Functional morphology and evolution of the hyper-elongated intromittent organ in Cassida leaf beetles (Coleoptera: Chrysomelidae: Cassidinae).
TL;DR: The morphology of the reproductive organs of two species of the beetle genus Cassida, with a special focus on the male structures, was scrutinised in detail during copulation and at rest using different microscopy techniques and found that the hyper-elongated structure of the intromittent organ, called flagellum, is part of the male ejaculatory duct.
About: This article is published in Zoology.The article was published on 2017-02-01. It has received 15 citations till now. The article focuses on the topics: Intromittent organ & Ejaculatory duct.
Citations
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TL;DR: This review examines several aspects of and gaps in the current understanding of spermatheca biology, including morphology, function, reservoir filling, development, and biochemistry.
72 citations
TL;DR: X-ray micro-CT scanning is used to examine the proximate mechanisms of traumatic mating in C. maculatus in unprecedented detail and shows that significant tract wounding occurs before the onset of female kicking, supporting recent suggestions that kicking is not an effective female counter-adaptation to reduce copulatory wounding in this species.
Abstract: In the seed beetle Callosobruchus maculatus, the male intromittent organ is covered in sharp spines that pierce the female copulatory tract wall during mating. Although the fitness consequences of traumatic mating are well studied in this species, we know much less about how the male and female genitalia interact during mating. This is partly due to the fact that genital interactions occur primarily inside the female, and so are difficult to observe. In this study, we use X-ray micro-CT scanning to examine the proximate mechanisms of traumatic mating in C. maculatus in unprecedented detail. We show that this technique can be used to identify female tissue damage before the melanization of wound sites. We visualize the positioning of the male intromittent organ inside the female copulatory tract during mating, and show how this relates to tract wounding in three dimensions. By scanning pairs flash-frozen at different times during mating, we show that significant tract wounding occurs before the onset of female kicking. There is thus some degree of temporal separation between the onset of wounding and the onset of kicking, which supports recent suggestions that kicking is not an effective female counter-adaptation to reduce copulatory wounding in this species. We also present evidence that the sharp teeth protruding from the female tract wall are able to pierce the spermatophore as it is deposited, and may thus function to aid sperm release.
33 citations
TL;DR: The apparently simple flagellum penetration is achieved with numerous elaborate mechanical adaptations, which might be helpful for, for example, in the development of harmless catheters.
Abstract: Hyper-elongated structures and their penetration are widespread among insects, for example, intromittent organs, ovipositors, and piercing-sucking mouthparts. The penetration of thin structures with high aspect ratio without buckling and rupturing is mechanically very challenging. However, this problem is economically solved in nature, and the solutions might be helpful for, for example, in the development of harmless catheters. We focus on the penetration process of a hyper-elongated structure of a cassidine beetle intromittent organ, termed a flagellum. We applied a three-point bending test for the flagellum to measure its bending stiffness along the entire flagellum. We demonstrated the bending stiffness gradient, in which the basal half is relatively stiff and the apical half is softer, whose good performance during copulation had been previously numerically demonstrated. The stiffness gradient is the result of the flagellum shape, which is cylindrical and tapered toward the tip. Moreover, the curved tip comprises a harder outer curve and a softer inner curve. Considering the findings of preceding studies, the flagellum works in the following way: (i) the bending stiffness gradient supports the flagellum, easily fitting to a shape of a highly coiled spermathecal duct, (ii) the stiffness property of the very tip may make the tip tougher, and (iii) the curled tip and homogeneously cylindrical shape of the organ help the very tip to fit the shape of the spermathecal duct of the female. Our study shows that the apparently simple flagellum penetration is achieved with numerous elaborate mechanical adaptations.
26 citations
TL;DR: It is suggested that modulating the material properties along the length of the antenna could constitute an additional mechanism for resonant tuning in these species.
Abstract: The antennae of mosquitoes are model systems for acoustic sensation, in that they obey general principles for sound detection, using both active feedback mechanisms and passive structural adaptations. However, the biomechanical aspect of the antennal structure is much less understood than the mechano-electrical transduction. Using confocal laser scanning microscopy, we measured the fluorescent properties of the antennae of two species of mosquito- Toxorhynchites brevipalpis and Anopheles arabiensis-and, noting that fluorescence is correlated with material stiffness, we found that the structure of the antenna is not a simple beam of homogeneous material, but is in fact a rather more complex structure with spatially distributed discrete changes in material properties. These present as bands or rings of different material in each subunit of the antenna, which repeat along its length. While these structures may simply be required for structural robustness of the antennae, we found that in FEM simulation, these banded structures can strongly affect the resonant frequencies of cantilever-beam systems, and therefore taken together our results suggest that modulating the material properties along the length of the antenna could constitute an additional mechanism for resonant tuning in these species.
23 citations
TL;DR: A functional switching valve within the female genitalia of the Brazilian cave insect Neotrogla is reported, enabling females to compete for seminal gifts in their nutrient-poor cave habitats through long copulation times and multiple seminal injections.
Abstract: In dry caves of southeastern Brazil, live a group of insects named Neotrogla that are perhaps best known because the egg-producing females have penises while the sperm-producing males have vaginas. The sex roles of these Brazilian cave insects are also reversed: females compete over the males, who in turn are selective of their female partners. This sex role reversal likely evolved within Neotrogla because the males’ semen represents a rich and reliable source of energy within a nutrient-poor cave environment. When females are not using semen to fertilize their eggs, they consume it. Yet, while other animals show sex role reversal, Neotrogla species alone have reversed sexual organs. Neotrogla penises are spiky and may have evolved so that females can anchor themselves to males and then mate for prolonged periods. This would allow the females to stock up on the nutritious semen. Compared to their closest relatives, Neotrogla species can hold twice as much semen within their sperm storage organs. Scientists have speculated that a valve-like structure within this organ enables this extra storage by allowing the female to redirect semen into two separate chambers. But the organ’s small size has made it difficult to determine its inner workings, and scientists have yet to discover a switching valve that serves such a purpose within the animal kingdom. Yoshizawa et al. examined three Neotrogla species using advanced imaging technology and detected the first example of a biological switching valve. Neotrogla females can control this valve, switching the flow of semen between two slots. In this way, females can store two batches of semen at once. Seemingly exploiting this adaptation, the females’ spiky penises help them restrain males until they have received multiple semen injections. Yoshizawa et al. therefore suggest the emergence of this valve within the sperm storage organ may have promoted the evolution of the female penis. Along with giving insight into the lives of cave insects, these findings are of interest to engineers, who face challenges when constructing valves on a microscopic scale. The unique switching valve of female Neotrogla may one day inspire new man-made machinery that could advance a range of industries.
8 citations
References
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TL;DR: Fiji is a distribution of the popular open-source software ImageJ focused on biological-image analysis that facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system.
Abstract: Fiji is a distribution of the popular open-source software ImageJ focused on biological-image analysis. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biology research communities.
43,540 citations
"Functional morphology and evolution..." refers methods in this paper
...…of male and female genitalia during mating, we used micro-computed tomography (µCT) as a non-invasive method which recently has been used for studies of different animal genitalia (Matsumura et al., 2014; Dougherty et al., 2015; Sentenská et al., 2015; Willkommen et al., 2015; Wulff et al., 2015)....
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...Visualisation of the relative positions of genitalia To visualise the relative positions of male and female genitalia during mating, we used micro-computed tomography (μCT) as a non-invasive method which recently has been used for studies of different animal genitalia (Matsumura et al., 2014; Dougherty et al., 2015; Sentenská et al., 2015; Willkommen et al., 2015; Wulff et al., 2015)....
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12 Nov 1998
TL;DR: The aim of this monograph is to clarify the role of pheromones and chemicals in the lives of Insects and to propose a strategy to address their role in the food web.
Abstract: The Insects has been the standard textbook in the field since the first edition published over forty years ago. Building on the strengths of Chapman's original text, this long-awaited 5th edition has been revised and expanded by a team of eminent insect physiologists, bringing it fully up-to-date for the molecular era. The chapters retain the successful structure of the earlier editions, focusing on particular functional systems rather than taxonomic groups and making it easy for students to delve into topics without extensive knowledge of taxonomy. The focus is on form and function, bringing together basic anatomy and physiology and examining how these relate to behaviour. This, combined with nearly 600 clear illustrations, provides a comprehensive understanding of how insects work. Now also featuring a richly illustrated prologue by George McGavin, this is an essential text for students, researchers and applied entomologists alike.
2,922 citations
"Functional morphology and evolution..." refers background in this paper
...In general, this orientation of muscles is rarely found in insect ejaculatory ducts (Snodgrass, 1935; Chapman, 1998)....
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...15 muscle contractions are limited to a ‘certain range’ by the length of the I bands of the sarcomeres (Chapman, 1998)....
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...The inner wall of ejaculatory ducts is typically covered with cuticular epidermis layers (Snodgrass, 1935; Gerber, 1978; Heming, 2003), and the cuticle moulting takes place along with the production of a new cuticle layer prior to eclosion (e.g., Chapman, 1990, 1998; Heming, 2003)....
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...However, in many insect species the muscle contractions are limited to a ‘certain range’ by the length of the I bands of the sarcomeres (Chapman, 1998)....
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1,420 citations
Book•
01 Dec 1985
TL;DR: This booklet contains useful information on how to select the best book to buy for your home, as well as practical suggestions for improving the quality of the books you buy.
Abstract: *Prices in US$ apply to orders placed in the Americas only. Prices in GBP apply to orders placed in Great Britain only. Prices in € represent the retail prices valid in Germany (unless otherwise indicated). Prices are subject to change without notice. Prices do not include postage and handling if applicable. Free shipping for non-business customers when ordering books at De Gruyter Online. RRP: Recommended Retail Price. Order now! orders@degruyter.com
1,409 citations
"Functional morphology and evolution..." refers background in this paper
...These intromittent organs are overbuilt in many cases (e.g., hyper-elongated, oversized or equipped with conspicuous processes; summarised in Eberhard, 1985)....
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...Tremendous diversity and complexity of intromittent organs are wide-spread phenomena in groups of animals (Eberhard, 1985; Arnqvist, 1998; Hosken and Stockley, 2004; Simmons, 2014)....
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TL;DR: Several studies now link variation in genital morphology directly to male fertilization success, and modern comparative techniques have confirmed predicted associations between genital complexity and mating patterns across species.
Abstract: Genitalia are conspicuously variable, even in closely related taxa that are otherwise morphologically very similar. Explaining genital diversity is a longstanding problem that is attracting renewed interest from evolutionary biologists. New studies provide ever more compelling evidence that sexual selection is important in driving genital divergence. Importantly, several studies now link variation in genital morphology directly to male fertilization success, and modern comparative techniques have confirmed predicted associations between genital complexity and mating patterns across species. There is also evidence that male and female genitalia can coevolve antagonistically. Determining mechanisms of genital evolution is an important challenge if we are to resolve current debate concerning the relative significance of mate choice benefits and sexual conflict in sexual selection.
640 citations
"Functional morphology and evolution..." refers background in this paper
...Tremendous diversity and complexity of intromittent organs are wide-spread phenomena in groups of animals (Eberhard, 1985; Arnqvist, 1998; Hosken and Stockley, 2004; Simmons, 2014)....
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