Characterization of the chemoreceptor repertoire of a highly specialized fly with comparisons to other Drosophila species.

To explore the diversity of scenarios in nature, animals have evolved tools to interact with different environmental conditions. Chemoreceptors are an important interface component and among them, olfactory receptors (ORs) and gustatory receptors (GRs) can be used to find food and detect healthy resources. Drosophila is a model organism in many scientific fields, in part due to the diversity of species and niches they occupy. The contrast between generalists and specialists Drosophila species provides an important model for studying the evolution of chemoreception. Here, we compare the repertoire of chemoreceptors of different species of Drosophila with that of D. incompta, a highly specialized species whose ecology is restricted to Cestrum flowers, after reporting the preferences of D. incompta to the odor of Cestrum flowers in olfactory tests. We found evidence that the chemoreceptor repertoire in D. incompta is smaller than that presented by species in the Sophophora subgenus. Similar patterns were found in other non-Sophophora species, suggesting the presence of underlying phylogenetic trends. Nevertheless, we also found autapomorphic gene losses and detected some genes that appear to be under positive selection in D. incompta, suggesting that the specific lifestyle of these flies may have shaped the evolution of individual genes in each of these gene families.

Comparative mitogenomics of Drosophilidae and the evolution of the Zygothrica genus group (Diptera, Drosophilidae).

The Zygothrica genus group of Drosophilidae encompasses more than 437 species and five genera. Although knowledge regarding its diversity has increased, uncertainties about its monophyly and position within Drosophilidae remain. Genomic approaches have been widely used to address different phylogenetic questions and analyses involving the mitogenome have revealed a cost-efficient tool to these studies. Thus, this work aims to characterize mitogenomes of three species of the Zygothrica genus group (from the Hirtodrosophila, Paraliodrosophila and Zygothrica genera), while comparing them with orthologous sequences from other 23 Drosophilidae species and addressing their phylogenetic position. General content concerning gene order and overlap, nucleotide composition, start and stop codon, codon usage and tRNA structures were compared, and phylogenetic trees were constructed under different datasets. The complete mitogenomes characterized for H. subflavohalterata affinis H002 and P. antennta present the PanCrustacea gene order with 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, 13 protein coding genes and an A+T rich region with two T-stretched elements. Some peculiarities such as the almost complete overlap of genes tRNAH/ND4, tRNAF/ND5 and tRNAS2/ND1 are reported for different Drosophilidae species. Non-canonical secondary structures were encountered for tRNAS1 and tRNAY, revealing patterns that apply at different phylogenetic scales. According to the best depiction of the mitogenomes evolutionary history, the three Neotropical species of the Zygothrica genus group encompass a monophyletic lineage sister to Zaprionus, composing with this genus a clade that is sister to the Drosophila subgenus.

Phylogenetic relationships between fungus-associated Neotropical species of the genera Hirtodrosophila, Mycodrosophila and Zygothrica (Diptera, Drosophilidae), with insights into the evolution of breeding sites usage.

The Neotropical region harbors an astonishing diversity of species, but still encompasses the least studied biogeographic region of the world. These properties apply for different taxonomic groups, and can be exemplified by drosophilids. In fact, high levels of cryptic diversity have recently been discovered for Neotropical species of the Zygothrica genus group, but relationships among these species, or them and other Drosophilidae species still remains to be addressed. Therefore, the aim of this study was to evaluate the phylogenetic relationships between fungus-associated Neotropical species of the genera Hirtodrosophila, Mycodrosophila and Zygothrica, which together with Paramycodrosophila and Paraliodrosophila compose the Zygothrica genus group. For this, fragments of the mitochondrial cytochrome oxidase subunits I (COI) and II (COII) genes, and the nuclear alpha methyldopa (Amd) and dopa decarboxylase (Ddc) genes were newly characterized for 43 Neotropical specimens of fungus-associated drosophilids, and analyzed in the context of 51 additional Drosophilinae sequences plus one Steganinae outgroup. Based on the resulting phylogeny, the evolution of breeding sites usage was also evaluated through ancestral character reconstructions. Our results revealed the Zygothrica genus group as a monophyletic lineage of Drosophila that branches after the subgenera Sophophora and Drosophila. Within this lineage, Mycodrosophila species seem to encompass the early offshoot, followed by a grade of Hirtodrosophila species, with derived branches mostly occupied by representatives of Zygothrica. This genus, in particular, was subdivided into five major clades, two of which include species of Hirtodrosophila, whose generic status needs to be reevatuated. According to our results, the use of fungi as breeding sites encompasses a symplesiomorphy for the Zygothrica genus group, since one of the recovered clades is currently specialized in using flowers as breeding sites whereas a sole species presents a reversal to the use of fruits of a plant of Gentianales. So, in general, this study supports the paraphyly of Drosophila in relation to fungus-associated Neotropical species of Drosophilidae, providing the first molecular insights into the phylogenetic patterns related to the evolution of this diverse group of species and some of its characteristic traits.

New insights on evolutionary aspects of Pythium insidiosum and other peronosporaleans.

BACKGROUND: The evolution of pathogenic mechanisms is a major challenge, which requires a thorough comprehension of the phylogenetic relationships of pathogens. Peronosporaleans encompasses a heterogeneous group of oomycetes that includes some animal/human pathogens, like Pythium insidiosum. OBJECTIVE: We analysed here the phylogenetic positioning and other evolutionary aspects related to this species and other peronosporaleans, using a multi-locus approach with one mitochondrial and three nuclear genes. METHODOLOGY: Phylogenetic patterns of 55 oomycetes were inferred by maximum likelihood and Bayesian analysis, and a relaxed molecular clock method was applied to infer the divergence time of some peronosporaleans branches. RESULTS: Pythium insidiosum was monophyletic with a major and polytomous clade of American isolates; however, Pythium spp. was found to be paraphyletic with Phytopythium sp. and Phytophthora spp. In general, peronosporaleans subdivided into four lineages, one of which evidenced a close relationship of P insidiosum, P aphanidermatum and P arrhenomanes. This lineage diverged about 63 million years ago (Mya), whereas P insidiosum diversified at approximately 24 Mya. The divergence of American and Thai isolates seems to have occurred at approximately 17 Mya, with further American diversification at 2.4 Mya. CONCLUSION: Overall, this study clarifies the phylogenetic relationships of P insidiosum regarding other peronosporaleans in a multi-locus perspective, despite previous claims that phylogenomic analyses are needed to accurately infer the patterns and processes related to the evolution of different lineages in this group. Additionally, this is the first time that a molecular clock was applied to study the evolution of P insidiosum.

Systematics and phylogeography of bats of the genus Rhynchonycteris (Chiroptera: Emballonuridae): Integrating molecular phylogenetics, ecological niche modeling and morphometric data.

Rhynchonycteris is a monotypic genus of Embalonurid bats, whose geographic distribution extends from southern Mexico to tropical regions of the South American continent, including Trinidad and Tobago. Although species that have a wide geographic distribution are frequently revealed to be polytypic, to date, no study has evaluated the taxonomic status of populations of Rhynchonycteris naso. Thus, the aim of this study is to address the patterns of phylogeographic structure and taxonomic subdivision of R. naso using molecular phylogenetics, morphometric data and ecological niche modeling. Phylogenetic results recovered using the genes COI, Cytb, Chd1, Dby, and Usp9x, supported the monophyly of the genus Rhynchonycteris, in addition, a deep phylogeographic structure was revealed by the mitochondrial gene COI for the populations of Belize and Panama in comparison to those of South America. The PCA, and the linear morphometry indicated an apparent differentiation between the cis-Andean and trans-Andean populations. Furthermore, according to the skull morphology, at least two morphotypes were identified. Ecological niche modeling projections in the present have shown that the Andean cordillera acts as a climatic barrier between these two populations, with the depression of Yaracuy (Northwest Venezuela) being the only putative climatically suitable path that could communicate these two populations. On the other hand, projections for the last glacial maximum showed a drastic decrease in climatically suitable areas for the species, suggesting that cycles of lower temperatures played an important role in the separation of these populations.

Unveiling the Mycodrosophila projectans (Diptera, Drosophilidae) species complex: Insights into the evolution of three Neotropical cryptic and syntopic species.

The Zygothrica genus group has been shown to be speciose, with a high number of cryptic species. DNA barcoding approaches have been a valuable tool to uncover cryptic diversity in this lineage, as recently suggested for the Neotropical Mycodrosophila projectans complex, which seems to comprise at least three different species. The aim of this study was to confirm the subdivision of the M. projectans complex while shedding some light on the patterns and processes related to its diversification. In this sense, the use of single and multi-locus datasets under phylogenetic, distance, coalescence, and diagnostic nucleotide approaches confirmed the presence of at least three species under the general morphotype previously described as M. projectans. Only a few subtle morphological differences were found for the three species in terms of aedeagus morphology and abdominal color patterns. Ecologically, sympatry and syntopy seem to be recurrent for these three cryptic species, which present widely overlapping niches, implying niche conservatism. This morphological and ecological similarity has persisted though cladogenesis within the complex, which dates back to the Miocene, providing an interesting example of morphological conservation despite ancient divergence. These results, in addition to contrasting patterns of past demographic fluctuations, allowed us to hypothesize patterns of allopatric or parapatric diversification with secondary contact in Southern Brazil. Nevertheless, genetic diversity was generally high within species, suggesting that migration may encompass an adaptive response to the restrictions imposed by the ephemerality of resources.

Molecular phylogeny of the Austrolebias/ adloffi/ group (Cyprinodontiformes, Rivulidae), with description of two new endangered and highly endemic species of annual killifishes from the Laguna dos Patos system, southern Brazil.

The Austrolebias adloffi species group encompasses a diverse lineage of annual killifishes that occurs along the Laguna dos Patos/Lagoa Mirim system, in both Brazilian and Uruguayan territories. We herein employ an integrative taxonomy approach to describe two new species of the group, inferring their phylogenetic relationships and evaluating their conservation status. Austrolebias cheffei sp. nov. and Austrolebias lourenciano sp. nov. are herein described from the western portion of the Laguna dos Patos system. Austrolebias cheffei is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green or yellowish blue dorsal fin, with wide black to dark brown bars extending from the base to the middle portion of the dorsal and anal fins in the males. Austrolebias lourenciano is distinguished from the remaining species of the A. adloffi species group by presenting a yellowish green dorsal fin, with light yellow or light bluish bars forming small triangles, interspersed with small dark brown rows of blotches in the dorsal fin base, and greenish blue anal fin, sometimes with lighter elongated yellowish iridescent blotches, limited to the basal region. According to mitochondrial cytb sequences, both species are reciprocally monophyletic relative to other species of the A. adloffi species group, and present positive barcoding gap values. Interestingly, both new species form a grade that is closely related to Austrolebias aff. minuano 1, an undescribed species that occurs at the opposite margin of the Laguna dos Patos. Among the other evaluated species, A. bagual, A. aff. minuano 1, A. nigrofasciatus, A. pelotapes, A. pongondo, A. arachan, and A. viarius also revealed to be reciprocally monophyletic, whereas A. minuano and A. adloffi revealed to be paraphyletic in regard to A. charrua and A. aff. minuano 2, respectively, and A. nachtigalli is subdivided in two clades, one of which including A. reicherti, which points to the need of a taxonomic review of the group. In addition, we discussed the conservation status of the new species, corrected the type locality of A. pongondo, and provided a dichotomous identification key of the A. adloffi species group.

Four new Neotropical species in the Hirtodrosophila hirticornis species group (Diptera: Drosophilidae).

Hirtodrosophila Duda, 1923 (Diptera, Drosophilidae) is a worldwide genus associated with fungi that encompasses 30 Neotropical species. They are gathered into four clusters: glabrifrons species group (Burla 1956), hirticornis species group (Burla 1956), magnarcus species group (Frota-Pessoa 1951), and thoracis species group (Grimaldi 1987), although there are still some ungrouped species. Nevertheless, their species richness is highly underestimated, and several unknown species of the genus have been sampled in different Brazilian regions. The known Neotropical flies of the hirticornis group belong to a set of four yellow sibling species, which are very difficult to identify based only on external morphology, a fact that partially explains the knowledge gap regarding ecology, biology, and evolution of the group. However, these species are easily sampled around some fungi fruiting bodies, particularly over Auricularia spp. (Auriculariales, Auriculariaceae). In the last years, we collected some hundreds of specimens, which allowed us to detect some common but yet undescribed species. Thus, here we describe four new Neotropical species in the hirticornis group.

Evolutionary history and classification of Micropia retroelements in Drosophilidae species.

Transposable elements (TEs) have the main role in shaping the evolution of genomes and host species, contributing to the creation of new genes and promoting rearrangements frequently associated with new regulatory networks. Support for these hypotheses frequently results from studies with model species, and Drosophila provides a great model organism to the study of TEs. Micropia belongs to the Ty3/Gypsy group of long terminal repeats (LTR) retroelements and comprises one of the least studied Drosophila transposable elements. In this study, we assessed the evolutionary history of Micropia within Drosophilidae, while trying to assist in the classification of this TE. At first, we performed searches of Micropia presence in the genome of natural populations from several species. Then, based on searches within online genomic databases, we retrieved Micropia-like sequences from the genomes of distinct Drosophilidae species. We expanded the knowledge of Micropia distribution within Drosophila species. The Micropia retroelements we detected consist of an array of divergent sequences, which we subdivided into 20 subfamilies. Even so, a patchy distribution of Micropia sequences within the Drosophilidae phylogeny could be identified, with incongruences between the species phylogeny and the Micropia phylogeny. Comparing the pairwise synonymous distance (dS) values between Micropia and three host nuclear sequences, we found several cases of unexpectedly high levels of similarity between Micropia sequences in divergent species. All these findings provide a hypothesis to the evolution of Micropia within Drosophilidae, which include several events of vertical and horizontal transposon transmission, associated with ancestral polymorphisms and recurrent Micropia sequences diversification.

Study of VIPER and TATE in kinetoplastids and the evolution of tyrosine recombinase retrotransposons.

BACKGROUND: Kinetoplastids are a flagellated group of protists, including some parasites, such as Trypanosoma and Leishmania species, that can cause diseases in humans and other animals. The genomes of these species enclose a fraction of retrotransposons including VIPER and TATE, two poorly studied transposable elements that encode a tyrosine recombinase (YR) and were previously classified as DIRS elements. This study investigated the distribution and evolution of VIPER and TATE in kinetoplastids to understand the relationships of these elements with other retrotransposons. RESULTS: We observed that VIPER and TATE have a discontinuous distribution among Trypanosomatidae, with several events of loss and degeneration occurring during a vertical transfer evolution. We were able to identify the terminal repeats of these elements for the first time, and we showed that these elements are potentially active in some species, including T. cruzi copies of VIPER. We found that VIPER and TATE are strictly related elements, which were named in this study as VIPER-like. The reverse transcriptase (RT) tree presented a low resolution, and the origin and relationships among YR groups remain uncertain. Conversely, for RH, VIPER-like grouped with Hepadnavirus, whereas for YR, VIPER-like sequences constituted two different clades that are closely allied to Crypton. Distinct topologies among RT, RH and YR trees suggest ancient rearrangements/exchanges in domains and a modular pattern of evolution with putative independent origins for each ORF. CONCLUSIONS: Due to the presence of both elements in Bodo saltans, a nontrypanosomatid species, we suggested that VIPER and TATE have survived and remained active for more than 400 million years or were reactivated during the evolution of the host species. We did not find clear evidence of independent origins of VIPER-like from the other YR retroelements, supporting the maintenance of the DIRS group of retrotransposons. Nevertheless, according to phylogenetic findings and sequence structure obtained by this study and other works, we proposed separating DIRS elements into four subgroups: DIRS-like, PAT-like, Ngaro-like, and VIPER-like.

Microevolutionary analyses of Pythium insidiosum isolates of Brazil and Thailand based on exo-1,3-ß-glucanase gene.

Pythium insidiosum is an important oomycete due to its ability to infect humans and animals. It causes pythiosis, a disease of difficult treatment that occurs more frequently in humans in Thailand and in horses in Brazil. Since cell-wall components are frequently related to host shifts, we decided here to use sequences from the exo-1,3-ß-glucanase gene (exo1), which encodes an immunodominant protein putatively involved in cell wall remodeling, to investigate the microevolutionary relationships of Brazilian and Thai isolates of P. insidiosum. After neutrality ratification, the phylogenetic analyses performed through Maximum parsimony (MP), Neighbor-joining (NJ), Maximum likelihood (ML), and Bayesian analysis (BA) strongly supported Thai isolates being paraphyletic in relation to those from Brazil. The structure recovered by these analyses, as well as by Spatial Analysis of Molecular Variance (SAMOVA), suggests the subdivision of P. insidiosum into three clades or population groups, which are able to explain almost 81% of the variation encountered for exo1. Moreover, the two identified Thai clades were almost as strongly differentiated between each other, as they were from the Brazilian clade, suggesting an ancient Asian subdivision. The derived positioning in the phylogenetic tree, linked to the lower diversity values and the recent expansion signs detected for the Brazilian clade, further support this clade as derived in relation to the Asian populations. Thus, although some patterns presented here are compatible with those recovered with different molecular markers, exo1 was revealed to be a good marker for studying evolution in Pythium, providing robust and strongly supported results with regard to the patterns of origin and diversification of P. insidiosum.

Two new species of Mycodrosophila (Diptera, Drosophilidae) proposed by molecular and morphological approaches, with a key to American species

ABSTRACT There are approximately 130 species of MycodrosophilaOldenberg, 1914 worldwide, although only nine species were recorded in American countries so far, three of which are exclusively Nearctic, five exclusively Neotropical and one found in both biogeographic regions (Mycodrosophila projectans). Such a small number of American species is likely a consequence of collecting bias, which favors the capture of frugivorous drosophilids, and to the general absence of Neotropical Mycodrosophila studies in the last 50 years. Here, we describe two commonly sampled species of Mycodrosophila from the Amazonian and Pampa Brazilian biomes, which share morphological similarities with Mycodrosophila neoprojectans and M. projectans, respectively. We compared sequences of the mitochondrial gene cytochrome oxidase subunit I (COI), external morphology characteristics and male terminalia among these species. Based on a DNA barcoding approach coupled to morphological differences, we proposed the delimitation of two new species, Mycodrosophila hofmanni sp. nov. and Mycodrosophila valentae sp. nov. An updated key to identifying Neotropical and Nearctic Mycodrosophila species is also provided.

First evidence of methylation in the genome of Drosophila willistoni.

DNA methylation has been studied abundantly in vertebrates and recent evidence confirms that this phenomenon could be disseminated among some invertebrates groups, including Drosophila species. In this paper, we used the Methylation-Sensitive Restriction Endonuclease (MSRE) technique and Southern blot with specific probes, to detect methylation in the Drosophila willistoni species. We found differential cleavage patterns between males and females that cannot be explained by Mendelian inheritance, pointing to a DNA methylation phenomenon different from the Drosophila melanogaster one. The sequencing of some of these bands showed that these fragments were formed by different DNA elements, among which rDNA. We also characterized the D. willitoni dDnmt2 sequence, through a Mega Blast search against the D. willistoni Trace Archive Database using the D. melanogaster dDnmt2 nucleotide sequence as query. The complete analysis of D. willistoni dDnmt2 sequence showed that its promoter region is larger, its dDnmt2 nucleotide sequence is 33% divergent from the D. melanogaster one, Inverted Terminal Repeats (ITRs) are absent and only the B isoform of the enzyme is produced. In contrast, ORF2 is more conserved. Comparing the D. willistoni and D. melanogaster dDnmt2 protein sequences, we found higher conservation in motifs from the large domain, responsible for the catalysis of methyl transfer, and great variability in the region that carries out the recognition of specific DNA sequences (TRD). Globally, our results reveal that methylation of the D. willistoni genome could be involved in a singular process of species-specific dosage compensation and that the DNA methylation in the Drosophila genus can have diverse functions. This could be related to the evolutionary history of each species and also to the acquisition time of the dDnmt2 gene.