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Auswahl der wissenschaftlichen Literatur zum Thema „Arthropodes – Reproduction (biologie)“
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Zeitschriftenartikel zum Thema "Arthropodes – Reproduction (biologie)"
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Pascar, Jane, und Christopher H. Chandler. „A bioinformatics approach to identifyingWolbachiainfections in arthropods“. PeerJ 6 (03.09.2018): e5486. http://dx.doi.org/10.7717/peerj.5486.
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Wolbachiais the most widespread endosymbiont, infecting >20% of arthropod species, and capable of drastically manipulating the host’s reproductive mechanisms. Conventionally, diagnosis has relied on PCR amplification; however, PCR is not always a reliable diagnostic technique due to primer specificity, strain diversity, degree of infection and/or tissue sampled. Here, we look for evidence ofWolbachiainfection across a wide array of arthropod species using a bioinformatic approach to detect theWolbachiagenesftsZ, wsp,and thegroEoperon in next-generation sequencing samples available through the NCBI Sequence Read Archive. For samples showing signs of infection, we attempted to assemble entireWolbachiagenomes, and in order to better understand the relationships between hosts and symbionts, phylogenies were constructed using the assembled gene sequences. Out of the 34 species with positively identified infections, eight species of arthropod had not previously been recorded to harborWolbachiainfection. All putative infections cluster with known representative strains belonging to supergroup A or B, which are known to only infect arthropods. This study presents an efficient bioinformatic approach for post-sequencing diagnosis and analysis ofWolbachiainfection in arthropods.
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Johnson, Marc T. J., Mark Vellend und John R. Stinchcombe. „Evolution in plant populations as a driver of ecological changes in arthropod communities“. Philosophical Transactions of the Royal Society B: Biological Sciences 364, Nr. 1523 (12.06.2009): 1593–605. http://dx.doi.org/10.1098/rstb.2008.0334.
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Heritable variation in traits can have wide-ranging impacts on species interactions, but the effects that ongoing evolution has on the temporal ecological dynamics of communities are not well understood. Here, we identify three conditions that, if experimentally satisfied, support the hypothesis that evolution by natural selection can drive ecological changes in communities. These conditions are: (i) a focal population exhibits genetic variation in a trait(s), (ii) there is measurable directional selection on the trait(s), and (iii) the trait(s) under selection affects variation in a community variable(s). When these conditions are met, we expect evolution by natural selection to cause ecological changes in the community. We tested these conditions in a field experiment examining the interactions between a native plant ( Oenothera biennis ) and its associated arthropod community (more than 90 spp.). Oenothera biennis exhibited genetic variation in several plant traits and there was directional selection on plant biomass, life-history strategy (annual versus biennial reproduction) and herbivore resistance. Genetically based variation in biomass and life-history strategy consistently affected the abundance of common arthropod species, total arthropod abundance and arthropod species richness. Using two modelling approaches, we show that evolution by natural selection in large O. biennis populations is predicted to cause changes in the abundance of individual arthropod species, increases in the total abundance of arthropods and a decline in the number of arthropod species. In small O. biennis populations, genetic drift is predicted to swamp out the effects of selection, making the evolution of plant populations unpredictable. In short, evolution by natural selection can play an important role in affecting the dynamics of communities, but these effects depend on several ecological factors. The framework presented here is general and can be applied to other systems to examine the community-level effects of ongoing evolution.
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Sterkel, Marcos, und Pedro L. Oliveira. „Developmental roles of tyrosine metabolism enzymes in the blood-sucking insect Rhodnius prolixus“. Proceedings of the Royal Society B: Biological Sciences 284, Nr. 1854 (03.05.2017): 20162607. http://dx.doi.org/10.1098/rspb.2016.2607.
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The phenylalanine/tyrosine degradation pathway is frequently described as a catabolic pathway that funnels aromatic amino acids into citric acid cycle intermediates. Previously, we demonstrated that the accumulation of tyrosine generated during the hydrolysis of blood meal proteins in Rhodnius prolixus is potentially toxic, a harmful outcome that is prevented by the action of the first two enzymes in the tyrosine degradation pathway. In this work, we further evaluated the relevance of all other enzymes involved in phenylalanine/tyrosine metabolism in the physiology of this insect. The knockdown of most of these enzymes produced a wide spectrum of distinct phenotypes associated with reproduction, development and nymph survival, demonstrating a highly pleiotropic role of tyrosine metabolism. The phenotypes obtained for two of these enzymes, homogentisate dioxygenase and fumarylacetoacetase, have never before been described in any arthropod. To our knowledge, this report is the first comprehensive gene-silencing analysis of an amino acid metabolism pathway in insects. Amino acid metabolism is exceptionally important in haematophagous arthropods due to their particular feeding behaviour.
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Wang, He, Renate Matzke-Karasz, David J. Horne, Xiangdong Zhao, Meizhen Cao, Haichun Zhang und Bo Wang. „Exceptional preservation of reproductive organs and giant sperm in Cretaceous ostracods“. Proceedings of the Royal Society B: Biological Sciences 287, Nr. 1935 (16.09.2020): 20201661. http://dx.doi.org/10.1098/rspb.2020.1661.
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The bivalved crustacean ostracods have the richest fossil record of any arthropod group and display complex reproductive strategies contributing to their evolutionary success. Sexual reproduction involving giant sperm, shared by three superfamilies of living ostracod crustaceans, is among the most fascinating behaviours. However, the origin and evolution of this reproductive mechanism has remained largely unexplored because fossil preservation of such features is extremely rare. Here, we report exceptionally preserved ostracods with soft parts (appendages and reproductive organs) in a single piece of mid-Cretaceous Kachin amber (approximately 100 Myr old). The ostracod assemblage is composed of 39 individuals. Thirty-one individuals belong to a new species and genus, Myanmarcypris hui gen. et sp. nov., exhibiting an ontogenetic sequence from juveniles to adults (male and female). Seven individuals are assigned to Thalassocypria sp. (Cypridoidea, Candonidae, Paracypridinae) and one to Sanyuania sp. (Cytheroidea, Loxoconchidae). Our micro-CT reconstruction provides direct evidence of the male clasper, sperm pumps (Zenker organs), hemipenes, eggs and female seminal receptacles with giant sperm. Our results reveal that the reproduction behavioural repertoire, which is associated with considerable morphological adaptations, has remained unchanged over at least 100 million years—a paramount example of evolutionary stasis. These results also double the age of the oldest unequivocal fossil animal sperm. This discovery highlights the capacity of amber to document invertebrate soft parts that are rarely recorded by other depositional environments.
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Zhang, Qiang, Wei Dou, Clauvis Nji Tizi Taning, Shan-Shan Yu, Guo-Rui Yuan, Feng Shang, Guy Smagghe und Jin-Jun Wang. „miR-309a is a regulator of ovarian development in the oriental fruit fly Bactrocera dorsalis“. PLOS Genetics 18, Nr. 9 (16.09.2022): e1010411. http://dx.doi.org/10.1371/journal.pgen.1010411.
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Fecundity is arguably one of the most important life history traits, as it is closely tied to fitness. Most arthropods are recognized for their extreme reproductive capacity. For example, a single female of the oriental fruit fly Bactrocera dorsalis, a highly invasive species that is one of the most destructive agricultural pests worldwide, can lay more than 3000 eggs during its life span. The ovary is crucial for insect reproduction and its development requires further investigation at the molecular level. We report here that miR-309a is a regulator of ovarian development in B. dorsalis. Our bioinformatics and molecular studies have revealed that miR-309a binds the transcription factor pannier (GATA-binding factor A/pnr), and this activates yolk vitellogenin 2 (Vg 2) and vitellogenin receptor (VgR) advancing ovarian development. We further show that miR-309a is under the control of juvenile hormone (JH) and independent from 20-hydroxyecdysone. Thus, we identified a JH-controlled miR-309a/pnr axis that regulates Vg2 and VgR to control the ovarian development. This study has further enhanced our understanding of molecular mechanisms governing ovarian development and insect reproduction. It provides a background for identifying targets for controlling important Dipteran pests.
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Liana, Marcin, und Wojciech Witaliński. „Microorganisms in the oribatid mite Hermannia gibba (C. L. Koch, 1839) (Acari: Oribatida: Hermanniidae)“. Biological Letters 47, Nr. 1 (01.01.2010): 37–43. http://dx.doi.org/10.2478/v10120-009-0018-9.
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Microorganisms in the oribatid mite Hermannia gibba (C. L. Koch, 1839) (Acari: Oribatida: Hermanniidae) Symbiotic microorganisms associated with arthropods are known to play a significant role in the life of their hosts. Most commonly, the symbionts improve their host's food digestion and modify their meiosis/reproduction. The usual mode of parent-to-offspring transmission of the symbionts is transovarial transmission (vertical) via oocytes. Using transmission electron microscopy, we found extracellular yeast-like and bacteroid microorganisms in food boli, as well as intracellular symbiotic bacteria within cells of the digestive tract and in reproductive cells in both sexes of the oribatid mite Hermannia gibba. In the digestive tract, the scarce bacteria were lying individually within midgut cells. The bacteria observed in developing oocytes were numerous and formed large aggregates close to the nuclear envelope and clusters of mitochondria. In spermatocytes we found a few single bacteria located at the cell periphery. The bacteria in the digestive cells may assist in digestion of plant food, whereas the meiotic drive function of the gonad-invading microbes is uncertain. The studied mite species is biparental and its sex ratio is not biased.
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Döll, Katharina, Subhankar Chatterjee, Stefan Scheu, Petr Karlovsky und Marko Rohlfs. „Fungal metabolic plasticity and sexual development mediate induced resistance to arthropod fungivory“. Proceedings of the Royal Society B: Biological Sciences 280, Nr. 1771 (22.11.2013): 20131219. http://dx.doi.org/10.1098/rspb.2013.1219.
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Prey organisms do not tolerate predator attack passively but react with a multitude of inducible defensive strategies. Although inducible defence strategies are well known in plants attacked by herbivorous insects, induced resistance of fungi against fungivorous animals is largely unknown. Resistance to fungivory is thought to be mediated by chemical properties of fungal tissue, i.e. by production of toxic secondary metabolites. However, whether fungi change their secondary metabolite composition to increase resistance against arthropod fungivory is unknown. We demonstrate that grazing by a soil arthropod, Folsomia candida , on the filamentous fungus Aspergillus nidulans induces a phenotype that repels future fungivores and retards fungivore growth. Arthropod-exposed colonies produced significantly higher amounts of toxic secondary metabolites and invested more in sexual reproduction relative to unchallenged fungi. Compared with vegetative tissue and asexual conidiospores, sexual fruiting bodies turned out to be highly resistant against fungivory in facultative sexual A. nidulans . This indicates that fungivore grazing triggers co-regulated allocation of resources to sexual reproduction and chemical defence in A. nidulans . Plastic investment in facultative sex and chemical defence may have evolved as a fungal strategy to escape from predation.
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Duplouy, Anne, und Emily A. Hornett. „Uncovering the hidden players in Lepidoptera biology: the heritable microbial endosymbionts“. PeerJ 6 (08.05.2018): e4629. http://dx.doi.org/10.7717/peerj.4629.
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The Lepidoptera is one of the most widespread and recognisable insect orders. Due to their remarkable diversity, economic and ecological importance, moths and butterflies have been studied extensively over the last 200 years. More recently, the relationship between Lepidoptera and their heritable microbial endosymbionts has received increasing attention. Heritable endosymbionts reside within the host’s body and are often, but not exclusively, inherited through the female line. Advancements in molecular genetics have revealed that host-associated microbes are both extremely prevalent among arthropods and highly diverse. Furthermore, heritable endosymbionts have been repeatedly demonstrated to play an integral role in many aspects of host biology, particularly host reproduction. Here, we review the major findings of research of heritable microbial endosymbionts of butterflies and moths. We promote the Lepidoptera as important models in the study of reproductive manipulations employed by heritable endosymbionts, with the mechanisms underlying male-killing and feminisation currently being elucidated in moths and butterflies. We also reveal that the vast majority of research undertaken of Lepidopteran endosymbionts concernsWolbachia. While this highly prevalent bacterium is undoubtedly important, studies should move towards investigating the presence of other, and interacting endosymbionts, and we discuss the merits of examining the microbiome of Lepidoptera to this end. We finally consider the importance of understanding the influence of endosymbionts under global environmental change and when planning conservation management of endangered Lepidoptera species.
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Perlman, Steve J., Martha S. Hunter und Einat Zchori-Fein. „The emerging diversity of Rickettsia“. Proceedings of the Royal Society B: Biological Sciences 273, Nr. 1598 (21.04.2006): 2097–106. http://dx.doi.org/10.1098/rspb.2006.3541.
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The best-known members of the bacterial genus Rickettsia are associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. These species include the agents of acute human disease such as typhus and Rocky Mountain spotted fever. However, many other Rickettsia have been uncovered in recent surveys of bacteria associated with arthropods and other invertebrates; the hosts of these bacteria have no relationship with vertebrates. It is therefore perhaps more appropriate to consider Rickettsia as symbionts that are transmitted vertically in invertebrates, and secondarily as pathogens of vertebrates. In this review, we highlight the emerging diversity of Rickettsia species that are not associated with vertebrate pathogenicity. Phylogenetic analysis suggests multiple transitions between symbionts that are transmitted strictly vertically and those that exhibit mixed (horizontal and vertical) transmission. Rickettsia may thus be an excellent model system in which to study the evolution of transmission pathways. We also focus on the emergence of Rickettsia as a diverse reproductive manipulator of arthropods, similar to the closely related Wolbachia , including strains associated with male-killing, parthenogenesis, and effects on fertility. We emphasize some outstanding questions and potential research directions, and suggest ways in which the study of non-pathogenic Rickettsia can advance our understanding of their disease-causing relatives.
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Masui, Shinji, Tetsuhiko Sasaki und Hajime Ishikawa. „Genes for the Type IV Secretion System in an Intracellular Symbiont, Wolbachia, a Causative Agent of Various Sexual Alterations in Arthropods“. Journal of Bacteriology 182, Nr. 22 (15.11.2000): 6529–31. http://dx.doi.org/10.1128/jb.182.22.6529-6531.2000.
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ABSTRACT Wolbachia species are intracellular bacteria known to cause reproductive abnormalities in their hosts. In this study, we identified Wolbachia genes encoding homologs to the type IV secretion system by which many pathogenic bacteria secrete macromolecules. The genes identified encoded most of the essential components of the secretion system and were cotranscribed as an operon.
Dissertationen zum Thema "Arthropodes – Reproduction (biologie)"
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Gauthier, Maxime. „Implication de l’acide rétinoïque dans la reproduction et le développement et perturbations par des pesticides chez le gammare (Gammarus fossarum) et l’abeille domestique (Apis mellifera)“. Electronic Thesis or Diss., Lyon 1, 2023. http://www.theses.fr/2023LYO10072.
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La présence de pesticides dans les compartiments écosystémiques terrestres et aquatiques soulève d’importantes préoccupations pour les espèces fauniques non ciblées. Grâce au développement et à l’utilisation de biomarqueurs, une biosurveillance efficace peut déceler de façon précoce les dérèglements de ces organismes. Les rétinoïdes (RETs, vitamine A et dérivés) sont des composés essentiels pour les vertébrés, et sont utilisés comme biomarqueurs pour témoigner de la pression chimique des écosystèmes. Plusieurs études laissent présager d’une implication de l’acide rétinoïque (AR, forme active de la vitamine A) dans le développement et la reproduction des arthropodes. Afin de statuer sur le potentiel des RETs comme biomarqueurs, nous avons étudié deux arthropodes, le gammare Gammarus fossarum (crustacé) et l’abeille domestique Apis mellifera (insecte). Ainsi nous avons 1) identifié et mesuré les RETs de ces modèles, 2) étudié l’implication de l’AR dans la reproduction et le développement et 3) évalué les effets de pesticides sur les RETs et sur ces deux fonctions. Une nouvelle méthode analytique mise au point (CLUHP-MS/MS) a permis l’observation d’une diminution des RETs précurseurs rétinaldéhyde (RALD) et rétinol (ROL) ainsi qu’une augmentation des métabolites de l’AR au cours de la reproduction de G. fossarum et du développement de A. mellifera, respectivement, Les fluctuations à la hausse ou à la baisse en AR ainsi que les effets sur la croissance des abeilles et sur l’ovogénèse, l’embryogénèse et la mue des gammares à la suite des expositions à l’AR et au citral (CIT, inhibiteur de sa synthèse), laissent présager d’un rôle de l’AR dans ces fonctions. Une exposition au MET a modifié le ratio entre les isomères de l’AR chez G. fossarum ce qui pourrait expliquer les effets sur l’oogenèse et la mue. Les expositions au MET et au GLY ont entraîné des perturbations dans les RETs de l’abeille (larves, nymphes et adultes), mais seul le MET a perturbé le développement. Ces résultats montrent que le système des RETs de ces modèles est influencé par la présence de pesticides et ouvrent une piste de recherche pour le développement de biomarqueurs chez les arthropodesThe presence of pesticides in both terrestrial and aquatic ecosystem compartments is of significant concern for non-target wildlife species. The use of biomarkers allows an effective biomonitoring and points out early imbalances in these organisms. Retinoids (RETs, vitamin A and their derivatives) are essential compounds for vertebrates and are used as biomarkers to assess the chemical pressure in ecosystems. Several studies suggested the involvement of retinoic acid (RA, active form of vitamin A) in the development and reproduction of arthropods. In order to establish the potential of RETs in view of biomarkers development, we studied two arthropods, the gammarid Gammarus fossarum (crustacean) and the honey bee Apis mellifera (insect). The obectives orour study was to 1) identify and measure the RETs of these models, 2) study the involvement of AR in reproduction and development, and 3) evaluate the effects of pesticides on the RETs and on these two functions in G. fossarum and A. mellifera. A new analytical method (UHPLC-MS/MS) allowed the observation of a decrease in the RET precursors retinaldehyde (RALD) and retinol (ROL) during the reproduction of G. fossarum and the development of A. mellifera, respectively, as wel as an increase in RA metabolites. The upward and downward fluctuations in RA concentrations affected the growth of bees and the oogenesis, embryogenesis and molting of gammarids following exposure to AR and citral (CIT, a RA synthesis inhibitor) suggesting endogenous functions of RA in these arthropods. Exposure to MET altered the RA isomers ratio in G. fossarum which may be associated with the observed effects on oogenesis and molting. Exposures to MET and GLY induced disturbances in the bee’s RETs (larvae, pupae, and adults), but only MET interfered with its development. The results suggest an involvement of RA in the reproduction and molting of G. fossarum and in the development of A. mellifera. Here, we demonstrate that the RETs system of these models is influenced by the presence of pesticides. These results open a research avenue for RET-based biomarkers in arthropods
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Hull, Scott D. „The relationships among vegetative structure, arthropod populations, and grassland bird abundance and reproductive success on wildlife production areas in Ohio /“. The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486457871784286.
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Chentoufi, Ahmed. „Etude de la régulation photopériodique et thermopériodique des cycles de reproduction chez le crustacé isopode terrestre armadillidium vulgare latreille : analyse expérimentale de la mesure du temps photopériodique“. Poitiers, 1988. http://www.theses.fr/1988POIT2016.
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Soyez, Daniel. „L'Hormone inhibitrice de la vitellogenèse du homard, homarus americanus : isolement, caractérisation et specificité“. Paris 6, 1987. http://www.theses.fr/1987PA066630.
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Ciocchetta, Silvia. „The vector potential of the mosquito Aedes koreicus“. Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/119157/1/Silvia%20Ciocchetta%20Thesis.pdf.
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Despite the recent establishment and spread of Aedes koreicus mosquitoes in Europe, its natural history and its potential public health impact remain poorly described. This thesis provides the first detailed insights into the biology of Aedes koreicus and its capacity to transmit arboviral diseases. Field work in Italy evaluated a variety of surveillance techniques for this species and its propensity to bite humans. A laboratory colony established in Australia was used to characterise its reproductive biology and its ability to transmit chikungunya virus. The findings help us understand the invasion risks and the public health threat posed by Aedes koreicus
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Brey, Paul Timothy. „Pathologie comparee de l'infection fongique d'insectes aeriens (pucerons) et aquatiques (larves de moustiques) par deux phycomycetes“. Paris 6, 1987. http://www.theses.fr/1987PA066283.
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Morphologie et ultrastructure de la spore infectante (conidie ou zoospore) des 2 entomopathogenes. Production des tubes germinatifs de c. Obscurus stimulee par lipides epicuticulaires et miellat du puceron. Suivi des differentes etapes d'infection de l'hote par les pathogenes (germination spores, penetration tegument, developpement dans hemococle, reactions de defense); mise en evidence des differences, en particulier au niveau de la realisation et de l'encapsulation. Dans le couple l. Giganteum - a. Aegypti,des cellules sanguines vivantes sont impliques dans l'encapsulation tumorale. Modalites de la reproduction sexuee de l. Giganteum (differenciation morphologique des cellules reproductrices, "copulation" entre gametes)
Bücher zum Thema "Arthropodes – Reproduction (biologie)"
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Shattuck, S. Australian Ants. CSIRO Publishing, 1999. http://dx.doi.org/10.1071/9780643100671.
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Ants are one of the most influential elements in Australian ecosystems, having a major impact on plant growth and reproduction, and soil structure. They act as predators and competitors of other arthropods, and are an important food source for other animals.
The book provides details on separating genera from those which are superficially similar and those which are commonly confused. The distribution, habitat preferences and general biologies of each genus are discussed, and there is an introduction to the more important research papers investigating each group.
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Booij, Kees, und Loes Den Nijs. Arthropod Natural Enemies in Arable Land 2: Survival, Reproduction and Enhancement (Natural Science Series, 10). Aarhus Universitetsforlag, 1996.
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Chipman, Ariel D. „Arthropoda I“. In Organismic Animal Biology, 121–32. Oxford University PressOxford, 2024. http://dx.doi.org/10.1093/oso/9780192893581.003.0021.
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Abstract The arthropods are among the most familiar and most common animals on earth. They include insects, centipedes, crabs and shrimps, spider and scorpions, and many others. By any metric, they are the most successful group of animals on the planet. The unparalleled diversity of arthropods is based on variations on a conserved body plan, which includes a segmented body enclosed in a rigid exoskeleton, with a pair of appendages on each segment or on most segments. The different clades within Arthropoda are characterized by specific organization of the segments into functional units known as tagmata. Chelicerates are characterized by two tagmata: a prosoma, including sense organs, feeding appendages, and walking appendages, and an opisthosoma, containing the digestive and reproductive systems and usually no appendages. Nearly all chelicerates are predators, and many of them have some sort of venom and venom delivery system. The greatest diversity of chelicerates is in the terrestrial arachnids. In addition, there are two smaller marine taxa, pycnogonids or sea spiders and xiphosurans or horseshoe crabs.
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Farley, Roger. „Structure, Reproduction, and Development“. In Scorpion Biology and Research, 13–78. Oxford University PressNew York, NY, 2001. http://dx.doi.org/10.1093/oso/9780195084344.003.0002.
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Abstract In the absence of fossils, some aspects of scorpion evolution may be inferred from examination of embryos and comparison with structures in related taxa. In this chapter, scorpion reproduction and development are examined in relation to paleontological information. Extant scorpions are viviparous and. unlike many other arthropods, they do not have a separate larval stage with extensive transformation during metamorphosis to the adult (Hjelle, 1990; Polis and Sissom, 1990; Farley, HJ99a). The embryos may thereby demonstrate some changes that occurred in the evolution of adult structures of present terrestrial forms. Gould (1977) and Willmer (1990) discuss uncertainties and the caution that must be applied to infer recapitulation from embryonic structures.
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Jaglarz, Mariusz K., und Szczepan M. Bilinski. „Oogenesis in Crustaceans: Ultrastructural Aspects and Selected Regulating Factors“. In Reproductive Biology, 29–59. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190688554.003.0002.
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This chapter explores ultrastructural aspects of crustacean oogenesis. It focuses on various cellular processes associated with female germline development in selected crustacean groups. Oogenesis in crustaceans comprises four stages: proliferation of germline cells, previtellogenesis, vitellogenesis, and formation of egg coverings. The greater part of oogenesis occurs in the ovary. In Crustacea, two structurally and functionally distinct types of ovary are recognized: panoistic and meroistic. In panoistic ovaries, all germline cells differentiate into oocytes, and this type of ovarian organization occurs in a great majority of crustaceans, including Malacostraca. In contrast, in the meroistic ovaries, oogonial cells are connected by intercellular bridges and form characteristic linear cysts. Within each cyst, only one cell becomes an oocyte, and the remaining cells differentiate into nurse cells. Meroistic ovaries are typical for Branchiopoda and Ostracoda: Podocopida. Ultrastructural studies reveal that the nucleus and cytoplasmic organelles of the oocyte are highly synthetically active in the panoistic ovary, whereas in the meroistic type, oocyte development is supported, to some extent, by accompanying nurse cells. During previtellogenesis, oocytes accumulate large numbers of various organelles, e.g. ribosomes, mitochondria, and cisternae of endoplasmic reticulum. The oocyte cytoplasm also contains characteristic disc-shaped bodies and cortical granules. A comparative analysis of the proteinaceous yolk formation in different crustaceans reveals two distinct types of vitellogenesis (autosynthesis and heterosynthesis), and indicates that a mixed type prevails in these arthropods. In most crustacean species, germline cells associate with somatic follicle cells that may fulfill several functions during oogenesis.
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Anderson, Roy M., und Robert M. May. „Biology of host-macroparasite associations“. In Infectious Diseases of Humans, 433–66. Oxford University PressOxford, 1991. http://dx.doi.org/10.1093/oso/9780198545996.003.0015.
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Abstract Many important diseases of humans, particularly in tropical and subtropical regions, arise from infection by macroparasites or metazoan (multicellular) organisms. The major parasites belong to the helminth and arthropod groups, and include flukes (the trematodes), tapeworms (the cestodes), nematodes, lice, fleas, and ticks. These organisms tend to have much longer generation times than microparasites; they often possess complex life cycles involving two or more obligatory host species, and direct multiplication within the definitive or final host (i.e. humans) is either absent or occurs at a low rate. Sexual reproduction often occurs in the human host, but this process entails the production of transmission stages, such as eggs or larvae, which leave the host to complete further development and maturation. Direct asexual reproduction may occur in intermediate hosts such as in the life cycle of the digenetic flukes (e.g. the schistosome parasites).
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Vogt, Günter. „An Overview of Sexual Systems“. In Reproductive Biology, 145–76. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190688554.003.0006.
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The Crustacea have evolved a broad range of sexual systems, including various types of gonochorism, hermaphroditism, and parthenogenesis. This chapter provides an overview of sexual systems in Crustacea and compares them in the species-rich Decapoda, Isopoda, Amphipoda, Cirripedia, Cladocera, Copepoda, and Ostracoda, which differ considerably with respect to phylogeny, ecology, and life histories. Gonochorism is considered to be the ancient sexual system of Crustacea. Hermaphroditism and parthenogenesis originated many times independently from gonochorism and occur in an estimated 2.2% and 2.4% of species, respectively. Crustaceans differ from the other arthropod groups mainly by the abundance and diversity of hermaphroditic reproduction. Phylogenetic analysis of extant species, the fossil record, and evolutionary ecological theory enable the reconstruction and explanation of divergent evolutionary trajectories of sexuality in the crustacean groups. The specificities can partly be attributed to differences in lifestyle, life history, and adaptive responses to different environments, but may also be the result of evolutionary constraint and competing adaptive strategies that lower the propensity of sexual system shifts. The genetic underpinning and molecular mediation of sexual system shifts are beginning to be unraveled in entomostracan and malacostracan models. A better understanding of the sexual systems in Crustacea may help to optimize their culture and conservation and answer key evolutionary questions like the enigma of sex.
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Klaoudatos, S. D., und D. S. Klaoudatos. „Phylogeny Biology and Ecology of Crustaceans (Phylum Arthropoda; Subphylum Crustacea)“. In Reproductive Biology of Crustaceans, 13–90. CRC Press, 2008. http://dx.doi.org/10.1201/9781439843345-2.
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Klaoudatos, Spyros, und Dimitris Klaoudatos. „Phylogeny Biology and Ecology of Crustaceans (Phylum Arthropoda;Subphylum Crustacea)“. In Reproductive Biology of Crustaceans, 13–90. Science Publishers, 2008. http://dx.doi.org/10.1201/9781439843345-c2.
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