Cladistic analysis of Zethus Fabricius, 1804 (Hymenoptera, Vespidae): a new subgeneric classification

Zethus is the largest genus in Vespidae with over 270 species. It is currently divided into four subgenera: Z. (Zethus), Z. (Zethoides), Z. (Zethusculus) and Z. (Madecazethus). While the last three are restricted to certain biogeographic areas, the first is spread through western and eastern hemispheres. Studies have shown possible phylogenetic incongruence regarding this current division and even raised the possibility of paraphyly in the genus. To evaluate this classification, morphological pasimony analyses under implied weights was carried out, examining external morphology and male genitalia. Analyses showed paraphyly of the genus under various “k” values and paraphyly of two subgenera. Ischnocoelia and Ctenochilus are lowered to subgenera of Zethus. Zethus (Madecazethus) is no longer restricted to Malagasy species and now includes those of the African continent as well. Zethus (Zethastrum)subg. nov. is defined for Oriental representatives. Z. (Zethus) is subdivided into three subgenera: Z. (Zethus), Z. (Didymogastra) and Z. (Wettsteinia). Zethus (Zethusculus) and Z. (Zethoides) are monophyletic and hold their status as subgenera. Three species-groups are Incertae sedis: Z. albopictus, Z. pallidus and Z. spinosus.

Subspecies divergence and pronounced phylogenetic incongruence in the East-Asia-endemic shrub Magnolia sieboldii

Background and Aims The biogeographic patterns of the East-Asia-endemic shrub Magnolia sieboldii, in which the range of the subsp. sieboldii is interposed with the disjunct distribution of subsp. japonica, implies a complex evolutionary history, involving rapid speciation and hybridization. Here, we aim to reveal the evolutionary and phylogeographic histories of the species with a particular focus on the time of subspecies divergence, the hypothesis of secondary hybridization and the Pleistocene survival of each subspecies, using a combination of genetic analyses and ecological niche modelling. Methods Genetic variation, genetic structures and phylogenetic relationships were elucidated based on nuclear low-copy genes, chloroplast DNA, and nuclear simple sequence repeats (SSRs). A scenario selection analysis and divergence time estimation were performed using coalescent simulation in DIYABC and *BEAST. Ecological niche modelling and a test of niche differentiation were performed using Maxent and ENMTools. Key Results All marker types showed deep, but pronouncedly incongruent, west–east genetic divergences, with the subspecies being delineated only by the nuclear low-copy genes. Phylogenetic tree topologies suggested that ancient hybridization and introgression were likely to have occurred; however, this scenario did not receive significant support in the DIYABC analysis. The subspecies differentiated their niches, but both showed a dependence on high humidity and were predicted to have persisted during the last glacial cycle by maintaining a stable latitudinal distribution via migration to lower altitudes. Conclusions We found a deep genetic divergence and a pronounced phylogenetic incongruence among the two subspecies of M. sieboldii, which may have been driven by major paleogeographic and paleoclimatic events that have occurred since the Neogene in East Asia, including global cooling, climate oscillations and the formation of land bridges. Both subspecies were, however, considered to persist in situ in stable climatic conditions during the late Pleistocene.

Evaluation of the multispecies coalescent method to explore intra-Trypanosoma cruzi I relationships and genetic diversity

Chagas Disease is a zoonosis caused by the parasite Trypanosoma cruzi. Several high-resolution markers have subdivided T. cruzi taxon into at least seven lineages or Discrete Typing Units (DTUs) (TcI-TcVI and TcBat). Trypanosoma cruzi I is the most diverse and geographically widespread DTU. Recently a TcI genotype related to domestic cycles was proposed and named as TcIDOM. Herein, we combined traditional markers and housekeeping genes and applied a Multispecies Coalescent method to explore intra-TcI relationships, lineage boundaries and genetic diversity in a random set of isolates and DNA sequences retrieved from Genbank from different countries in the Americas. We found further evidence supporting TcIDOM as an independent and emerging genotype of TcI at least in Colombia and Venezuela. We also found evidence of high phylogenetic incongruence between parasite's gene trees (including introgression) and embedded species trees, and a lack of genetic structure among geography and hosts, illustrating the complex dynamics and epidemiology of TcI across the Americas. These findings provide novel insights into T. cruzi systematics and epidemiology and support the need to assess parasite diversity and lineage boundaries through hypothesis testing using different approaches to those traditionally employed, including the Bayesian Multispecies coalescent method.

Horizontally transferred genes in the ctenophore Mnemiopsis leidyi

Horizontal gene transfer (HGT) has had major impacts on the biology of a wide range of organisms from antibiotic resistance in bacteria to adaptations to herbivory in arthropods. A growing body of literature shows that HGT between non-animals and animals is more commonplace than previously thought. In this study, we present a thorough investigation of HGT in the ctenophore Mnemiopsis leidyi. We applied tests of phylogenetic incongruence to identify nine genes that were likely transferred horizontally early in ctenophore evolution from bacteria and non-metazoan eukaryotes. All but one of these HGTs (an uncharacterized protein) are homologous to characterized enzymes, supporting previous observations that genes encoding enzymes are more likely to be retained after HGT events. We found that the majority of these nine horizontally transferred genes were expressed during development, suggesting that they are active and play a role in the biology of M. leidyi. This is the first report of HGT in ctenophores, and contributes to an ever-growing literature on the prevalence of genetic information flowing between non-animals and animals.

Horizontally transferred genes in the ctenophore Mnemiopsis leidyi

Horizontal gene transfer has had major impacts on the biology of a wide range of organisms from antibiotic resistance in bacteria to adaptations to herbivory in arthropods. A growing body of literature shows that horizontal gene transfer (HGT) between non-animals and animals is more commonplace than previously thought. In this study, we present a thorough investigation of HGT in the ctenophore Mnemiopsis leidyi. We applied tests of phylogenetic incongruence to identify nine genes that were likely transferred horizontally early in ctenophore evolution from bacteria and non-metazoan eukaryotes. All but one of these HGTs (an uncharacterized protein) are homologous to characterized enzymes, supporting previous observations that genes encoding enzymes are more likely to be retained after HGT events. We found that the majority of these nine horizontally transferred genes were expressed during development, suggesting that they are active and play a role in the biology of M. leidyi. This is the first report of HGT in ctenophores, and contributes to an ever-growing literature on the prevalence of genetic information flowing between non-animals and animals.

Horizontally transferred genes in the ctenophore Mnemiopsis leidyi

Horizontal gene transfer has had major impacts on the biology of a wide range of organisms from antibiotic resistance in bacteria to adaptations to herbivory in arthropods. A growing body of literature shows that horizontal gene transfer (HGT) between non-animals and animals is more commonplace than previously thought. In this study, we present a thorough investigation of HGT in the ctenophore Mnemiopsis leidyi. We applied tests of phylogenetic incongruence to identify nine genes that were likely transferred horizontally early in ctenophore evolution from bacteria and non-metazoan eukaryotes. All but one of these HGTs (an uncharacterized protein) are homologous to characterized enzymes, supporting previous observations that genes encoding enzymes are more likely to be retained after HGT events. We found that the majority of these nine horizontally transferred genes were expressed during development, suggesting that they are active and play a role in the biology of M. leidyi. This is the first report of HGT in ctenophores, and contributes to an ever-growing literature on the prevalence of genetic information flowing between non-animals and animals.