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bioRxiv2017

Diet predicts milk composition in primates

Mammalian mothers pay heavy energetic costs to fuel the growth of their offspring. These costs are highest during lactation. Energy transmitted to offspring in the form of milk must ultimately come from the maternal diet, but there have been few comparative studies of the relationship between milk properties and mammalian diets. We used interspecific data on primate milk composition and wild diets to establish that concentrations of milk protein and sugar are predicted by diet independent of maternal mass, litter mass, and infant parking behavior such that increasing folivory or faunivory increases protein concentration but decreases sugar concentration. Milk energy density is unrelated to diet, though infant parking species do produce more energy-dense milk. While parking effects have been previously explained as a result of mother-infant separation, the mechanisms causing the relationship between nutrient packaging in milk and maternal diet are currently unclear. However, they likely reflect evolved differences in maternal energetics related to maternal foraging ecology, infant growth patterns, or the relative dietary abundance of nutrients costly to synthesize in milk among primate species.

zoology↗

bioRxiv2017

Biomechanics of the peafowl’s crest: a potential mechanosensory role for feathers during social displays

Feathers act as vibrotactile sensors that can detect mechanical stimuli during avian flight and tactile navigation, suggesting that they may also detect stimuli during social displays. In this study, we present the first measurements of the biomechanical properties of the feather crests found on the heads of birds, with an emphasis on those from the Indian peafowl (Pavo cristatus). We show that in peafowl these crest feathers are coupled to filoplumes, small feathers known to function as mechanosensors. We also determined that airborne stimuli with the frequencies used during peafowl courtship and social displays couple efficiently via resonance to the vibrational response of their feather crests. Specifically, vibrational measurements showed that although different types of feathers have a wide range of fundamental resonant frequencies, peafowl crests are driven near-optimally by the shaking frequencies used by peacocks performing train-rattling displays. Peafowl crests were also driven to vibrate near resonance in a playback experiment that mimicked the effect of these mechanical sounds in the acoustic very near-field, reproducing the way peafowl displays are experienced at distances [≤] 1.5m in vivo. When peacock wing-shaking courtship behaviour was simulated in the laboratory, the resulting airflow excited measurable vibrations of crest feathers. These results demonstrate that peafowl crests have mechanical properties that allow them to respond to airborne stimuli at the frequencies typical of this species social displays. This suggests a new hypothesis that mechanosensory stimuli could complement acoustic and visual perception and/or proprioception of social displays in peafowl and other bird species. We suggest behavioral studies to explore these ideas and their functional implications.

zoology↗

bioRxiv2017

Cryptic phylogeographic history sheds light on the generation of species diversity in sky-island mountains

Biodiversity hotspots should be given high priority for conservation under the situation of global climate change. The sky islands in southwestern China are characterized by extraordinarily high species diversity and are among one of the worlds top biodiversity hotspots. However, neither the actual species diversity in this region or mechanisms generating this diversity are well explored. Here, we report on the phylogeographic analysis of the long-tailed mole (Scaptonyx fusicaudus), a semi-fossorial mammal that inhabits the montane cool forests across the Chinese sky islands and is considered to represent one species divided into two subspecies. Analyses using DNA sequence data from one mitochondrial and six nuclear genes revealed that populations inhabiting different mountains exhibited exceptionally strong geographic structure. The lowlands and large rivers act as \"soft\" and \"hard\" barriers to dispersal, respectively, isolating evolutionary lineages for up to 11 million years. Our results suggest that the mountain ranges act as interglacial refugia buffering populations from climate fluctuations, further facilitating allopatric diversification. Strikingly, species delimitation analyses suggests that the long-tailed mole may comprise 18 operational taxonomic units and 17 putative species. Our results suggest that for low-vagility species, the complex topography of the Chinese sky islands has shaped genetic diversity and structure and promoted exceptional diversification through a combination of eco-environmental stability as well as geographic fragmentation. The patterns observed in S. fusicaudus may be representative for other cold- adapted species, reflecting the generation of mammalian faunal diversity in the sky-island mountains of southwestern China.

zoology↗

bioRxiv2017

Placozoans are eumetazoans related to Cnidaria

The phylogenetic placement of the morphologically simple placozoans is crucial to understanding the evolution of complex animal traits. Here, we examine the influence of adding new genomes from placozoans to a large dataset designed to study the deepest splits in the animal phylogeny. Using site-heterogeneous substitution models, we show that it is possible to obtain strong support, in both amino acid and reduced-alphabet matrices, for either a sister-group relationship between Cnidaria and Placozoa, or for Cnidaria and Bilateria (=Planulozoa), also seen in most published work to date, depending on the orthologues selected to construct the matrix. We demonstrate that a majority of genes show evidence of compositional heterogeneity, and that the support for Planulozoa can be assigned to this source of systematic error. In interpreting this placozoan-cnidarian clade, we caution against a peremptory reading of placozoans as secondarily reduced forms of little relevance to broader discussions of early animal evolution.

zoology↗

bioRxiv2017

Bird songs on the shelf: assessing vocal activity and output using data hidden in sound archives

Understanding how often do animals emit communication signals is of critical importance to address a variety of research questions in behavioral ecology and sexual selection. However, information on vocal output, a central component of investment in signaling, is lacking for most species employing acoustic communication. Because this lack of information is partly due to logistical and methodological difficulties in monitoring animal signaling over time, developing new approaches to quantify vocal output is of special importance. We asked whether the number of recordings of avian vocalizations in sound archives and the times when such recordings were obtained reflect estimates of vocal output and temporal patterns of vocal activity obtained through systematic monitoring of wild bird populations in tropical forest sites. Based on a sample of 43 montane forest species, we found significant relationships between the number of recordings of species detected through continuous monitoring over several months and the number of recordings archived in sound collections, especially when accounting for the area of distribution of each species. In addition, daily activity patterns based on data collected through continuous monitoring over several days did not differ from those based on recordings archived in sound collections in 12 of 15 species of lowland forest birds. Annual patterns in vocal activity of two species estimated based on recordings in collections closely resembled previously published patterns. We conclude that recordings in sound collections contain valuable yet previously unappreciated information about the vocal output and temporal patterns in vocal activity of birds. This opens the possibility of using sound collections to assess vocal output and to consider it as a variable of interest in studies on the ecology and evolution of birds and other animals that use acoustic signals for communication. We encourage field workers to keep the ears wide open, and the recorders wide ready to record.

zoology↗

bioRxiv2017

Down Feather Structure Varies Between High And Low Elevation Male Andean Torrent Ducks (Merganetta armata)

Feathers are one of the defining characteristics of birds and serve a critical role in thermal insulation and physical protection against the environment. Feather structure is known to vary among individuals, and it has been suggested that populations exposed to different environmental conditions may exhibit different patterns in feather structure. We examined both down and contour feathers from two populations of male Torrent Ducks (Merganetta armata) from Lima, Peru, including one high-altitude population from the Chancay-Huaral River at approximately 3500 meters (m) elevation and one low-altitude population from the Chillon River at approximately 1500 m. Down feather structure differed significantly between the two populations. Ducks from the high-altitude population had longer, denser down compared with low-altitude individuals. Contour feather structure varied greatly among individuals but showed no significant difference between populations. These results suggest that the innermost, insulative layer of plumage (the down), may have developed in response to lower ambient temperatures at high elevations. The lack of observable differences in the contour feathers may be due to the general constraints of the waterproofing capability of this outer plumage layer.\n\nResumenEl plumaje es una caracteristica que define a las aves y cumple roles criticos en el aislamiento termico y proteccion fisica del ambiente. Se sabe que la estructura de las plumas varia ente individuos, y se ha sugerido que poblaciones expuestas a diferentes condiciones ambientales pueden exhibir diferentes patrones en la estructura de las plumas. En este estudio se examinaron tanto el plumon como las plumas de contorno de machos adultos del Pato de los Torrentes (Merganetta armata) de dos poblaciones, una en el rio Chancay-Huaral a 3,500 msnm y otra en el rio Chillon a 1,500 msnm, ubicadas en Lima, Peru. La estructura de los plumones difiere significativamente entre las dos poblaciones. Los patos de la poblacion a grandes elevaciones tienen plumones largos, y densos comparados con los individuos de las partes bajas. La estructura de las plumas de contorno varia ampliamente entre individuos pero no muestra diferencias significativas entre poblaciones. Estos resultados sugieren que las diferencias entre las capas interiores de aislamiento del plumaje (plumon), haberse desarrollado como respuesta en ambientes de bajas temperaturas a grandes elevaciones. En cambio la falta de detectables diferencias en las plumas de contorno puede ser debido a la constante seleccion en la capacidad impermeable de la capa de plumas exteriores.

zoology↗

bioRxiv2017

Calling song maturity in two-spotted cricket, Gryllus bimaculatus: its patterns and a possible physical explanation

Males of Gryllus bimaculatus (two-spotted cricket) emit acoustic signals by stridulating two forewings. One of their songs, calling song, plays a role in attracting females to mate, yet the significance of each song trait in attracting conspecific females remains unclear. Among such traits, the relevance of frequency component (i.e. song pitch) has been underestimated, as orthopterans had long been believed incapable of song pitch recognition. However, recent literatures suggested that ears of orthopteran species are capable of frequency recognition as mammalians do. My previous report demonstrated that their calling song recorded from mature adults has constant and pure peak frequency component around 5.7 kHz, further supporting a biological significance of the frequency component. In this study, I tracked its change over time in sexual maturity phase (i.e. from early adult phase). 300 calling songs were recorded over time from a pool of 122 adult crickets, as it required large number of animals because the crickets rarely sing at very early adult stage. A maturation process of calling song was observed, where the peak frequency distributed lower and more variable frequency in early adult phase (e.g. mean peak value was 4.9 kHz on day 3), then it gradually increased and converged to 5.8 kHz with two weeks. The coefficient of variance also decreased over the process, showing minimum around day 20. Also, I found that the young crickets (supposed to emit immature song), emit perfectly tuned calling song with 5.8 kHz peak in helium-substituted (80% Helium and 20% Oxygen) environment. These findings suggest that the robustly regulated frequency of the calling song is acquired during the early-to-mid adult stage, and it may be associated with sexual maturity of males. Also, the helium-substitution experiment suggests that physical resistance from surrounding gas molecules negatively impacts stability of calling songs of young males, implying that a muscle development and/or forewing hardening may help song maturation. This study highlights a biological significance of the frequency component, such that females may adaptively select sexually mature males based on the song trait.

zoology↗

bioRxiv2017

The radiation of alopiine clausiliids in the Sicilian Channel (Central Mediterranean): phylogeny, patterns of morphological diversification and implications for taxonomy and conservation of Muticaria and Lampedusa

The phylogeny, biogeography and taxonomy of the alopiine clausiliids of the Sicilian Channel, belonging to the genera Lampedusa and Muticaria, were investigated using morphological (shell characters and anatomy of the reproductive system) and genetic (sequencing of a fragment of the mitochondrial large ribosomal subunit 16S rRNA, and the nuclear internal transcriber spacer 1, ITS-1 rRNA) data. Classically, the genus Lampedusa includes three species: L. imitatrix and L. melitensis occurring in circumscribed localities in western Malta and on the islet of Filfla, and L. lopadusae on Lampedusa and Lampione. The genus Muticaria includes two species in southeastern Sicily (M. siracusana and M. neuteboomi) and one in the Maltese islands (M. macrostoma), which is usually subdivided into four entities based on shell characters (macrostoma on Gozo, Comino, Cominotto and central-eastern Malta; mamotica in southeastern Gozo; oscitans on Gozo and central-western Malta; scalaris in northwestern Malta). These have sometimes been considered as subspecies and sometimes as mere morphs.\n\nThe Lampedusa of Lampedusa and Lampione form a well distinct clade from those of the Maltese Islands. The population of Lampione islet is a genetically distinct geographic form that deserves formal taxonomic recognition (as L. nodulosa or L. l. nodulosa). The Lampedusa of Malta are morphologically distinct evolutionary lineages with high levels of genetic divergence and are confirmed as distinct species (L. imitatrix and L. melitensis).\n\nThe Muticaria constitute a clearly different monophyletic clade divided into three geographical lineages corresponding to the Sicilian, Maltese and Gozitan populations. The Sicilian Muticaria form two morphologically and genetically distinguishable subclades that may either be considered subspecies of a polytypic species, or two distinct species. The relationships of Maltese and Gozitan Muticaria are complex. Two of the three Maltese morphotypes resulted monophyletic (oscitans and scalaris) while the other was separated in two lineages (macrostoma); however this picture may be biased as only few samples of macrostoma were available to study. The Gozitan morphotypes (macrostoma, mamotica and oscitans) where resolved as polyphyletic but with clear molecular evidence of mixing in some cases, indicating possible relatively recent differentiation of the Gozitan Muticaria or repetitive secondary contacts between different morphotypes. Definitive taxonomic conclusions from these results are premature. Maltese Muticaria could be subdivided into three taxa according to morphological and molecular data (M. macrostoma or M. m. macrostoma, M. oscitans or M. m. oscitans and M. scalaris or M. m scalaris). Gozitan Muticaria could be considered a distinct polytypic species (for which the oldest available name is Muticaria mamotica) subdivided into subspecies showing a morphological range from macrostoma-like to mamotica-like and oscitans like.\n\nOnly the two Maltese species of Lampedusa are legally protected (by the European Unions Habitats Directive and Maltese national legislation). The present study has shown that the alopiine clausiliids of the Sicilian Channel constitute a number of genetically and/or morphologically distinct populations that represent important pools of genetic diversity, with, in some cases, a very circumscribed distribution. As such, these populations deserve legal protection and management. It is argued that without formal taxonomic designation, it would be difficult to extend international legal protection to some of the more threatened of these populations.

zoology↗

bioRxiv2017

Interrelationship of photoperiod and feed utilization on growth and reproductive performance in the Red eyed orange molly (Poecilia sphenops)

Light is a major environmental factors that synchronize all life-stages of fish, from body growth to sexual maturation. The objective of this research is to enhance the growth and reproductive performance in the test fish, red eyed orange molly (Poecilia sphenops) exposed to standardized manipulated photoperiod. In present study, growth and gonadal development of the test fish with an average initial weight (0.52g) and an average total length (3.2cm) exposed to two photoperiods (18L:6D and 10L:14D) at constant light intensity (1500 lx) for a period of 60 days was investigated. The fish were fed with formulated feed twice a day as per 10% of body weight. During a long day photoperiod (18L:6D) significant increase in growth parameters such as, weight gain (2.2 {+/-} 0.04), feed conversion ratio (8.9 {+/-} 0.004) and specific growth rate (1.2 {+/-} 0% day-1) was observed. Mean gonadosomatic index (GSI) in female (30.4{+/-} 0.11) and male fish (2.0 {+/-} 0.17) was also significantly higher in long-day photoperiod followed by short day photoperiod (10L:14D). The results confirm that manipulated long-day photoperiod induced somatic growth and enhanced gonadal development in P. sphenops without causing any stress.\n\nSummaryThis work is novel to research field since photoperiodic effect on Poecilia sphenops, a live-bearer fish under artificial environmental conditions resulted in enhanced growth and reproductive performance with fry production.

zoology↗

bioRxiv2017

Avian thermoregulation in the heat: phylogenetic variation among avian orders in evaporative cooling capacity and heat tolerance

Little is known about the phylogenetic variation of avian evaporative cooling efficiency and heat tolerance in hot environments. We quantified thermoregulatory responses to high air temperature (Ta) in ~100-g representatives of three orders: African cuckoo (Cuculus gularis, Cuculiformes), lilac-breasted roller (Coracias caudatus, Coraciiformes), and Burchells starling (Lamprotornis australis, Passeriformes). All three species initiated respiratory mechanisms to increase evaporative heat dissipation when body temperature (Tb) approached 41.5{degrees}C in response to increasing Ta, with gular flutter observed in cuckoos and panting in rollers and starlings. Resting metabolic rate (RMR) and evaporative water loss (EWL) increased by quantitatively similar magnitudes in all three species, although maximum rates of EWL were proportionately lower in starlings. Evaporative cooling efficiency [defined as the ratio of evaporative heat loss (EHL) to metabolic heat production (MHP)] generally remained below 2.0 in cuckoos and starlings, but reached a maximum of ~3.5 in rollers. The high value for rollers reveals a very efficient evaporative cooling mechanism, and is similar to EHL/MHP maxima for similarly sized columbids which very effectively dissipate heat via cutaneous evaporation. This unexpected phylogenetic variation among the orders tested in the physiological mechanisms of heat dissipation is an important step toward determining the evolution of heat tolerance traits in desert birds.\n\nSummary statementWe show that avian evaporative cooling efficiency and heat tolerance display substantial taxonomic variation that are, unexpectedly, not systematically related to the use of panting versus gular flutter processes.

zoology↗

bioRxiv2017

Functional Plasticity of the gut and the Malpighian tubules underlies cold acclimation and mitigates cold-induced hyperkalemia in Drosophila melanogaster

At low temperatures, Drosophila, like most insects, lose the ability to regulate ion and water balance across the gut epithelia, which can lead to a lethal increase of [K+] in the hemolymph (hyperkalemia). Cold-acclimation, the physiological response to low temperature exposure, can mitigate or entirely prevent these ion imbalances, but the physiological mechanisms that facilitate this process are not well understood. Here, we test whether plasticity in the ionoregulatory physiology of the gut and Malpighian tubules of Drosophila may aid in preserving ion homeostasis in the cold. Upon adult emergence, D. melanogaster females were subjected to seven days at warm (25{degrees}C) or cold (10{degrees}C) acclimation conditions. The cold acclimated flies had a lower critical thermal minimum (CTmin), recovered from chill coma more quickly, and better maintained hemolymph K+ balance in the cold. The improvements in chill tolerance coincided with increased Malpighian tubule fluid secretion and better maintenance of K+ secretion rates in the cold, as well as reduced rectal K+ reabsorption in cold-acclimated flies. To test whether modulation of ion-motive ATPases, the main drivers of epithelial transport in the alimentary canal, mediate these changes, we measured the activities of Na+-K+-ATPase and V-type H+-ATPase at the Malpighian tubules, midgut, and hindgut. Na+/K+-ATPase and V-type H+-ATPase activities were lower in the midgut and the Malpighian tubules of cold-acclimated flies, but unchanged in the hindgut of cold acclimated flies, and were not predictive of the observed alterations in K+ transport. Our results suggest that modification of Malpighian tubule and gut ion and water transport likely prevents cold-induced hyperkalemia in cold-acclimated flies and that this process is not directly related to the activities of the main drivers of ion transport in these organs, Na+/K+- and V-type H+-ATPases.\n\nSummary StatementAt low temperatures, insects lose the ability to regulate ion and water balance and can experience a lethal increase in hemolymph [K+]. Previous exposure to low temperatures can mitigate this effect and improve chill tolerance. Here, we show that plasticity of ion and fluid transport across the Malpighian tubule and rectal epithelia likely drive this response.

zoology↗

bioRxiv2017

Equine strongyle communities are constrained by horse sex and species dipersal-fecundity trade-off

Equine strongyles are a major health issue. Large strongyles can cause death of horses while cyathostomins (small strongyles) have shown increased resistance to anthelmintics worldwide. Description of strongyle communities have accumulated but little is known about the diversity of these communities and underpinning environmental factors.\n\nThis study analysed the diversity of strongyle communities in 48 horses from Poland. Strongyle species fell into two groups, contrasted by their prevalence and relative abundance. Seven horses were necessary to sample at least 90% of strongyle community diversity, providing a minimal cut-off to implement sampling trial in the field. Strongyle communities entertained a network of mostly positive interactions and species co-occurrence was found more often than expected by chance. In addition, species fecundity and prevalence were negatively correlated r=-0.78), suggesting functional trade-offs between species dispersal abilities and fecundity. This functional trade-off may underpin species coexistence. Horse sex was also a significant constraint shaping strongyle communities. Indeed, mares generally displayed more similar strongyle communities than stallions (p=0.004) and Cylicostephanus calicatus was more abundant in stallions suggesting sex-specific interactions (p=0.02). While niche partitioning is likely to explain some of the positive interactions between equine strongyle species, coexistence may also result from a functional trade-off between dispersal ability and fecundity. There is significant evidence that horse sex drives strongylid community structure, which may require differential control strategies between mares and stallions.

zoology↗

bioRxiv2017

What goes up must come down - Biomechanical impact analysis of jumping locusts

Many insects are able to precisely control their jumping movements. Previous studies have shown that many falling insects have some degree of control of their landing-orientation, indicating a possible significant biomechanical role of the exoskeleton in air righting mechanisms. Once in the air, the properties of the actual landing site are almost impossible to predict. Falling insects thus have to cope mostly with the situation at impact. What exactly happens at the impact? Do locusts actively prepare for landing while falling, or do they just crash into the substrate?\n\nDetailed impact analyses of free falling Schistocerca gregaria locusts show that most insects typically crashed onto the substrate. There was no notable impact-reducing behaviour (protrusion of legs, etc.). Independent of dropping angle, both warm and cooled locusts mostly fell onto head and thorax first. Our results also show that alive warm locusts fell significantly faster than inactive or dead locusts. This indicates a possible tradeoff between active control vs. reduced speed. Looking at the morphology of the head-thorax connection in locusts, we propose that the anterior margin of the pronotum might function as a toby collar structure, reducing the risk of impact damage to the neck joint. Interestingly, at impact alive insects also tended to perform a bending movement of the body.\n\nThis biomechanical adaptation might reduce the rebound and shorten the time to recover. The adhesive pads also play an important role to reduce the time to recover by anchoring the insect to the substrate.

zoology↗

bioRxiv2017

Spawning Biology and Induced Breeding of freshwater catfish Mystus dibrugarensis: An approach to conservation

Spawning biology of hormone induced bagridae catfish, Mystus dibrugarensis was observed in captive condition. Active involvement of male in courtship after 5-9 hr. of hormone administration was observed. Different doses of ovaprim 0.4, 0.6, 0.8, 1.0 ml/kg were used by maintaining 1:1, 2:1 and 3:1 ratio of M:F. All female successfully bred in all the condition in more or less amount. Overall 24.5-77.5% fertilization and 12-76% hatching rate was observed. However, considering the rate of fertilization, and hatching success in the present case, at 0.8 ml/kg body weight and sex ratio 2[male]: 1 [female] seems ideal for induced breeding of M. dibrugarensis. Apart from induced breeding certain reproductive aspects were also studied in the present experiment.

zoology↗

bioRxiv2017

A eDNA-qPCR combination assay to non-invasively detect the presence of the parasite Schistocephalus solidus inside its intermediate host, the threespine stickleback

Detecting the presence of a parasite within its host is crucial to the study of host-parasite interactions. The Schistocephalus solidus - threespine stickleback pair has been studied extensively to investigate host phenotypic alterations associated with a parasite with a complex life cycle. This cestode is localized inside the sticklebacks abdominal cavity and can be visually detected only once it passes a mass threshold. We present a non-invasive quantitative PCR approach based on detection of environmental DNA from the worm(eDNA),sampled in the fish abdominal cavity. Using this approach on two fish populations (n=151), 98% of fish were correctly assigned to their S. solidus infection status. There was a significant correlation between eDNA concentration and total parasitic mass. We also assessed ventilation rates as a complimentary mean to detect infection. Our eDNA detection method gives a reliable presence/absence response and its future use for quantitative assessment is promising.

zoology↗

bioRxiv2017

Tetrapods on the EDGE: Overcoming data limitations to identify phylogenetic conservation priorities

The scale of the ongoing biodiversity crisis requires both effective conservation prioritisation and urgent action. The EDGE metric, which prioritises species based on their Evolutionary Distinctiveness (ED) and Global Endangerment (GE), relies on adequate phylogenetic and extinction risk data to generate meaningful priorities for conservation. However, comprehensive phylogenetic analyses of large clades are extremely rare and, even when available, become quickly out-of-date due to the rapid rate of species descriptions and taxonomic revisions. Thus, it is important that conservationists can use the available data to incorporate evolutionary history into conservation prioritisation. We compared published and new methods to impute ED for species missing from a phylogeny whilst simultaneously correcting the ED scores of their close taxonomic relatives. We found that following artificial removal of species from a phylogeny, the new method provided the closest estimates of their \"true\" score, differing from the true ED score by an average of less than 1%, compared to the 31% and 38% difference of the previous imputation methods. Previous methods also substantially under- and over-estimated scores as more species were artificially removed from a phylogeny. We therefore used the new method to estimate ED scores for all tetrapods. From these scores we updated EDGE prioritisation rankings for all tetrapod species with IUCN Red List assessments, including the first EDGE prioritisation for reptiles. Further, we identified criteria to identify robust priority species in an effort to further inform conservation action whilst limiting uncertainty and anticipating future phylogenetic advances.

zoology↗

bioRxiv2017

Phylogenomics offers resolution of major tunicate relationships

Tunicata, a diverse clade of approximately 3,000 described species of marine, filter-feeding chordates, is of great interest to researchers because tunicates are the closest living relatives of vertebrates and they facilitate comparative studies of our own biology. The group also includes numerous invasive species that cause considerable economic damage and some species of tunicates are edible. Despite their diversity and importance, relationships among major lineages of Tunicata are not completely resolved. Here, we supplemented public data with transcriptomes from seven species spanning the diversity of Tunicata and conducted phylogenomic analyses on data sets of up to 798 genes. Sensitivity analyses were employed to examine the influences of reducing compositional heterogeneity and branch-length heterogeneity. All analyses maximally supported a monophyletic Tunicata within Olfactores (Vertebrata + Tunicata). Within Tunicata, all analyses recovered Appendicularia sister to the rest of Tunicata and confirmed (with maximal support) that Thaliacea is nested within Ascidiacea. Stolidobranchia is the sister taxon to all other tunicates except Appendicularia. In most analyses, phlebobranch tunicates were recovered paraphyletic with respect to Aplousobranchia. Support for this topology varied but was strong in some cases. However, when only the 50 best genes based on compositional heterogeneity were analysed, we recovered Phlebobranchia and Aplousobranchia reciprocally monophyletic with strong support, consistent with most traditional morphology-based hypotheses. Examination of internode certainty also cast doubt on results of phlebobranch paraphyly, which may be due to limited taxon sampling. Taken together, these results provide a higher-level phylogenetic framework for our closest living invertebrate relatives.

zoology↗

bioRxiv2017

Physical properties characterization of Natural Protein Fibre Peacock Feather Barbs

In the present study, the barbs of peacock feather were subjected to its physio-mechanical characterisation. Various properties of barbs viz., bundle strength, diameter, moisture regain, thermal stability, X-ray diffraction, colour intensity and FTIR was studied according standard analytical methods. The surface morphology of the barbs was examined using SEM images. The results indicate that the barb is a hollow vertical structure made up of protein. The average length and diameter of the barb was found to be 45 mm and 82 m respectively. The FTIR study confirms the presence of characteristic peaks for protein, related to the keratinous material. The barbs seem to be semi-crystalline in nature, as indicated by X-ray study.

zoology↗