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bioRxiv2015

Blood circulation in the tunicate Corella inflata (Corellidae).

The ascidian tunicate Corella inflata is relatively transparent compared to other solitary tunicates and the circulatory system can be visualized by injecting high molecular weight fluorescein labeled dextran into the beating heart or the large vessels at the ends of the heart. In addition, after staining with neutral red the movement of blood cells can be followed to further define and characterize the circulatory system. The heart is a gently curved tube with a constriction in the middle and extends across the width of the animal. As in other tunicates, pumping is peristaltic and periodically reverses direction. During the abvisceral directional phase blood leaves the anterior end of the heart in two asymmetric vessels that connect to the two sides of the branchial basket (or pharynx), in contrast to the direct connection between the heart and the endostyle seen in the commonly studied tunicate Ciona intestinalis. In Corella inflata blood then flows in both transverse directions through a complex system of ducts in the branchial basket into large ventral and dorsal vessels and then to the visceral organs in the posterior of the animal. During the advisceral phase blood leaves the posterior end of the heart in vessels that repeatedly bifurcate to fan into the stomach and gonads. Blood speed, determined by following individual cells, is high and pulsatory near the heart, but decreases and becomes more constant in peripheral regions. Estimated blood flow volume during one directional phase is greater than the total volume of the animal. Circulating blood cells are confined to vessels or ducts in the visible parts of the animal and retention of high molecular weight dextran in the vessels is comparable to that seen in vertebrates. These flow patterns are consistent with a closed circulatory network.

Zoology↗

bioRxiv2015

Changes in the milk metabolome of the giant panda (Ailuropoda melanoleuca) with time after birth: Three phases in early lactation and progressive individual differences

Ursids (bears) in general, and giant pandas in particular, are highly altricial at birth. The components of bear milks and their changes with time may be uniquely adapted to nourish relatively immature neonates, protect them from pathogens, and support the maturation of neonatal digestive physiology. Serial milk samples collected from three giant pandas in early lactation were subjected to untargeted metabolite profiling and multivariate analysis. Changes in milk metabolites with time after birth were analysed by Principal Component Analysis, Hierarchical Cluster Analysis and further supported by Orthogonal Partial Least Square-Discriminant Analysis, revealing three phases of milk maturation: days 1-6 (Phase 1), days 7-20 (Phase 2), and beyond day 20 (Phase 3). While the compositions of Phase 1 milks were essentially indistinguishable among individuals, divergences emerged during the second week of lactation. OPLS regression analysis positioned against the growth rate of one cub tentatively inferred a correlation with changes in the abundance of a trisaccharide, isoglobotriose, previously observed to be a major oligosaccharide in ursid milks. Three artificial milk formulae used to feed giant panda cubs were also analysed, and were found to differ markedly in component content from natural panda milk. These findings have implications for the dependence of the ontogeny of all species of bears, and potentially other members of the Carnivora and beyond, on the complexity and sequential changes in maternal provision of micrometabolites in the immediate period after birth.

Zoology↗

bioRxiv2015

Biomechanics of shear-sensitive adhesion in climbing animals: peeling, pre-tension and sliding-induced changes in interface strength

Rapid control of adhesive forces is one of the key benchmarks where footpads of climbing animals outperform conventional adhesives, promising novel bio-inspired attachment systems. All climbing animals use shear forces to switch rapidly between firm attachment and easy detachment, but the detailed mechanisms underlying shear-sensitive adhesion have remained unclear. Here, we show that attachment forces of stick insects follow classic peeling theory when shear forces are small, but strongly exceed predictions as soon as their pads start to slide due to high shear forces. Pad sliding dramatically increases the critical peel force via a combination of two distinct mechanisms. First, partial sliding will pre-stretch the pads, so that they are effectively stiffer upon detachment and peel increasingly like inextensible tape. We demonstrate how this effect can be directly related to peeling theories which account for frictional dissipation. Second, pad sliding reduces the thickness of the secretion layer in the contact zone, thereby decreasing the interfacial mobility, and increasing the stress levels required for peeling. The approximately linear increase of adhesion with friction results in a sharp increase of adhesion at peel angles less than ca. 30{degrees}, allowing rapid switching between attachment and detachment during locomotion. Our results may apply to diverse climbing animals independent of pad morphology and adhesive mechanism, and highlight that control of adhesion is not solely achieved by direction-dependence and morphological anisotropy, suggesting promising new routes for the development of bio-inspired adhesives.

Zoology↗

bioRxiv2015

Phenotypes in insect biodiversity research

Introduction Introduction Phenotype data: past and... Phenotype data: present and... Challenges and future directions References Phenotypes, here defined as the observable characteristics of organisms, including morphology, behavior, and physiological products (e.g., nests and galls)--the results of gene expression, in an environment--are the primary data for research on the evolution and taxonomy of insects (Deans et al., 2012a). The shapes, textures, colors, or simply the presence or absence of anatomical features or behaviors help us determine taxa and guide our hypotheses regarding their evolutionary history. Phenotype data are relevant to most other research on insects as well, including biomechanics (Labonte and Federle, 2015), bioinspired engineering ( ...

Zoology↗

bioRxiv2015

Evidence of adoption, monozygotic twinning, and low inbreeding rates in a large genetic pedigree of polar bears

Multigenerational pedigrees have been developed for free-ranging populations of many species, are frequently used to describe mating systems, and are used in studies of quantitative genetics. Here, we document the development of a 4449-individual pedigree for the Western Hudson Bay subpopulation of polar bears (Ursus maritimus), created from relationships inferred from field and genetic data collected over six generations of bears sampled between 1966 and 2011. Microsatellite genotypes for 22-25 loci were obtained for 2945 individuals, and parentage analysis was performed using the program FRANO_SCPLOWZC_SCPLOW, including additional offspring-dam associations known only from capture data. Parentage assignments for a subset of 859 individuals were confirmed using an independent high-density set of single nucleotide polymorphisms. To account for unsampled males in our population, we performed half-sib-full-sib analysis to reconstruct males using the program COLONY, resulting in a final pedigree containing 2957 assigned maternities and 1861 assigned paternities with only one observed case of inbreeding between close relatives. During genotyping, we identified two independently captured two-year-old males with identical genotypes at all 25 loci, showing--for the first time--a case of monozygotic twinning among polar bears. In addition, we documented six new cases of cub adoption, which we attribute to cub misidentification or misdirected maternal care by a female bereaved of her young. Importantly, none of these adoptions could be attributed to reduced female vigilance caused by immobilization to facilitate scientific handling, as has previously been suggested.

Zoology↗

bioRxiv2015

Structural specialities, curiosities and record-breaking features of crustacean reproduction

Crustaceans are a morphologically, physiologically and ecologically highly diverse animal group and correspondingly diverse are their reproductive characteristics. They have evolved structural specialities with respect to penis construction, sperm form, sperm storage, fertilization and brood care. Unique in the animal kingdom are safety lines that safeguard hatching and first molting. Further curiosities are dwarf males in parasitic and sessile taxa and bacteria-induced gigantism and infectious feminization in crustacean hosts. Record-breaking features in animals are relative penis length, clutch size, sperm size, chromosome number, viability of resting eggs, and fossil ages of penis, sperm and brooded embryos. These reproductive peculiarities are reviewed and their implication for basic and applied biology is discussed, including the early evolution and diversification of brood care in arthropods, sperm competition and assurance of paternity, posthumous paternity and sustainable male-based fishery, and ecotype changes by man-made pollution.

Zoology↗

bioRxiv2015

New records of Atlantic humpback dolphin in Guinea, Nigeria, Cameroon and Togo underscore fisheries pressure and generalised marine bushmeat demand

In northern Guinea, we sighted two groups of Sousa teuszii (n=25; n=40 dolphins) off the Tristao Islands during exploratory small-boat surveys in 2011-12. Based on these and recent (2013) observations in the contiguous Rio Nunez estuary, we propose a single Guineas stock, combining the former Rio do Jeba-Bijagos and South Guinea stocks. Significant mortality of S. teuszii from fisheries interactions is widely recognised however not quantifiable as monitoring effort is sporadic. In Guinea, catches were documented in 2002 (n=1) and in 2011-12 (n=5). Landed specimens were recorded in Cameroon (n=2) and Nigeria (n=2). All individuals were killed in small-scale coastal fisheries, presumably as accidental net entanglements, though directed takes cannot be excluded. All landed dolphins were butchered for human consumption (marine bushmeat). Nigerian fishers indicated also an alternative use as shark bait. If local markets in cetacean bushmeat and bait develop, as in Ghana, that will exacerbate pressures by encouraging directed takes. Catch records in Nigeria and sightings in Togo authenticate both nations as (long-suspected) range states for S. teuszii, a belated documenting of the primary, historical distribution. The Gulf of Guinea stock ( Cameroon dolphins) extends at least from Togo to southern Cameroon, and probably into Equatorial Guinea. However, rare sightings of small groups point to remnant, not thriving, dolphin communities. We anticipate de novo distribution gaps emerging and consolidating, following decades of fisheries interactions and creeping encroachment on once pristine coastal habitat. Developed coastlines in Ghana and Cote dIvoire devoid of records may already constitute such gaps. As the lack or scarcity of records warn about formidable challenges to the long-term survival of S. teuszii, innovative, workable protection measures are needed, soonest. We recommend the implementation of several new border-straddling marine protected areas (cf. Saloum Delta-Niumi National Park Complex) which could bring forth a major conservation effect. Binational involvement bears obvious advantages, from sharing responsibilities and allowing for larger protected areas. Suggested dolphin sanctuary examples could include MPAs straddling borders between Cameroon/Equatorial Guinea and Guinea-Bissau/Guinea-Conakry.

Zoology↗

bioRxiv2016

Physiological reason for ceasing growth of unfertilized eggs produced by unmated queens in the subterranean termite Reticulitermes chinensis

In Reticulitermes chinensis, a close relative of R. speratus with asexual queen succession, unfertilized eggs can be produced but are not incubated. To explain this phenomenon, we analysed the physiological differences between unfertilized eggs/unmated queens and fertilized eggs/mated queens. Fertilized eggs consumed significantly larger quantities of five amino acids (Cys, Met, Ile, Leu and Tyr), Ca, protein and cholesterol during incubation. The higher levels of four trace elements (Na, K, Zn and Fe) in fertilized eggs and their lower levels in mated queens indicated that mated queens might transfer these trace elements to fertilized eggs to complete incubation. The higher levels of Mn, triglycerides and serotonin in mated queens and higher levels of Mn and glucose in fertilized eggs suggested that these substances are very important for normal ovarian and embryonic growth. The different expression of three reproductive genes (vtgl, rabil and JHE1) suggested that they might be involved in the regulation of ovarian and embryonic growth. Overall, changes in these physiological indices may substantially affect ovarian and embryonic growth and prohibit the incubation of unfertilized eggs in R. chinensis.

Zoology↗

bioRxiv2016

Nuclear and mitochondrial phylogeny of Rossella (Hexactinellida: Lyssacinosida, Rossellidae): a species and a species flock in the Southern Ocean

Hexactinellida (glass sponges) are abundant and important components of Antarctic benthic communities. However, the relationships and systematics within the common genus Rossella Carter, 1872 (Lyssacinosida: Rossellidae) are unclear and in need of revision. The species content of this genus has changed dramatically over the years depending on the criteria used by the taxonomic authority consulted. Rossella was formerly regarded as a putatively monophyletic group distributed in the Southern Ocean and the North Atlantic. However, molecular phylogenetic analyses have shown that Rossella is restricted to the Southern Ocean, where it shows a circum-Antarctic and subantarctic distribution. Herein, we provide a molecular phylogenetic analysis of the genus Rossella, based on mitochondrial (16S rDNA and COI) and nuclear (28S rDNA) markers. We corroborate the monophyly of Rossella and provide evidence supporting the existence of one species, namely Rossella antarctica Carter, 1872 and a species flock including specimens determined as Rossella racovitzae Topsent, 1901, Rossella nuda Topsent, 1901, Rossella fibulata Schulze & Kirkpatrick, 1910, and Rossella levis (Kirkpatrick, 1907).

Zoology↗

bioRxiv2016

Omura’s whale (Balaenoptera omurai) stranding on Qeshm Island, Iran: further evidence for a wide (sub)tropical distribution, including the Persian Gulf

A small, juvenile rorqual live-stranded on Qeshm Island, Iran, in the northern Strait of Hormuz (Persian Gulf) in September 2007. Cause of stranding remains unknown but the whale (QE22.09.2007) showed no severe traumatic injuries nor was emaciated. Based on at least seven morphological features, considered diagnostic in combination, allowed a positive identification as Omuras whale Balaenoptera omurai. Features included diminutive body size (397 cm), a large number of ventral grooves (n=82) extending caudad of the umbilicus, a strongly falcate dorsal fin, asymmetric colouration of the head (especially lower jaws) reminiscent of fin whale, including three unilateral dark stripes, faint/incomplete lateral rostral ridges, record low number of short, broad baleen plates (204 in right jaw). The likelihood for the existence of a local B. omurai population in the eastern Persian Gulf or northern Arabian Sea seems higher than the wandering of a very young animal or mother/calf pair from any of the known distant distribution areas in the eastern Indian Ocean or SW Indian Ocean (Madagascar). This is the first record of B. omurai in the NW Indian Ocean.

Zoology↗

bioRxiv2016

A NEW SPECIES OF SEEDEATER (EMBERIZIDAE: SPOROPHILA) FROM THE IBERA GRASSLANDS, IN NORTHEAST ARGENTINA

We describe a new species of capuchino of the genus Sporophila (Emberizidae) of the Esteros del Ibera, province of Corrientes, in northeastern Argentina. This species would have remained unidentified due to lack of ornithological explorations in the central area of the Esteros del Ibera. It has been confused with immature individuals of other Sporophila species. We made observations of behavior and habitat, playback experiments, comparative analyzes of the vocalizations and plumage with other sympatric species of the same genus, and we found this species, which we have named Sporophila iberaensis, inhabiting wet grasslands from the edges of the marshes, having a unique vocal repertoire and a unique plumage. Because of its restricted geographical distribution and the threats that have their habitat, this new species should be categorized as Vulnerable on the IUCN Red List.

zoology↗

bioRxiv2016

Fate of glair glands and oocytes in unmated crayfish: a comparison between gonochoristic slough crayfish and parthenogenetic marbled crayfish

In the period before spawning, freshwater crayfish females develop glair glands on the underside of the pleon. These glands produce the mucus for a transient tent-like structure in which the eggs are fertilized and attached to the pleopods. Long-term observation of females of the bisexually reproducing slough crayfish, Procambarus fallax, kept in captivity revealed that glair glands developed in late winter and late summer of each year independent of the presence of males. However, in contrast to mated females unmated females did neither form a fertilization tent nor spawn. Their glair glands persisted for an unusually long period of time and disappeared only during the next moult. Apparently, females use information on sperm availability to either reproduce or save the resources. Marbled crayfish, Procambarus virginalis, a parthenogenetic descendant of slough crayfish, developed glair glands in approximately the same periods of the year but spawned despite of the absence of mating. These findings indicate that on their way from gonochorism to parthenogenesis regulation of glair gland activity and spawning has been decoupled from mating. Therefore, the species pair Procambarus fallax/Procambarus virginalis seems to be particularly suitable to investigate the physiological, molecular and genetic mechanisms underlying spawning in freshwater crayfish.

Zoology↗

bioRxiv2016

Physiological and biochemical changes associated with experimental dehydration in the desert adapted cactus mouse, Peromyscus eremicus

Characterizing traits critical for adaptation to a given environment is an important first step in understanding how phenotypes evolve. How animals adapt to the extreme heat and aridity commonplace to deserts represents is an exceptionally interesting example of these processes, and has been the focus of study for decades. In contrast to those studies, where experiments are conducted on either wild animals or captive animals held in non-desert conditions, the study described here leverages a unique environmental chamber that replicates desert conditions for captive Peromyscus eremicus (cactus mouse). Here we establish baseline values for daily water intake and for serum electrolytes, as well as the response of these variables to experimental dehydration. In brief, P. eremicus daily water intake is very low. Its serum electrolytes are distinct from many previously studied animals, and its response to acute dehydration is profound, though not suggestive of renal impairment, which is atypical of mammals.\n\nSummary statementThe establishment of baseline values for serum electrolytes and water intake, as well as their response to acute dehydration is critical for characterizing the physiology necessary for desert survival.\n\nConflict of Interest StatementThe authors declare no conflict of interest.

Zoology↗

bioRxiv2016

All alloparents are not equally valuable: Primary breeders and group size explain group reproductive success in cooperatively breeding primates

Prior research on cooperative breeders has considered correlations between group reproductive output (GRO) and the number of individuals in each age-sex class, but without controlling for uneven sampling efforts, the underlying effects of group size, and pseudoreplication at the group and species levels. Among callitrichids, age-sex classes do not provide meaningful categories, as individuals within an age-sex class can demonstrate varying reproductive development due to reproductive dominance of a few individuals per group. This study re-assesses the drivers of GRO in callitrichids by a) conducting a meta-analysis of published studies of callitrichid group composition; b) determining a novel method to assign developmental class based on reproductive morphology; and c) utilizing a multistep modelling approach to assess whether any sex-based developmental class predicts both the presence and the numbers of surviving offspring among free-ranging saddleback (Leontocebus weddelli) and emperor tamarins (Saguinus imperator) in Peru. The meta-analysis utilizing a historical dataset revealed that adult females and group size, but not the number of adult males is significantly correlated with GRO. Statistical models of the new dataset revealed that only mature males predicted if groups had any infants at all, but that the number of surviving infants was predicted by mature females and group size. Thus mature males appear to be necessary for groups to raise any infants, but mature females and a larger group size increase group reproductive output overall.

Zoology↗

bioRxiv2016

Description of a new genus of primitive ants from Canadian amber, with the study of relationships between crown ants and stem ants (Hymenoptera: Formicidae)

A detailed study of the holotype of Sphecomyrma canadensis Wilson, 1985 from Canadian amber has led to the conclusion that the specimen belongs to a new genus, here named Boltonimecia gen.n. Since the taxonomy of stem-group ants is not well understood, in order to find the taxonomic position of this genus, it is necessary to review the classification of stem-group ants in a study of their relation to crown-group ants. In the absence of data for traditional taxonomic approaches, a statistical study was done based on a morphometric analysis of antennae. Scape elongation is believed to play an important role in the evolution of eusociality in ants; however, this hypothesis has never been confirmed statistically. The statistical analysis presented herein lends support to the view that antennal morphology reliably distinguishes stem-group ants from crown-group ants to determine whether a species belongs to one or the other group. This, in turn, may indicate a relationship exists between eusociality and scape elongation. A review of Cretaceous records of ants is made and the higher classification of Formicidae with definitions of stem and crown groups is proposed. Newly obtained data are discussed focusing particularly on the origin, evolution and diversity of ants.

Zoology↗

bioRxiv2016

Changeover from signalling to energy-provisioning lipids during transition from colostrum to mature milk in the giant panda (Ailuropoda melanoleuca)

Among the large eutherian ( placental) mammals, ursids (bears) give birth to the most altricial neonates with the lowest neonatal:maternal body mass ratios. This is particularly exemplified by giant pandas in whom the transition from colostrum to main-phase lactation is unusually prolonged. To examine whether there is compensation for the provision of developmentally important nutrients that other species groups may provide in utero, we examined colostrum and milk lipids from birth until the transition was complete. Lipids known to be developmental signals or their precursors, and those that are fundamental to nervous system construction, such as docosahexaenoic acid (DHA) and phosphatidylserines containing DHA, appear early and then fall dramatically in concentration to a baseline at about 20 days. This also applies to other signalling lipids such as lysophosphatidylserines. The dynamics of lysophosphatidic acid and eicosanoids display a similar pattern, albeit less clearly and with differences between mothers. Triglycerides occur at relatively low levels initially and then increase in concentration with time post-partum until a plateau is reached at about 30 days or later. These patterns indicate an early provision of signalling lipids and their precursors, and lipids crucial to brain, retinal and central nervous system construction, followed by a changeover to lipids for energy metabolism. Thus, in giant pandas, and possibly among ursids in general, lactation is adapted to provisioning a highly altricial neonate to a degree that approximates to an extension of gestation.

Zoology↗

bioRxiv2016

Quantifying climate change impacts emphasises the importance of managing regional threats in an endangered species

As a global issue the effects of climate change are difficult to manage on a region scale. However, more often than not it is only one of many problems that need to be addressed in species conservation. Non-climatic factors - especially those of anthropogenic origins - play equally if not more important roles with regards to population developments of species and often provide much better toeholds for conservation activities. We examined the population trends of the endangered Yellow-eyed penguin (Megadyptes antipodes) in New Zealand using monitoring data dating back to the 1980s. We developed a Bayesian population model incorporating various climatic factors to assess the relative influence of climate change on the penguin numbers over the past 30 years. Sea surface temperature (SST) proved to be the dominating factor influencing survival of both adult birds and fledglings. Increasing SST since the mid-1990s went along with a reduction in survival rates and population decline. The population model showed that 33% of the variation in population numbers could be explained by SST alone, significantly increasing pressure on the penguin population. Consequently, the population becomes less resilient to nonclimate related impacts, such as fisheries interactions, habitat degradation and human disturbance. But their exact contribution towards population trends is extremely difficult to assess principally due to the absence of quantifiable data. This potentially creates an analysis bias towards climate variables, effectively distracting from non-climate factors that can be managed on a regional scale to ensure the viability of the population.

Zoology↗

bioRxiv2016

Inferring physiological energetics of loggerhead turtle (Caretta caretta) from existing data using a general metabolic theory

Loggerhead turtle is an endangered sea turtle species with a migratory lifestyle and worldwide distribution, experiencing markedly different habitats throughout its lifetime. Environmental conditions, especially food availability and temperature, constrain the acquisition and the use of available energy, thus affecting physiological processes such as growth, maturation, and reproduction. These physiological processes at the population level determine survival, fecundity, and ultimately the population growth rate--a key indicator of the success of conservation efforts. As a first step towards the comprehensive understanding of how environment shapes the physiology and the life cycle of a loggerhead turtle, we constructed a full life cycle model based on the principles of energy acquisition and utilization embedded in the Dynamic Energy Budget (DEB) theory. We adapted the standard DEB model using data from published and unpublished sources to obtain parameter estimates and model predictions that could be compared with data. The outcome was a successful mathematical description of ontogeny and life history traits of the loggerhead turtle. Some deviations between the model and the data existed (such as an earlier age at sexual maturity and faster growth of the post-hatchlings), yet probable causes for these deviations were found informative and discussed in great detail. Physiological traits such as the capacity to withstand starvation, trade-offs between reproduction and growth, and changes in the energy budget throughout the ontogeny were inferred from the model. The results offer new insights into physiology and ecology of loggerhead turtle with the potential to lead to novel approaches in conservation of this endangered species.

Zoology↗