Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 5.110
Filtrar
1.
PLoS One ; 15(8): e0237499, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32833963

RESUMO

Herein we describe Ocrepeira klamt sp. n. (Araneae: Araneidae), a new orb-weaving spider species from a Colombian páramo, which was formerly inaccessible for scientific studies due to decades long armed conflicts. Both, phenotypic and molecular data are used to confirm genus affiliation, and the new species is placed into phylogenetic context with other araneid spiders. Morphological characteristics and ecological notes of Ocrepeira klamt sp. n. are reported together with the sequence of the barcoding region of cytochrome c oxidase subunit I (COI) to provide a comprehensive description of the spider, facilitating future identification beyond taxonomic experts. With this study we contribute to the taxonomic knowledge that is required to inventory the hyper diverse yet threatened ecosystem of the Colombian páramos.


Assuntos
Estruturas Animais/anatomia & histologia , Estruturas Animais/fisiologia , Aranhas/anatomia & histologia , Aranhas/classificação , Distribuição Animal , Animais , Colômbia , Código de Barras de DNA Taxonômico , Ecossistema , Complexo IV da Cadeia de Transporte de Elétrons/genética , Filogenia , Aranhas/fisiologia
2.
PLoS One ; 15(5): e0232450, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433692

RESUMO

Many insects show discontinuous respiration with three phases, open, closed, and fluttering, in which the spiracles open and close rapidly. The relative durations of the three phases and the rate of fluttering during the flutter phase vary for individual insects depending on developmental stage and activity, vary between insects of the same species, and vary even more between different species. We studied how the rate of oxygen uptake during the flutter phase depends on the rate of fluttering. Using a mathematical model of oxygen diffusion in the insect tracheal system, we derive a formula for oxygen uptake during the flutter phase and how it depends on the length of the tracheal system, percentage of time open during the flutter phase, and the flutter rate. Surprisingly, our results show that an insect can have its spiracles closed a high percentage of time during the flutter phase and yet receive almost as much oxygen as if the spiracles were always open, provided the spiracles open and close rapidly. We investigate the respiratory gain due to fluttering for four specific insects. Our formula shows that respiratory gain increases with body size and with increased rate of fluttering. Therefore, insects can regulate their rate of oxygen uptake by varying the rate of fluttering while keeping the spiracles closed during a large fraction of the time during the flutter phase. We also use a mathematical model to show that water loss is approximately proportional to the percentage of time the spiracles are open. Thus, insects can achieve both high oxygen intake and low water loss by keeping the spiracles closed most of the time and fluttering while open, thereby decoupling the challenge of preventing water loss from the challenge of obtaining adequate oxygen uptake.


Assuntos
Insetos/fisiologia , Modelos Biológicos , Oxigênio/fisiologia , Estruturas Animais/anatomia & histologia , Estruturas Animais/fisiologia , Animais , Água Corporal/metabolismo , Himenópteros/fisiologia , Insetos/anatomia & histologia , Lepidópteros/fisiologia , Conceitos Matemáticos , Respiração , Mecânica Respiratória/fisiologia , Traqueia/anatomia & histologia , Traqueia/fisiologia
3.
J Fish Biol ; 97(1): 293-297, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32333611

RESUMO

The recessus orbitalis is an accessory organ of flatfishes functioning in the protrusion of the eyes. This character, along with cranial asymmetry and a forward insertion of the dorsal fin, have been considered synapomorphies for the Pleuronectiformes. New dissections and examination of images taken in the wild show that the recessus orbitalis is present in all representatives of Pleuronectoidei examined but is absent in the single species of Psettoidei dissected. Psettoidei, the most primitive pleuronectiform lineage, contains three recognized species; thus, the absence of the recessus orbitalis in this whole lineage is unclear without further dissections. Ancestral character estimation at the family level for the recessus orbitalis indicates that the recessus orbitalis was likely absent in the common ancestor of Pleuronectiformes but was most likely present in the common ancestor of the Pleuronectoidei. Given that so few species of flatfishes have been assessed for the recessus orbitalis to date, additional characterization of the distribution of the recessus orbitalis across flatfishes will further inform what states this character may have and if it is a synapomorphy of Pleuronectiformes or simply a derived character state of Pleuronectoidei.


Assuntos
Estruturas Animais/anatomia & histologia , Linguados/anatomia & histologia , Crânio/anatomia & histologia , Animais , Filogenia
4.
J Morphol ; 281(6): 591-607, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32271501

RESUMO

The presence of claspers is one of the main characteristics of the cartilaginous fishes, but its variations across taxa have received limited use in shark systematics and have generally been neglected in descriptions of species. Clasper descriptions are available only for a few catshark species and most of these are focused only in external morphology. Besides that, divergences regarding the identification of some structures persist in the literature emphasizing the need of more encompassing morphological comparative analyses on claspers of scyliorhinids. In this study, claspers structures of almost all catshark genera were examined, described, and illustrated (except Akheilos and Pentanchus) and comments on their phylogenetic significance are provided. Some characters such as degree of development of rhipidions and terminal dermal cover, occurrence, position and size of accessory marginal and terminal cartilages proved to be useful for taxonomic purposes and their significance along carcharhiniforms systematics needs to be further investigated. RESEARCH HIGHLIGHTS: Clasper morphology of catsharks is described and compared and its systematic significance is discussed here. External morphology and skeleton components of claspers vary widely among scyliorhinids and may be useful in phylogenetic analyses.


Assuntos
Anatomia Comparada , Estruturas Animais/anatomia & histologia , Filogenia , Tubarões/anatomia & histologia , Animais , Osso e Ossos/anatomia & histologia
5.
Nat Commun ; 11(1): 862, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-32054841

RESUMO

Complex hierarchical structure governs emergent properties in biopolymeric materials; yet, the material processing involved remains poorly understood. Here, we investigated the multi-scale structure and composition of the mussel byssus cuticle before, during and after formation to gain insight into the processing of this hard, yet extensible metal cross-linked protein composite. Our findings reveal that the granular substructure crucial to the cuticle's function as a wear-resistant coating of an extensible polymer fiber is pre-organized in condensed liquid phase secretory vesicles. These are phase-separated into DOPA-rich proto-granules enveloped in a sulfur-rich proto-matrix which fuses during secretion, forming the sub-structure of the cuticle. Metal ions are added subsequently in a site-specific way, with iron contained in the sulfur-rich matrix and vanadium coordinated by DOPA-catechol in the granule. We posit that this hierarchical structure self-organizes via phase separation of specific amphiphilic proteins within secretory vesicles, resulting in a meso-scale structuring that governs cuticle function.


Assuntos
Materiais Revestidos Biocompatíveis/química , Metaloproteínas/química , Mytilus edulis/química , Estruturas Animais/anatomia & histologia , Estruturas Animais/química , Estruturas Animais/ultraestrutura , Animais , Di-Hidroxifenilalanina/química , Imageamento Tridimensional , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Mytilus edulis/anatomia & histologia , Mytilus edulis/ultraestrutura , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Vesículas Secretórias/química , Vesículas Secretórias/ultraestrutura
6.
J Morphol ; 281(3): 316-325, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31905257

RESUMO

Orbital glands are found in many tetrapod vertebrates, and are usually separate structures, consisting of individual glands lying in the eyelids and both canthi of the orbit. In cetaceans, however, the orbital glandular units are less distinct and have been described by numerous authors as a single, periorbital mass. There are few histochemical and immunhistochemical studies to date of these structures. In this study, we examined the orbital glandular region of both the bowhead whale (Balaena mysticetus: Mysticeti) and the beluga whale (Delphinapterus leucas: Odontoceti) using histological, histochemical, and immunohistochemical techniques. Histologically, in the bowhead, three glandular areas were noted (circumorbital, including Harderian and lacrimal poles), palpebral (midway in the lower eyelid), and rim (near the edge of the eyelid). In the beluga, there was only a large, continuous mass within the eyelid itself. Histochemical investigation suggests neither sexual dimorphism nor age-related differences, but both whales had two cell types freely intermingling with each other in all glandular masses. Large cells (cell type 1) were distended by four histochemically distinct intracellular secretory granules. Smaller cells (cell type 2) were not distended (fewer granules) and had two to three histochemically distinct intracellular secretory granules. The beluga orbital glands had additional lipid granules in cell type 1. Counterintuitively, both lipocalin and transferrin were localized to cell type 2 only. This intermingling of cell types is unusual for vertebrates in whom individual orbital glands usually have one cell type with one to two different secretory granules present. The heterogeneity of the orbital fluid produced by cetacean orbital glands implies a complex function, or series of functions, for these orbital glands and their role in producing the tear fluid.


Assuntos
Beluga/anatomia & histologia , Beluga/fisiologia , Baleia Franca/anatomia & histologia , Baleia Franca/fisiologia , Estruturas Animais/anatomia & histologia , Animais , Feminino , Masculino
7.
J Morphol ; 281(2): 273-293, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31886901

RESUMO

The Weberian apparatus, a diagnostic feature of otophysan fishes, is a novel hearing adaptation integrating several developmental and morphological systems (ear-vertebral column-swim bladder). Otophysan fishes are one of the largest and most successful freshwater clades, with over 10,000 species across most continents. The largest otophysan order, Cypriniformes, dominates the freshwaters of Asia, Europe, North America, and Africa. Spanning such a wide variety of environments, the Weberian apparatus undergoes morphological modifications to maintain functionality. Within Cypriniformes, we propose three distinct morphological classes of the Weberian apparatus based on the level of skeletal expansion around the swim bladder: simple (typical of most Cyprinidae), anterior plate (found in families such as Gyrinocheilidae, Catostomidae, and Botiidae), and encapsulated (either single-capsule as found, e.g., in Gobionidae and Cobitidae, or double-capsule as found, e.g., in Nemacheilidae and Balitoridae). Little ontological or comparative data exists regarding the construction or integration of these different morphologies, and less is known about the tissue level integration and variation within these morphologies. We used paraffin histology to document the hard and soft tissue anatomy of the Weberian apparatus in six species representing all morphological classes. We found sites of similarity across the morphologies including size and structure of the saccule, aspects of ossicle ossification, and swim bladder tunica composition, indicating potential sites of developmental and functional constraint. In contrast, we found differences across both auditory and nonauditory features in otic chamber size, ossification within ossicles and other vertebral elements, and composition of ligaments, indicating likely sites of adaptability. Some of these changes are likely evolutionary (taxonomic), but may be influenced by the environmental niche occupied by the clade. These results show a clear need for increased ontological and comparative study of the complete cypriniform Weberian apparatus, particularly histologically, as well as increased auditory studies across morphological types.


Assuntos
Estruturas Animais/anatomia & histologia , Estruturas Animais/citologia , Cipriniformes/anatomia & histologia , Sacos Aéreos/anatomia & histologia , Animais , Cipriniformes/classificação , Orelha/anatomia & histologia , Ligamentos/anatomia & histologia , Osteogênese
8.
J Morphol ; 281(1): 33-46, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31750976

RESUMO

Tentacles are remarkable anatomical structures in invertebrates for their diversity of form and function. In bivalves, tentacular organs are commonly associated with protective, secretory, and sensory roles. However, anatomical details are available for only a few species, rendering the diversity and evolution of bivalve tentacles still obscure. In Pteriomorphia, a clade including oysters, scallops, pearl oysters, and relatives, tentacles are abundant and diverse. We investigated tentacle anatomy in the group to understand variation, infer functions, and investigate patterns in tentacle diversity. Six species from four pteriomorphian families (Ostreidae, Pinnidae, Pteriidae, and Spondylidae) were collected and thoroughly investigated with integrative microscopy techniques, including histology, scanning electron microscopy, and confocal microscopy. Tentacles can be classified as middle fold tentacles (MFT) and inner fold tentacles (IFT) according to their position with respect to the folds of the mantle margin. While MFT morphology indicates intense secretion of mucosubstances, no evidence for secretory activity was found for IFT. However, both tentacle types have appropriate ciliary distribution and length to promote mucus transportation for cleaning and lubrication. Protective and sensory functions are discussed based on different lines of evidence, including secretion, cilia distribution, musculature, and innervation. Our results support the homology of MFT and IFT only for Pterioidea and Ostreoidea, considering their morphology, the presence of ciliated receptors at the tips, and branched innervation pattern. This is in accordance with recent phylogenetic hypotheses that support the close relationship between these superfamilies. In contrast, major structural differences indicate that MFT and IFT are probably not homologous across all pteriomorphians. By applying integrative microscopy, we were able to reveal anatomical elements that are essential for the understanding of homology and function when dealing with such superficially similar structures.


Assuntos
Estruturas Animais/anatomia & histologia , Bivalves/anatomia & histologia , Bivalves/fisiologia , Estruturas Animais/ultraestrutura , Animais , Bivalves/ultraestrutura , Filogenia
9.
J Morphol ; 281(9): 1059-1071, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-33448468

RESUMO

The most common European gastropod species, Arion vulgaris, is one of the most troublesome pests for private garden owners and commercial agriculturists. The sticky and hard to remove secretion produced by these animals allows them to overcome most artificial and natural barriers. However, this highly adherent biopolymer has recently shown great potential for novel wound-healing applications in medicine. Nevertheless, our knowledge of the underlying gland system is still limited and few studies on the ventral gland system are available. We studied the lateral and ventral pedal glands in Arion vulgaris to determine their secretory content histochemically and through lectin assays. Using these histological and histochemical methods we differentiate five gland types with different mucus composition in the lateral pedal region of the foot of Arion vulgaris. These contain sulphated and carboxylated mucosubstances (positive Alcian blue staining) but lack hexose-containing mucosubstances (negative PAS staining). In the ventral pedal region, four gland types can be differentiated producing sulphated and carboxylated mucosubstances. Within the ventral mucus, a high affinity for the lectins PNA and WGA is observed. While the lateral glands are histochemically negative for PAS, a positive staining with the lectin JAC is observed. Arion vulgaris shows clear morphological differences from other arionid species. This raises the question whether the variation in the chemistry of the secretory material and mucus composition is the result of different functions and/or is related to the animals' different environmental conditions. A comparison of some glands of Arion vulgaris with those of the helicid species Helix pomatia and Cepaea hortensis indicates morphological similarities.


Assuntos
Estruturas Animais/anatomia & histologia , Gastrópodes/anatomia & histologia , Estruturas Animais/ultraestrutura , Animais , Epitélio/anatomia & histologia , Epitélio/ultraestrutura , Gastrópodes/ultraestrutura , Muco/metabolismo , Espectrometria por Raios X
10.
Zootaxa ; 4897(1): zootaxa.4897.1.1, 2020 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-33756842

RESUMO

Even after more than 250 years of taxonomic research on bees, there are still many gaps in the knowledge about their identity, classification and distribution patterns. Regarding the New World tribe Augochlorini, many efforts have been made in the last years to describe and organize its diversity. Within the tribe, Augochlora Smith has the widest distribution range, as these bees occur from Argentina to Southern Canada, including Caribbean islands. The genus comprises 124 described species in two extant subgenera, and, to date, two partial revisions are available, accounting for central Argentina and Uruguay and for northeastern Brazil. In the present study we review the Augochlora species occurring in Argentina, Paraguay, Uruguay and the southern Brazilian states of Paraná, Rio Grande do Sul, and Santa Catarina. Specimens from other Brazilian states and South American countries were also examined to help with species circumscription. We found 27 species in the studied area, including nine new species (Augochlora atlantica sp. nov., A. australis sp. nov., A. genalis sp. nov., A. helena sp. nov., A. hestia sp. nov., A. hirsuta sp. nov., A. laevicarinata sp. nov., A. mendax sp. nov., and A. scabrata sp. nov.) and the remaining redescribed when necessary. A key for the species occurring in the studied area is provided. Five new synonymies are proposed and the lectotypes of Augochlora francisca and Halictus esox are presently designated. The geographic distribution of most studied species is associated with the Atlantic biome in many ways.


Assuntos
Abelhas/classificação , Himenópteros , Distribuição Animal , Estruturas Animais/anatomia & histologia , Estruturas Animais/crescimento & desenvolvimento , Animais , Argentina , Abelhas/anatomia & histologia , Abelhas/crescimento & desenvolvimento , Filogenia
11.
Parasit Vectors ; 12(1): 579, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31829242

RESUMO

BACKGROUND: Species belonging to the genus Lernaea are cosmopolitan parasites that can infect many different freshwater fish hosts. Due to a high degree of morphological intraspecific variability and high levels of interspecific similarities, their classification is extremely difficult and controversial. Although the suitability of the shape of cephalic horns has been questioned decades ago by some experimental infection studies, this character still plays the central role in the identification of Lernaea spp. METHODS: We used the nominal species Lernaea cyprinacea and Lernaea cruciata to test the hypothesis that the shape of the anchor can exhibit host-induced morphological variability, and that the two taxa may be synonymous. RESULTS: We examined 517 wild or farmed specimens of five host fish species (four cyprinids and a mosquitofish), and found that all 16 parasite specimens collected from mosquitofish could be morphologically identified as L. cruciata, whereas the remaining 25 parasite specimens were all identified as L. cyprinacea. We experimentally infected goldfish and mosquitofish specimens with offspring (copepodids) of a single L. cyprinacea specimen: the adult parasites from goldfish were morphologically identified as L. cyprinacea, and those from mosquitofish as L. cruciata. We then used molecular data to corroborate that all these specimens are conspecific. CONCLUSIONS: Our results suggest that L. cyprinacea and L. cruciata may be synonyms, misidentified as different species as a result of host-induced morphological variation. Given the current shortage of molecular data for the genus Lernaea, in order to resolve the taxonomy of this genus (determine the exact number of species), future studies should aim to sequence as much molecular data as possible, and conduct further experimental infections.


Assuntos
Estruturas Animais/anatomia & histologia , Classificação/métodos , Copépodes/anatomia & histologia , Copépodes/classificação , Animais , Copépodes/crescimento & desenvolvimento , Peixes/parasitologia
12.
J Morphol ; 280(12): 1839-1849, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31680307

RESUMO

The Atlantic-Mediterranean polychaete Sabellaria alveolata lives in agglutinated tubes adjoined to each other to form discrete reef-like bioconstructions in shallow-water settings characterised by high hydrodynamic energy where sediment particles are constantly resuspended. Tubes are built with sand grains glued by proteinaceous secretions. Analyses of a reef fragment collected near Sampieri (SE Sicily, Sicily Strait) allowed the first detailed description of the tube architecture and biocement of this worms from the Mediterranean. The tube consists of an inner thin organic membrane and three agglutinated layers including: (a) a thin inner layer of flat grains arranged side by side; (b) a thick mid layer with a frame of relatively large sub-rounded grains with cavities partly filled by small grains; and (c) a thin outer layer of large, flat to curved, usually biogenic clasts diverging towards the opening. This particular architecture is distinctive of the family. Morphological and epifluorescence observations revealed that biocement consists of drops at the contact between sub-spherical grains and strips along edges of flat grains. Biocement is a solid foam-like material characterised by high abundance of carbon; the presence of phosphorous and nitrogen confirms its proteinaceous composition. Due to the electrostatic interaction with the proteins, calcium and magnesium are most likely complexed to the cement rather than being trapped in the cells. These elements contribute to the solidification of the glue and stabilisation of the tube structure. However, the organic nature of cement and the high energy of their habitat, make sabellariid reefs dynamic and ephemeral, and the preservation as fossils unlikely, with a confident record only extending back to the Miocene.


Assuntos
Poliquetos/anatomia & histologia , Estruturas Animais/anatomia & histologia , Estruturas Animais/química , Estruturas Animais/metabolismo , Animais , Fenômenos Biomecânicos , Cálcio/química , Cálcio/metabolismo , Mar Mediterrâneo , Poliquetos/química , Poliquetos/metabolismo , Proteínas/química , Proteínas/metabolismo
13.
Nature ; 573(7775): 586-589, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31511691

RESUMO

The chelicerates are a ubiquitous and speciose group of animals that has a considerable ecological effect on modern terrestrial ecosystems-notably as predators of insects and also, for instance, as decomposers1. The fossil record shows that chelicerates diversified early in the marine ecosystems of the Palaeozoic era, by at least the Ordovician period2. However, the timing of chelicerate origins and the type of body plan that characterized the earliest members of this group have remained controversial. Although megacheirans3-5 have previously been interpreted as chelicerate-like, and habeliidans6 (including Sanctacaris7,8) have been suggested to belong to their immediate stem lineage, evidence for the specialized feeding appendages (chelicerae) that are diagnostic of the chelicerates has been lacking. Here we use exceptionally well-preserved and abundant fossil material from the middle Cambrian Burgess Shale (Marble Canyon, British Columbia, Canada) to show that Mollisonia plenovenatrix sp. nov. possessed robust but short chelicerae that were placed very anteriorly, between the eyes. This suggests that chelicerae evolved a specialized feeding function early on, possibly as a modification of short antennules. The head also encompasses a pair of large compound eyes, followed by three pairs of long, uniramous walking legs and three pairs of stout, gnathobasic masticatory appendages; this configuration links habeliidans with euchelicerates ('true' chelicerates, excluding the sea spiders). The trunk ends in a four-segmented pygidium and bears eleven pairs of identical limbs, each of which is composed of three broad lamellate exopod flaps, and endopods are either reduced or absent. These overlapping exopod flaps resemble euchelicerate book gills, although they lack the diagnostic operculum9. In addition, the eyes of M. plenovenatrix were innervated by three optic neuropils, which strengthens the view that a complex malacostracan-like visual system10,11 might have been plesiomorphic for all crown euarthropods. These fossils thus show that chelicerates arose alongside mandibulates12 as benthic micropredators, at the heart of the Cambrian explosion.


Assuntos
Artrópodes/anatomia & histologia , Artrópodes/classificação , Fósseis/anatomia & histologia , Estruturas Animais/anatomia & histologia , Animais , Colúmbia Britânica , Brânquias/anatomia & histologia , Especificidade da Espécie
14.
PLoS One ; 14(8): e0220287, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31412067

RESUMO

A new species of Eigenmannia is described from the rio Mutum, tributary of upper rio Juruena, rio Tapajós basin, Comodoro, Mato Grosso, Brazil. The new species is distinguished from all congeners by coloration pattern, position of the mouth, number of scales rows above lateral line, number of premaxillary and dentary teeth, number of precaudal vertebrae, orbital diameter, mouth width, relative depth of posterodorsal expansion on infraorbitals 1+2 and relative size of coronomeckelian bone. Comments on potentially useful characters in phylogenetic studies derived from musculature, discussion on Eigenmannia species-group and the first dichotomous key for Eigenmannia are provided.


Assuntos
Estruturas Animais/anatomia & histologia , Osso e Ossos/anatomia & histologia , Face/anatomia & histologia , Gimnotiformes/classificação , Boca/anatomia & histologia , Animais , Brasil , Gimnotiformes/anatomia & histologia , Gimnotiformes/crescimento & desenvolvimento , Filogenia , Especificidade da Espécie
15.
Naturwissenschaften ; 106(9-10): 50, 2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31456022

RESUMO

The cavities of bamboos (Poaceae) are used by various animals. Most of the animals access these cavities either by existing cracks or by excavating bamboos with soft walls or small, thin-walled bamboos. Only a few animals excavate into the cavities of large and thick- and hard-walled internodes of mature bamboos. We studied two lizard beetle species (Coleoptera: Erotylidae: Languriinae), Doubledaya ruficollis and Oxylanguria acutipennis, that excavate into large internode cavities of recently dead mature bamboos and have morphological modifications. We observed that females of D. ruficollis used their mandibles to bore oviposition holes on Schizostachyum sp. (mean wall thickness = 3.00 mm) and O. acutipennis did so on Dendrocalamus sp. (3.37 mm) bamboos. Previous studies suggested that the markedly asymmetrical mandibles and needle-like ovipositors of females in the genus Doubledaya are adaptive traits for excavating hard-walled bamboos for oviposition. Therefore, we measured their mandibular lengths and ovipositor lengths. D. ruficollis females had greater asymmetry in the mandibles and shorter and less-sclerotized ovipositors than females of congeners using small bamboos. In contrast, O. acutipennis females had slightly asymmetrical mandibles and elongated, well-sclerotized ovipositors. Oviposition holes of D. ruficollis were cone-shaped (evenly tapering), whereas those of O. acutipennis were funnel-shaped (tube-like at the internal apex). This suggests that D. ruficollis females excavate oviposition holes using the mandibles only, and O. acutipennis females use both the mandibles and ovipositors. These differences suggest different oviposition-associated morphological specialization for using large bamboos: the extremely asymmetrical mandibles in D. ruficollis and elongated, needle-like ovipositors in O. acutipennis.


Assuntos
Besouros/anatomia & histologia , Besouros/fisiologia , Estruturas Animais/anatomia & histologia , Animais , Comportamento Animal/fisiologia , Feminino , Tamanho do Órgão/fisiologia , Poaceae/anatomia & histologia , Poaceae/parasitologia
16.
Zoology (Jena) ; 136: 125694, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31434022

RESUMO

Sexually dimorphic traits are the outcome of a network of selective pressures acting upon each sex. While male secondary sexual traits are frequently restricted to intrasexual competition, female ornaments or weapons are mostly associated to social interactions for the access to limited resources. Here we investigate a sexually dimorphic trait expressed within the female's sternum of the spider species Holocnemus pluchei (Pholcidae), and its adaptive maintenance under the three leading hypotheses: sexual receptivity signaling, mate choice and sexual conflict hypothesis. We provide fine-scaled behavioral descriptions of the copulatory behavior of Holocnemus pluchei, corroborating that mating interactions are mediated by the female's sternum projection. The single moment of contact between the female projection and male body occurs during sperm transfer, always followed by a reduction on the intensity of the male genital movement. Additionally, biometrical properties of the female sternum projection corroborate our functional interpretation for the trait as restricting the intensity of males' copulatory movements. We claim that female sternum projection is a sexually selected trait mediating sexual conflict, with several adaptive consequences upon the sexes.


Assuntos
Aranhas/anatomia & histologia , Aranhas/fisiologia , Adaptação Fisiológica , Estruturas Animais/anatomia & histologia , Animais , Feminino , Reprodução , Caracteres Sexuais , Comportamento Sexual Animal
17.
Biol Bull ; 237(1): 1-15, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31441702

RESUMO

The pen, or gladius, of the squid is an internalized shell. It serves as a site of attachment for important muscle groups and as a protective barrier for the visceral organs. The pen's durability and flexibility are derived from its unique composition of chitin and protein. We report the characterization of the structure, development, and composition of pens from Doryteuthis pealeii. The nanofibrils of the polysaccharide ß-chitin are arranged in an aligned configuration in only specific regions of the pen. Chitin is secreted early in development, enabling us to characterize the changes in pen morphology prior to hatching. The chitin and proteins are assembled in the shell sac surrounded by fluid that has a significantly different ionic composition from squid plasma. Two groups of proteins are associated with the pen: those on its surface and those embedded within the pen. Only 20 proteins are identified as embedded within the pen. Embedded proteins are classified into six groups, including chitin associated, protease, protease inhibitors, intracellular, extracellular matrix, and those that are unknown. The pen proteins share many conserved domains with proteins from other chitinous structures. We conclude that the pen is one of the least complex, load-bearing, chitin-rich structures currently known and is amenable to further studies to elucidate natural construction mechanisms using chitin and protein.


Assuntos
Quitina/metabolismo , Decapodiformes/anatomia & histologia , Proteínas/metabolismo , Estruturas Animais/anatomia & histologia , Estruturas Animais/química , Estruturas Animais/crescimento & desenvolvimento , Animais , Decapodiformes/química , Decapodiformes/crescimento & desenvolvimento
18.
Biol Bull ; 237(1): 36-47, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31441703

RESUMO

The pteropod mollusc Clione limacina is a feeding specialist, preying on shelled pteropods of the genus Limacina. Specialized prey-capture structures, called buccal cones, are hydraulically everted from within the mouth to capture the prey. Once captured, the prey is manipulated so the shell opening is over the mouth of Clione. Analyses of high-speed cine sequences of prey capture suggest that the mouth is actively opened rather than passively forced open by buccal cone eversion. The inflated buccal cones are initially straight and form a wide angle (maximum, 113°) prior to prey contact. Individual buccal cones bend orally following prey contact, suggesting a sensory trigger. To determine the muscular basis of buccal cone movements, the musculature of the buccal cones is described. Three distinct muscle fiber types include circular smooth muscle, longitudinal smooth muscle, and longitudinal striated muscle. The organization, distribution, and innervation of the muscle types suggest that circular muscle is used during buccal cone eversion, longitudinal smooth muscle is used for buccal cone withdrawal, and longitudinal striated muscle is used for oral bending of the buccal cones after prey contact and for manipulation of the prey.


Assuntos
Clione/anatomia & histologia , Comportamento Alimentar/fisiologia , Estruturas Animais/anatomia & histologia , Animais , Clione/fisiologia , Músculo Liso/anatomia & histologia , Músculo Liso/inervação , Músculo Estriado/anatomia & histologia , Músculo Estriado/inervação
19.
J Morphol ; 280(7): 999-1025, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31066961

RESUMO

Osteostracans are the closest jawless relatives of jawed vertebrates, informing the gradual assembly of the vertebrate mineralised skeleton. Conflicting interpretations of their dermal skeletal histology arise from failure to account for topological variation, obscuring their significance in elucidating vertebrate skeletal evolution. To resolve this, we characterize the cranial and trunk dermal skeleton of a single individual of Tremataspis mammillata (Osteostraci, Thyestiida) at submicron resolution using synchrotron- and computed- tomography. Our results show that the architecture of the Tremataspis dermal skeleton is, for the most part, conserved over the skeleton and is broadly consistent with previous histological hypotheses based on 2D thin section study. We resolve debate over the homology of the basal layer, identifying it as osteogenic acellular isopedin rather than odontogenic elasmodine or metaplastic ossification of the stratum compactum of the dermis. We find topological variation between all dermal skeletal elements studied, and particularly between the cranial and postcranial dermal skeleton. This variation can be largely explained by reduction in differentiation due to geometric constraints imposed within smaller skeletal elements, such as scales. Our description of the dermal skeleton of Tremataspis mammillata provides a foundation for interpreting data from cursory topological samples of dermal skeletal diversity obtained in other osteostracans. This reveals general aspects of histological structure that must be ancestral for osteostracans and, likely, ancestral jawed vertebrates. Finally, we draw the distinction between hypotheses and descriptions in palaeohistology.


Assuntos
Derme/anatomia & histologia , Gnathostoma/anatomia & histologia , Arcada Osseodentária/anatomia & histologia , Estruturas Animais/anatomia & histologia , Animais , Cabeça/anatomia & histologia , Imageamento Tridimensional , Odontogênese , Osteogênese , Filogenia
20.
PLoS One ; 14(4): e0214889, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30995262

RESUMO

Atractaspidines are poorly studied, fossorial snakes that are found throughout Africa and western Asia, including the Middle East. We employed concatenated gene-tree analyses and divergence dating approaches to investigate evolutionary relationships and biogeographic patterns of atractaspidines with a multi-locus data set consisting of three mitochondrial (16S, cyt b, and ND4) and two nuclear genes (c-mos and RAG1). We sampled 91 individuals from both atractaspidine genera (Atractaspis and Homoroselaps). Additionally, we used ancestral-state reconstructions to investigate fang and diet evolution within Atractaspidinae and its sister lineage (Aparallactinae). Our results indicated that current classification of atractaspidines underestimates diversity within the group. Diversification occurred predominantly between the Miocene and Pliocene. Ancestral-state reconstructions suggest that snake dentition in these taxa might be highly plastic within relatively short periods of time to facilitate adaptations to dynamic foraging and life-history strategies.


Assuntos
Viperidae/classificação , Viperidae/genética , Estruturas Animais/anatomia & histologia , Estruturas Animais/fisiologia , Animais , Citocromos b/genética , Evolução Molecular , Genes Mitocondriais , Genes RAG-1 , Genes mos , NADH Desidrogenase/genética , Filogenia , Comportamento Predatório , RNA Ribossômico 16S/genética , Fatores de Tempo , Viperidae/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...