Chaunacoidei）与目前的线粒体基因组树一致或在统计学上不可区分，但主要生活在深海中层水域的生物（Ceratioidei）的关系却无法与分子系统发育相协调。对分歧时间的放松分子钟贝叶斯分析表明，所有的亚目多样化都发生在大约 1 亿到 1.3 亿年前（早白垩世到中白垩世）的一个相对较短的时间内。
线粒体基因组分析揭示了鮟鱇目亚目和鮟鱇科之间以前未被认识到的系统发育关系。尽管这些关系与基于形态的早期假设无法协调，但我们发现，简单排除还原或简化的特征可以缓解一些冲突。新特征的获得，如雄性矮小、生物发光诱饵和独特的生殖模式，使深海鮟鱇鱼能够在食物匮乏的深海中层（200-2000 米深度）迅速多样化，而其他生活在浅海沿岸地区的鮟鱇鱼则相对较少。
