Three new species of Pristionchus (Nematoda: Diplogastridae) show morphological divergence through evolutionary intermediates of a novel feeding-structure polymorphism
Developmental plasticity is often correlated with diversity and has been proposed as a facilitator of phenotypic novelty. Yet how a dimorphism arises or how additional morphs are added is not understood, and few systems provide experimental insight into the evolution of polyphenisms. Because plastic...
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Published in | Zoological journal of the Linnean Society Vol. 168; no. 4; pp. 671 - 698 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Oxford
Blackwell Publishing Ltd
01.08.2013
Oxford University Press |
Subjects | |
Online Access | Get full text |
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Summary: | Developmental plasticity is often correlated with diversity and has been proposed as a facilitator of phenotypic novelty. Yet how a dimorphism arises or how additional morphs are added is not understood, and few systems provide experimental insight into the evolution of polyphenisms. Because plasticity correlates with structural diversity in Pristionchus nematodes, studies in this group can test the role of plasticity in facilitating novelty. Here, we describe three new species, Pristionchus fukushimae sp. nov., Pristionchus hoplostomus sp. nov., and the hermaphroditic Pristionchus triformis sp. nov., which are characterized by a novel polymorphism in their mouthparts. In addition to showing the canonical mouth dimorphism of diplogastrid nematodes, comprising a stenostomatous (‘narrow‐mouthed’) and a eurystomatous (‘wide‐mouthed’) form, the new species exhibit forms with six, 12, or intermediate numbers of cheilostomatal plates. Correlated with this polymorphism is another trait that varies among species: whereas divisions between plates are complete in P. triformis sp. nov., which is biased towards a novel ‘megastomatous’ form comprising 12 complete plates, the homologous divisions in the other new species are partial and of variable length. In a reconstruction of character evolution, a phylogeny inferred from 26 ribosomal protein genes and a partial small subunit rRNA gene supported the megastomatous form of P. triformis sp. nov. as the derived end of a series of split‐plate forms. Although split‐plate forms were normally only observed in eurystomatous nematodes, a single 12‐plated stenostomatous individual of P. hoplostomus sp. nov. was also observed, suggesting independence of the two types of mouth plasticity. By introducing these new species to the Pristionchus model system, this study provides further insight into the evolution of polymorphisms and their evolutionary intermediates. © 2013 The Linnean Society of London |
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Bibliography: | ark:/67375/WNG-WQ4XGZPC-L ArticleID:ZOJ12041 Alexander von Humboldt Foundation istex:E3F497C436F6CB7D56C8F4A804CDDBA7A4615D5B ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0024-4082 1096-3642 |
DOI: | 10.1111/zoj.12041 |