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bioRxiv2018

Applying generalised allometric regressions to predict live body mass of tropical and temperate arthropods

1. The ecological implications of body size extend from the biology of individual organisms to ecosystem-level processes. Measuring body mass for high numbers of invertebrates can be logistically challenging, making length-mass regressions useful for predicting body mass with minimal effort. However, standardised sets of scaling relationships covering a large range in body length, taxonomic groups, and multiple geographical regions are scarce.\n\n2. We collected 6293 arthropods from 19 higher-level taxa in both temperate and tropical locations to compile a comprehensive set of linear models relating live body mass to a range of predictor variables. For each individual, we measured live weight (hereafter, body mass), body length and width, and conducted linear regressions to predict body mass using body length, body width, taxonomic group and geographic region. Additionally, we quantified prediction error when using parameters from arthropods of a different geographic region.\n\n3. Incorporating body width into taxon- and region-specific length-mass regressions yielded the highest prediction accuracy for body mass. Using regression parameters from a different geographic location increased prediction error, causing over- or underestimation of body mass depending on geographical origin and whether body width was included.\n\n4. We present a comprehensive range of parameters for predicting arthropod body mass and provide guidance for selecting optimal scaling relationships. Given the importance of body mass for functional invertebrate ecology and a paucity of adequate regressions to predict arthropod body mass from different geographical regions, our study provides a long-needed resource for quantifying live body mass in invertebrate ecology research.

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bioRxiv2018

Multinomial-Poisson mixture models reveal unexpected higher density estimates of an Andean threatened bird

Multinomial-Poisson mixture models reveal unexpected higher density estimates of an Andean threatened bird.Distance sampling and repeated counts are important tools to estimate population density of birds with low detectability. Here we use model based approach to assess the population density of a threatened bird, the Multicolored Tanager (Chlorochrysa nitidissima). We conducted 144 fixed point counts samplings to record all the individuals of the Multicolored Tanager detected by visual and aural observations from different habitats (forest edge, mature, secondary, and riparian forest), during four months in an Important Bird Area of Central Andes of Colombia. We used spatially replicated counts, distance sampling, and multinomial- Poisson mixture models to estimate the population density of the Multicolored Tanager. Accumulated sampling effort was of 576 repetitions in 144 point counts with 96 h of observation. The Multinomial-Poisson mixture model showed the best fit due low variance of density estimations in comparison to the conventional distance sampling and the spatially replicated counts. Results of this model evidenced a remarkable higher density estimates (1.3 - 2.05 individuals/ha) of the Multicolored Tanager, particularly in mature and secondary forest, as a result of detection correction, instead of sampling effort, by our model based analysis in contrast to index density used in previous studies. We discuss the advantages of model based methods over density indexes in designs monitoring programs of endangered species as the Multicolored Tanager, in order to obtain better and comparable assessment of density estimations along multiple localities.\n\nResumenLa combinacion de modelos multi-nominales y Poisson revelan estimaciones de densidad altas inesperadas en un ave amenazada Andina. Los muestreos por distancias y los conteos repetidos son herramientas importantes para estimar la densidad de poblacion de aves con baja deteccion. Aqui utilizamos un enfoque basado en modelos para evaluar la densidad de poblacion de un ave amenazada, la tangara multicolor (Chlorochrysa nitidissima). Realizamos 144 muestreos de conteos de puntos fijos para registrar todos los individuos de la tangara multicolor detectados por observaciones visuales y auditivas en diferentes habitats (borde del bosque, bosque maduro, bosque secundario y bosque ribereno), durante cuatro meses en un Area Importante para la Conservacion de las Aves en los Andes centrales de Colombia. Utilizamos conteos replicados espacialmente, muestreos de distancia y la combinacion de modelos multi-nominales y Poisson para estimar la densidad de poblacion de la tangara multicolor. El esfuerzo de muestreo acumulado fue de 576 repeticiones en 144 puntos de conteo con 96 h de observacion. La combinacion de modelos multi-nominales y Poisson mostro el mejor ajuste debido a la baja varianza de las estimaciones de densidad en comparacion con el muestreo de distancias y los conteos replicados espacialmente. Los resultados de este modelo evidenciaron una notable estimacion de mayor densidad (1.3 - 2.05 individuos / ha) de la tangara multicolor, principalmente en bosques maduros y secundarios, como resultado de la correccion de la deteccion por nuestro analisis basado en modelos, en lugar del esfuerzo de muestreo, en contraste con los indices de densidad utilizados en estudios previos. Discutimos las ventajas de los metodos basados en modelos sobre los indices de densidad en los disenos de programas de monitoreo de especies en peligro como la tangara multicolor, con el fin de obtener una evaluacion mejor y comparable de las estimaciones de densidad a lo largo de multiples localidades.

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bioRxiv2018

Avoiding misinterpretation of regression lines in allometry: is sexual dimorphism in digit ratio spurious?

The statistical analysis of allometry (size-dependence of traits) is fraught with difficulty that is often underestimated. In light of some recent controversies about statistical methods and the resulting biological conclusions, I here discuss the interpretation of regression lines and show how to avoid spurious effects. General linear models based on ordinary least square (OLS) regression are often used to quantify sexual dimorphism in a trait of interest that is modelled as a function of sex while controlling for size as a covariate. However, an analysis of artificially generated data where males and females differ in size only, but are otherwise built according to the same principles, shows that the OLS method induces a spurious dimorphism where there is none. Hence, OLS-based general linear models should not be regarded as a fail-proof tool that automatically provides the correct answer to whatever question one has in mind. Here I show how to avoid misinterpretation and how to best proceed with answering the recent debate about sexual dimorphism in digit ratio, a trait that is thought to reflect sex-hormone levels during development. The limited data, currently available to me, suggests that the widely accepted sexual dimorphism in digit ratio might well be only a by-product of an allometric shift in shape, urgently calling for a re-examination in larger data sets on humans and other vertebrates.

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bioRxiv2018

The effect of symbiosis between silkworm (Bombyx mori) and Firmicutes on silk production

Silkworm conditioning systems are widely popular due to enhancements observed in productivity and in resource efficiencies. However, limited knowledge is available on how intra-gut interspecific collaboration between the work and gut bacteria affects silk dry matter biomass production. The study was to study how gut bacteria, specifically fermicutes boost the dry silk production in Bombyx mori by altruistic/symbiotic interactions. Materials and methodsGreenhouse experiments were carried out to test the yield, biomass, nutrient uptake, parameters of gut morphology traits and glycolysis in 2017, the experiment included three treatments: no barrier treatment (NB) allowing complete gut collaboration, mesh barrier (MB) of partial gut collaboration and solid barrier (SB) without any exchanges of water and nutrients and gut collaboration. ResultsThe yield of silk production was increased by 53.6% and 27.8% in the treatments with complete gut collaborations compared to that without gut collaborations. Nitrogen (N), phosphorus (P) and Potassium (K) acquisitions of silk proteins were 1.71, 1.97 and 1.47 times for silkworm, and 1.25, 1.21, and 1.19 times for firmicutes in complete gut collaborations as high as in no gut collaborations, respectively. The length and surface area was increased by 42.9% and 43.6% for silkworm, 62.4% and 58.8% for firmicutes in complete gut collaborations compared to that in no gut collaborations. The worm length, leave number and net photosynthetic rate of silkworm were significantly boosted, while there is no significant effect on firmicutes. ConclusionsThe improvement of yield and nutrient acquisition may result from silkworm morphological and functional pliability induced from altruistic collaborations of firmicutes. The results would contribute to a comprehensive understanding of the response of silkworm and firmicutes to the gut collaboration on the basis of interspecific facilitation for silkworm/firmicutes system.

zoology↗

bioRxiv2018

Experimental increases in glucocorticoids alter function of the neuroendocrine stress axis in wild red squirrels without negatively impacting survival and reproduction

Hormones such as glucocorticoids (colloquially referred to as "stress hormones") have important effects on animal behavior and life history traits, yet most of this understanding has come through correlative studies. While experimental studies offer the ability to assign causality, there are important methodological concerns that are often not considered when manipulating hormones, including glucocorticoids, in wild animals. In this study, we examined how experimental elevations of cortisol concentrations in wild North American red squirrels (Tamiasciurus hudsonicus) affected their hypothalamic-pituitary-adrenal (HPA) axis reactivity, and life history traits including body mass, litter survival, and adult survival. The effects of exogenous cortisol on plasma cortisol concentrations depended on the time between treatment consumption and blood sampling. In the first nine hours after consumption of exogenous cortisol, individuals had significantly higher true baseline plasma cortisol concentrations, but adrenal gland function was impaired as indicated by their dampened response to capture and handling and to injections of adrenocorticotropic hormone compared to controls. Approximately 24 hours after consumption of exogenous cortisol, individuals had much lower plasma cortisol concentrations than controls, but adrenal function was restored. Corticosteroid binding globulin (CBG) concentrations were also significantly reduced in squirrels treated with cortisol. Despite these profound shifts in the functionality of the HPA axis, squirrel body mass, offspring survival, and adult survival were unaffected by experimental increases in cortisol concentrations. Our results highlight that even short-term experimental increases in glucocorticoids can affect adrenal gland functioning and CBG concentrations but without other side-effects.

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bioRxiv2018

A feeding aggregation of Omura‘s whale Balaenoptera omurai off Nosy Be, Mozambique Channel

A feeding aggregation of Omuras whales Balaenoptera omurai was documented off Nosy Be Island at the northeastern entrance of Mozambique Channel in November 1994. Underwater photographs of live individuals illustrated sub-surface skimming as main feeding behaviour, with small crustaceans, small jellyfish, and other gelatinous micronecton identified as prey. A precise description of the whales pigmentation patterns completes previous descriptions from the recent literature.

zoology↗

bioRxiv2018

Sperm morphology differences associated with pig fertility

Artificial insemination (AI) is commonplace in commercial pig breeding, and as such, ensuring sperm sample quality is of utmost importance to avoid reduced farrowing rates and litter sizes. Here, we have used high-throughput nuclear morphometric analysis to compare pig sperm samples categorised as meeting the AI standard (AIS) or not meeting the AI standard (N-AIS). We find that pig sperm nuclei are asymmetric, and that samples contain phenotypic shape abnormalities that show continuous variation. Samples classed as N-AIS have more abnormally shaped sperm than AIS samples, but conventional analysis misses many. The specific phenotypes identified suggest aspects of spermiogenesis that may be disrupted and indicate future avenues for improving pig sperm quality. This method reveals a significant difference in sperm head morphology between AIS and N-AIS pig sperm samples and has the potential to be further developed as a high-throughput tool for sperm head morphology assessment both in the pig breeding industry and in other species.

zoology↗

bioRxiv2018

Phylogenetic, population genetic, and morphological analyses reveal evidence for one species of Eastern Indigo Snake (Drymarchon couperi)

Accurate species delimitation and description are necessary to guide effective conservation management of imperiled species. The Eastern Indigo Snake (Drymarchon couperi) is a large species in North America that is federally-protected as Threatened under the Endangered Species Act. Recently, two associated studies hypothesized that Drymarchon couperi is two species. Here, we use diverse approaches to test the two-species hypothesis for D. couperi. Our analyses reveal that (1) phylogenetic reconstruction in previous studies was based entirely on variance of mitochondrial DNA sequence data, (2) microsatellite data demonstrate significant population admixture and nuclear gene flow between mitochondrial lineages, and (3) morphological analyses recover a single diagnosable species. Our results are inconsistent with the two-species hypothesis, thus we reject it and formally place Drymarchon kolpobasileus into synonymy with D. couperi. We suggest inconsistent patterns between mitochondrial and nuclear DNA may be driven by high dispersal of males relative to females. We caution against species delimitation exercises when one or few loci are used without evaluation of contemporary gene flow, particularly species with strong sex-biased dispersal (e.g., squamates) and/or when results have implications for ongoing conservation efforts.

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bioRxiv2018

A new subspecies of gray wolf, recently extinct, from Sicily, Italy (Carnivora, Canidae)

A new endemic subspecies of gray wolf from the island of Sicily (Italy) is described. While usually considered extinct before 1940, theres some evidence it may have survived up to 1970. This wolf was widespread throughout the island and characterized by a smaller size and a paler coloration than the Apennine wolf (Canis lupus italicus) from Central-Southern Italy.\n\nThis subspecies is described from a mounted specimen (the holotype) including also a separate skull stored at the Museo di Storia Naturale La Specola, Universita di Firenze, Italy. The three paratypes are: a) a mounted specimen stored at the Museo Regionale Interdisciplinare di Terrasini in Terrasini (PA), Italy, b) a mounted specimen stored at the Museo di Zoologia Pietro Doderlein, Universita di Palermo, Palermo, Italy, c) a mounted specimen stored at the Museo Civico Baldassarre Romano in Termini Imerese (PA), Italy.\n\nThis new subspecies is described as Canis lupus cristaldii subsp. nov. We suggest Sicilian wolf as common name for this new taxon.

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bioRxiv2018

Diurnal active photolocation enhances predator detection in a marine fish

Active sensing by means of light is rare. In vertebrates, it is known only from chemiluminescent fish with light organs below their pupils, an anatomical arrangement that is ideal to generate eyeshine in the pupils of nearby organisms. Here, we test whether diurnal fish can achieve the same by redirecting sunlight through reflection instead. We recently showed that small (< 5 cm), benthic, marine triplefin fish actively redirect downwelling light using their iris. We hypothesized that this mechanism allows triplefins to improve detection of a cryptic organism by generating eyeshine in its pupil. Here, we tested this by attaching small dark hats to triplefins to shade their iris from downwelling light. Two controls consisted of triplefins with a clear or no hat. These treatments test the prediction that light redirection increases the visual detection ability of triplefins. To this end, we placed treated fish in a tank with a display compartment containing either a stone as the control stimulus, or a scorpionfish, i.e. a cryptic, motionless triplefin predator with retroreflective eyes. After overnight acclimatization, we determined the average distance triplefins kept from the display compartment over two days. Both in the laboratory (n = 15 replicates per treatment) and in a similar field experiment at 15 m depth (n = 43 replicates per treatment) fish kept longer distances from the scorpionfish than from the stone. This response varied between hat treatments: shaded triplefins stayed significantly closer to the scorpionfish in the laboratory and in one of two orientations tested in the field. A follow-up field experiment at 10 m depth revealed the immediate response of triplefins to a scorpionfish. At first, many individuals (n = 80) moved towards it, with shaded triplefins getting significantly closer. All individuals then gradually moved to a safer distance at the opposite half of the tank. Visual modelling supported the experimental results by showing that triplefins can redirect enough light with their iris to increase a scorpionfishs pupil brightness above detection threshold at a distance of 7 cm under average field conditions and at more than 12 cm under favorable conditions. We conclude that triplefins are generally good in the visual detection of a cryptic predator, but can significantly improve this ability when able to redirect downwelling light with their iris and induce eyeshine in the predators pupil. We discuss the consequences of \"diurnal active photolocation\" for visual detection and camouflage among fish species.

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bioRxiv2018

Radiographic evaluation of subcutaneously injected, water-soluble, iodinated contrast for lymphography in dogs

Sentinel lymph node (SLN) mapping is common in many types of human cancers, and is gaining utility in veterinary medicine. There are currently many different methods described in veterinary medicine for pre-operative SLN mapping, however, most of these are restricted to referral institutions due to cost and need for specialized equipment. The purpose of this prospective, pilot study was to evaluate the feasibility of radiographic evaluation of water-soluble, iodinated contrast (WIC) injected subcutaneously for lymphography in dogs. Eight dogs were injected with 1-2 milliliters of WIC into the subcutaneous tissues overlying the tarsus in 4 separate locations mimicking a circumferential, peri-tumoral injection. Radiographs were taken at select time points up to 50 minutes. Image sequences were evaluated by a single, board-certified radiologist. All 8 dogs had visible contrast-enhancing lymphatic channels. Median time to lymphatic enhancement was immediately post-injection. Seven dogs (88%) had 8 contrast enhancing lymph nodes (7 popliteal and 1 superficial inguinal). Median time to lymph node enhancement was 20 minutes. In this study, the plantar aspect of the pes drained to the superficial inguinal lymph node, and the dorsal aspect of the pes drained to the popliteal lymph node. Subcutaneously-injected WIC was readily identifiable in the lymphatic channels and draining lymph node(s). Subcutaneously injected WIC may offer a practical alternative to previously described pre-operative methods of SLN mapping. Additionally, one cannot assume that the popliteal lymph node alone, drains the distal pelvic limb.

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bioRxiv2018

Annelid Brain and Nerve Cord in Siboglinid Riftia pachyptila

Vestimentifera is a peculiar group of marine gutless siboglinids which has uncertain position in annelid tree. The detailed study of the fragmentary explored central nervous system of vestimentiferans and other siboglinids is requested to trace the evolution of the siboglinid group. Among all siboglinids the vestimentiferans preserve the gut rudiment what makes them a key group to homologize main cerebral structures with the ones of typical annelids, such as supra- and subesophageal commissures, cirsumesophageal connectives etc. Histologically we revealed main annelid brain structures in the compact large brain of Riftia pachyptila: circumesophageal connectives (longitudinal nerve tracts) and commissures (dorsal, supra- and subenteral commissures). Innervation of tentacles makes them homologous to peristomial palps of the rest annelids. The single nerve cord is represented by paired intraepidermal longitudinal strands associated with the ventral ciliary field in vestimentum and bearing giant axons originating from at least four pairs of perikarya. The absence of regularly positioned ganglia and lateral nerves in the nerve cord in vestimentum and trunk and presence of them in the opisthosome segments. Among siboglinids, the vestimentiferans distinguished by a large and significatly differentiated brain which is reflection of the high development of the palp apparatus. Osedax, frenulates and Sclerolinum have less developped brain. Frenulates and Sclerolinum have good ganglionization in the opisthosome, which probably indicates its high mobility. Comparative neuroanatomical analysis of the siboglinids and annelid sister clades allows us to hypothesize that the last common ancestor of siboglinids might had brain with a dorsal commissure giving rise neurite bundles to palps and paired ventral nerve cord.

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bioRxiv2018

Visual modelling validates prey detection by means of diurnal active photolocation in a small cryptobenthic fish

Active sensing has been well documented in animals that use echolocation and electrolocation. Active photolocation, or active sensing using light, has received much less attention, and only in bioluminescent nocturnal species. Recently, however, evidence has suggested the diurnal triplefin Tripterygion delaisi uses controlled iris radiance, termed ocular sparks, for prey-detection. While this form of diurnal active photolocation was behaviourally described, a study exploring the complete physical and theoretical process would provide a more compelling case supporting this mechanism. In this paper, we investigate the conditions under which diurnal active photolocation could assist T. delaisi in detecting potential prey items. In the field, we sampled prey gammarids (Genus Cheirocratus) from foraging substrates, and characterized the spectral properties of their body and eyes, which possess strong reflectors between the ommatidia. In the laboratory, we quantified ocular spark sizes and the angular dependence of their radiance. Together with environmental light measurements and the visual properties of T. delaisi, we modeled diurnal active photolocation under various scenarios. Our results corroborate that diurnal active photolocation can help T. delaisi detect gammarids at distances relevant to foraging, 4.5 cm under favourable conditions and up to 2.5 cm under average conditions. Because ocular sparks are widespread across many different fish species, diurnal active photolocation for micro-prey may be a common predation strategy.

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bioRxiv2018

Effects of sublethal concentrations and application concentration of SYP-9625 on Tetranychus cinnabarinus (Boisduval) and its natural enemy, Neoseiulus californicus (McGregor)

ObjectiveExploring the effects of acaricides on predatory mites is crucial for the combination of biological and chemical control of pests. In this study, sublethal effects of the new acaricide SYP-9625 on Tetranychus cinnabarinus (Boisduval), effects of application concentration of SYP-9625 on the predatory mite Neoseiulus californicus (McGregor) and functional responses of N. californicus were assessed. The aim of the present study was to evaluate and explore the application of new acaricide SYP-9625 with natural enemy N. californicus.\n\nMethodAll the experiments were under laboratory conditions [25 {+/-} 1 {degrees}C, 16:8 (L:D) h and 75 {+/-} 5% RH] and based on an age-stage, two-sex life table. The sublethal concentrations against T. cinnabarinus, including LC10 (0.375 g/mL) and LC30 (0.841 g/mL) and the application concentration (100 g/mL) of SYP-9625, were used to evaluate effects on population parameters of N. californicus.\n\nResultT. cinnabarinus females treated with LC30 exhibited significantly reduced net reproductive rates (R0=11.02) of offspring compared to females treated with LC10 (R0=14.96) and untreated females (>R0=32.74). However, the intrinsic rate of increase (rm) and finite rate of increase ({lambda}) of N. californicus indicated that the application concentration of SYP-9625 had no significant negative effect on treated N. californicus eggs (rm=0.277,{lambda} =1.319) compared to the control (rm=0.292,{lambda} =1.338). Additionally, the sublethal concentrations against T. cinnabarinus including LC10 and LC30 showed a dose-dependent mechanism on the predatory mite. SYP-9625 also stimulated the predatory capacity of N. californicus against immobile stages such as eggs and larvae.\n\nConclusionIt is demonstrated that sublethal concentrations of SYP-9625 can inhibit population growth of T. cinnabarinus. And the sublethal concentrations and application concentration had little effect on the population growth of N. californicus. The two advantages showed great commercial potential of this new acaricide. Therefore, N. californicus can manage T. cinnabarinus populations effectively with appropriate SYP-9625 concentrations.

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bioRxiv2018

A Fixed Moderate-dose Combination of Tiletamine+Zolazepam Outperforms Midazolam in Induction of Short-term Immobilization of Ball Pythons (Python regius)

Laboratory animals are commonly anesthetized to prevent pain and distress and to provide safe handling. Anesthesia procedures are well-developed for common laboratory mammals, but not as well established in reptiles. We assessed the performance of intramuscularly injected tiletamine (dissociative anesthetic) and zolazepam (benzodiazepine sedative) in fixed combination (2 mg/kg and 3 mg/kg) in comparison to 2 mg/kg of midazolam (benzodiazepine sedative) in ball pythons (Python regius). We measured heart and respiratory rates and quantified induction parameters (i.e., time to loss of righting reflex, time to loss of withdrawal reflex) and recovery parameters (i.e., time to regain righting reflex, withdrawal reflex, normal behavior). Mild decreases in heart and respiratory rates (median decrease of <10 beats per minute and <5 breaths per minute) were observed for most time points among all three anesthetic dose groups. No statistically significant difference between the median time to loss of righting reflex was observed among animals of any group (p = 0.783). However, the withdrawal reflex was lost in all snakes receiving 3mg/kg of tiletamine+zolazepam but not in all animals of the other two groups (p = 0.0004). In addition, the time for animals to regain the righting reflex and resume normal behavior was longer in the drug combination dose groups compared to the midazolam group (p = 0.0055). Our results indicate that midazolam is an adequate sedative for ball pythons but does not suffice to achieve reliable immobilization or anesthesia, whereas tiletamine+zolazepam achieves short-term anesthesia in a dose-dependent manner.

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bioRxiv2018

What is the Best Available Science?: Conservation Status of Two California Desert Vertebrates

Scientific progress depends on evidence-based research, and reliance on accurate scholarship is essential when making management decisions for imperiled species. However, erroneous claims are sometimes perpetuated in the scientific and technical literature, which can complicate policy and regulatory judgments. The literature associated with two enigmatic California desert vertebrates, the Panamint alligator lizard Elgaria panamintina and the Inyo Mountains salamander Batrachoseps campi, exemplifies this problem. We produced a comprehensive threat analysis and status assessment for these species, which are both under review for possible listing under the US Endangered Species Act (ESA). Despite uncertainties and limited data, we find that many sources contain factual errors about the status of these two species, particularly the original petition that advocated for ESA listing. Although localized declines may have gone undetected, no evidence exists of population declines, population extirpation, or population-scale habitat conversion for E. panamintina. However, there is evidence of recent flash flood damage to some occupied B. campi habitat, which has possibly led to population declines at those localities. Contrary to inaccurate statements by some authors, all known populations of both species occur exclusively on federal lands, and numerous populations have likely benefited from recent federal management targeted at reducing known threats. Of the 12 threats that we identified for one or both species, only three currently appear to be serious: water diversions, climate change, and flash floods. The remaining threats are neither widespread nor severe, despite numerous contrary yet poorly supported statements in the literature. We thus evaluate the contemporary conservation status of both species as relatively secure, although B. campi is more at-risk compared to E. panamintina. This conclusion is independently supported by a recent review. Nonetheless, ongoing stewardship of these species in a multi-use context by federal agencies remains vital, and we identify several priority management actions and research needs for both species. We also recommend updated determinations on the IUCN Red List, and the Species of Conservation Concern list of the Inyo National Forest. To maximize the quality and effectiveness of conservation planning, we urge government agencies, non-governmental organizations, and individual scientists to maintain high standards of scholarship and decision-making.

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bioRxiv2018

Opening the Pandora Box: DNA-barcoding evidence limitations of morphology to identify Spanish mosquitoes

Cryptic speciation is frequent in the medically important mosquitoes. While most findings have been reported in tropical regions, it is an unexplored topic in countries where mosquito-borne diseases are not endemic, like Spain. The occurrence of recent outbreaks in Europe has increased the awareness on the native and invasive mosquito fauna present in the continent. Therefore, the central question of this study is whether the typological approach is sufficient to identify Spanish mosquitoes. To address this problem, we confronted the results of the morphological identification of 62 adult specimens collected from four different regions of Spain (La Rioja, Navarra, Castellon and the Island of Majorca) with the results obtained through DNA-barcoding. We conducted a comprehensive phylogenetic analysis of the COI gene region and compared this with the results of four species delimitation algorithms (ABGD initial partition, ABGD P=0.46%, bPTP and TCS). We report strong evidence for cryptic speciation in Anopheles algeriensis and Aedes vexans and reproductive isolation of the rock pool mosquito Aedes mariae. In addition, we report that the character present in the wings is not efficient to distinguish species Culiseta annulata from Culiseta subochrea, which distribution in the country may be different than previously described.

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bioRxiv2018

De novo transcriptomic characterization of Betta splendens for identifying sex-biased genes potentially involved in aggressive behavior modulation and EST-SSR maker development

Betta splendens is not only a commercially important labyrinth fish but also a nice research model for understanding the biological underpinnings of aggressive behavior. However, the shortage of basic genetic resource severely inhibits investigations on the molecular mechanism in sexual dimorphism of aggressive behavior typicality, which are essential for further behavior-related studies. There is a lack of knowledge regarding the functional genes involved in aggression expression. The scarce marker resource also impedes research progress of population genetics and genomics. In order to enrich genetic data and sequence resources, transcriptomic analysis was conducted for mature B. splendens using a multiple-tissues mixing strategy. A total of 105,505,486 clean reads were obtained and by de novo assembly, 69,836 unigenes were generated. Of which, 35,751 unigenes were annotated in at least one of queried databases. The differential expression analysis resulted in 17,683 transcripts differentially expressed between males and females. Plentiful sex-biased genes involved in aggression exhibition were identified via a screening from Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes pathways, such as htr, drd, gabr, cyp11a1, cyp17a1, hsd17b3, dax1, sf-1, hsd17b7, gsdf1 and fem1c. These putative genes would make good starting points for profound mechanical exploration on aggressive behavioral regulation. Moreover, 12,751 simple sequence repeats were detected from 9,617 unigenes for marker development. Nineteen of the 100 randomly selected primer pairs were demonstrated to be polymorphic. The large amount of transcript sequences will considerably increase available genomic information for gene mining and function analysis, and contribute valuable microsatellite marker resources to in-depth studies on molecular genetics and genomics in the future.

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