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1.
Zoolog Sci ; 25(8): 838-42, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18795818

RESUMO

The Ogasawara (Bonin) Islands are oceanic islands of volcanic origin located in the northwestern Pacific Ocean about 1,000 km south of the Japanese mainland. A large carpenter bee, Xylocopa (Koptortosoma) ogasawarensis, is endemic to the islands but its closest relative is unknown. The Ogasawara Islands are geographically closest to the Japanese Archipelago, but this area is inhabited only by species of a different subgenus, Alloxylocopa. Thus, X. ogasawarensis is commonly thought to have originated from other members of Koptortosoma, which is widely distributed in the Oriental tropical region. In this study, we investigated the origin of X. ogasawarensis using a phylogenetic analysis of Xylocopa based on four genes: mitochondrial cytochrome oxidase subunit I (COI) and cytochrome b (Cyt b), and nuclear elongation factor-1alpha (EF-1alpha) and phosphoenolpyruvate carboxykinase (PEPCK). A combined analysis of the four genes strongly suggests that Koptortosoma is a large, polyphyletic group, within which Alloxylocopa is embedded. Xylocopa ogasawarensis emerged as the species most closely related to Alloxylocopa and not to Oriental species of Koptortosoma. Contrary to previous views of the origin of X. ogasawarensis, our results suggest that X. ogasawarensis and Alloxylocopa share a common origin and diverged after they colonized the island regions of East Asia.


Assuntos
Abelhas/classificação , Abelhas/genética , Grupo dos Citocromos b/genética , DNA Mitocondrial/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Fator 1 de Elongação de Peptídeos/genética , Animais , Teorema de Bayes , Abelhas/enzimologia , Grupo dos Citocromos b/classificação , DNA Mitocondrial/classificação , Evolução Molecular , Genes Mitocondriais , Especiação Genética , Cadeias de Markov , Oceano Pacífico , Fosfoenolpiruvato Carboxiquinase (ATP)/genética , Filogenia , Análise de Sequência de DNA , Tóquio
2.
Mol Phylogenet Evol ; 49(2): 503-13, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18755281

RESUMO

Sennertia mites live as inquilines in the nests of carpenter bees and disperse as deutonymphs on newly emerged adult bees. Because their life cycle is tightly linked to that of the host bees, Sennertia may diverge in response to speciation in the hosts. However, the majority of Sennertia species are associated with several closely related carpenter bees, suggesting that host speciation may not be reflected in mite genetic structure. Here we investigate the extent of host-associated genetic differentiation in two Sennertia mites (S. alfkeni and S. japonica) that share four closely related, strictly allopatric large carpenter bees (Xylocopa). Analysis of the mitochondrial cytochrome oxidase subunit I (COI) gene in Sennertia unexpectedly indicates that the two species represent morphological variants of a single species, and they collectively group into four distinct, allopatric clades that are uniquely associated with a single Xylocopa host. An exception is the mites associated with X. amamensis of the northernmost populations, which have genotypes typical of those associated with neighboring X. appendiculatacircumvolans. Additional analysis using amplified fragment length polymorphism (AFLP) further corroborates the presence of four mite clades but contrary to the COI data, suggests that the mites of the southernmost population of X. appendiculatacircumvolans have genetic profiles typical of those associated with X. amamensis. These results indicate that some mites have undergone secondary host switch after the formation of the four mite lineages and further experienced mitochondrial introgression during period of lineage coexistence. Overall, our results strongly urge reappraisal of deutonymph-based mite taxonomy and illuminate the importance of host-associated divergence during incipient stage of speciation in chaetodactylid mites. Furthermore, the occurrence of host switch and introgression between genetically differentiated mites entails that two host species have co-occurred in the past, thus providing a unique source of evidence for migration and competitive exclusion between the presently allopatric Xylocopa hosts.


Assuntos
Abelhas/classificação , Abelhas/parasitologia , Especiação Genética , Interações Hospedeiro-Parasita/genética , Ácaros/classificação , Análise do Polimorfismo de Comprimento de Fragmentos Amplificados , Animais , Teorema de Bayes , Abelhas/genética , DNA Mitocondrial/genética , Genes de Insetos , Genes Mitocondriais , Japão , Funções Verossimilhança , Cadeias de Markov , Ácaros/genética , Mitocôndrias/genética , Método de Monte Carlo , Filogenia , Alinhamento de Sequência , Análise de Sequência de DNA , Especificidade da Espécie
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