Field-collected Specimens Research Articles

Resistance Status of Aedes aegypti to Deltamethrin, Malathion, and Temephos in Ecuador.

In Ecuador, the status of insecticide resistance for Aedes aegypti, the principal arboviral vector in the country, has not been previously evaluated. The aim of this research was to describe the resistance status of Ae. aegypti to the principal insecticides used for vector control in provinces with high reports of arboviral clinical cases. This was a descriptive study performed on Ae. aegypti collected from 2016 to 2017 in 14 localities of Ecuador. The larvae were reared and tested using bioassays applying the adulticides malathion and deltamethrin, and the larvicide temephos. The lethal concentrations were obtained for field-collected specimens and compared to the susceptible reference strain ROCK, MRA-734. Mosquitoes from all the localities showed resistance to deltamethrin and susceptibility to malathion. On the other hand, mosquitoes demonstrated resistance to the larvicide temephos in 5 of the 14 localities analyzed. The results obtained in this research may be used by healthcare decision-makers to improve vector control in Ecuador. Rotation of insecticides and alternative biological vector control strategies should be considered to manage the resistance observed in Ae. aegypti to deltamethrin and temephos. New strategies to use insecticides should also be aimed to prevent selective pressure with malathion.

Intraspecific polyploidy correlates with colonization by arbuscular mycorrhizal fungi in Heuchera cylindrica

Polyploidy is known to cause physiological changes in plants which, in turn, can affect species interactions. One major physiological change predicted in polyploid plants is a heightened demand for growth-limiting nutrients. Consequently, we expect polyploidy to cause an increased reliance on the belowground mutualists that supply these growth-limiting nutrients. An important first step in investigating how polyploidy affects nutritional mutualisms in plants, then, is to characterize differences in the rate at which diploids and polyploids interact with belowground mutualists. We used Heuchera cylindrica (Saxifragaceae) to test how polyploidy influences interactions with arbuscular mycorrhizal fungi (AMF). Here we first confirmed the presence of AMF in H. cylindrica, and then we used field-collected specimens to quantify and compare the presence of AMF structures while controlling for site-specific variation. Tetraploids had higher colonization rates as measured by total, hyphal, and nutritional-exchange structures; however, we found that diploids and tetraploids did not differ in vesicle colonization rates. The results suggest that polyploidy may alter belowground nutritional mutualisms with plants. Because colonization by nutritional-exchange structures was higher in polyploids but vesicle colonization was not, polyploids might form stronger associations with their AMF partners. Controlled experiments are necessary to test whether this pattern is driven by the direct effect of polyploidy on AMF colonization.

Biology and morphology of immature stages of banana-associated Protosternum beetles, with comments on the status of Taiwanese endemic P. abnormale (Coleoptera: Hydrophilidae)

The available data on the biology of the water scavenger beetle genus Protosternum Sharp, 1890 (Hydrophilidae: Sphaeridiinae: Protosternini) are summarized, indicating an obligate association of Protosternum beetles with banana plants (Musaceae): they inhabit decaying tissues of old banana stems in which adult feeding, larval development and pupation takes place. Second and third instar larvae and pupa of the Taiwanese-endemic P. abnormale (Orchymont, 1913) are described in detail, based on field-collected specimens associated with co-occurring adults by cox1 DNA barcodes. Larvae are unique in the Hydrophiloidea by having strongly asymmetrical mouthparts with a large basal bifid tooth on the right mandible, indicating a specialized prey preference. Putative larval synapomorphies of the Protosternini are revealed, based on the comparison of the Protosternum larva with that of Sphaerocetum. Taxonomic status of P. abnormale is revealed to be confused by previous authors due to the absence of male specimens and is clarified here. Two new species are described based on specimens previously misidentified as P. abnormale: P. malayanum sp. nov. from Sumatra and Peninsular Malaysia, and P. hainanense sp. nov. from Hainan.

A Comparative Study of Energy Contents in Mosquito Vectors of Malaria and Dengue Prevailing in Jodhpur City (Thar Desert) of Rajasthan State, India

Transmission of malaria and dengue in the desert part of India is mainly caused by Anopheles stephensi and Aedes aegypti respectively. The maintenance and transmission of the pathogens that cause malaria and dengue are dependent on the physiology of the mosquito vectors. We aimed to measure the energy contents in the mosquitoes transmitting malaria and dengue in the desert part of the country. Immature stages of mosquitoes were collected from six different larval habitats situated in Jodhpur City of Rajasthan state, India. The immature stages of both the mosquitoes were collected once in fortnightly from each location. Quantitative estimations of the lipid, glucose, and glycogen of the laboratory-reared and field collected An. stephensi and Ae. aegypti were made by spectrophotometric method. The energy contents of the larvae, pupae, females, and males were estimated in triplicates on six different occasions. The lipid content of laboratory-reared larvae, pupae and female mosquitoes of An. stephensi and Ae. aegypti was found to be lower than their conspecific field-collected specimens. Whereas, the glycogen content in the laboratory-reared larvae, pupae and female mosquitoes of An. stephensi and Ae. aegypti was higher than that of their conspecific field-collected specimens. The glucose content in all the stages of the laboratory-reared An. stephensi was lower than their conspecific field-collected specimens except in few cases. The higher amount of lipid in field-collected mosquitoes may be because of the availability of food in the natural habitat and adaptation of mosquitoes. Mosquitoes living in desert climate are physiologically better equipped to survive in the desert environment.

<p><strong>Gynandromorphs in <em>Chrysotus spectabilis</em> (Diptera: Dolichopodidae) and considerations for sclerite homology for the Diptera terminalia</strong></p>

Field-collected gynandromorph specimens of Chrysotus spectabilis (Loew) (Diptera: Dolichopodidae) from the Brazilian State of Paraná are described and illustrated, with special reference to their terminalia morphology and intersexual homology between sclerites. Based both on the position of the male clasping structures in the female gynander (arising dorsally from the acanthophorites) and the acanthophorites in the male gynander (arising from the genital capsule), it is argued that the “revised epandrial hypothesis” offers a more robust explanation for the male terminalia homology in Diptera than alternative hypotheses (namely, periandrial and hinge hypotheses). Additionally, the segmental origin of female acanthophorites is re-evaluated and assumed to be a product of fusion between tergites 9 and 10, rather than the tergite 10 only.

Distributional patterns and conservation planning for a snake assemblage from temperate South America

We analyzed the spatial distribution of a snake assemblage from the Sierras de Ventania mountain range, a rich endemism area in east-central Argentina. We used field-collected and museum specimens combined with high-resolution environmental variables to identify common distributional patterns, estimate the suitable habitat for each species, and develop a conservation proposal related to the Protected Natural Areas (PNAs) system. Distributional models diverged into two opposite patterns: suitable habitats for most species at relatively high altitude in the hills, and suitable habitats for Bothrops ammodytoides and Lygophis anomalus at relatively low altitude in the surrounding hill plain. We assessed two proposals based on different conservation algorithms: the additive benefit function (ABF), which favours hilly environments, prioritizing areas with high specific richness, and the core-area zonation (CAZ), which prioritizes the distribution of all species, further indicating areas with low richness in the surrounding plain. Regardless of the algorithm used, our results indicated that the existing PNAs are not effective in protecting the snake assemblage. Protecting at least 5% of the highest species richness areas (ABF) or 5% of the distribution core areas of all species (CAZ), the existing PNAs only represented 2.2% of these priority areas. Our findings are largely consistent with previous work, highlighting that a widespread area needs to be assigned for conservation purposes. Thus, protection of the snake assemblage should take place both inside and outside the PNAs.

Bolstering Species Delimitation in Difficult Species Complexes by Analyzing Herbarium and Common Garden Morphological Data: A Case Study Using the New Zealand Native Myosotis pygmaea Species Group (Boraginaceae)

Species delimitation in recent radiations is challenging because these species often display overlap in their expression of morphological characters. Here we analyze morphological characters measured from field-collected herbarium specimens and compare them to measurements from live plants grown in a common garden to determine reliable characters that could be used to delimit species in the Myosotis pygmaea (Boraginaceae) species group in New Zealand. This species complex is of primary interest because it includes many threatened species as well as several taxonomically indeterminate entities. The common garden experiment revealed high levels of morphological plasticity within the M. pygmaea species group, as plants in the common garden grew to be strikingly larger than those in the field. The M. pygmaea species complex was found to be a morphologically definable group, and several taxonomically indeterminate entities were placed as being either morphologically similar to the M. pygmaea species group or to other species complexes. In multidimensional scaling analyses of morphological data, of the five named species that make up the M. pygmaea species group, three formed separate clusters (M. pygmaea, M. glauca, and M. brevis), and the two others were indistinguishable from each other (M. antarctica and M. drucei). This study represents an important step towards a planned integrative taxonomic revision of the M. pygmaea species group, and highlights the value of morphological data collected from a common garden experiment.

The first transcriptomes from field-collected individual whiteflies ( Bemisia tabaci, Hemiptera: Aleyrodidae):a case study of the endosymbiont composition.

Background:Bemisia tabaci species ( B. tabaci), or whiteflies, are the world's most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead to high heterozygosity and skewed representation of the genetic diversity. The ability to extract enough RNA from a single whitefly has remained elusive due to their small size and technological limitations. Methods: In this study, we optimised a single whitefly RNA extraction procedure, and sequenced the transcriptome of four individual adult Sub-Saharan Africa 1 (SSA1) B. tabaci. Transcriptome sequencing resulted in 39-42 million raw reads. De novo assembly of trimmed reads yielded between 65,000-162,000 Contigs across B. tabaci transcriptomes. Results: Bayesian phylogenetic analysis of mitochondrion cytochrome I oxidase (mtCOI) grouped the four whiteflies within the SSA1 clade. BLASTn searches on the four transcriptomes identified five endosymbionts; the primary endosymbiont Portieraaleyrodidarum and four secondary endosymbionts: Arsenophonus, Wolbachia, Rickettsia, and Cardinium spp. that were predominant across all four SSA1 B. tabaci samples with prevalence levels of between 54.1 to 75%. Amino acid alignments of the NusG gene of P. aleyrodidarum for the SSA1 B. tabaci transcriptomes of samples WF2 and WF2b revealed an eleven amino acid residue deletion that was absent in samples WF1 and WF2a. Comparison of the protein structure of the NusG protein from P. aleyrodidarum in SSA1 with known NusG structures showed the deletion resulted in a shorter D loop. Conclusions: The use of field-collected specimens means time and money will be saved in future studies using single whitefly transcriptomes in monitoring vector and viral interactions. Our method is applicable to any small organism where RNA quantity has limited transcriptome studies.

The first transcriptomes from field-collected individual whiteflies ( Bemisia tabaci, Hemiptera: Aleyrodidae).

Background: Bemisia tabaci species ( B. tabaci), or whiteflies, are the world's most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead to high heterozygosity and skewed representation of the genetic diversity. The ability to extract enough RNA from a single whitefly has remained elusive due to their small size and technological limitations. Methods: In this study, we optimised a single whitefly RNA extraction procedure, and sequenced the transcriptome of four individual adult Sub-Saharan Africa 1 (SSA1) B. tabaci. Transcriptome sequencing resulted in 39-42 million raw reads. De novo assembly of trimmed reads yielded between 65,000-162,000 Contigs across B. tabaci transcriptomes. Results: Bayesian phylogenetic analysis of mitochondrion cytochrome I oxidase (mtCOI) grouped the four whiteflies within the SSA1 clade. BLASTn searches on the four transcriptomes identified five endosymbionts; the primary endosymbiont Portiera aleyrodidarum and four secondary endosymbionts: Arsenophonus, Wolbachia, Rickettsia, and Cardinium spp. that were predominant across all four SSA1 B. tabaci samples with prevalence levels of between 54.1 to 75%. Amino acid alignments of the NusG gene of P. aleyrodidarum for the SSA1 B. tabaci transcriptomes of samples WF2 and WF2b revealed an eleven amino acid residue deletion that was absent in samples WF1 and WF2a. Comparison of the protein structure of the NusG protein from P. aleyrodidarum in SSA1 with known NusG structures showed the deletion resulted in a shorter D loop. Conclusions: The use of field-collected specimens means time and money will be saved in future studies using single whitefly transcriptomes in monitoring vector and viral interactions. Our method is applicable to any small organism where RNA quantity has limited transcriptome studies.

The first transcriptomes from field-collected individual whiteflies ( Bemisia tabaci, Hemiptera: Aleyrodidae): a case study of the endosymbiont composition

Background: Bemisia tabaci species ( B. tabaci), or whiteflies, are the world’s most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead to high heterozygosity and skewed representation of the genetic diversity. The ability to extract enough RNA from a single whitefly has remained elusive due to their small size and technological limitations. Methods: In this study, we optimised a single whitefly RNA extraction procedure, and sequenced the transcriptome of four individual adult Sub-Saharan Africa 1 (SSA1) B. tabaci. Transcriptome sequencing resulted in 39-42 million raw reads. De novo assembly of trimmed reads yielded between 65,000-162,000 Contigs across B. tabaci transcriptomes. Results: Bayesian phylogenetic analysis of mitochondrion cytochrome I oxidase (mtCOI) grouped the four whiteflies within the SSA1 clade. BLASTn searches on the four transcriptomes identified five endosymbionts; the primary endosymbiont Portiera aleyrodidarum and four secondary endosymbionts: Arsenophonus, Wolbachia, Rickettsia, and Cardinium spp. that were predominant across all four SSA1 B. tabaci samples with prevalence levels of between 54.1 to 75%. Amino acid alignments of the NusG gene of P. aleyrodidarum for the SSA1 B. tabaci transcriptomes of samples WF2 and WF2b revealed an eleven amino acid residue deletion that was absent in samples WF1 and WF2a. Comparison of the protein structure of the NusG protein from P. aleyrodidarum in SSA1 with known NusG structures showed the deletion resulted in a shorter D loop. Conclusions: The use of field-collected specimens means time and money will be saved in future studies using single whitefly transcriptomes in monitoring vector and viral interactions. Our method is applicable to any small organism where RNA quantity has limited transcriptome studies.

The first transcriptomes from field-collected individual whiteflies (Bemisia tabaci, Hemiptera: Aleyrodidae)

Background: Bemisia tabaci species (B. tabaci), or whiteflies, are the world’s most devastating insect pests. They cause billions of dollars (US) of damage each year, and are leaving farmers in the developing world food insecure. Currently, all publically available transcriptome data for B. tabaci are generated from pooled samples, which can lead to high heterozygosity and skewed representation of the genetic diversity. The ability to extract enough RNA from a single whitefly has remained elusive due to their small size and technological limitations. Methods: In this study, we optimised the single whitefly RNA extraction procedure, and sequenced the transcriptome of four individual adult Sub-Saharan Africa (SSA1) B. tabaci. Transcriptome sequencing resulted in 39-42 million raw reads. De novo assembly of trimmed reads yielded between 65,000-162,000 transcripts across B. tabaci transcriptomes. Results: Bayesian phylogenetic analysis of mitochondrion cytochrome I oxidase (mtCOI) grouped the four whiteflies within the SSA1 clade. BLASTn searches on the four transcriptomes identified five endosymbionts; the primary endosymbiont Portiera aleyrodidarum and four secondary endosymbionts: Arsenophonus, Wolbachia, Rickettsia, and Cardinium spp. that were predominant across all four SSA1 B. tabaci samples with prevalence levels between 54.1-75%. Amino acid alignments of the NusG gene of P. aleyrodidarum for the SSA1 B. tabaci transcriptomes of samples WF2 and WF2b revealed an eleven amino acid residue deletion that was absent in samples WF1 and WF2a. Comparison of the protein structure of the NusG protein from P. aleyrodidarum in SSA1 with known NusG structures showed the deletion resulted in a shorter D loop. Conclusions: The use of field-collected specimens means time and money will be saved in future studies using single whitefly transcriptomes in monitoring vector and viral interactions. Our method is applicable to any small organism where RNA quantity has limited transcriptome studies.

Bactrocera oleae pupae predation by Ocypus olens detected by molecular gut content analysis

The pupae of Bactrocera oleae (Diptera: Tephritidae) complete their development during autumn and winter in the soil, rather than in the drupe, resulting susceptible to edaphic predators. Environmentally friendly methods to control this olive pest involve the identification of its natural enemies. This study evaluated the role of Ocypus olens (Coleoptera: Staphylinidae) in the predation of B. oleae pupae, by means of molecular gut content analysis. Modified dry pitfall traps were used to collect live specimens from low-input olive orchards in Tuscany (Italy). Sampling was fine-tuned with a degree-day model estimating the presence of pest pupae in the soil. PCR analyses carried out on field-collected specimens demonstrated that O. olens is a predator of B. oleae, at least during autumn. These results are consistent with predictions of the degree-day model. Knowledge on species composition, traits and complementarity of the natural enemies of B. oleae pupae needs further investigation to advance conservation biological control strategies.

Chagas disease vector blood meal sources identified by protein mass spectrometry.

Chagas disease is a complex vector borne parasitic disease involving blood feeding Triatominae (Hemiptera: Reduviidae) insects, also known as kissing bugs, and the vertebrates they feed on. This disease has tremendous impacts on millions of people and is a global health problem. The etiological agent of Chagas disease, Trypanosoma cruzi (Kinetoplastea: Trypanosomatida: Trypanosomatidae), is deposited on the mammalian host in the insect’s feces during a blood meal, and enters the host’s blood stream through mucous membranes or a break in the skin. Identifying the blood meal sources of triatomine vectors is critical in understanding Chagas disease transmission dynamics, can lead to identification of other vertebrates important in the transmission cycle, and aids management decisions. The latter is particularly important as there is little in the way of effective therapeutics for Chagas disease. Several techniques, mostly DNA-based, are available for blood meal identification. However, further methods are needed, particularly when sample conditions lead to low-quality DNA or to assess the risk of human cross-contamination. We demonstrate a proteomics-based approach, using liquid chromatography tandem mass spectrometry (LC-MS/MS) to identify host-specific hemoglobin peptides for blood meal identification in mouse blood control samples and apply LC-MS/MS for the first time to Triatoma dimidiata insect vectors, tracing blood sources to species. In contrast to most proteins, hemoglobin, stabilized by iron, is incredibly stable even being preserved through geologic time. We compared blood stored with and without an anticoagulant and examined field-collected insect specimens stored in suboptimal conditions such as at room temperature for long periods of time. To our knowledge, this is the first study using LC-MS/MS on field-collected arthropod disease vectors to identify blood meal composition, and where blood meal identification was confirmed with more traditional DNA-based methods. We also demonstrate the potential of synthetic peptide standards to estimate relative amounts of hemoglobin acquired when insects feed on multiple blood sources. These LC-MS/MS methods can contribute to developing Ecohealth control strategies for Chagas disease transmission and can be applied to other arthropod disease vectors.

Evolutionary history of enigmatic bears in the Tibetan Plateau-Himalaya region and the identity of the yeti.

Although anecdotally associated with local bears (Ursus arctos and U. thibetanus), the exact identity of ‘hominid’-like creatures important to folklore and mythology in the Tibetan Plateau–Himalaya region is still surrounded by mystery. Recently, two purported yeti samples from the Himalayas showed genetic affinity with an ancient polar bear, suggesting they may be from previously unrecognized, possibly hybrid, bear species, but this preliminary finding has been under question. We conducted a comprehensive genetic survey of field-collected and museum specimens to explore their identity and ultimately infer the evolutionary history of bears in the region. Phylogenetic analyses of mitochondrial DNA sequences determined clade affinities of the purported yeti samples in this study, strongly supporting the biological basis of the yeti legend to be local, extant bears. Complete mitochondrial genomes were assembled for Himalayan brown bear (U. a. isabellinus) and black bear (U. t. laniger) for the first time. Our results demonstrate that the Himalayan brown bear is one of the first-branching clades within the brown bear lineage, while Tibetan brown bears diverged much later. The estimated times of divergence of the Tibetan Plateau and Himalayan bear lineages overlap with Middle to Late Pleistocene glaciation events, suggesting that extant bears in the region are likely descendants of populations that survived in local refugia during the Pleistocene glaciations.

Vector competence of field populations of the mosquito species Aedes japonicus japonicus and Culex pipiens from Switzerland for two West Nile virus strains.

Aedes (Hulecoeteomyia) japonicus japonicus (Diptera: Culicidae) (Theobald) is an invasive mosquito species in Central Europe, where it has colonized several areas. In this study, field-collected specimens of Ae. japonicus and Culex pipiens (Diptera: Culicidae) (Linnaeus) from Zürich (Switzerland) were orally exposed to two strains (NY99 and FIN) of the avian zoonotic pathogen West Nile virus (WNV) (family Flaviviridae, genus Flavivirus). Dissemination and transmission of the viruses after incubation for 12-15 days under a fluctuating Central European midsummer temperature regime (24 ± 7 °C) was investigated by detection of viral RNA in homogenates of pools of both head/thorax and saliva by reverse transcription real-time polymerase chain reaction (PCR). Culex pipiens was susceptible to WNV NY99 only, whereas both virus strains could be detected in Ae. japonicus, with the additional isolation of WNV NY99 in Vero cell culture from one saliva pool. Given the high abundances of Ae. japonicus in many newly colonized areas, its recently demonstrated broad host range, including mammalian and avian blood hosts, and its vector competence, this species is a potential key bridge vector of WNV in Central Europe.

The coralline genera Sporolithon and Heydrichia (Sporolithales, Rhodophyta) clarified by sequencing type material of their generitypes and other species

Interspecific systematics in the red algal order Sporolithales remains problematic. To re-evaluate its species, DNA analyses were performed on historical type material and recently collected specimens assigned to the two genera Sporolithon and Heydrichia. Partial rbcL sequences from the lectotype specimens of Sporolithon ptychoides (the generitype species) and Sporolithon molle, both from El Tor, Egypt, are exact matches to field-collected topotype specimens. Sporolithon crassum and Sporolithon erythraeum also have the same type locality; material of the former appears to no longer exist, and we were unable to PCR amplify DNA from the latter. A new species, Sporolithon eltorensis, is described from the same type locality. We have not found any morpho-anatomical characters that distinguish these three species. No sequenced specimens reported as S.ptychoides from other parts of the world represent this species, and likely reports of S.ptychoides and S.molle based on morpho-anatomy are incorrect. A partial rbcL sequence from the holotype of Sporolithon dimotum indicates it is not a synonym of S.ptychoides, and data from the holotype of S.episporum confirm its specific recognition. DNA sequences from topotype material of Heydrichia woelkerlingii, the generitype species, and isotype material of Heydrichia cerasina confirm that these are distinct species; the taxon reported to be H.woelkerlingii from New Zealand is likely an undescribed species. Type specimens of all other Sporolithon and Heydrichia species need to be sequenced to confirm that they are distinct species; morpho-anatomical studies have proved inadequate for this task.

Description of the mature larva and pupa of Anthonomus santacruzi Hustache (Coleoptera, Curculionidae), a biological control agent of Solanum mauritianum Scop. (Solanaceae), and remarks about its biology

The mature larva and pupa of Anthonomus santacruzi Hustache (Coleoptera, Curculionidae) are illustrated and described for the first time. Biological data obtained from field-collected specimens are also presented and discussed. Lastly, an upgraded key for selected Anthonomini pupae is also given.

Siphonaptera from Western North American Chipmunks

ABSTRACT: Several species of western North American chipmunks (Rodentia: Tamias) are distributed in overlapping ranges. Field-collected specimens of 9 species of chipmunks from 8 U.S. states were examined externally for fleas (Siphonaptera). We document flea infestations and 1 new range extension. This work demonstrates that ongoing field collection can shed light on host and parasite distributions over large geographical areas.

Pastinaca erzincanensis (Apiaceae), A New Species from Eastern Turkey and Its Phylogenetic Position within Tordylieae

Pastinaca erzincanensis Menemen & Kandemir (Apiaceae) is described as a new species, restricted to a single location in Erzincan Province, Turkey. To describe the species and assess its phylogenetic placement, field-collected and herbarium specimens were examined for morphological, fruit anatomical/micromorphological and palynological variation and included in a molecular phylogenetic study. Comparisons of leaf morphology, palynology and fruit anatomy suggest an affinity with Pastinaca (Tordylieae tribe Tordyliinae), although the presence of vittae in the fruit ribs is unique within the genus. Maximum parsimony and maximum likelihood analyses of nrDNA ITS sequences from representative members of tribe Tordylieae show that P. erzincanensis nests within a well-supported clade comprising members of Pastinaca, Malabaila and Trigonosciadium. Within a poorly supported Pastinaca s. lato clade, P. erzincanensis is sister group to M. pastinacifolia, with P. pimpinellifolia, P. yildizii and M. brachytaenia placed a...

Evidence for Karyotype Polymorphism in the Free-Living Flatworm, Macrostomum lignano, a Model Organism for Evolutionary and Developmental Biology.

Over the past decade, the free-living flatworm Macrostomum lignano has been successfully used in many areas of biology, including embryology, stem cells, sexual selection, bioadhesion and aging. The increased use of this powerful laboratory model, including the establishment of genomic resources and tools, makes it essential to have a detailed description of the chromosome organization of this species, previously suggested to have a karyotype with 2n = 8 and one pair of large and three pairs of small metacentric chromosomes. We performed cytogenetic analyses for chromosomes of one commonly used inbred line of M. lignano (called DV1) and uncovered unexpected chromosome number variation in the form of aneuploidies of the largest chromosomes. These results prompted us to perform karyotypic studies in individual specimens of this and other lines of M. lignano reared under laboratory conditions, as well as in freshly field-collected specimens from different natural populations. Our analyses revealed a high frequency of aneuploids and in some cases other numerical and structural chromosome abnormalities in laboratory-reared lines of M. lignano, and some cases of aneuploidy were also found in freshly field-collected specimens. Moreover, karyological analyses were performed in specimens of three further species: Macrostomum sp. 8 (a close relative of M. lignano), M. spirale and M. hystrix. Macrostomum sp. 8 showed a karyotype that was similar to that of M. lignano, with tetrasomy for its largest chromosome being the most common karyotype, while the other two species showed a simpler karyotype that is more typical of the genus Macrostomum. These findings suggest that M. lignano and Macrostomum sp. 8 can be used as new models for studying processes of partial genome duplication in genome evolution.