Scale‐stacking in the live‐bearer Belonesox belizanus (Poeciliidae)

An incidence of scale‐stacking was found in a museum collection of Belonesox belizanus (Poeciliidae) from the Río Tesechocán, Veracruz, México. This phenomenon is thought to be unique to lepidophagous East African cichlids, although no studies have addressed the behaviour in any detail. This finding in B. belizanus, the first in Cyprinodontiformes, indicates Belonesox is able to manipulate scales into stacks in the buccal cavity.     

Population structure,reproduction and laboratory behavior of the introduced Belonesox belizanus (Poeciliidae) in Florida

Synopsis The pike killifish, Belonesox belizanus, is native to Mexico and Central America and was introduced into Dade County, Florida in 1957. This study reports on the structure and reproduction of the Florida population and compares the species with other members of the family Poeciliidae. The mean standard length (SL) of mature females was about 103 mm. Most females larger than 75 mm SL contained yolked ova, fertilized eggs, or embryos. Mature males averaged about 72 mm SL, and most males larger than 55 mm SL were mature. The sex ratio was significantly skewed in favor of females among adults, but it did not differ significantly from 1:1 among immature fish. Average brood size was about 99, and there was a significant positive correlation of brood size with size of the parent female. There was no evidence of superfetation. Sizes and weights of embryos and neonates were the largest reported for the family. There was a significant decrease in mean embryo weight as development proceeded, indicating that developing embryos received little or no nutrient input from the maternal system after fertilization. The average interbrood interval of aquarium-held females was 42 days, and females stored viable sperm at least 47 days. Reproduction continued year round in the field. Laboratory-born neonates were immediately piscivorous and exhibited distinctive behavior associated with filling the swimbladder and with avoiding detection by predators.     

Artificial evolution of the morphology and kinematics in a flapping-wing mini-UAV

Birds demonstrate that flapping-wing flight (FWF) is a versatile flight mode, compatible with hovering, forward flight and gliding to save energy. This extended flight domain would be especially useful on mini-UAVs. However, design is challenging because aerodynamic efficiency is conditioned by complex movements of the wings, and because many interactions exist between morphological (wing area, aspect ratio) and kinematic parameters (flapping frequency, stroke amplitude, wing unfolding). Here we used artificial evolution to optimize these morpho-kinematic features on a simulated 1 kg UAV, equipped with wings articulated at the shoulder and wrist. Flight tests were conducted in a dedicated steady aerodynamics simulator. Parameters generating horizontal flight for minimal mechanical power were retained. Results showed that flight at medium speed (10-12 m s(-1)) can be obtained for reasonable mechanical power (20 W kg(-1)), while flight at higher speed (16-20 m s(-1)) implied increased power (30-50 W kg(-1)). Flight at low speed (6-8 m s(-1)) necessitated unrealistic power levels (70-500 W kg(-1)), probably because our simulator neglected unsteady aerodynamics. The underlying adaptation of morphology and kinematics to varying flight speed were compared to available biological data on the flight of birds.     

Functional morphology of the pharyngeal jaw apparatus in moray eels

Moray eels (Muraenidae) are a relatively large group of anguilliform fishes that are notable for their crevice-dwelling lifestyle and renowned for their ability to consume large prey. Morays apprehend their prey by biting and then transport prey by extreme protraction and retraction of their pharyngeal jaw apparatus. Here, we present a detailed interpretation of the mechanisms of pharyngeal jaw transport based on work with Muraena retifera. We also review what is known of the moray pharyngeal jaw apparatus from the literature and provide comparative data on the pharyngeal jaw elements and kinematics for other moray species to determine whether interspecific differences in morphology and behavior are present. Rather than comprising broad upper and lower processing tooth plates, the pharyngeal jaws of muraenine and uropterygiine morays, are long and thin and possess large, recurved teeth. Compared with the muraenines, the pharyngobranchials of the uropterygiines do not possess a horn-shaped process and their connection to the fourth epibranchial is dorsal rather than medial. In addition, the lower tooth plates do not exhibit a lateral groove that serves as a site of muscle attachment for the pharyngocleitheralis and the ventral rather than the lateral side of the lower tooth plate attaches to the fourth ceratobranchial. In all morays, the muscles positioned for protraction and retraction of the pharyngeal apparatus have undergone elongation, while maintaining the generalized attachment sites on the bones of the skull and axial skeleton. Uropterygiines lack a dorsal retractor muscle and we presume that retraction of the pharyngeal jaws is achieved by the pharyngocleitheralis and the esophagus. The fifth branchial adductor is greatly hypertrophied in all species examined, suggesting that morays can strongly adduct the pharyngeal jaws during prey transport. The kinematics of biting behavior during prey capture and transport resulted in similar magnitudes of cranial movements although the timing of kinematic events was significantly different and the duration of transport was twice as long as prey capture. We speculate that morays have evolved this alternative prey transport strategy as a means of overcoming gape constraints, while hunting in the confines of coral reefs.     

Head morphology and piscivory of European eels,Anguilla anguilla,predict their probability of infection by the invasive parasitic nematode Anguillicoloides crassus

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Functional anatomy and kinematics of the oral jaw system during terrestrial feeding in Periophthalmus barbarus

Cover illustration . Skeletal body plan of the Atlantic mudskipper (Periophthalmus barbarus) from a lateral view. The mudskipper uses its fish feeding apparatus to successfully feed in the terrestrial environment. Each color represents a unit of fused or otherwise firmly interconnected ossified structures. Presented from a micro CT‐scan using Amira (FEI Visualization Sciences Group). See Michel et al. (pp. 1145–1160 10.1002/jmor.20291 ) for further details.     

Molecular and cellular changes associated with the evolution of novel jaw muscles in parrots

Vertebrates have achieved great evolutionary success due in large part to the anatomical diversification of their jaw complex, which allows them to inhabit almost every ecological niche. While many studies have focused on mechanisms that pattern the jaw skeleton, much remains to be understood about the origins of novelty and diversity in the closely associated musculature. To address this issue, we focused on parrots, which have acquired two anatomically unique jaw muscles: the ethmomandibular and the pseudomasseter. In parrot embryos, we observe distinct and highly derived expression patterns for Scx, Bmp4, Tgfβ2 and Six2 in neural crest-derived mesenchyme destined to form jaw muscle connective tissues. Furthermore, immunohistochemical analysis reveals that cell proliferation is more active in the cells within the jaw muscle than in surrounding connective tissue cells. This biased and differentially regulated mode of cell proliferation in cranial musculoskeletal tissues may allow these unusual jaw muscles to extend towards their new attachment sites. We conclude that the alteration of neural crest-derived connective tissue distribution during development may underlie the spatial changes in jaw musculoskeletal architecture found only in parrots. Thus, parrots provide valuable insights into molecular and cellular mechanisms that may generate evolutionary novelties with functionally adaptive significance.     

Fine morphology of the jaw apparatus of Puncturella noachina (Fissurellidae,Vetigastropoda)

Jaws of various kinds occur in virtually all groups of Mollusca, except for Polyplacophora and Bivalvia. Molluscan jaws are formed by the buccal epithelium and either constitute a single plate, a paired formation or a serial structure. Buccal ectodermal structures in gastropods are rather different. They can be nonrenewable or having final growth, like the hooks in Clione (Gastropoda, Gymnosomata). In this case, they are formed by a single cell. Conversely, they can be renewable during the entire life span and in this case they are formed by a set of cells, like the formation of the radula. The fine structure of the jaws was studied in the gastropod Puncturella noachina. The jaw is situated in the buccal cavity and consists of paired elongated cuticular plates. On the anterior edge of each cuticular plate there are numerous longitudinally oriented rodlets disposed over the entire jaw surface and immersed into a cuticular matrix. The jaw can be divided into four zones situated successively toward the anterior edge: 1) the posterior area: the zone of formation of the thick cuticle covering the entire jaw and forming the electron‐dense outer layer of the jaw plate; 2) the zone of rodlet formation; 3) the zone of rodlet arrangement; and 4) the anterior zone: the free scraping edge of the plate, or the erosion zone. In the general pattern of jaw formation, Puncturella noachina resembles Testudinalia tessulata (Patellogastropoda) studied previously. The basis of the jaw is a cuticular plate formed by the activity of the strongly developed microvillar apparatus of the gnathoepithelium. However, the mechanism of renewal of the jaw anterior part in P. noachina is much more complex as its scraping edge consists not just of a thick cuticular matrix rather than of a system of denticles being the projecting endings of rodlets. J. Morphol. 275:775–787, 2014. © 2014 Wiley Periodicals, Inc.     

Changes in oviductal morphology of the skink, Lampropholis guichenoti, associated with egg production

We describe changes in the morphology of the oviductal epithelium of an oviparous skink, Lampropholis guichenoti, during the course of egg production and oviposition: to characterize the luminal epithelial changes; to provide a baseline for understanding uterine changes in viviparous species; and to establish whether the plasma membrane transformation of uterine epithelial cells is indeed a feature restricted to viviparous species. Oviducts from vitellogenic, gravid, and postgravid females were observed using scanning electron microscopy. Cellular characteristics of the oviductal epithelium previously used to determine the plasma membrane transformation were assessed morphologically. Three anatomically different areas were defined within the oviduct, but no plasma membrane transformation was observed in the oviparous skink, suggesting that this is a phenomenon particular to viviparity.     

Unusual fractures associated with osteoporosis in premenopausal women.

Two premenopausal women (aged 40 and 34 years) and multiple undisplaced, often asymptomatic fractures of the femurs, ribs, metatarsals and other bones. The fractures, which appeared on roentgenograms as transverse radiolucent zones with variable callus formation, healed slowly or not at all despite treatment with calcium and vitamin D. They resembled pseudofractures (Looser''s transformation zones) radiologically, but the biochemical and histologic findings were those of idiopathic osteoporosis rather than osteomalacia. Since neither patient had been subjected to unusual stress it was concluded that the fractures had resulted from normal activity in abnormal bone.     

Lake eutrophication associated with geographic location,lake morphology and climate in China

Lake eutrophication is influenced by both anthropogenic and natural factors. Few studies have examined relationships between eutrophication parameters and natural factors at a large spatial scale. This study explored these relationships using data from 103 lakes across China. Eutrophication parameters including total nitrogen (TN), total phosphorus (TP), TN:TP ratio, chemical oxygen demand (COD_Mn), chlorophyll-a (Chl-a), Secchi depth (SD), and trophic state index (TSI) were collected for the period 2001–2005. Sixteen natural factors included three of geographic location, five of lake morphology, and eight of climate variables. Pearson correlation analysis showed that TP and TSI were negatively related to elevation, lake depth, and lake volume, and positively related to longitude. All eutrophication parameters, except for COD_Mn and Chl-a, showed no significant correlation with climate variables. Multiple regression analyses indicated that natural factors together accounted for 13–58% of the variance in eutrophication parameters. When the 103 study lakes were classified into different groups based on longitude and elevation, regression analyses demonstrated that natural factors explained more variance in TN, TP, COD_Mn, Chl-a, and TSI in western lakes than in eastern lakes. Lake depth, volume, elevation, and mean annual precipitation were the main predictors of eutrophication parameters for different lake groups. Although anthropogenic impacts such as point- and nonpoint-source pollution are considered as the main determinants of lake eutrophication, our results suggest that some natural factors that reflect lake buffer capacity to nutrient inputs can also play important roles in explaining the eutrophication status of Chinese lakes.     

The relationship between limb morphology, kinematics, and force during running: the evolution of locomotor dynamics in lizards

Terrestrial locomotion occurs via the hierarchical links between morphology, kinematics, force, and center-of-mass mechanics. In a phylogenetically broad sample of seven lizard species, we show that morphological variation drives kinematic variation, which, in turn, drives force variation. Species with short limbs use a short stride–high frequency strategy when running at steady-speed and to change speeds. This link between morphology and kinematics results in relatively small vertical forces during the support phase of the stride cycle. Conversely, species with long limbs use a long stride–low frequency strategy, resulting in large vertical forces during the support phase. In view of these findings, we suggest that limb length may predict locomotor energetics in lizards because energetics are largely determined by vertical forces and stride frequency. Additionally, we propose an energetic trade-off with both long- and short-limbed species paying the most energy to move, whereas intermediate-limbed species move using less energy. Finally, when these traits are mapped onto a lizard phylogeny, we show that locomotor functional morphology exhibits both deep phylogenetic effects and contemporary patterns of evolutionary convergence. Overall, the present study provides a foundation for testing hypotheses regarding the integration and evolution of functional traits in lizards and animals in general.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 97 , 634–651.     

Placental structures and their association with matrotrophy and superfetation in poeciliid fishes

Both matrotrophy, the maternal provisioning of nutrients to developing embryos after fertilization, and superfetation, the simultaneous presence of two or more groups of embryos at different stages of development, occur at varying degrees among species of the fish family Poeciliidae. However, it is still unclear if these two reproductive modes depend on the presence of relatively complex placentas. We describe the ultrastructure of the maternal follicular placenta of 11 poeciliid fishes using electron microscopy. In addition, we quantified six ultrastructure characteristics that reflect the degree of complexity (number of vesicles, area of vesicles, number of microvilli, microvilli length, thickness of the maternal follicle and follicular area). Using phylogenetic comparative methods, we evaluated the relationship between degree of matrotrophy and placental characteristics. We also analysed the potential effect of the presence of superfetation on placental complexity. We found a positive relationship between the degree of matrotrophy and follicular area, number of microvilli and number and area of vesicles. Similarly, follicular area and number of microvilli were larger in species with superfetation than in those without superfetation. We conclude that high degrees of matrotrophy and superfetation are associated with placental characteristics that increase the efficiency of nutrient transfer between mother and embryos.     

The functional relationship between feeding type and jaw and cranial morphology in ungulates

The relationship between jaw and skull morphology and feeding type (grazer, mixed feeder, browser, frugivorous, omnivorous) was analysed in 94 species of extant ungulates. A total of 21 morphological traits of the jaw and skull (17 and 4, respectively) were analysed using analysis of covariance, with body mass as covariate. To take into account the phylogenetic effect, simulations were generated under the Brownian motion model of character evolution. Analysis of covariance was applied to these simulations and the simulated F-ratios were used to assess the signification of the F-ratios for the real values of the traits. The feeding types had a weak effect on ungulate cranial and jaw morphology in comparison with the phylogenetic effect, since, before phylogeny correction, the analysis of covariance showed statistically significant differences associated with feeding type in 15 out of the 21 traits analysed. After controlling for phylogeny, only 2 significant traits remained, the length of the coronoid process and the occipital height. Omnivorous species had shorter coronoid processes than grazers or mixed feeders, and the occipital height was greater in the omnivorous species than in the grazers, mixed feeders or browsers. The coronoid process is involved in the generation of bite force, being the effective moment arm of the temporalis muscle, and occipital height is positively related to the force exerted by the temporalis muscle. This result matches the hypothesis that species with a toughness diet should show higher bite force (“toughness” describes the resistance of a material to being mechanically broken down). When the omnivorous species were excluded from the analysis, no differences in jaw and skull morphology were detected between the rest of the feeding types. Received: 1 September 1998 / Accepted: 2 November 1998     

Streptozotocin-induced diabetes in the rat is associated with changes in vaginal hemodynamics, morphology and biochemical markers

Background  

Diabetes is associated with declining sexual function in women. However, the effects of diabetes on genital tissue structure, innervation and function remains poorly characterized. In control and streptozotocin-treated female rats, we investigated the effects of diabetes on vaginal blood flow, tissue morphology, and expression of arginase I, endothelial nitric oxide synthase (eNOS) and cGMP-dependent protein kinase (PKG), key enzymes that regulate smooth muscle relaxation. We further related these changes with estrogen receptor alpha (ERα) and androgen receptor (AR) expression.     

Functional morphology of jaw trabeculation in the lesser electric ray Narcine brasiliensis, with comments on the evolution of structural support in the Batoidea

The design of minimum-weight structures that retain their integrity under dynamic loading regimes has long challenged engineers. One solution to this problem found in both human and biological design is the optimization of weight and strength by hollowing a structure and replacing its inner core with supportive struts. In animals, this design is observed in sand dollar test, avian beak, and the cancellous bone of tetrapod limbs. Additionally, within the elasmobranch fishes, mineralized trabeculae (struts) have been reported in the jaws of durophagous myliobatid stingrays (Elasmobranchii: Batoidea), but were believed to be absent in basal members of the batoid clade. This study, however, presents an additional case of batoid trabeculation in the lesser electric ray, Narcine brasiliensis (Torpediniformes). The trabeculae in these species likely play different functional roles. Stingrays use their reinforced jaws to crush bivalves, yet N. brasiliensis feeds by ballistically protruding its jaws into the sediment to capture polychaetes. In N. brasiliensis, trabeculae are localized to areas likely to experience the highest load: the quadratomandibular jaw joints, hyomandibular-cranial joint, and the thinnest sections of the jaws immediately lateral to the symphyses. However, the supports perform different functions dependent on location. In regions where the jaws are loaded transversely (as in durophagous rays), "load leading" trabeculae distribute compressive forces from the cortex through the lumen of the jaws. In the parasymphyseal regions of the jaws, "truss" trabeculae form cross-braces perpendicular to the long axes of the jaws. At peak protrusion, the jaw arch is medially compressed and the jaw loaded axially such that these trabeculae are positioned to resist buckling associated with excavation forces. "Truss" trabeculae function to maintain the second moment of area in the thinnest regions of the jaws, illustrating a novel function for batoid trabeculation. Thus, this method of structural support appears to have arisen twice independently in batoids and performs strikingly different ecological functions associated with the distribution of extreme loading environments.