Chastity Belts And Planktotrophic Larvae: Constraints On Gecarcinid Reproductive Behaviour

Author(s):  
Irina V. Bogdashina

The article reveals the measures undertaken by the Soviet state during the “thaw” in the fi eld of reproductive behaviour, the protection of motherhood and childhood. Compilations, manuals and magazines intended for women were the most important regulators of behaviour, determining acceptable norms and rules. Materials from sources of personal origin and oral history make it possible to clearly demonstrate the real feelings of women. The study of women’s everyday and daily life in the aspect related to pregnancy planning, bearing and raising children will allow us to compare the real situation and the course of implementation of tasks in the fi eld of maternal and child health. The demographic surge in the conditions of the economy reviving after the war, the lack of preschool institutions, as well as the low material wealth of most families, forced women to adapt to the situation. In the conditions of combining the roles of mother, wife and female worker, women entrusted themselves with almost overwork, which affected the health and well-being of the family. The procedure for legalising abortion gave women not only the right to decide the issue of motherhood themselves, but also made open the already necessary, but harmful to health, habitual way of birth control. Maternal care in diffi cult material and housing conditions became the concern of women and the older generation, who helped young women to combine the role of a working mother, which the country’s leadership confi dently assigned to women.


Author(s):  
Derek Burton ◽  
Margaret Burton

Interspecific fish reproductive patterns, outputs and life cycles display the greatest variability within the vertebrates. Early stages of oogenesis can be repeated in adult fish, contrasting with mammals; the pre-set sequence of cell divisions in gametogenesis is otherwise similar and is described in detail. Most fish deposit much yolk (vitellogenesis) in developing eggs. Migrations, beach-spawning and mouth-brooding are some of the interesting variations. Fertilization is predominantly external but is internal in some groups such as chondrichthyans. The omission of annual reproduction is well established in some freshwater species and the idea that this may also be the case for marine teleosts is gaining acceptance. This should be taken into account for intensively fished species. The possible roles of external cues, hormones, pheromones and neural factors acting as ‘switches’ and coordinators in gametogenesis and reproductive behaviour are discussed.


Author(s):  
Cynthia D. Trowbridge

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sougata Sadhukhan ◽  
Holly Root-Gutteridge ◽  
Bilal Habib

AbstractPrevious studies have posited the use of acoustics-based surveys to monitor population size and estimate their density. However, decreasing the bias in population estimations, such as by using Capture–Mark–Recapture, requires the identification of individuals using supervised classification methods, especially for sparsely populated species like the wolf which may otherwise be counted repeatedly. The cryptic behaviour of Indian wolf (Canis lupus pallipes) poses serious challenges to survey efforts, and thus, there is no reliable estimate of their population despite a prominent role in the ecosystem. Like other wolves, Indian wolves produce howls that can be detected over distances of more than 6 km, making them ideal candidates for acoustic surveys. Here, we explore the use of a supervised classifier to identify unknown individuals. We trained a supervised Agglomerative Nesting hierarchical clustering (AGNES) model using 49 howls from five Indian wolves and achieved 98% individual identification accuracy. We tested our model’s predictive power using 20 novel howls from a further four individuals (test dataset) and resulted in 75% accuracy in classifying howls to individuals. The model can reduce bias in population estimations using Capture-Mark-Recapture and track individual wolves non-invasively by their howls. This has potential for studies of wolves’ territory use, pack composition, and reproductive behaviour. Our method can potentially be adapted for other species with individually distinctive vocalisations, representing an advanced tool for individual-level monitoring.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Donghui Ma ◽  
Mengjie Lu ◽  
Zhichang Cheng ◽  
Xingnan Du ◽  
Xiaoyu Zou ◽  
...  

Abstract Background Parental investment by birds is limited by the habitat environment, and a male parent increases its effort to reproduce in birds that live in high-altitude areas. Methods A study of the reproductive behaviour of the Saxaul Sparrow (Passer ammodendri) and the Isabelline Shrike (Lanius isabellinus) was carried out at the Gansu An’xi Extremely Arid Desert National Nature Reserve in northwest China to determine the reproductive input of passerine species in desert habitats. Results In Saxaul Sparrows, compared to the female parent, the male parent exhibited a significantly higher frequency of nest-defense behaviour (chirping and warning) during nesting, hatching and feeding periods. In addition, in comparison to the female parent, the male parent exhibited almost equal frequencies of nesting and incubation but fed nestlings significantly more times. Similar to the male sparrows, the feeding rates of the male Isabelline Shrikes were significantly higher than those of the females. The hatching rate and fledging rate of the Saxaul Sparrow on average in this study were 81.99 and 91.92%, respectively, while those of the shrike were 69.00 and 96.53%, respectively. Conclusions These two different passerine species living in the same desert environment exhibited the same trend in their reproductive investments. Adapting to desert environments is a strategy that may have evolved in passerines where male parent birds put more effort than females into reproduction to ensure high reproductive output.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Álvaro Figueroa ◽  
Antonio Brante ◽  
Leyla Cárdenas

AbstractThe polychaete Boccardia wellingtonensis is a poecilogonous species that produces different larval types. Females may lay Type I capsules, in which only planktotrophic larvae are present, or Type III capsules that contain planktotrophic and adelphophagic larvae as well as nurse eggs. While planktotrophic larvae do not feed during encapsulation, adelphophagic larvae develop by feeding on nurse eggs and on other larvae inside the capsules and hatch at the juvenile stage. Previous works have not found differences in the morphology between the two larval types; thus, the factors explaining contrasting feeding abilities in larvae of this species are still unknown. In this paper, we use a transcriptomic approach to study the cellular and genetic mechanisms underlying the different larval trophic modes of B. wellingtonensis. By using approximately 624 million high-quality reads, we assemble the de novo transcriptome with 133,314 contigs, coding 32,390 putative proteins. We identify 5221 genes that are up-regulated in larval stages compared to their expression in adult individuals. The genetic expression profile differed between larval trophic modes, with genes involved in lipid metabolism and chaetogenesis over expressed in planktotrophic larvae. In contrast, up-regulated genes in adelphophagic larvae were associated with DNA replication and mRNA synthesis.


2021 ◽  
pp. 1-12
Author(s):  
Hongyan Qiu ◽  
Qun Zhang ◽  
Jin Zhang ◽  
Qingshan Wang ◽  
Lihong Liu ◽  
...  

Abstract In October 2015, the Chinese Government announced that the one-child policy had finally been replaced by a universal two-child policy. China’s universal two-child policy is highly significant because, for the first time in 36 years, no one in an urban city is restricted to having just one child. This cross-sectional study was conducted to explore future fertility intentions and factors influencing individual reproductive behaviour (whether to have two children) in Dalian City. A total of 1370 respondents were interviewed. The respondents’ mean ideal number of children was only 1.73, and urban respondents’ sex preference was symmetrical. A total of 19.0% of the respondents were unmarried, 64.5% were married and had childbearing experience and only 6.3% of married respondents had two children. Among the 1370 participants, 30.4% stated that they would have a second child, while 69.6% refused to have a second child in the future. Binary logistic regression analysis (Model 1) showed that the following characteristics were associated with having only one child in the future: being female, being older, having a lower education level, being born in Dalian, having a lower family income and reporting one child as the ideal number of children. Model 2 (comprising only respondents with childbearing experience) showed that respondents who were female, had a lower family income and were unable to obtain additional financial support from parents were more likely to intend to stick at one child. In addition, respondents’ ideal number of children and childbearing experiences had a significant influence on future fertility intentions. These results suggest that fertility intentions and reproductive behaviours are still below those needed for replacement level fertility in Dalian City. China’s policymakers should pay more attention to these factors (socioeconomic characteristics, economic factors, desired number of children and childbearing experiences) and try to increase individual reproductive behaviour.


2021 ◽  
pp. 1-14
Author(s):  
Subasri Narasimhan ◽  
Jessica D. Gipson

Abstract Amidst persistently high unintended pregnancy rates and lags in contraceptive use, novel methodological approaches may prove useful in investigating sexual and reproductive health outcomes in the Philippines. Systematic Anomalous Case Analysis (SACA) – a mixed-methods technique – was employed to examine predictors of women’s lifetime contraceptive use. First, multivariable, longitudinal Poisson regression models predicted fertility and sexual debut using the 1998–2009 Cebu Longitudinal Health and Nutrition Surveys (CLHNS), then regression outliers and normative cases were used to identify 48 participants for in-depth interviews (2013–2014) for further examination. Qualitative findings from 24 women highlighted ‘control over life circumstances’ was critical, prompting the addition of two items to the original quantitative models predicting any contraceptive use (n=532). Each of the items, ‘what happens to [them] is their own doing’ and ‘[I] do not [have] enough control over direction life is taking [me]’, significantly and independently predicted any contraceptive use (aOR: 2.37 (CI: 1.24–4.55) and aOR: 0.46 (CI: 0.28–0.77), respectively). The findings demonstrate the utility of SACA to improve the understanding and measurement of sexual and reproductive health outcomes and underscore the importance of integrating psychosocial constructs into existing models of fertility and reproductive behaviour in the Philippines to improve sexual and reproductive health outcomes.


Sign in / Sign up

Export Citation Format

Share Document