Feeding Adaptations Research Articles

ON THE REVERSIBILITY OF MANDIBULAR SYMPHYSEAL FUSION

Experimental and comparative studies suggest that a major determinant of increased ossification of the mandibular symphysis is elevated masticatory stress related to a mechanically challenging diet. However, the morphology of this joint tracks variation in dietary properties in only some mammalian clades. Extant anthropoid primates are a notable exception: synostosis is ubiquitous in this speciose group, despite its great age and diverse array of feeding adaptations. One possible explanation for this pattern is that, once synostosis evolves, reversion to a lesser degree of fusion is unlikely or even constrained. If correct, this has important implications for functional and phylogenetic analyses of the mammalian feeding apparatus. To test this hypothesis, we generated a molecular tree for 76 vespertilionoid and noctilionoid chiropterans using Bayesian phylogenetic analysis and examined character evolution using parsimony and likelihood ancestral-state reconstructions along with the binary state speciation and extinction (BiSSE) model. Results indicate that reversals have occurred within Vespertilionoidea. In contrast, noctilionoids exhibit an anthropoid-like pattern, which suggests that more detailed comparisons of the functional and developmental bases for fusion in these bat clades may provide insight into why fusion is maintained in some lineages but not in others. Potential functional and developmental explanations for the lack of reversal are discussed.

Diet-Morphology Correlations in the Radiation of South American Geophagine Cichlids (Perciformes: Cichlidae: Cichlinae)

Genera within the South American cichlid tribe Geophagini display specialized feeding and reproductive strategies, with some taxa specialized for both substrate-sifting and mouth brooding. Several lineages within the clade also possess an epibranchial lobe (EBL), a unique pharyngeal structure that has been proposed to have a function in feeding and/or mouth brooding. A recently published genus-level phylogeny of Neotropical cichlids was used as the evolutionary framework for investigating the evolution of morphological features presumably correlated with diet and mouth brooding in the tribe Geophagini. We tested for possible associations between the geophagine epibranchial lobe and benthic feeding and mouth brooding. We also addressed whether the EBL may be associated with unique patterns of diversification in certain geophagine clades. Tests of binary character correlations revealed the EBL was significantly associated with mouth brooding. We also tested for a relationship between diet and morphology. We analyzed stomach contents and morphometric variation among 21 species, with data for two additional species obtained from the literature. Principal Components Analysis revealed axes of morphological variation significantly correlated with piscivory and benthivory, and both morphology and diet were significantly associated with phylogeny. These results suggest that the EBL could be an adaptation for either feeding or mouth brooding. The EBL, however, was not associated with species richness or accelerated rates of phyletic diversification.

Esophageal Motility after Laparoscopic Roux-en-Y Gastric Bypass: the Manometry Should Be Preoperative Examination Routine?

Our goal was to identify the changes of esophageal motility, lower esophageal sphincter (LES) function, and eating adaptation before and after Roux-en-Y gastric bypass (RYGBP) and whether manometry should be a routine examination in patients who undergo this procedure. A total of 81 patients underwent manometry before surgery and 1 year after surgery. The control group consisted of 10 nonobese volunteers. Patients were classified as presenting with vomiting and without vomiting 1 year after surgery. Manometric variables were compared before and after surgery. Statistical analysis was performed using Wilcoxon and Mann-Whitney test. The patients (45.6%) had preoperative manometric findings, 29.8% had LES hypertonia, 18.9% LES hypotonia, 43.2% increase in wave amplitude of contraction, and three 8.1% abnormal peristalsis. One year after surgery manometry was abnormal in 62.9% of patients, 11.7% with hypertonia and 15.7% with hypotonia of the LES, 53% with changes in amplitude contraction and 19.6% with abnormal peristalsis. The control group showed no manometric abnormalities. Chronic vomiting was noted in 21% of patients. When comparing all variables between the pre and postoperative periods, there was no significant difference for all of them except for peristalsis. Comparing the results of manometric findings between the vomiting and non-vomiting groups, no significant changes were found in the variables studied. There was an association between RYGBP and motor abnormalities in the esophagus but no differences in postoperative feeding adaptation. Thus, we conclude that esophageal manometry is not necessary as a routine preoperative examination.

Gross morphology and histology of head and salivary apparatus of the predatory bug, Rhynocoris marginatus.

Rhynocoris marginatus Fabricius (Hemiptera: Reduviidae) is an important biological control agent against more than 25 insect pests in India. For a better understanding of the feeding adaptation of this bug, the gross morphology and histology of its head and salivary apparatus were studied using both a light microscope and scanning electron microscope. The head is more or less elongate, mobile, and immersed into the eyes. R. marginatus has a three-segmented curved rostrum; the middle segment is longer than the other two segments. The terminal rostral segment bears spines and trichobothria externally. Stylet bundles bear two pairs of maxillary and mandible stylets in the curved rostrum with serrations. The stylets help to penetrate into the tissue and directly pump the toxic venomous saliva deep into the prey. The principal gland is bi-lobed (anterior lobe and posterior lobe), whereas the accessory gland is uni-lobed, exhibiting distinct functional and histological differences. These glands receive tracheal and nerve supply. Mononucleated, binucleated, trinucleated and polynucleated cells are distributed both in anterior and posterior lobes of the principal gland. The cytoplasm has collecting vacuoles with secretions. Therefore, this predator is highly equipped with well-developed mouthparts that are attached to the salivary apparatus.

Effects of aging and caloric restriction on brainstem satiety center signals in rats

Age-related increases of body weight and adiposity, indicating dysregulation of food intake/energy expenditure, can be prevented in rodents by long-term 40% caloric restriction. The dorsal vagal complex (DVC), the brainstem center mediating the satiety reflex, has recently emerged as a determinant effector of long-term feeding adaptation. To study the effects of aging and caloric restriction on satiety circuits, leptin and brain-derived neurotrophic factor (BDNF) signaling systems were studied in 2- and 19-month-old ad libitum-fed (AL) and 19-month-old calorie-restricted (CR) rats. Age-induced hyperleptinemia in AL rats was correlated with elevated DVC BDNF immunoreactive concentrations and satiety threshold stability, suggesting functional desensitization of the DVC to these signals. To better understand this phenomenon, mRNA levels of receptor and post-receptor signaling effectors were measured by real-time RT-PCR. Aging selectively increased BDNF receptors and suppressor of cytokine signaling-3 (SOCS-3) mRNA levels. Caloric restriction prevented age-related increases of serum leptin, DVC BDNF and SOCS-3 mRNA levels, but not those of BDNF receptors. In CR rats, prevention of leptin resistance-promoting SOCS-3 induction was also observed at the protein level. This study suggests that leptin post-receptor targets and BDNF signaling play a role in the establishment of age-related DVC dysfunction.

Prey capture in lizards: differences in jaw-neck-forelimb coordination

607..622 Although prey capture is thought to be based on the coordinated movements of the jaw and locomotor apparatus (i.e. the vertebral column and the limbs), jaw–neck–forelimb coordination has never been compared among related species. The kinematics of jaw, neck, and forelimb movements were recorded in lizards that use jaw prehension: Gerrhosaurus major, Tupinambis merianae, Varanus niloticus, and Varanus ornatus. These species provide a comparative framework to discuss the influence of morphological differences and ecological convergence on the jaw–neck–forelimb coordination patterns. Jaw–neck–forelimb coordination was quantified by determining whether maximum neck elevation and maximum forelimb flexion are synchronized with either the start of jaw opening or maximum gape. Significant differences in the jaw–neck–forelimb coordination pattern among species were observed, with maximum neck elevation being synchronized with the start of jaw opening in varanids, whereas in T. merianae and G. major, it is achieved closer to maximum gape. Differences in locomotor–feeding integration are suggested to be related to dietary specializations, and as such may play a role in feeding adaptation. The jaw–neck–forelimb coordination pattern used by varanids may indeed be advantageous to prepare a quick strike triggered from further away, providing a critical advantage when feeding on evasive prey. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105, 607–622.

Geometric morphometrics shows differences and similarities in skull shape between the red and giant pandas

AbstractA morphometric analysis of the skull of the red or lesser panda, Aiulurus fulgens (Ailuridae), and the giant panda, Ailuropoda melanoleuca (Ursidae), was performed for evaluating the importance of natural selection and phylogenetic constraints in shaping the convergent morphological adaptations of these peculiar carnivores for feeding on bamboo. Principal components and discriminant analyses of landmark data was used in a comparative study across the families Procyonidae, Ursidae and Ailuridae. Skull morphospaces show that major patterns of morphological variation among these arctoid carnivorans correlate with differences in their feeding behavior. More specifically, this study has shown an extreme convergence in skull shape between the two bamboo specialists. Following the most recent molecular and morphological phylogenies, as well as the poor evidence from the fossil record, it seems highly improbable that homology could explain the shared morphology of the giant and red pandas, which lineages diverged ∼40 million years ago. On the contrary, most phylogenetic and paleontological data suggest that convergent or parallel evolution (homoplasy) would be the evolutionary process shaping the common morphological traits of these unusual carnivorans. Therefore, the overall resemblance in skull shape between the giant and red pandas was probably driven by extrinsic factors (natural selection and adaptation for feeding on bamboo) as well as by intrinsic ones (the shared developmental pathway of the carnivoran skull, which posed some biomechanical constraints on the direction of the evolution of pandas).

Microwear, mechanics and the feeding adaptations of Australopithecus africanus

Recent studies of dental microwear and craniofacial mechanics have yielded contradictory interpretations regarding the feeding ecology and adaptations of Australopithecus africanus. As part of this debate, the methods used in the mechanical studies have been criticized. In particular, it has been claimed that finite element analysis has been poorly applied to this research question. This paper responds to some of these mechanical criticisms, highlights limitations of dental microwear analysis, and identifies avenues of future research.

Ecosystem consequences of selective feeding of an insect herbivore: palatability-decomposability relationship revisited

1. The relationship between leaf palatability and litter decomposability is critical to understanding the effects of selective feeding by herbivores on decomposition processes, and several studies have reported that there is a positive relationship between them. 2. However, palatability is not always positively correlated with decomposability, because of species-specific feeding adaptation of herbivores to host plants. Moreover, the effects of selective feeding by herbivores on soil decomposition processes should be understood in terms of the inputs of leaf litter and excrement. 3. The present study examined the relationships between leaf palatability and the decomposability of litter and frass, using Lymantria dispar Linnaeus and 15 temperate deciduous tree species. 4. Larvae of L. dispar exhibited a clear feeding preference, and subsequently the excreted frass mass differed among tree species. Litter and frass decomposability also differed among tree species, and frass was more rapidly decomposed than litter. There were no positive or negative correlations between palatability and decomposability of litter and frass. 5. These results indicate that L. dispar larvae may accelerate the decomposition process in temperate deciduous forests through selective feeding on plants with relatively low litter decomposability and the production of frass with higher decomposability than the litter.

Sensory perception, neurobiology, and behavioral adaptations for predator avoidance in planktonic copepods

Copepods are important grazers on microplankton in marine food webs and are, in turn, preyed upon by a wide range of predators with diverse feeding adaptations. Although copepods have evolved numerous adaptations to help them avoid predation, their escape behavior sets them apart from many other planktonic organisms. Mechanoreception is widely used by copepods to detect hydrodynamic disturbances created by approaching predators. When these disturbances are detected, copepods respond quickly with escape jumps that can accelerate them from a stationary position to speeds of over 600 body lengths per second within a few milliseconds. Myelinated nerves may improve the escape behavior of some copepods through faster conduction of nerve impulses. The differences in response latencies between myelinate and amyelinate copepod species are greatest in larger copepod species, where nerve signals must be conducted over longer distances. Environmental variability such as turbulence may affect the ability of both prey to detect predators and predators to capture their planktonic prey. Small amounts of turbulence favor the predator, while too much turbulence reduces predation. Understanding the sensory physiology of copepods and their behavioral adaptations for avoiding predation will increase knowledge of the factors affecting the structure and function of marine pelagic food webs.

Mosquito Aedes aegypti (L.) leucokinin receptor is critical for in vivo fluid excretion post blood feeding

The evolution of the blood feeding adaptation in mosquitoes required hormonal coordination of multiple physiological processes (behavior, digestion, diuresis, oogenesis). The Aedes kinins (leucokinin-like neuropeptides) are involved in post blood feeding physiological processes, having diuretic and myotropic functions. To understand the in vivo contribution of the kinin receptor to overall female post-prandial fluid excretion, RNAi knockdown was followed by fluid secretion assays which proved its fundamental role in rapid diuresis. The Aedes kinin receptor was also localized in several tissues not previously reported in mosquitoes. Results highlight the integrative role of the Aedes kinins in the success of the blood feeding adaptation.

Out of Africa: Fossils shed light on the origin of the hoatzin, an iconic Neotropic bird

We describe the earliest fossils of the enigmatic avian taxon Opisthocomiformes (hoatzins) from the Oligo-Miocene (22-24mya) of Brazil. The bones, a humerus, scapula and coracoid, closely resemble those of the extant hoatzin, Opisthocomus hoazin. The very similar osteology of the pectoral girdle in the new Brazilian fossil compared to the extant O. hoazin, in which it reflects peculiar feeding adaptations, may indicate that hoatzins had already evolved their highly specialized feeding behavior by the mid-Cenozoic. We further show that Namibiavis senutae from the early Miocene of Namibia is another, previously misclassified representative of Opisthocomiformes, which documents that the extant Neotropic distribution of hoatzins is relictual. Because of the weak flight capabilities of hoatzins, their occurrence on both sides of the South Atlantic is of particular biogeographic interest. We detail that this distribution pattern is best explained by dispersal from Africa to South America, and that Opisthocomiformes provide the first example of transatlantic rafting among birds.

OL-017 Aquaporin water channel AgAQP1 in the malaria vector mosquito Anopheles gambiae during blood feeding and humidity adaptation

OL-017 Aquaporin water channel AgAQP1 in the malaria vector mosquito Anopheles gambiae during blood feeding and humidity adaptation

Preliminary gut content and dentition analysis reveal subtle resource partitioning and feeding adaptations within a haplochromine cichlid community of Lake Victoria satellite lake

The trophic relationships between six haplochromine cichlids of Lake Kanyaboli, a satellite lake of Lake Victoria that has not been infested by the Nile perch ( Lates niloticus ), were studied as a first step towards understanding the cichlid community structure in this threatened wetland ecosystem. Coefficient of similarity analysis of diet revealed subtle trophic resource partitioning within this haplochromine community. Trophic specializations are further revealed by differences in dentition structures. Of the six haplochromine species examined, Astatotilapia nubila and Astatoreochromis alluadi had the highest coefficient of similarity (0.5256±0.300), indicating highest diet overlap, while Astatotilapia ‘big eye’ and Xistichromis phytophagus were the most ecologically separated (0.0210±0.019). Resource partitioning is further enhanced by a diurnal spatial distribution of the six species within the lake. Overall, the haplochromine cichlid community of Lake Kanyaboli is characterized by a relatively high trophic diversity compared to Lake Victoria. Small water bodies (SWBs) thus present opportunities for conservation of trophic diversity threatened by introduction of exotics in the Lake Victoria basin. Key words: Community structure, haplochromines, resource partitioning, satellite lakes, trophic ecology.

Short-Snouted Toothless Ichthyosaur from China Suggests Late Triassic Diversification of Suction Feeding Ichthyosaurs

BackgroundIchthyosaurs were an important group of Mesozoic marine reptiles and existed from the Early Triassic to the early Late Cretaceous. Despite a great diversity in body shapes and feeding adaptations, all share greatly enlarged eyes, an elongated rostrum with numerous conical teeth, and a streamlined body.Methodology/Principal FindingsBased on new material from China and the restudy of Shastasaurus pacificus, we here reinterpret the classical large-bodied Late Triassic ichthyosaur genus Shastasaurus to differ greatly from the standard ichthyosaurian body plan, indicating much greater morphological diversity and range of feeding adaptations in ichthyosaurs than previously recognized. Phylogenetic analysis indicates a monophyletic clade consisting of the giant Shonisaurus sikanniensis, Guanlingsaurus liangae, and Shastasaurus pacificus to which the genus name Shastasaurus is applied. Shastasaurus liangae comb. nov. is from the Late Triassic (Carnian) Xiaowa Formation of Guizhou Province, southwestern China. The species combines a diminutive head with an entirely toothless and greatly reduced snout. The species also has by far the highest vertebral count among ichthyosaurs (86 presacral vertebrae and >110 caudal vertebrae), a count that is also very high for tetrapods in general. A reduced toothless snout and a diminutive head is also apparently present in the giant S. sikanniensis and presumably in S. pacificus.Conclusions/SignificanceIn analogy to many modern odontocetes, Shastasaurus is interpreted as a specialized suction feeder on unshelled cephalopods and fish, suggesting a unique but widespread Late Triassic diversification of toothless, suction-feeding ichthyosaurs. Suction feeding has not been hypothesized for any of the other diverse marine reptiles of the Mesozoic before, but in Shastasaurus may be linked to the Late Triassic minimum in atmospheric oxygen.

Functional and comparative digestive system anatomy of Arctic ungulates

Dietary niche, feeding type classification and seasonal strategies of Rangifer tarandus and Ovibos moschatus discussed in relation to the anatomy of their digestive system. Classification criteria for the flexible feeding type system, originally established in bovids and later adapted to cervids, are substantiated and critically discussed in the light of recent attempts to invalidate the system. Eurasian mountain reindeer, North American barren-ground caribou, Svalbard reindeer and Victoria Island caribou are seasonally adaptable, opportunistic ruminants of the intermediate feeding type but the long evolutionary sepatation of Svalbard reindeer has modified several morphological features for winter survival without lichen, resulting in better adaptation to fibrous forage. Muskoxen, despite their seasonal selectivity, are typical grass and roughage eaters with extremely long mean retention time. Detailed data on the entire digestive system from muzzle to anus on both species are still insufficient and extended studies are worthwhile for understanding their nutritional niche and feeding adaptations.

Feeding habits of Plio-Pleistocene large carnivores as revealed by the mandibular geometry

ABSTRACT Extant large members of the order Carnivora show high variability in feeding adaptation. Morphology of their teeth and skull is a primer to predict diet in both extant and extinct species. Here I present a complete geometric morphometric survey of mandible of large (>7 kg) Carnivora in order to make paleoecological predictions for selected Plio-Pleistocene taxa. Mandibular size and shape data support a strong differentiation between families but also convergence due to functional adaptations to hunting prey. Linear discriminant function analyses are performed in order to obtain dietary predictions on fossil taxa with statistical accuracy. There is a high level of discrimination among dietary categories, especially when subsets of predator and non-predator carnivores are analyzed separately. New insights emerge for Plio-Pleistocene fossil taxa whose paleoecology was previously inferred. Mandibular size and shape data are accurate dietary predictors in large carnivores, with size being more relevant to clarify adaptations in killing prey of different size classes.

Analysis of Food And Feeding Habits of Catfish (<i>Bagrus bayad, Macropterus</i> (<i>Daget>/i>) in River Rima and Goronyo Dam, in Sokoto State, Nigeria

Food and feeding habits of the two size class of Bagrus bayad caught in River Rima and Goronyo Dam in north western Nigeria between October, 2002 and September, 2003 were studied for feeding adaptations and stomach contents. Feeding adaptive features such as mouth, gill rakers, dentition and gut system were examined. Gut length and fish length indicated rectilinear positive relationship. The regression coefficient (b) and correlation coefficient (r) of gut length to fish length were highly significant (p

Feeding of the megamouth shark (Pisces: Lamniformes: Megachasmidae) predicted by its hyoid arch: A biomechanical approach

Studies of the megamouth shark, one of three planktivorous sharks, can provide information about their evolutionary history. Megamouth shark feeding has never been observed in life animals, but two alternative hypotheses on biomechanics suggest either feeding, i.e., ram feeding or suction feeding. In this study, the second moment of area of the ceratohyal cartilages, which is an indicator of the flexural stiffness of the cartilages, is calculated for 21 species of ram- and suction-feeding sharks using computed tomography. The results indicate that suction-feeding sharks have ceratohyal cartilages with a larger second moment of area than ram-feeding sharks. The result also indicates that the ram-suction index, which is an indicator of relative contribution of ram and suction behavior, is also correlated with the second moment of area of the ceratohyal. Considering that large bending stresses are expected to be applied to the ceratohyal cartilage during suction, the larger second moment of area of the ceratohyal of suction-feeding sharks can be interpreted as an adaptation for suction feeding. Based on the small second moment of area of the ceratohyal cartilage of the megamouth shark, the feeding mode of the megamouth shark is considered to be ram feeding, similar to the planktivorous basking shark. From these results, an evolutionary scenario of feeding mechanics of three species of planktivorous sharks can be suggested. In this scenario, the planktivorous whale shark evolved ram feeding from a benthic suction-feeding ancestor. Ram feeding in the planktivorous megamouth shark and the basking shark evolved from ram feeding swimming-type ancestors and that both developed their unique filtering system to capture small-sized prey.

Natural Food Selectivity Changes with Weights of Nile Tilapia, Oreochromis niloticus (Linnaeus), Reared in Fertilized Earthen Ponds

This work was carried out to study the relationship between fish weight and natural food selectivity of Nile tilapia, Oreochromis niloticus (Linnaeus) reared in earthen ponds without supplementary diet and to guide the adaptation of feeding and fertilization strategies. Fish were stocked (1.5 fish/m2) in four fertilized earthen ponds (0.1 ha) for 6 months. Fifty fish were sampled monthly to estimate individual total weight and length and evaluate stomach contents. Fish specimens were categorized into different weight classes: <25 g, 25–50 g, 50–75 g, 75–100 g, and 100–125 g. Overall, the 50–75 g weight class had the highest degree of stomach fullness. The intestinal length-fish length ratio was similar across all fish weights, ranging from 2.9–3.4. Likewise, the composition of food items found in fish stomach was ranked as phytoplankton > detritus > zooplankton. Phytoplankton contribution to gut content increased with increasing fish weight, while detritus and zooplankton contribution decreased. Zooplankton never exceeded 1% of total stomach contents. Cyanobacteria, Chlorophyceae, Bacillariophyceae and Euglenophyceae mostly represented the phytoplankton. Bacillariophyceae dominated the phytoplanktonic portion of stomach contents at small fish size (<75 g/fish), while Chlorophyceae is the dominant group at large fish size (> 75 g/fish). Fish could select Cyanobacteria and Euglenophyceae at all fish weights, meanwhile Chlorophyceae and Bacillariophyceae were eaten with slight selectivity at larger weights..