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Adult Morphology (adult + morphology)
Selected AbstractsOntogeny of robusticity of craniofacial traits in modern humans: A study of South American populationsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010Paula N. Gonzalez Abstract To date, differences in craniofacial robusticity among modern and fossil humans have been primarily addressed by analyzing adult individuals; thus, the developmental basis of such differentiation remains poorly understood. This article aims to analyze the ontogenetic development of craniofacial robusticity in human populations from South America. Geometric morphometric methods were used to describe cranial traits in lateral view by using landmarks and semilandmarks. We compare the patterns of variation among populations obtained with subadults and adults to determine whether population-specific differences are evident at early postnatal ontogeny, compare ontogenetic allometric trajectories to ascertain whether changes in the ontogeny of shape contribute to the differentiation of adult morphologies, and estimate the amount of size change that occurs during growth along each population-specific trajectory. The results obtained indicate that the pattern of interpopulation variation in shape and size is already established at the age of 5 years, meaning that processes acting early during ontogeny contribute to the adult variation. The ontogenetic allometric trajectories are not parallel among all samples, suggesting the divergence in the size-related shape changes. Finally, the extension of ontogenetic trajectories also seems to contribute to shape variation observed among adults. Am J Phys Anthropol 2010. © 2009 Wiley-Liss, Inc. [source] Testosterone metabolites differentially maintain adult morphology in a sexually dimorphic neuromuscular systemDEVELOPMENTAL NEUROBIOLOGY, Issue 4 2010Tom Verhovshek Abstract The lumbar spinal cord of rats contains the sexually dimorphic, steroid-sensitive spinal nucleus of the bulbocavernosus (SNB). Androgens are necessary for the development of the SNB neuromuscular system, and in adulthood, continue to influence the morphology and function of the motoneurons and their target musculature. However, estrogens are also involved in the development of the SNB system, and are capable of maintaining function in adulthood. In this experiment, we assessed the ability of testosterone metabolites, estrogens and nonaromatizable androgens, to maintain neuromuscular morphology in adulthood. Motoneuron and muscle morphology was assessed in adult normal males, sham-castrated males, castrated males treated with testosterone, dihydrotestosterone, estradiol, or left untreated, and gonadally intact males treated with the 5,-reductase inhibitor finasteride or the aromatase inhibitor fadrozole. After 6 weeks of treatment, SNB motoneurons were retrogradely labeled with cholera toxin-HRP and reconstructed in three dimensions. Castration resulted in reductions in SNB target muscle size, soma size, and dendritic morphology. Testosterone treatment after castration maintained SNB soma size, dendritic morphology, and elevated target muscle size; dihydrotestosterone treatment also maintained SNB dendritic length, but was less effective than testosterone in maintaining both SNB soma size and target muscle weight. Treatment of intact males with finasteride or fadrozole did not alter the morphology of SNB motoneurons or their target muscles. In contrast, estradiol treatment was completely ineffective in preventing castration-induced atrophy of the SNB neuromuscular system. Together, these results suggest that the maintenance of adult motoneuron or muscle morphology is strictly mediated by androgens. © 2009 Wiley Periodicals, Inc. Develop Neurobiol 70: 206,221, 2010. [source] METAMORPHOSIS AND NEOTENY: ALTERNATIVE PATHWAYS IN AN EXTINCT AMPHIBIAN CLADEEVOLUTION, Issue 7 2006Rainer R. Schoch Abstract The Branchiosauridae was a clade of small amphibians from the Permo-Carboniferous with an overall salamander-like appearance. The clade is distinguished by an extraordinary fossil record that comprises hundreds of well-preserved specimens, representing a wide range of ontogenetic stages. Branchiosaurids had external gills and weakly ossified skeletons, and due to this larval appearance their status as neotenic (perennibranchiate) froms has long been accepted. Despite their extensive fossil record large specimens with an adult morphology appeared to be lacking altogether, but recently two adult specimens were identified in a rich sample of Apateon gracilis collected in the 19th century from a locality near Dresden, Saxony. These specimens are unique among branchiosaurids in showing a high level of ossification, including bones that have never been reported in a branchiosaur. These highlight the successive formation of features believed to indicate terrestrial locomotion, as well as feeding on larger prey items. Moreover, these transformations occurred in a small time window (whereas the degree of size increase is used as a proxy of time) and the degree of concentration of developmental events in branchiosaurids is unique among tetrapods outside the lissamphibians. These specimens are compared with large adults of the neotenic branchiosaurid Apateon caducus from the Saar-Nahe Basin, which despite their largetr body size lack the features found in the adult. A. gracilis specimens. These specimens give new insight into patterns of metamorphosis (morphological transformation) in branchiosaurids that are believed to be correlated to a change of habitat, and clearly show that different life-history pathways comparable to those of modern salamanders were already estabilshed in this Paleozoic clade. [source] Early Distal-less expression in a developing crustacean limb bud becomes restricted to setal-forming cellsEVOLUTION AND DEVELOPMENT, Issue 1 2008Terri A. Williams SUMMARY Distal-less (Dll) plays a well-known role in patterning the distal limb in arthropods. However, in some taxa, its expression even during early limb development is not always limited to the distal limb. Here, I trace the expression of Distal-less in a crustacean (Thamnocephalus platyurus) from the early limb bud to later stages of limb development, a period that includes differentiation of juvenile and adult morphology. During early development, I find two distinct types of DLL expression: one correlated with proximal distal leg patterning and the other restricted to setal-forming cells. Later in development, all the DLL expression is restricted to setal-forming cells. Based on the particular cells expressing DLL, I hypothesize an ancestral role for Dll function in the formation accessory cells of sensilla. [source] Cranial modularity and sequence heterochrony in mammalsEVOLUTION AND DEVELOPMENT, Issue 3 2007Anjali Goswami SUMMARY Heterochrony, the temporal shifting of developmental events relative to each other, requires a degree of autonomy among those processes or structures. Modularity, the division of larger structures or processes into autonomous sets of internally integrated units, is often discussed in relation to the concept of heterochrony. However, the relationship between the developmental modules derived from studies of heterochrony and evolutionary modules, which should be of adaptive importance and relate to the genotype,phenotype map, has not been explicitly studied. I analyzed a series of sectioned and whole cleared-and-stained embryological and neonatal specimens, supplemented with published ontogenetic data, to test the hypothesis that bones within the same phenotypic modules, as determined by morphometric analysis, are developmentally integrated and will display coordinated heterochronic shifts across taxa. Modularity was analyzed in cranial bone ossification sequences of 12 therian mammals. A dataset of 12,18 developmental events was used to assess if modularity in developmental sequences corresponds to six phenotypic modules, derived from a recent morphometric analysis of cranial modularity in mammals. Kendall's , was used to measure rank correlations, with randomization tests for significance. If modularity in developmental sequences corresponds to observed phenotypic modules, bones within a single phenotypic module should show integration of developmental timing, maintaining the same timing of ossification relative to each other, despite differences in overall ossification sequences across taxa. Analyses did not find any significant conservation of developmental timing within the six phenotypic modules, meaning that bones that are highly integrated in adult morphology are not significantly integrated in developmental timing. [source] The metamorphic fate of supernumerary caudal vertebrae in South Asian litter frogs (Anura: Megophryidae)JOURNAL OF ANATOMY, Issue 3 2007Gregory R. Handrigan Abstract Tadpoles of the Megophryidae, a South Asian family of litter frogs, are unique among anurans by virtue of their expanded caudal skeletons, which include supernumerary vertebral centra. The number of these vertebrae varies widely within the family, with tadpoles of Leptobrachella having as many as 30 and Leptolalax only five. Vertebral morphology is also quite variable, ranging from complete, perichordal centra to fragmentary ossifications. This variation in the caudal osteology of larval megophryids, however, is not manifested in the adult morphology. Post-metamorphic litter frogs have a typical anuran axial skeleton, invariably comprising eight presacral vertebrae, a single sacral vertebra and, postsacrally, the urostyle. To resolve this incongruity between life phases and to determine the precise metamorphic fate of supernumerary caudal vertebrae in megophryids, we examined metamorphic specimens from the genera Leptobrachella, Leptolalax, Ophryophryne and Megophrys. In all four, the caudal larval skeleton undergoes massive reduction, leaving only the coccyx and hypochord untouched. Caudal centra are apparently degraded by osteoclasts, which have not previously been implicated in vertebral remodelling during anuran metamorphosis. In Megophrys and Ophryophryne metamorphs, presacral centra also undergo resorption, consistent with an epichordal mode of centrum formation. The conservation of megophryid adult axial osteology in the face of extensive larval skeletal diversity reveals the role of metamorphosis in constraining anuran morphology. [source] Ossification sequence of the avian order anseriformes, with comparison to other precocial birdsJOURNAL OF MORPHOLOGY, Issue 9 2008Erin E. Maxwell Abstract Ossification sequences are poorly known for most amniotes, and yet they represent an important source of morphogenetic, phylogenetic, and life history information. Here, the author describes the ossification sequences of three ducks, the Common Eider Somateria mollissima dresseri, the Pekin Duck Anas platyrhynchos, and the Muscovy Duck Cairina moschata. Sequence differences exist both within and among these species, but are generally minor. The Common Eider has the most ossified skeleton prior to hatching, contrary to what is expected in a subarctic migrant species. This may be attributed to a tradeoff between growth rate and locomotory performance. Growth rate is higher in hatchlings with more cartilaginous skeletons, but this may compromise locomotion. No major ossification sequence differences were observed in the craniofacial skeleton when compared with Galliformes, which suggests that the influence of adult morphology on ossification sequence might be relatively minor in many taxa. Galliformes and Anseriformes, while both highly ossified at hatching, differ in the location of their late-stage ossification centers. In Anseriformes, these are most often located in the appendicular skeleton, whereas in Galliformes they are in the thoracic region and form the ventilatory apparatus. J. Morphol., 2008. © 2008 Wiley-Liss, Inc. [source] Skeletal development of the Mexican spadefoot, Spea multiplicata (Anura: Pelobatidae)JOURNAL OF MORPHOLOGY, Issue 7 2006Barbara Banbury Abstract The larval chondrocranium of Spea multiplicata is described, as is the development and adult morphology of the skeleton. There are major modifications to the larval chondrocranium throughout development, including the presence of embryonic trabeculae in young tadpoles and significant reorganization of cartilaginous structures at metamorphosis. The first bone to ossify is the parasphenoid (Stage 35), followed by the presacral neural arches, ilium, and femur (Stage 36). By Stage 39, most of the postcranial elements have begun to ossify. Metamorphic climax is accomplished over three Gosner stages (39,41) and involves major modifications to the chondrocranium, as well as the appearance of three cranial elements (septomaxilla, nasal, and premaxilla). After metamorphosis, the exoccipital, vomer, dentary, angulosplenial, squamosal, pterygoid, sphenethmoid, ischium, and hyoid begin to ossify. The stapes, mentomeckelian, operculum, carpals, and tarsals do not appear until juvenile and adult stages. The development of the hyoid and cartilaginous condensations of the carpals and tarsals are described. In addition, phenotypic plasticity within the genus and the absence of a palatine (= neopalatine) bone are discussed. J. Morphol. © 2006 Wiley-Liss, Inc. [source] Limb morphogenesis in the branchiopod crustacean, Thamnocephalus platyurus, and the evolution of proximal limb lobes within AnostracaJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2007T. A. Williams Abstract Crustacean limbs exhibit highly diverse morphologies. One major route of diversification is in the number and position of branches arising from the proximal part of the limb. Here I describe development of larvae of the branchiopod crustacean, Thamnocephalus platyurus and describe in detail the development of the thoracic limbs. The thoracic limbs bear proximal branches both medially and laterally. The most proximal branches on either side (gnathobase and pre-epipod) show a similar developmental history: they develop via fusion of two rudiments into a single adult branch. However, phylogenetic analysis suggests that the developmental fusions have distinct evolutionary histories. In one case (gnathobase), the developmental rudiments reflect the ancestral adult morphology of two distinct branches. In the other (pre-epipod), the rudiments are an apparent novelty within the Anostraca and develop into two adult structures in only a single derived family. Zusammenfassung Die Extremitäten von Krebsen zeigen eine Vielfalt an unterschiedlichen Morphologien. Diversifikation findet zum Grossteil über Anzahl und Position der aus dem proximalen Anteil der Extremitäten entspringenden Äste statt. In dieser Studie wird die Larvalentwicklung von Thamnocephalus platyurus, einem branchiopoden Krebs, beschrieben, vor allem die Entwicklung der Extremitäten der Thoracalsegmente. Diese tragen proximale Äste, sowohl medial, als auch lateral. Die proximalsten Äste beider Seiten (Gnathobasis und Praeepipodit) zeigen ähnliche Entwicklungen: Beide entstehen durch Fusion zweier Rudimente zu einem einzigen Ast im Adultstadium. Phylogenetische Analysen lassen darauf schließen, dass diese Fusionen während der Entwicklung unabhängig entstanden sind. In einem Fall (Gnathobasis) spiegeln die Rudimente im Entwicklungsstadium die ancestrale adulte Morphologie zweier unterschiedlicher Äste wieder. Im anderen Fall (Praeepipodit) sind die Rudimente vermutlich Innovationen innerhalb der Anostraca und entwickeln sich zu zwei verschiedenen Strukturen in nur einer einzigen Familie. [source] Population structure of the peridomestic mosquito Ochlerotatus notoscriptus in AustraliaMEDICAL AND VETERINARY ENTOMOLOGY, Issue 2 2004D. H. Foley Abstract.,Ochlerotatus notoscriptus (Skuse) (Diptera: Culicidae) is the predominant peridomestic mosquito in Australia where it is the primary vector of dog heartworm, Dirofilaria immitis (Leidy), and a potentially important vector of arboviruses (Barmah Forest, Ross River) with geographical variation of vector competence. Although widespread, Oc. notoscriptus has low dispersal ability, so it may have isolated subpopulations. The identification of gene flow barriers may assist in understanding arbovirus epidemiology and disease risk, and for developing control strategies for this species. We investigated the population structure of Oc. notoscriptus from 17 sites around Australia, using up to 31 putative allozyme loci, 11 of which were polymorphic. We investigated the effect of larval environment and adult morphology on genetic variation. At least five subpopulations were found, four in New South Wales (NSW) and one unique to Darwin. Perth samples appear to be a product of recent colonization from the Australian east coast. For NSW sites, a Mantel test revealed an isolation by distance effect and spatial autocorrelation analysis revealed an area of effective gene flow of 67 km, which is high given the limited dispersal ability of this species. No consistent difference was observed between ,urban' and ,sylvan' habitats, which suggests frequent movement between these sites. However, a finer-scaled habitat study at Darwin revealed small but significant allele frequency differences, including for Gpi. No fixed allozyme differences were detected for sex, size, integument colour or the colour of species-diagnostic pale scales on the scutum. The domestic habit of Oc. notoscriptus and assisted dispersal have helped to homogenize this species geographically but population structure is still detectable on several levels associated with geographical variation of vector competence. [source] A comparison of the ontogeny of shape variation in the anthropoid scapula: Functional and phylogenetic signalAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2008Nathan M. Young Abstract This article compares ontogenetic shape variation in the scapula of 17 anthropoid species using three-dimensional landmark-based geometric morphometrics. These data are used to investigate functional and phylogenetic signal in the major components of scapular variation and to evaluate the degree to which postnatal growth contributes to interspecific differences in shape. Results indicate that the shape of the infant and adult scapula is primarily associated with positional behavior (e.g., orthograde suspensory nonquadrupeds versus pronograde quadrupeds), but within this functional structure there is phylogenetic signal, particularly at infant stages. Growth most closely correlates with infant/adult shape and locomotor function. These results suggest that the shape of the infant scapula drives the pattern of postnatal scapular growth and adult morphology. As such, variation in postnatal growth is not the primary source of interspecific variation in adult shape. Instead, interspecific differences in scapular morphology are hypothesized to be the result of selection for variation in embryonic developmental processes that affect shape. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc. [source] Revision of the Australian species of Hyalobathra Meyrick (Lepidoptera: Pyraloidea: Crambidae: Pyraustinae) based on adult morphology and with description of a new speciesAUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 3 2003Hari Sutrisno Abstract The genus Hyalobathra Meyrick is redefined based on five Australian species including the type species. The four named Australian species, H. archeleuca Meyrick, H. unicolor (Warren), H. miniosalis (Guenée) and H. minialis (Warren), are redescribed and a new species, H. crenulata sp. n., is described. Hyalobathra unicolor is removed from synonymy with H. illectalis (Walker), and lectotypes are designated for H. archeleuca, H. minialis and for H. rhodoplecta Turner, a synonym of H. miniosalis. The presence of H. paupellalis (Lederer) in Australia could not be confirmed, but its genitalia are figured. Two previously included species, ,Hyalobathra'aequalis (Lederer) and ,H.' brevialis (Walker), are excluded from Hyalobathra, as they lack its generic apomorphies, but cannot at present be assigned to any other genus. [source] Phylogeny of the Myllaenini and related taxa (Coleoptera: Staphylinidae: Aleocharinae)CLADISTICS, Issue 2 2004Kee-Jeong Ahn A cladistic analysis of the tribe Myllaenini Ganglbauer and related genera is presented. Monophyly of the Myllaenini is tested, and the tribe is hypothesized to be a monophyletic group consisting of nine genera (Myllaena Erichson, Amazonopora Pace, Dimonomera Cameron, Bryothinusa Casey, Philomina Blackwelder, Polypea Fauvel, Brachypronomaea Sawada, Rothium Moore and Legner, and Lautaea Sawada), based on the synapomorphy of antero-lateral angles of mentum prolonged into spinose processes. A history of the classification of the Myllaenini is discussed. The data set for phylogenetic analysis comprised 99 characters representing 297 character states derived from adult morphology. The analysis agrees on the monophyly of the Myllaenini and the monophyly of the Pronomaeini Ganglbauer (Pronomaea Erichson, Pseudomniophila Pace, Nopromaea Cameron and Tomoxelia Bernhauer). The tribe Dimonomerini (Dimonomera Cameron) is confirmed to be a member of the Myllaenini. Masuriini is a possible sister group of the Myllaenini. Stylopalpus Cameron shows a sister group relationship to the Pronomaeini. Several other clades are also consistently recovered. However, the phylogenetic relationships of the genus Dysacrita are ambiguous. The rogue genus Diglotta Champion is not recovered as a member of the Myllaenini or Pronomaeini. On the contrary, it forms a monophyletic clade with the liparocephaline genera Halorhadinus Sawada and Amblopusa Casey. Evolution of the defensive gland on abdominal tergite VII among aleocharine lineages is reconsidered, and the origin of an intertidal habitat in the Myllaenini is discussed. [source] Do larvae evolve the same way as adults in Tingidae (Insecta: Heteroptera)?CLADISTICS, Issue 2 2004Eric Guilbert A recent cladistic analysis showed that adult traits of Tingidae, which exhibit a great variety of shapes, evolved homoplastically from simple to complex (Guilbert, 2001). These complex traits, often exaggerated, were hypothesized to be adaptive. However, this study, as well as another by Lis (1999), both based on adult morphology, contradict the traditional classification of Tingidae. A new analysis is performed here, that includes larval characters, which, like those of adults, have a great variety of shapes. The results corroborate the traditional classification of the Tingidae. No clear divisions among Tinginae are drawn from the analysis, but an evolutionary pattern of shapes among Tingidae emerges from this study. There is a global tendency for larval traits to evolve convergently from simple to complex, as suggested for adults. The pattern seen in adult and larval traits is independent, but consistent. These traits can be used in the same anti-predation context, but with different roles. [source] The phylogeny of the Histeroidea (Coleoptera: Staphyliniformia)CLADISTICS, Issue 4 2002Michael S. Caterino For its size (ca. 4000 species) the Histeridae is one of the most ecologically and morphologically diverse families of beetles. Its mostly predaceous members occupy a wide variety of habitats for which their morphologies may be highly modified. Previous attempts to resolve the phylogeny of the family based on morphological data have left many difficult issues unresolved. This study is the first to utilize either larval or molecular (18S rDNA) data in combination with adult morphology in an attempt to resolve these issues. We compare the performance of optimization alignment with a fixed positional homology approach, over a range of parameter space. Optimizing alignment parameters for combined analyses of 18S and morphology for both approaches resulted in very similar topologies. Contrary to previous hypotheses which held the cylindrical, subcortical forms of the family (e.g., Niponius, Trypanaeus, Trypeticus) to be the most primitive, our analyses find these to be highly specialized forms derived from within other more generalized taxa. Basal lineages within the family instead include Onthophilus, Anapleus, and Dendrophilus, all of which are ovoid, mainly generalist forms. [source] Topographical anatomy of Spiegel's lobe and its adjacent organs in mid-term fetuses: Its implication on the development of the lesser sac and adult morphology of the upper abdomenCLINICAL ANATOMY, Issue 6 2010Si Eun Hwang Abstract At 8,16 weeks of gestation, Spiegel's lobe of the caudate lobe appears as a sac-like herniation of the liver parenchyma between the inferior vena cava and ductus venosus or Arantius' duct. In 5 of 11 fetuses at 20,30 weeks of gestation, we found that an external notch was formed into the posterior aspect of the caudate lobe by a peritoneal fold containing the left gastric artery. This notch appeared to correspond to that observed in adults, which is usually seen at the antero-inferior margin of the lobe after rotation of the lobe along the horizontal or transverse axis. However, the notch did not accompany two of the three fetuses in which the left hepatic artery originated from the left gastric artery. Notably, until 9,10 weeks of gestation, the inferior and left part of Spiegel's lobe rode over the hepatoduodenal ligament and protruded medially into the lesser sac (bursa omentalis) behind the stomach. Thus, the fetal Winslow's foramen was located at the "superior" side of the ligament. However, as seen in adults, the protruding Spiegel's lobe was located at the posterior side of the lesser omentum. Therefore, a hypothetical rotation along the transverse axis in the later stages of development seems necessary to explain this repositioning. Considering that Spiegel's lobe develops faster than surrounding structures, it is likely that the lesser sac resulting from the rotation of the gastrointestinal tract, which actively contributes to facilitate the growth of the Spiegel lobe. Clin. Anat. 23:712,719, 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||