Fly wing evolution explained by a neutral model with mutational pleiotropy.

To what extent the speed of mutational production of phenotypic variation determines the rate of long-term phenotypic evolution is a central question. Houle et al. recently addressed this question by studying the mutational variances, additive genetic variances, and macroevolution of locations of vein intersections on fly wings, reporting very slow phenotypic evolution relative to the rates of mutational input, high phylogenetic signals, and a strong, linear relationship between the mutational variance of a trait and its rate of evolution. Houle et al. found no existing model of phenotypic evolution to be consistent with all these observations, and proposed the improbable scenario of equal influence of mutational pleiotropy on all traits. Here, we demonstrate that the purported linear relationship between mutational variance and evolutionary divergence is artifactual. We further show that the data are explainable by a simple model in which the wing traits are effectively neutral at least within a range of phenotypic values but their evolutionary rates are differentially reduced because mutations affecting these traits are purged owing to their different pleiotropic effects on other traits that are under stabilizing selection. Thus, the evolutionary patterns of fly wing morphologies are explainable under the existing theoretical framework of phenotypic evolution.

Contrasting levels of genotype by environment interaction for life history and morphological traits in invasive populations of Zaprionus indianus (Diptera: Drosophilidae).

It has been demonstrated that phenotypic plasticity and genotype by environment interaction are important for coping with new and heterogeneous environments during invasions. Zaprionus indianus Gupta (Diptera: Drosophilidae) is an Afrotropical invasive fly species introduced to the South American continent in 1999. This species is generalist and polyphagous, since it develops and feeds in several different fruit species. These characteristics of Z. indianus suggest that phenotypic plasticity and genotype by environment interaction may be important in this species invasion process. In this sense, our aim was to investigate the role of genetic variation for phenotypic plasticity (genotype by environment interaction) in Z. indianus invasion of the South American continent. Specifically, we quantified quantitative genetic variation and genotype by environment interactions of morphological and life history traits in different developmental environments, that is, host fruits. This was done in different populations in the invasive range of Z. indianus in Argentina. Results showed that Z. indianus populations have considerable amounts of quantitative genetic variation. Also, genotype by environment interactions was detected for the different traits analyzed in response to the different developmental environments. Interestingly, the amounts and patterns of these parameters differed between populations. We interpreted these results as the existence of differences in evolutionary potential between populations that have an important role in the short- and long-term success of the Z. indianus invasion process.

Redescription of Sibling Species of Rhinoleucophenga (Diptera: Drosophilidae): R. brasiliensis and R. fluminensis.

Rhinoleucophenga Hendel comprises an unusual Drosophilidae (Diptera) genus with predaceous larvae, currently compounded by 29 nominal species with New World distribution. In the present study, Rhinoleucophenga brasiliensis (Costa Lima) and R. fluminensis (Costa Lima) are redescribed. These two species are commonly misidentified in Drosophilidae species inventories, mainly by the few morphological character details presented in the original taxonomic description. Thus, by the morphological review performed here, lectotype and paralectotypes designed to R. brasiliensis and R. fluminensis, as well as new morphological characters, drawings and photos (for the first time) are presented in order to avoid further taxonomic mistakes with those referred sibling species of Rhinoleucophenga.

A new species of the genus Rhinoleucophenga (Diptera: Drosophilidae) and redescription of five species from Neotropical region.

The genus Rhinoleucophenga Hendel comprises 29 nominal species with New World distribution. In the present study five species are redescribed: R. angustifrons Malogolowkin; R. lopesi Malogolowkin; R. matogrossensis Malogolowkin; R. nigrescens Malogolowkin and Rhinoleucophenga personata Malogolowkin. R. capixabensis Culik & Ventura is proposed as a new junior synonymy of R. lopesi. Other species, R. jacareacanga sp. nov., is described from the specimens deposited at CEIOC/Fiocruz. The description of new species and review of some former descriptions of Rhinoleucophenga is indispensable since the distribution records of some species are doubtful.

The genus Leucophenga (Diptera, Drosophilidae), part VI: the argentata species group from the East Asia, with morphological and molecular evidence.

Six species of the Leucophenga argentata species group from East Asia are examined (including one known and five new ones): L. argentata (de Meijere, 1914); L. bicuspidata sp. nov.; L. fuscivena sp. nov.; L. longipenis sp. nov.; L. quadricuspidata sp. nov.; L. tricuspidata sp. nov.; the diagnoses for Asian species of the argentata group and a key to these species are provided. A total of 44 DNA sequences of the mitochondrial COI (cytochrome c oxidase subunit I) gene with BOLD process ID and GenBank accession numbers are provided for these species. The intra- and interspecific pairwise p-distances are summarized. The NJ (Neighbor-joining) and the Bayesian analyses are used to conduct a molecular phylogenetic analysis for the above-mentioned species. The molecular data are used as complementary evidence for the identification of the argentata group species with sexually dimorphic abdominal tergites.

A new genus of anthophilous drosophilids, Impatiophila (Diptera, Drosophilidae): morphology, DNA barcoding and molecular phylogeny, with descriptions of thirty-nine new species.

Breeding habits of essential dependence on flowers for larval food resources have evolved repeatedly in separate lineages of the Drosophilidae. However, flowers of Impatiens L. have never been recognized as hosts for drosophilid flies until recently: two Hirtodrosophila species, H. actinia (Okada) and H. yapingi Gao, were found feeding and breeding on Impatiens flowers. During our recent field surveys in central and southern China, a great number of drosophilid flies morphologically resembling the two species were collected, almost exclusively from flowers of Impatiens (family Balsaminaceae) and the family Gesneriaceae. In the present study, these specimens were identified on the basis of morphological characters and/or partial DNA sequences of the mitochondrial COI (cytochrome c oxidase subunit I gene, used as a barcoding marker). As a result, 39 new species were recognized. We then reconstructed the phylogenetic relationships among most of them, based on concatenated DNA sequences (3047 nucleotide sites) of two mitochondrial (COI and COII, i.e., cytochrome c oxidase subunits I and II, respectively) and three nuclear genes (ATPsyn-alpha, alphaTub84B and Hsc70cb, i.e., ATP synthase alpha, alpha-Tubulin at 84B and Hsc70Cb isoform H, respectively). In the resulting Bayesian and ML (maximum likelihood) trees, three well-supported clades were recognized, with a few species having remained uncertain for their phylogenetic positions. We also conducted a cladistic analysis with data of adult morphological characters to investigate the phylogenetic positions of a few species of which DNA sequence data were not available, and to investigate the classification of species groups with definition of their diagnoses. In consequence, we established a new genus, Impatiophila, for the species visiting flowers of Impatiens and Gesneriaceae, described all the new species, and revised the taxonomy of some known species.

The genus Leucophenga (Diptera, Drosophilidae), part V: the mutabilis species group from East Asia, with morphological and molecular evidence.

A total of seven known species of the Leucophenga mutabilis species group are resurveyed from the East Asia: L. angusta Okada, 1956; L. bellula Bergroth, 1894; L. magnipalpis Duda, 1924; L. nigripalpis Duda, 1924; L. orientalis Lin & Wheeler, 1972; L. striatipennis Okada, 1989 and L. taiwanensis Lin & Wheeler, 1972. The diagnosis of the mutabilis group is revised, and a key to the seven species of this group is provided. DNA sequences of the mitochondrial COI (cytochrome c oxidase subunit I) gene with BOLD process ID and GenBank accession numbers are provided for these species. The pairwise intra- and interspecific Kimura two-parameter COI distances among the aforementioned seven known species are summarized; and the utility of DNA barcoding in the genus Leucophenga is discussed.

Genetic variability and phenotypic plasticity of metric thoracic traits in an invasive drosophilid in America.

Thermal phenotypic plasticity of 5 metric thoracic traits (3 related to size and 2 to pigmentation) was investigated in Zaprionus indianus with an isofemale line design. Three of these traits are investigated for the first time in a drosophilid, i.e. thorax width and width of pigmented longitudinal white and black stripes. The reaction norms of white and black stripes were completely different: white stripes were insensitive to growth temperature while the black stripes exhibited a strong linear decrease with increasing temperatures. Thorax width exhibited a concave reaction norm, analogous but not identical to those of wing length and thorax length: the temperatures of maximum value were different, the highest being for thorax width. All traits exhibited a significant heritable variability and a low evolvability. Sexual dimorphism was very variable among traits, being nil for white stripes and thorax width, and around 1.13 for black stripes. The ratio thorax length to thorax width (an elongation index) was always >1, showing that males have a more rounded thorax at all temperatures. Black stripes revealed a significant increase of sexual dimorphism with increasing temperature. Shape indices, i.e. ratios between size traits all exhibited a linear decrease with temperature, the least sensitive being the elongation index. All these results illustrate the complexity of developmental processes but also the analytical strength of biometrical plasticity studies in an eco-devo perspective.

The New World genus Rhinoleucophenga (Diptera: Drosophilidae): new species and notes on occurrence records.

The genus Rhinoleucophenga Hendel comprises 26 nominal species with New World distribution. In the present study, two new species are described from samples in the Pampa and Caatinga biomes in Brazil, R. punctuloides sp. nov. and R. trivisualis sp. nov., respectively. Rhinoleucophenga punctuloides sp. nov. is a sibling species of R. punctulata Duda. Furthermore, two females of R. joaquina Schmitz, Gottschalk & Valente were found for the first time and a description is presented. A taxonomic dichotomous key with pictures is given for the Rhinoleucophenga species recorded in the Caatinga and Pampa biomes. The Neotropical open environments are areas of high diversity for Rhinoleucophenga. The description of new species and review of some older descriptions can change the area of species distribution and improve the faunistic knowledge of other localities in which previous studies have shown unidentified or misidentified Rhinoleucophenga species.

Four new species of the Stegana ornatipes species group (Diptera: Drosophilidae) from Yunnan, China, with DNA barcoding information.

Fore new species of Stegana (Steganina) ornatipes species group are found from Yunnan, China: S. (S.) angustifoliacea sp. nov., S. (S.) crinata sp. nov., S. (S.) nigripes sp. nov. and S. (S.) polysphyra sp. nov. The DNA sequences of the mitochondrial COI gene with BOLD Process ID and GenBank accession numbers are provided for the Chinese species. 

The genus Leucophenga (Diptera, Drosophilidae), part IV: the ornata species group from the East Asia, with morphological and molecular evidence (II).

Twenty-one species of the Leucophenga ornata species group are surveyed (including 12 new species): L. atrinervis Okada, 1968; L. digmasoma Lin & Wheeler, 1972; L. multipunctata Chen & Aotsuka, 2003; L. nigrinervis Duda, 1924; L. pectinata Okada, 1968; L. pentapunctata Panigrahy & Gupta, 1982; L. quadripunctata (de Meijere, 1908); L. regina Malloch, 1935; L. trivittata Okada, 1990; L. acutifoliacea sp. nov.; L. albiterga sp. nov.; L. angustifoliacea sp. nov.; L. baculifoliacea sp. nov.; L. cornuta sp. nov.; L. hirticeps sp. nov.; L. latifascia sp. nov.; L. pinguifoliacea sp. nov.; L. retihirta sp. nov. L. securis sp. nov.; L. sinupenis sp. nov.; L. villosa sp. nov.; these species (except for L. baculifoliacea sp. nov.) having pubescence on the distal portion of aedeagus. A key to all the examined species of the ornata group in this study is provided. We try to improve our species delimitation by integrating the DNA sequences data with morphological information. The intra- and interspecific pairwise K-2P (Kimura's two-parameter) distances are summarized.

Two new species of the new world genus Rhinoleucophenga (Diptera: drosophilidae).

The genus Rhinoleucophenga Hendel (1917) encompasses 21 described species but is still not well known as a taxon. Even the currently described species lack full descriptions, i.e., illustrations of the male genitalia are absent, which makes their identification difficult. This study describes two new species of Rhinoleucophenga with the illustration of their male genitalia.

Molecular phylogenetic analysis of the Amiota taurusata species group within the Chinese species, with descriptions of two new species.

The relationships among six species of the Amiota taurusata Takada, Beppu, & Toda (Diptera: Drosophilidae) species group were investigated based on DNA sequence data of the mitochondrial NADH dehydrogenase subunit 2 ( ND2) gene, using three species of the genus Amiota as outgroups. A mitochondrial gene, cytochrome c oxidase I ( COI), can be used to discriminate between species of the taurusata group. Two new species are described from South China: A. protuberantis Shao et Chen, sp. nov. and A. shennongi Shao et Chen, sp. nov. A key to all the species of the taurusata group based on morphological characters is provided.

The genera Luzonimyia and Pararhinoleucophenga from China (Diptera: Drosophilidae), with DNA barcoding information.

Four new species are described from Yunnan, China, which belong to two different genera within the subfamily Steganinae: Luzonimyia hirsutina sp. nov., Luzonimyia setocauda sp. nov., Pararhinoleucophenga amnicola sp. nov. and Pararhinoleucophenga sylvatica sp. nov. The DNA sequences and GenBank accession numbers of the mitochondrial COI gene among Chinese species are provided. 

High diversity of Drosophilidae (Insecta, Diptera) in the Pampas Biome of South America, with descriptions of new Rhinoleucophenga species.

In the last three decades some faunal surveys of Drosophilidae have been done in several environments in the Neotropical region, especially in Brazil. But approximately 30 to 50% of the drosophilids in Brazil have not yet been described, and the degradation of some biomes causes a profound loss of species diversity, as well as the loss of information about the present structureof their communities. This is the situation with the pampas biome, which covers southernmost Brazil, all of Uruguay, and the central region of eastern Argentina. For the present study, seasonal collections were made in a natural area of pampas within the limits of the municipality of Bossoroca in the state of Rio Grande do Sul, Brazil (28°45'01"S 54°56'55"W), from April 2011 to April 2012. A total of 7,164 drosophilids of 51 species were collected, comprising 36 species belonging to Drosophila Fallén, ten of Rhinoleucophenga Hendel, two of Amiota Loew, two of Zygothrica Wiedemann and one of Zaprionus Coquillett. Some species were recorded for the first time in pampas: Drosophila briegeri Pavan & Breuer, D. fuscolineata Duda, Rhinoleucophenga obesa (Loew), R. punctulata Duda, R. subradiata Duda and Zygothrica orbitalis (Sturtevant). Furthermore, three new species of genus Rhinoleucophenga were described: R. pampeana sp. nov., R. missionera sp. nov. and R. sulina sp. nov. A dichotomous key is given for the Rhinoleucophenga species recorded in pampas. An intensive literature search is reviewed of drosophilid species recorded in pampas of Brazil, Uruguay and Argentina, including taxonomic, genetic, evolutionary, and ecological studies. Despite Brazilian pampas being the richest when compared with Uruguay and Argentina, the three countries presented the same problem: huge areas with a barely surveyed Drosophilidae fauna. The combination of this information and the knowledge of the current state of preservation of pampas stress the necessity and importance of creating new conservation areas to preserve the natural biodiversity of pampas.

The genus Leucophenga (Diptera, Drosophilidae), part II: the ornata species group from East Asia, with morphological and molecular evidence (I).

Fifteen new species of the Leucophenga ornata species group are described from East Asia: L. apunctata Huang & Chen, sp. nov., L. arcuata Huang & Chen, sp. nov., L. brevifoliacea Huang & Chen, sp. nov., L. euryphylla Huang & Chen, sp. nov., L. falcata Huang & Chen, sp. nov., L. fuscinotata Huang & Chen, sp. nov., L. fuscithorax Huang & Chen, sp. nov., L. glabella Huang & Chen, sp. nov., L. hirsutina Huang & Chen, sp. nov., L. hirudinis Huang & Chen, sp. nov., L. piscifoliacea Huang & Chen, sp. nov., L. rectifoliacea Huang & Chen, sp. nov., L. serrateifoliacea Huang & Chen, sp. nov., L. subulata Huang & Chen, sp. nov., L. uncinata Huang & Chen, sp. nov. Four known species, L. ornata Wheeler, 1959, L. saigusai Okada, 1968, L. sculpta Chen & Toda, 1994 and L. todai Sidorenko, 1991 are redescribed as supplementary. A key to all the examined species in the ornata group is provided. We try to improve our species delimitation by integrating the DNA sequences data with morphological information. The intra- and interspecific pairwise K-2P (Kimura's two-parameter) distances are summaried.

The genus Leucophenga (Diptera, Drosophilidae), part III: the interrupta species group from the Oriental region, with morphological and molecular evidence.

A new species group, the interrupta group, is established within the genus Leucophenga based on two known and three new species, all of which are endemic to the Oriental region: L. interrupta Duda, 1924, L. neointerrupta Fartyal & Toda, 2005, L. bifurcata sp. nov., L. quadrifurcata sp. nov. and L. retifoliacea sp. nov. A key to the five species of the interrupta group is provided. Sixteen mtDNA COI sequences of the five species are analyzed; the molecular data are used as complementary evidence for the species boundaries defined by the morphological data. 

The genus Leucophenga (Diptera, Drosophilidae), Part I: The abbreviata species group from the Oriental region with morphological and molecular evidence.

A new species group, the abbreviata group is established within the genus Leucophenga based on one known and three new species, all of which are endemic to the Oriental region: L. abbreviata (de Meijere, 1911), L. brevivena sp. nov., L. sujuanae sp. nov. and L. zhenfangae sp. nov. A key to four species of the abbreviata group and the DNA barcoding are provided. Twenty-three mtDNA COI sequences belonging to the above species are analyzed; the molecular data are used as interactive evidence to evaluate the species boundaries defined by the morphological data.

Variation in mesoderm specification across Drosophilids is compensated by different rates of myoblast fusion during body wall musculature development.

BACKGROUND: It has been shown that species separated by relatively short evolutionary distances may have extreme variations in egg size and shape. Those variations are expected to modify the polarized morphogenetic gradients that pattern the dorso-ventral axis of embryos. Currently, little is known about the effects of scaling over the embryonic architecture of organisms. We began examining this problem by asking if changes in embryo size in closely related species of Drosophila modify all three dorso-ventral germ layers or only particular layers, and whether or not tissue patterning would be affected at later stages. PRINCIPAL FINDINGS: Here we report that changes in scale affect predominantly the mesodermal layer at early stages, while the neuroectoderm remains constant across the species studied. Next, we examined the fate of somatic myoblast precursor cells that derive from the mesoderm to test whether the assembly of the larval body wall musculature would be affected by the variation in mesoderm specification. Our results show that in all four species analyzed, the stereotyped organization of the body wall musculature is not disrupted and remains the same as in D. melanogaster. Instead, the excess or shortage of myoblast precursors is compensated by the formation of individual muscle fibers containing more or less fused myoblasts. CONCLUSIONS: Our data suggest that changes in embryonic scaling often lead to expansions or retractions of the mesodermal domain across Drosophila species. At later stages, two compensatory cellular mechanisms assure the formation of a highly stereotyped larval somatic musculature: an invariable selection of 30 muscle founder cells per hemisegment, which seed the formation of a complete array of muscle fibers, and a variable rate in myoblast fusion that modifies the number of myoblasts that fuse to individual muscle fibers.

Phylogeny of the African and Asian Phortica (Drosophilidae) deduced from nuclear and mitochondrial DNA sequences.

Phylogenetic relationships of 26 Phortica species were investigated based on DNA sequence data of two mitochondrial (ND2, COI) and one nuclear (28S rRNA) genes. Five monophyletic groups were recovered in the genus Phortica, of which three were established as new subgenera, Alloparadisa, Ashima, and Shangrila. The subgenus Allophortica was suggested as the most basal lineage in Phortica, followed by the lineage of P. helva + P. sobodo + P. varipes. The remaining Phortica species, most of Oriental distribution, formed a monophyletic group, and were subdivided into three lineages (i.e., the subgenera Ashima, Phortica, and Shangrila). The subgenera Shangrila and Phortica were suggested as sister taxa, and four clades were recovered in the subgenus Ashima. The result of reconstruction of ancestral distribution and estimation of divergence times indicates that, the ancestor of the genus Phortica restricted to Africa, its initial diversification was dated back to ca. 23 Mya (coinciding with the Oligocene/Miocene boundary); sympatric speciation and an Africa-to-Asia dispersal was proposed to account for the current distribution of Allophortica and the rest Phortica; most of the rest diversification of Phortica occurred in southern China, and the divergence between the African clade and its Oriental counterpart was suggested as a result of vicariance following a dispersal of their ancestral species from southern China to Africa.