No abstract

No abstract

BackgroundThe genus Polytremis, restricted to the continental part of the southeastern Palaearctic and northern Oriental regions, is one of the largest and most diverse lineages of the tribe Baorini. Previous studies on the genus were focused mainly on morphological classification and identification of new species. Due to the lack of effective and homologous traits of morphology, there were many challenges in the traditional classification. In this report, we reconstruct the phylogeny to provide a solid framework for these studies and to test the traditional limits and relationships of taxa.Methodology and Principal FindingsWe sequenced a mitochondrial and three nuclear gene fragments, coupled with an evaluation of traditional morphological characters, to determine the phylogenetic relationships for a total of 15 species representing all major species groups of the Polytremis genus in China, and to elucidate their taxonomic status.Conclusions and SignificanceAnalysis of mitochrondial and nuclear DNA showed considerable congruent phylogenetic signal in topology at the inter-species level. We found strong support for the monophyly of Polytremis and some clades were recognized with morphological data. Thus, the COI sequence in our study could be used as a DNA barcode to identify almost all members of the genus. However, incongruences of phylogenetic analyses occurred: in contrast to the phylogenetic trees of mitochondrial COI, it was not possible for nuclear rDNA to discriminate P. gotama from P. caerulescens, suggesting a possible recent separation of these two species. Additionally, P. theca was the only species with a greater intra-specific genetic distance compared to some inter-specific genetic distances in this study and some problems associated with the cryptic diversity of the species are discussed. The results of this study will helpful to reveal the causes of the high degree of diversity of butterflies, and possibly other groups of insects in China.

Wolbachia endosymbiont infections can persist and spread in insect populations without causing apparent effects on reproduction of their insect hosts, but the mechanisms involved are largely unknown. Here, we test for fitness effects of the wAu infection of Drosophila simulans by comparing multiple infected and uninfected polymorphic isofemale lines derived from nature. We show a fitness advantage (higher offspring number) for lines with the wAu Wolbachia infection when breeding on grapes, but only where there was Talaromyces and Penicillium fungal mycelial growth. When breeding on laboratory medium, the wAu infection extended the development time and resulted in larger females with higher fecundity, life history traits, which may increase fitness. A chemical associated with the fungi (ochratoxin A) did not specifically alter the fitness of wAu-infected larvae, which developed slower and emerged with a greater weight regardless of toxin levels. These findings suggest that the fitness benefits of Wolbachia in natural populations may reflect life history changes that are advantageous under particular circumstances, such as when breeding occurs in rotting fruit covered by abundant mycelial growth.

No abstract

The skipper Polytremis theca species complex is widely distributed in the south of the Qinling Mountains in China. A recent study of the Polytremis genus suggested that this species might encompass two differentiated lineages. We tested this hypothesis, by carrying out a phylogenetic study of this agricultural pest based on nationwide sampling and the evaluation of mitochondrial and nuclear DNA markers. We show that this species is actually an amalgamation of two sibling taxa (P. t. theca and P. t. fukia), which displayed levels of genetic divergence as great as those generally found between sister species in the Polytremis genus, suggesting that they actually correspond to two distinct species. The Divergence time estimates suggest that an active period of speciation within Polytremis occurred within the Pleistocene eras. Based on its distinct phylogenetic placement and geographical isolation, we suggest that the subspecies should be elevated to full species status under the phylogenetic species concept, which has significant management implications.

The family Taeniidae comprises many parasitic species, which cause serious zoonoses. However, effective identification of Taeniidae species is a long-standing problem, especially in samples from wild hosts with mixed infections of different Taeniidae species. DNA barcoding analysis of small fragments of the cytochrome c oxidase subunit I (COI) gene has been confirmed as an effective and useful method for identifying Taenia species. We therefore performed DNA barcoding analysis using a 351-bp region of the COI gene to identify 27 taeniid species including 9 in the genus Echinococcus, 2 in Hydatigera, 15 in Taenia, and 1 in Versteria. A total of 484 COI sequences were used to calculate genetic divergence expressed by the Kimura 2-parameter (K2P) distance. The mean intra-specific K2P distance in the family Taeniidae was 0.71 ± 0.17% (±SE), while inter-specific divergences were considerably higher. We found that, generally, a 2.0% optimal barcoding threshold could be set to distinguish taeniid species. Taenia polyacantha and Hydatigera taeniaeformis were the only 2 false-positive species identification cases in this study for their intra-specific divergences above the 2.0% optimal threshold. Their high intra-specific divergences coincided with fact that cryptic divergences exist in these 2 species, to which new taxa were recommended. On the other hand, sister species T. asiatica and T. saginata showed a 2.48 ± 0.83% inter-specific divergence, which was the smallest among all the taeniid species. Although fitting the 2.0% optimal species barcoding threshold, the close genetic relationship between T. asiatica and T. saginata implies that longer mitochondrial DNA sequences like the complete COI sequence are needed to strictly distinguish them. Therefore, we concluded that the barcoding technique based on a 351-bp region of the COI gene is able to distinguish taeniid species except for cryptic T. polyacantha and H. taeniaeformis and should be carefully used in distinguishing the closely related species T. asiatica and T. saginata .

No abstract