The association between non‐biting midges and Vibrio cholerae

Vibrio cholerae is a natural inhabitant of aquatic ecosystems, yet its interactions within this habitat are poorly understood. Here we describe the current knowledge on the interaction of V. cholerae with one group of co‐inhabitants, the chironomids. Chironomids, non‐biting midges (Chironomidae, Diptera), are an abundant macroinvertebrate group encountered in freshwater aquatic habitats. As holometabolous insects, chironomids start life when their larvae hatch from eggs laid at the water/air interface; through various feeding strategies, the larvae grow and pupate to become short‐lived, non‐feeding, adult flying insects. The discovery of the connection between V. cholerae and chironomids was accidental. While working with Chironomus transavaalensis, we observed the disintegration of its egg masses and searched for a possible microbial agent. We identified V. cholerae as the primary cause of this phenomenon. Haemagglutinin/protease, a secreted extracellular enzyme, degraded the gelatinous matrix surrounding the eggs, enabling bacterial growth. Observation of chironomids in relation to V. cholerae continuously for 7 years in various types of water bodies in Israel, India, and Africa revealed that environmental V. cholerae adhere to egg‐mass surfaces of various Chironomini (‘bloodworms’). The flying adults' potential to serve as mechanical vectors of V. cholerae from one water body to another was established. This, in turn, suggested that these insects play a role in the ecology of V. cholerae and possibly take part in the dissemination of the pathogenic serogroups during, and especially between, epidemics.     

Exploring species boundaries with multiple genetic loci using empirical data from non‐biting midges

Over the past decade, molecular approaches to species delimitation have seen rapid development. However, species delimitation based on a single locus, for example, DNA barcodes, can lead to inaccurate results in cases of recent speciation and incomplete lineage sorting. Here, we compare the performance of Automatic Barcode Gap Discovery (ABGD), Bayesian Poisson tree processes (PTP), networks, generalized mixed Yule coalescent (GMYC) and Bayesian phylogenetics and phylogeography (BPP) models to delineate cryptic species previously detected by DNA barcodes within Tanytarsus (Diptera: Chironomidae) non‐biting midges. We compare the results from analyses of one mitochondrial (cytochrome c oxidase subunit I [COI]) and three nuclear (alanyl‐tRNA synthetase 1 [AATS1], carbamoyl phosphate synthetase 1 [CAD1] and 6‐phosphogluconate dehydrogenase [PGD]) protein‐coding genes. Our results show that species delimitation based on multiple nuclear DNA markers is largely concordant with morphological variation and delimitations using a single locus, for example, the COI barcode. However, ABGD, GMYC, PTP and network models led to conflicting results based on a single locus and delineate species differently than morphology. Results from BPP analyses on multiple loci correspond best with current morphological species concept. In total, 10 lineages of the Tanytarsus curticornis species complex were uncovered. Excluding a Norwegian population of Tanytarsus brundini which might have undergone recent hybridization, this suggests six hitherto unrecognized species new to science. Five distinct species are well supported in the Tanytarsus heusdensis species complex, including two species new to science.     

A dated phylogeny of the palm tribe Chamaedoreeae supports Eocene dispersal between Africa, North and South America

The palm tribe Chamaedoreeae reaches its higher diversity in Central America, however, its distribution ranges from the north eastern part of Mexico to Bolivia with a disjunction to the Mascarene Islands in the Indian Ocean. The disjunct distribution of Chamaedoreeae is generally considered a result of Gondwana vicariance and extinction from Africa and/or Madagascar. However, latitudinal migrations and their role in shaping the distribution of this tribe in the Americas have been largely overlooked. In this study we used seven plastid and two nuclear DNA regions to investigate the phylogenetic relationships and biogeography of the Chamaedoreeae. The resulting phylogeny fully resolved the generic relationships within the tribe. The exact area of origin of the tribe remains uncertain, but dating analyses indicated an initial diversification of the Chamaedoreeae during the Early Eocene, followed by long distance dispersion to the Mascarene Islands in the late Miocene. The radiation of Hyophorbe could have taking place on islands in the Indian Ocean now submerged, but its former presence in Africa or Madagascar cannot be ruled out. At least two independent migrations between North and South America predating the rise of the Panama isthmus need to be postulated to explain the distribution of Chamaedoreeae, one during the Middle Eocene and a second during the Miocene. Whereas the traditional interpretation of distribution of Chamaedoreeae species assumes a west Gondwana origin of the group, the findings presented in this paper make it equally possible to interpret the group as a primarily boreotropical element.     

The lichen genus Physcia in Central and South America

Thirty-four species of the lichen genus Physcia (s. str.) in Central and South America are defined. Morphology, anatomy, chemistry, distribution, habitat, relation to other taxa and some evolutionary trends are discussed. A key to the species is presented. Eleven species are described as new; P. cinerea, P. convexella, P. coronifera, P. decorticata, P. kalbii, P. lobulata, P. lopezii, P. manuelii, P. rolfii, P. sinuosa , and P. tenuis. P. nubila is a new name for Heterodermia desertorum .     

Barcoding of biting midges in the genus Culicoides: a tool for species determination

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are insect vectors of economically important veterinary diseases such as African horse sickness virus and bluetongue virus. However, the identification of Culicoides based on morphological features is difficult. The sequencing of mitochondrial cytochrome oxidase subunit I (COI), referred to as DNA barcoding, has been proposed as a tool for rapid identification to species. Hence, a study was undertaken to establish DNA barcodes for all morphologically determined Culicoides species in Swedish collections. In total, 237 specimens of Culicoides representing 37 morphologically distinct species were used. The barcoding generated 37 supported clusters, 31 of which were in agreement with the morphological determination. However, two pairs of closely related species could not be separated using the DNA barcode approach. Moreover, Culicoides obsoletus Meigen and Culicoides newsteadi Austen showed relatively deep intraspecific divergence (more than 10 times the average), which led to the creation of two cryptic species within each of C. obsoletus and C. newsteadi. The use of COI barcodes as a tool for the species identification of biting midges can differentiate 95% of species studied. Identification of some closely related species should employ a less conserved region, such as a ribosomal internal transcribed spacer.     

Sugar‐feeding behaviour and longevity of European Culicoides biting midges

Most haematophagous insect vectors can also use sugar as an energy source; thus their sugar‐feeding behaviour influences their longevity and blood‐feeding rate and hence their vectorial capacity. Scant information is available on the sugar‐feeding behaviour of Culicoides Latreille biting midges (Diptera: Ceratopogonidae), which are vectors of bluetongue and Schmallenberg viruses. The longevity of laboratory‐reared Culicoides nubeculosus (Meigen) under fluctuating temperatures (16 and 28 °C) and with access to water or water and blood was on average 6.4 days and 8.9 days, respectively, which was around one third of the lifespan of siblings with access to sugar or sugar and blood (22.2 days and 27.1 days, respectively). Access to honeydew significantly increased the midge's longevity, whereas the provision of extrafloral nectaries had no impact. Females with access to sugar produced a significantly higher number of eggs (65.5 ± 5.2) than their starved sisters (45.4 ± 8.4). More than 80% of field‐caught female Culicoides from the two most abundant European groups, Obsoletus (n = 2243) and Pulicaris (n = 805), were fructose‐positive. Fructose‐positivity was high in all physiological stages and no seasonal variability was noted. The high rate of natural sugar feeding of Culicoides offers opportunities for the development of novel control strategies using toxic sugar baits and for the monitoring of vector‐borne diseases using sugar‐treated FTA (nucleic acid preservation) cards in the field.     

Further study on the phylogeny,taxonomy and distribution of the genus Veturius Kaup in Central and South America (Coleoptera: Passalidae)

This study provides data on the phylogeny, taxonomy and distribution of 14 known and five new species of the Neotropical genus Veturius Kaup (Proculini), belonging to various subgenera and species groups: V. (Veturius) latissimus n. sp. (Colombia, Central Andes) and V. (V.) calimanus n. sp. (Pacific slope of the Occidental Cordillera) are separated from V. (V.) caquetaensis Boucher, 1988, which seems restricted to the Amazonian slope of the Oriental Cordillera (Caquetá, Putumayo); V. (V.) sinuatomarginatus Luederwaldt, 1941 (Costa Rica), n. syn. of V. sinuatocollis Kuwert, 1890; V. sinuatocollis aculeatus Luederwaldt, 1941 (syntype from Costa Rica); V. (V.) aspina Kuwert, 1898 (located in Occidente of Ecuador, Guayaquil); V. (V.) yahua Boucher, 2006 (located in Occidente of Ecuador, Pichincha and SW Colombia, Nariño); V. (V.) guntheri Kuwert, 1898 (located in Peru, SE Puno and Colombia, W Putumayo); V. (V.) cephalotes (Le Peletier & Serville, 1825) (citation from Guyana); V. (V.) sinuatus (Eschscholtz, 1829) (previous synonymy); V. (V.) libericornis Kuwert, 1891 (located in Peru, Cuzco); V. (V.) lepidus Fonseca, 1999 (revision; located in Colombia, Amazonas, Putumayo and Peru, Loreto); V. (V.) transversus (Dalman, 1817) [syntype; previous synonymy of V. trituberculatus (Eschscholtz, 1829) with V. assimilis (Weber, 1801) and located in Brazil, Mato Grosso]; V. (V.) sinuosus (Drapiez, 1820) (corrected reference for Colombia); V. (Publius) crassus (Smith, 1852) (new syntype); V. (P.) danieli Boucher, 2006 (holotype deposit); V. (P.) vazdemelloi Boucher, n. sp. (Andes of Ecuador, Azuay); V. (Ouayana) unicornis Gravely, 1918 (located in Colombia, E Vaupés); V. (O.) costaianus Boucher, n. sp. (Venezuela, Amazonas, NW Pacaraima Massif); Ticoisthmus Boucher, n. subg., for the species group of V. (O.) laevior (Kaup, 1868), of southern Central America; and V. (T.) brachypterus Boucher, n. sp. (Costa Rica, Sierra Talamanca). Ticoisthmus is considered the sister group of Ouayana. It belongs to the Meso-American low mountain dispersion pattern and demonstrates, especially in the genus Veturius, but also more generally in the Neotropical passalids, the hot-spot characteristics, with diversity and endemism, of the narrow land between the Depression of Nicaragua and the Isthmus of Panama.     

A tale of North and South America: time and mode of dispersal of the amphitropical genus Munroa (Poaceae,Chloridoideae)

Plant disjunctions have provided some of the most intriguing distribution patterns historically addressed by biogeographers. We evaluated the three hypotheses that have been postulated to explain these patterns [vicariance, stepping‐stone dispersal and long‐distance dispersal (LDD)] using Munroa, an American genus of grasses with six species and a disjunct distribution between the desert regions of North and South America. The ages of clades, cytology, ancestral characters and areas of distribution were investigated in order to establish relationships among species, to determine the time of divergence of the genus and its main lineages, and to understand further the biogeographical and evolutionary history of this genus. Bayesian inference recovered the North American M. pulchella as sister species to the rest. Molecular dating and ancestral area analyses suggest that Munroa originated in North America in the late Miocene–Pliocene (7.2 Mya; 8.2–6.5 Mya). Based on these results, we postulate that two dispersal events modelled the current distribution patterns of Munroa: the first from North to South America (7.2 Mya; 8.2–6.5 Mya) and the second (1.8 Mya; 2–0.8 Mya) from South to North America. Arid conditions of the late Miocene–Pliocene in the Neogene and Quaternary climatic oscillations in North America and South America were probably advantageous for the establishment of populations of Munroa. We did not find any relationship between ploidy and dispersal events, and our ancestral character analyses suggest that shifts associated with dispersal and seedling establishment, such as habit, reproductive system, disarticulation of rachilla, and shape and texture of the glume, have been important in these species reaching new areas. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 110–125.     

Multi‐gene phylogeny of the Hemileuca maia complex (Saturniidae) across North America suggests complex phylogeography and rapid ecological diversification

The Hemileuca maia species complex occurs across the North American continent and consists of six named taxa, and several others that were recently synonymized. Taxa exhibit a wide span of adult flight periods, dramatic shifts in host‐plant use and occur in a range of habitats, all of which would suggest unrecognized diversity. We used one mitochondrial and three nuclear genes to generate 3900 bp per individual, including samples from every ecotype in the species group across the United States from New England to central Florida to California. We assessed phylogenetic relationships using both maximum likelihood and Bayesian phylogenetic methods. Results suggest very low levels of divergence across most of the continent and low levels of genetic structure – even between some recognized species that maintain clear ecological difference in sympatry. Our results suggest that meaningful and localized ecological divergence may occur in the absence of easily recognizable genetic divergence, due to either ongoing gene flow or the recent diversification in the group.     

Niche conservatism among non‐native vertebrates in Europe and North America

Niche conservatism, the hypothesis that niches remain constant through time and space, is crucial for the study of biological invasions as it underlies native‐range based predictions of invasion risk. Niche changes between native and non‐native populations are increasingly reported. However, it has been argued that these changes arise mainly because in their novel range, species occupy only a subset of the environments they inhabit in their native range, and not because they expand into environments entirely novel to them. Here, using occurrences of 29 vertebrate species native to either Europe or North America and introduced into the other continent, we assess the prevalence of niche changes between native and non‐native populations and assess whether the changes detected are caused primarily by native niche unfilling in the non‐native range rather than by expansion into novel environments. We show that niche overlap between native and non‐native populations is generally low because of a large degree of niche unfilling in the non‐native range. This most probably reflects an ongoing colonization of the novel range, as niche changes were smaller for species that were introduced longer ago and into a larger number of locations. Niche expansion was rare, and for the few species exhibiting larger amounts of niche overlap, an unfilling of the niche in the native range (e.g. through competition or dispersal limitations) is the most probable explanation. The fact that for most species, the realized non‐native niche is a subset of the realized native niche allows native‐range based niche models to generate accurate predictions of invasion risk. These results suggest that niche changes arising during biological invasions are strongly influenced by propagule pressure and colonization processes, and we argue that introduction history should be taken into account when evaluating niche conservatism in the context of biological invasions.     

Out of South America: multiple origins of non-native apple snails in Asia

Apple snails (Ampullariidae: Pomacea ) native to the New World have become agricultural and environmental pests widely in southern and eastern Asia since their introduction in about 1980. Although their impacts have been extensively documented, considerable confusion persists regarding their identities and geographical origins. Efforts to resolve the confusion have suffered from inadequate taxonomic and geographical sampling from both native and introduced ranges. Using phylogenetic and genealogical methods, we analysed 610–655 bp of cytochrome c oxidase subunit I DNA sequences from 783 apple snails from 164 Asian locations and 57 native South American locations. In Asia, we found four species of Pomacea in two clades: (1) Pomacea canaliculata and P. insularum , and (2) P. scalaris and P. diffusa . Parsimony networks and mismatch distributions indicate that the non-native ranges of the two most widespread species, P. canaliculata and P. insularum , probably result from multiple introductions. Molecular analyses are consistent with early accounts; non-native P. canaliculata populations trace back to multiple locations in Argentina and have probably been introduced more than once. In contrast, P. insularum was probably introduced from Brazil and Argentina independently. Multiple introductions may, in part, explain the success and rapid spread of these two species. Unlike P. canaliculata and P. insularum , P. scalaris and P. diffusa were probably introduced through the aquarium trade, derived originally from Argentina and Brazil, respectively. Possible physiological, ecological, and native range differences among these four species highlight the importance of accurate identification in understanding invasion patterns and processes, which is vital in developing and implementing management strategies.     

Genetic signals of artificial and natural dispersal linked to colonization of South America by non‐native Chinook salmon (Oncorhynchus tshawytscha)

Genetics data have provided unprecedented insights into evolutionary aspects of colonization by non‐native populations. Yet, our understanding of how artificial (human‐mediated) and natural dispersal pathways of non‐native individuals influence genetic metrics, evolution of genetic structure, and admixture remains elusive. We capitalize on the widespread colonization of Chinook salmon Oncorhynchus tshawytscha in South America, mediated by both dispersal pathways, to address these issues using data from a panel of polymorphic SNPs. First, genetic diversity and the number of effective breeders (N_b) were higher among artificial than natural populations. Contemporary gene flow was common between adjacent artificial and natural and adjacent natural populations, but uncommon between geographically distant populations. Second, genetic structure revealed four distinct clusters throughout the Chinook salmon distributional range with varying levels of genetic connectivity. Isolation by distance resulted from weak differentiation between adjacent artificial and natural and between natural populations, with strong differentiation between distant Pacific Ocean and Atlantic Ocean populations, which experienced strong genetic drift. Third, genetic mixture analyses revealed the presence of at least six donor geographic regions from North America, some of which likely hybridized as a result of multiple introductions. Relative propagule pressure or the proportion of Chinook salmon propagules introduced from various geographic regions according to government records significantly influenced genetic mixtures for two of three artificial populations. Our findings support a model of colonization in which high‐diversity artificial populations established first; some of these populations exhibited significant admixture resulting from propagule pressure. Low‐diversity natural populations were likely subsequently founded from a reduced number of individuals.     

Species‐specific mitochondrial gene rearrangements in biting midges and vector species identification

Abstract Partial mitochondrial gene sequences of 16 Culicoides species were determined to elucidate phylogenetic relations among species and to develop a molecular identification method for important virus vector species. In addition, the analysis found mitochondrial gene rearrangement in several species. Sequences of the mitochondrial genome region, cox1–trnL2–cox2 (1940–3785 bp) of 16 Culicoides and additional sequences were determined in some species, including whole mitochondrial genome sequences of Culicoides arakawae. Nine species showed common organization in this region, with three genes cox1–trnL2–cox2 and a small or no intergenic region (0–30 bp) between them. The other seven species showed translocation of tRNA and protein‐coding genes and/or insertion of AT‐rich non‐coding sequences (65–1846 bp) between the genes. The varied gene rearrangements among species within a genus is very rare for mitochondrial genome organization. Phylogenetic analyses based on the sequences of cox1+cox2 suggest a few clades among Japanese Culicoides species. No relationships between phylogenetic closeness and mitochondrial gene rearrangements were observed. Sequence data were used to establish a polymerase chain reaction tool to distinguish three important vector species from other Culicoides species, for which classification during larval stages is not advanced and identification is difficult.     

Evaluating large‐scale effects of Bacillus thuringiensis var. israelensis on non‐biting midges (Chironomidae) in a eutrophic urban lake

1. There is continued interest in controlling non‐biting midges (chironomids) in some freshwaters because of the potential nuisance caused by emergent adults. One option is to apply Bacillus thuringiensis var. israelensis (Bti), primarily used against mosquitoes and blackflies, to control benthic chironomid larvae. Chironomids are also at risk of collateral effects where Bti is used on other targets, and such instances may increase if climate change alters the incidence of dipteran‐borne diseases. However, most research on Bti effects on chironomids is available from mesocosms or ponds and might not scale‐up to larger waterbodies. 2. We present results on the effects of Bti on larval chironomids from eight experimental treatments, over 3 years, on a newly created eutrophic, urban lake of 200 ha, Cardiff Bay. 3. The first two experimental years provided limited evidence of Bti effects, with chironomid densities reduced by up to 14%. Increased scale of application and altered experimental design in the third year revealed reductions in chironomid larval densities of around 35% following Bti treatment, with suppression lasting several months. 4. These large‐scale Bti experiments – among the largest ever undertaken on chironomids – complement previous smaller‐scale experiments in illustrating how field conditions and application methods influence Bti effects on chironomid densities. Specifically, the work reveals how near‐neutral buoyancy formulations of Bti can reduce chironomid numbers in large lakes exceeding 3 m depth, but only where treatment methods avoid over‐dispersion. We advocate further evaluation to assess whether chironomids can be suppressed over longer periods using whole‐lake application without long‐term ecological implications or excessive cost. We also suggest further consideration be given to non‐buoyant Bti formulations for use in deeper lakes.     

Phylogeography of the whelk genus Cominella (Gastropoda: Buccinidae) suggests long‐distance counter‐current dispersal of a direct developer

The gastropod genus Cominella Gray, 1850 consists of approximately 20 species that inhabit a wide range of marine environments in New Zealand and Australia, including its external territory, the geographically isolated Norfolk Island. This distribution is puzzling, however, with apparently closely‐related species occurring either side of the Tasman Sea, even though all species are considered to have limited dispersal abilities. To determine how Cominella attained its current distribution, we derived a dated molecular phylogeny, which revealed a clade comprising all the Australian and Norfolk Island species nested within four clades of solely New Zealand species. This Australian clade diverged well after the vicariant separation of New Zealand from Australia, and implies two long‐distance dispersal events: a counter‐current movement across the Tasman Sea from New Zealand to Australia, occurring at the origination of the clade, followed by the colonization of Norfolk Island. The biology of Cominella suggests that the most likely method of long‐distance dispersal is rafting as egg capsules. Our robust phylogeny also means that the current Cominella classification requires revision. We propose that our clades be recognized as subgenera: Cominella (s.s.), Cominista, Josepha, Cominula, and Eucominia, with each subgenus comprising only of New Zealand or Australian species. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 315–332.     

A cryptic lineage within the pupfish Cyprinodon dearborni suggests multiple colonizations of South America

The coastal South American species Cyprinodon dearborni contains two lineages distinct at both mitochondrial and nuclear loci. One appears to be a long-term South American endemic, whereas the other is a more recent colonizer related to the widespread Cyprinodon variegatus .     

Recent vicariant and dispersal events affecting the phylogeny and biogeography of East Asian freshwater crab genus Nanhaipotamon (Decapoda: Potamidae)

The molecular phylogeny and biogeography of the East Asian freshwater crabs of the genus Nanhaipotamon (Decapoda: Brachyura: Potamidae) were studied, using two mitochondrial (16S rRNA and cytochrome oxidase I) and one nuclear (28S rRNA) markers, and correlated with various vicariant and dispersal events which have occurred in this region. The results showed Nanhaipotamon to be a monophyletic taxon with four clades which correspond to the topography of the coastal region of southeastern China and Taiwan Island. Mountains appear to play an important role in the distribution. The genus occurs only from east of the Wuyishan Range (Zhejiang and Fujian) and south of the Nanling Range (Guangdong) in southern China, and is also present west of the Central Range in Taiwan. The molecular and geological data suggest that Nanhaipotamon originated in an area between the Wuyishan and Nanling Ranges. In this area, the main and earliest cladogenesis occurred at ～4.8 million years ago (mya), with speciation probably taking place at around 4mya. The molecular evidence strongly supports the recent invasion of the genus into Taiwan Island from northeastern Fujian, via the paleo-Minjiang River on the landbridge of Taiwan Strait. The presence of the genus in Dongyin Island, however, is through invasion from southeastern Zhejiang, during the Pleistocene glaciation period. Nanhaipotamon reached Taiwan and Dongyin Island at ～1.0 and 0.4 mya, respectively. A small population of Nanhaipotamon formosanum from Penghu Islands (Pescadores) in the central Taiwan Strait has a slightly different genetic constitution and suggests it is a relict of past Pleistocene glaciations.