Phylogenetic relationship among genera of Polymorphidae (Acanthocephala), inferred from nuclear and mitochondrial gene sequences
Por:
Garcia-Varela, M, de Leon, GPP, Aznar, FJ, Nadler, SA
Publicada:
1 ago 2013
Resumen:
Acanthocephalans of the family Polymorphidae Meyer, 1931 are obligate
endoparasites with complex life cycles. These worms use vertebrates
(marine mammals, fish-eating birds and waterfowl) as definitive hosts
and invertebrates (amphipods, decapods and euphausiids) as intermediate
hosts to complete their life cycle. Polymorphidae has a wordwide
distribution, containing 12 genera, with approximately 127 species. The
family is diagnosed by having a spinose trunk, bulbose proboscis,
double-walled proboscis receptacle, and usually four to eight tubular
cement glands. To conduct a phylogenetic analysis, in the current study
sequences of the small (18S) and large-subunit (28S) ribosomal RNA, and
cytochrome c oxidase subunit 1 (cox I) were generated for 27 taxa
representing 10 of 12 genera of Polymorphidae, plus three additional
species of acanthocephalans that were used as outgroups. Maximum
likelihood (ML), maximum parsimony (MP), and Bayesian analyses were
conducted on a combined nuclear rRNA (18S + 28S) data set and on a
concatenated dataset of nuclear plus one mitochondrial gene (18S + 28S +
cox 1). Phylogenetic analyses inferred with the concatenated dataset of
three genes support the monophyly of nine genera (Andracantha,
Corynosoma, Bolbosoma, Profilicollis, Pseudocorynosoma, Southwellina,
Arhythmorhynchus, Hexaglandula and Ibirhynchus). However, the four
sampled species of Polymorphus were nested within several clades,
indicating that these species do not share a common ancestor, requiring
further taxonomic revision using phylogenetic systematics, and
reexamination of morphological and ecological data. By mapping
definitive and intermediate host association onto the resulting
cladogram, we observe that aquatic birds were the ancestral definitive
hosts for the family with a secondary colonization and diversification
to marine mammals. Whereas amphipods were ancestral intermediate hosts
and that the association with decapods represent episodes of secondary
colonization that arose several times during the evolutionary history of
the family. Our results are useful to start testing hypothesis about the
evolutionary history of this highly diverse family of acanthocephalans.
(C) 2013 Elsevier Inc. All rights reserved.
Filiaciones:
Garcia-Varela, M:
Univ Nacl Autonoma Mexico, Dept Zool, Inst Biol, Mexico City 04510, DF, Mexico
de Leon, GPP:
Univ Nacl Autonoma Mexico, Dept Zool, Inst Biol, Mexico City 04510, DF, Mexico
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