Courtship, copulation, and sperm trading in the sea slug, Navanax inermis (Opisthobranchia: Cephalaspidea)

1985 ◽  
Vol 63 (12) ◽  
pp. 2719-2729 ◽  
Author(s):  
Janet L. Leonard ◽  
Ken Lukowiak
Keyword(s):  
Mating System ◽  
Temporal Relationship ◽  
Trading System ◽  
Male Role ◽  
Sexual Role ◽  
Sea Slug ◽  
Sexual Roles ◽  
And Function ◽  
Simultaneous Hermaphrodites ◽  
Over Time

Navanax inermis are internally fertilizing, simultaneous hermaphrodites that normally mate in pairs. Copulations usually occur in bouts with active alternation of sexual roles and function. Over the study, individuals copulated equally often and for equal periods of time as each sex. The sequence of behaviors involved in courtship, copulation, and role switching is described. While the sequence of behaviors associated with each sexual role is quite stereotyped, the temporal relationship between the behaviors of the two partners is variable. A mating bout is initiated when one individual assumes the male role, finding and following a conspecific mucous trail, and then courts and copulates as a male. Each individual initiated approximately one-half of the copulatory bouts in which it was involved; size played no role in determining which individual initiated the bout. Our observations suggest that in N. inermis, individuals are always willing to be female, while willingness to be male varies over time. The mating system of N. inermis is based on sperm trading. Individuals apparently act as males, donating sperm, to obtain sperm, and are more willing to be fertilized than to fertilize, in violation of Bateman's principle. In N. inermis, females control fertilization and therefore copulation involves greater risks for males than females. The sperm-trading system is "enforced" by the maintenance of intromission until the partner shows courtship behaviour.

scholarly journals Sexual selection and hermaphroditic organisms: Testing theory

2013 ◽  
Vol 59 (4) ◽  
pp. 579-588 ◽  
Author(s):  
Janet L. Leonard
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Multiple Mating ◽  
The Other ◽  
Operational Sex Ratio ◽  
Sexual Role ◽  
Sexual Roles ◽  
Sexual Selection Theory ◽  
Variance In Reproductive Success ◽  
Simultaneous Hermaphrodites

Abstract Sexual selection is widespread if not ubiquitous in hermaphroditic organisms. Although many phenomena that have been described as sexual selection in gonochores, (e.g. harem polygamy, multiple mating, elaborate courtship, even secondary sexual characters) can be found in some hermaphrodites, what is more interesting is the ways in which sexual selection in hermaphrodites may differ from dioecious taxa. In hermaphrodites, an individual’s mating success includes its success from both sexual roles. Secondly, in many simultaneously hermaphroditic taxa there is strong evidence of sexual selection and yet the operational sex ratio is 1:1, by definition. Many simultaneous hermaphrodites have elaborate courtship and genital anatomy, suggesting sexual selection plays an important role in reproductive success. Sperm competition and cryptic female choice mean that the number of mates acquired is not necessarily a predictor of reproductive success. Even in simultaneous hermaphrodites with reciprocal mating, variance in reproductive success through the male role and through the female role may differ in a population. Moreover hermaphrodites may choose to emphasize one sexual role over the other. Data suggest that the preferred role varies in hermaphrodites, which creates an opportunity to test fundamental predictions and assumptions of sexual selection theory. Hermaphrodites may vary their emphasis on one sexual role over the other either developmentally or behaviorally in response to environmental or social parameters. How they use this capability in acquiring more or higher quality mates still requires study.

scholarly journals The evolution of egg trading in simultaneous hermaphrodites

2018 ◽  
Author(s):  
Jorge Peña ◽  
Georg Nöldeke ◽  
Oscar Puebla
Keyword(s):  
Mating System ◽  
Analytical Model ◽  
Egg Production ◽  
High Probability ◽  
Rare Occurrence ◽  
Male Role ◽  
Encounter Rates ◽  
Simultaneous Hermaphrodites

AbstractEgg trading, whereby simultaneous hermaphrodites exchange each other’s eggs for fertilization, constitutes one of the few rigorously documented and most widely cited examples of direct reciprocity among unrelated individuals. Yet how egg trading may initially invade a population of non-trading simultaneous hermaphrodites is still unresolved. Here, we address this question with an analytical model that considers mate encounter rates and costs of egg production in a population that may include traders (who provide eggs for fertilization only if their partners also have eggs to reciprocate), providers (who provide eggs regardless of whether their partners have eggs to reciprocate), and withholders (“cheaters” who only mate in the male role and just use their eggs to elicit egg release from traders). Our results indicate that a combination of inter-mediate mate encounter rates, sufficiently high costs of egg production, and a sufficiently high probability that traders detect withholders (in which case eggs are not provided) is conducive to the evolution of egg trading. Under these conditions traders can invade—and resist invasion from—providers and withholders alike. The prediction that egg trading evolves only under these specific conditions is consistent with the rare occurrence of this mating system among simultaneous hermaphrodites.

scholarly journals Effects of Dysbiosis and Dietary Manipulation on the Digestive Microbiota of a Detritivorous Arthropod

2021 ◽  
Vol 9 (1) ◽  
pp. 148
Author(s):  
Marius Bredon ◽  
Elisabeth Depuydt ◽  
Lucas Brisson ◽  
Laurent Moulin ◽  
Ciriac Charles ◽  
...  
Keyword(s):  
Crucial Role ◽  
Structure And Function ◽  
Ecological Interactions ◽  
Dietary Manipulation ◽  
Biotic Factors ◽  
Abiotic And Biotic Factors ◽  
And Function ◽  
Multicellular Organisms ◽  
Over Time

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

Testing evolutionary constraint hypotheses with early Paleozoic gastropods

Paleobiology ◽  
1995 ◽  
Vol 21 (3) ◽  
pp. 248-272 ◽  
Author(s):  
Peter J. Wagner
Keyword(s):  
Shell Morphology ◽  
Sister Species ◽  
Evolutionary Constraint ◽  
Early Paleozoic ◽  
Internal Anatomy ◽  
Morphometric Characters ◽  
Higher Taxa ◽  
Phylogenetic Constraints ◽  
And Function ◽  
Over Time

The evolution of higher taxa among early Paleozoic gastropods is similar to that among early metazoans as a whole, as higher taxa diversified rapidly and early. There are two issues pertinent to this pattern. First, were greater morphologic changes concentrated in the early phases of evolution? Second, does the pattern better fit models of increasing phylogenetic constraints or increasing ecologic restrictions? This paper presents a phylogeny-based method designed to test whether amounts of morphologic evolution decreased over time. It also explores whether the data better fits models of increasing phylogenetic (i.e., developmental or genetic) constraint or increasing ecologic restriction. Two metrics of morphologic separation (i.e., the morphologic difference between sister-species) are used: (1) Euclidean distance in morphospace and (2) transition magnitude. The latter metric is calculated by a multivariate analysis of sister-species contrasts, which determines both types and magnitudes of morphologic transitions. The advantage of using transition magnitudes is that it balances the effects of transitions that either affect more morphometric characters or occur more frequently. Both metrics indicate that larger morphologic separations between sister-species were concentrated early in gastropod evolution. Among gastropods, gross shell morphology often reflects basic trophic strategy and function whereas basic internal anatomy does not. Transition magnitudes can be broken down into transitions associated with differences in basic trophic strategies and shell functional biology (“external”), and those associated with differences in basic internal anatomy (“internal”). Internal transition magnitudes show a highly significant decrease over time (p < 10–04) whereas external transition magnitudes show a much less significant decrease over time (p < 0.10) and no significant decrease after the earliest Ordovician (p ≅ 0.50). The results therefore suggest that increasing phylogenetic constraints played a greater role in the early evolution of gastropods than did increasing ecologic ones.

scholarly journals Multidisciplinary Evaluation of Pacifier Removal on Oro-Dentofacial Structures: A Controlled Clinical Trial

2021 ◽  
Vol 9 ◽  
Author(s):  
Kelly Guedes de Oliveira Scudine ◽  
Camila Nobre de Freitas ◽  
Kizzy Silva Germano Nascimento de Moraes ◽  
Silvana Bommarito ◽  
Rosana de Fátima Possobon ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Mixed Model ◽  
Control Group ◽  
Controlled Clinical Trial ◽  
Functional Changes ◽  
Mixed Model Anova ◽  
And Function ◽  
Clinical Trials Registry ◽  
Facial Anthropometry ◽  
Over Time

It is well recognized that pacifier habit leads to occlusal and orofacial functional changes in children. However, the effects of the interruption of prolonged pacifier habit on the development of the dento-facial complex has not yet been fully characterized. Thus, the aim of this study was to investigate the influence of pacifier removal on aspects of oro-dentofacial morphology and function in preschool children. For that, a pacifier group (n = 28) and a control group (n = 32) of 4-year-old children with and without pacifier habit, respectively, were followed up by a group of dentists and speech therapists at baseline, 6 and 12 months after habit removal. Bite force and lip pressure were assessed using digital systems, and the evaluation of breathing and speech functions was performed using validated protocols, together with the measurements of dental casts and facial anthropometry. The Two-way mixed model ANOVA was used in data analysis. After 12 months, a decrease in malocclusion frequency was observed in pacifier group. Additionally, a change over time was observed in facial, intermolar and palate depth measurements, as well in bite and lip forces and speech function scores, increasing in both groups (p &lt; 0.01). The upper and lower intercanine widths and breathing scores differed between groups at baseline and changed over time reducing the differences. The presence of speech distortions was more frequent in the pacifier group at baseline and decreased over time (p &lt; 0.05). The interruption of pacifier habit improved the maxillary and mandibular intercanine widths, as well as the breathing and speech functions, overcoming the oro-dentofacial changes found.Trial Registration: This clinical trial was registered in the Brazilian Clinical Trials Registry (ReBEC; http://www.ensaiosclinicos.gov.br/), protocol no. RBR-728MJ2.

From Trauma to Healing

2021 ◽  
pp. 186-205
Author(s):  
Letizia Gambrell-Boone
Keyword(s):  
New Normal ◽  
Singular Event ◽  
Integral Role ◽  
And Function ◽  
Organizational Trauma ◽  
Unresolved Trauma ◽  
Over Time

Organizational trauma, which results from a singular event or the sum of multiple experiences that occur over time, has an impact on the individuals and the collective that constitute the organization. For an organization to overcome its challenges and function in a new normal, leadership must play an integral role in engaging its individuals in a way that is explicit and intentional. The efforts of the leadership must first effectively describe the culture, as well as define leadership and its role. Undiagnosed and/or unresolved trauma (both crisis and systemic organizational trauma) within an institution may have exponential implications for both the person and the organization as a whole. To restore the organization to a state of wholeness, there must be an acknowledgement of organizational trauma as well as a committed approach to organizational healing. These efforts shift the organization from one that is experiencing organizational trauma to one that is considered to be a restorative community.

Conclusion

2020 ◽  
pp. 315-322
Author(s):  
Douglas A. Irwin
Keyword(s):  
International Trade ◽  
World Trade ◽  
Trade Policies ◽  
Trading System ◽  
The World ◽  
World Trading System ◽  
And Function ◽  
Open Markets ◽  
The Impact ◽  
Role And Function

This chapter concludes that international trade and trade policies are frequently the object of condemnation rather than approbation. It explains how the condemnation are often the result of misconceptions about the benefits of international trade, the impact of trade policies, and the role and function of the World Trade Organization (WTO). Though the last few decades have been marked by a general reduction in trade barriers, the matter is not settled because the pressures to weaken the commitment to open markets never abate. The chapter emphasizes on difficult policy choices at the intersection of trade policy and climate change that could hold key battles over the world trading system in coming years. It also highlights the several benefits of world trade and the contribution of trade to the welfare and prosperity of billions of people around the world.

Introduction: how language works in politics

2018 ◽  
pp. 3-32
Author(s):  
Matthew Williams
Keyword(s):  
Computer Assisted ◽  
British Politics ◽  
Form And Function ◽  
It Impacts ◽  
Legislative Language ◽  
And Function ◽  
Assisted Analysis ◽  
The Impact ◽  
Over Time

This book examines how language works in democratic politics and how it impacts the effectiveness of policy. Using evidence from the first computer-assisted analysis of all 41.5 million words of legislation enacted from 1900 to 2015, it tracks the major changes in form and function that Parliament's use of language has undergone over time and the reasons for such changes. More importantly, it explores the policy and social implications of changes in legislative language as well as the issue of legislative indeterminacy. This introductory chapter discusses the questions, arguments and aims of the book and reviews the literature on the operation of language in British politics, along with the impact of legislative language on policy effectiveness. It also explains what specifically the book contributes to the existing literature, describes the research design, and provides an overview of the chapters that follow.

Pathosformel as grammar

2019 ◽  
Vol 68 (1) ◽  
pp. 100-135
Author(s):  
Edward H. Wouk
Keyword(s):  
Present Article ◽  
Visual Arts ◽  
Theory And Practice ◽  
Northern Europe ◽  
Artistic Creation ◽  
Visual Material ◽  
And Function ◽  
New Generation ◽  
Over Time

The artist and polymath Lambert Lombard of Liège developed a radical outlook on the theory and practice of artistic creation that he sought to illustrate in a ‘grammar’ of formal studies. Devised during a period of intense crisis for image-making in northern Europe, this ‘grammar’ offered a means to restore authority to the visual arts by recovering a canon of forms that had been perfected in antiquity yet became diluted over time. The present article examines the development and function of Lombard’s ‘grammar’, focusing on its role in the instruction he provided to a new generation of Netherlandish artists. It explores similarities between Lombard’s project and Aby Warburg’s celebrated Mnemosyne Atlas, compiled between 1924 and 1929. This comparison provides new insights into the visual, material and conceptual strategies through which Lombard’s ‘grammar’ illuminated the entwined properties of motion and emotion that he defined as the essence of perfect art.

Relation of changes over time in ventricular size and function to those in exercise capacity in patients with chronic heart failure

2000 ◽  
Vol 139 (5) ◽  
pp. 0913-0917
Author(s):  
Keishiro E. Kawamura ◽  
Viorel G. Florea ◽  
Michael Y. Henein ◽  
Stefan D. Anker ◽  
Darrel P. Francis ◽  
...  
Keyword(s):  
Heart Failure ◽  
Chronic Heart Failure ◽  
Exercise Capacity ◽  
Ventricular Size ◽  
And Function ◽  
Changes Over Time ◽  
Over Time
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