Covariation in life-history traits : differential effects of diet on condition, hormones, behavior, and reproduction in genetic finch morphs

The relative contribution of genetic and environmental factors in determining variation in life-history traits is of central interest to evolutionary biologists, but the physiological mechanisms underlying these traits are still poorly understood. Here we experimentally demonstrate opposing effects of nutritional stress on immune function, endocrine physiology, parental care, and reproduction between red and black head-color morphs of the Gouldian finch (Erythrura gouldiae). Although the body condition of black morphs was largely unaffected by diet manipulation, red birds were highly sensitive to dietary changes, exhibiting considerable within-individual changes in condition and immune function. Consequently, nutritionally stressed red birds delayed breeding, produced smaller broods, and reared fewer and lower-quality foster offspring than black morphs. Differences in offspring quality were largely due to morph-specific differences in parental effort: red morphs reduced parental provisioning, whereas black morphs adaptively elevated their provisioning effort to meet the increased nutritional demands of their foster brood. Nutritionally stressed genetic morphs also exhibited divergent glucocorticoid responses. Black morphs showed reduced corticosterone-binding globulin (CBG) concentrations and increased levels of free corticosterone, whereas red morphs exhibited reduced free corticosterone levels and elevated CBG concentrations. These opposing glucocorticoid responses highlight intrinsic differences in endocrine sensitivities and plasticity between genetic morphs, which may underlie the morph-specific differences in condition, behavior, and reproduction and thus ultimately contribute to the evolution and maintenance of color polymorphism.

Stress, cortisol and reproduction in female pigs

Two key hypotheses emerge in the literature regarding the impact of stress on reproduction in females of any species. First, prolonged stress impairs reproduction in females. Secondly, acute stress impairs reproduction, if it occurs at a critical time during the precisely timed series of endocrine events that induce oestrus and ovulation. We reviewed studies conducted in female pigs to find support or opposition for these hypotheses in female pigs. We also considered the role of cortisol. We found confirmation that prolonged stress or the prolonged elevation of cortisol can impair reproductive processes in female pigs, but also found that there appear to be some female pigs in which reproduction is resistant to such treatments. Reproduction in female pigs appears to be resistant to acute or repeated acute stress or elevation of cortisol, even if these occur during the series of precisely timed endocrine events that induce oestrus and ovulation. Thus, we propose modified versions of the above hypotheses that are specific to female pigs. Furthermore, while cortisol may mediate the effects of prolonged stress on reproduction in female pigs, there is evidence that, in female pigs, ACTH may require the presence of the adrenal glands to impair reproduction rather than having direct effects.

Age, growth and reproduction of deepwater dogfishes from southeastern Australia

The productivity of six deepwater dogfishes was investigated by examining their age, growth and reproductive biology. A new method of ageing was developed, and compared with existing techniques. Some species live greater than 50 years, and populations may not sustain commercial fisheries.

Visual discrimination and reproduction of movement by individuals with an intellectual disability

This study investigates the capacity of individuals with an intellectual disability to make accurate discriminations of computer-generated displays and also to reproduce the characteristics of those displays. The findings suggest that the learning of everyday motor skills in this population may be hampered by difficulties in visually perceiving important characteristics of the demonstration. Procedures, employed for teaching these skills to intellectually disabled, are being reassessed in the light of these findings.

Uomo universale : the imaginary relation between body and mathematic(s) in architecture

What is the role of the human figure in the drawing of the uomo universale? Interlocked with the “master architect” as a constituent component of the canonical bodies of architecture, is the idea of the uomo universale, the universal man, an idea that was especially compelling to Renaissance masters. In contemporary social theory the uomo universale is read for its generic sense as the “universal subject”. Critical to this is a dialectical sense in which “man” confronts its non-neutral association with a gender specificity, either man or woman. This paper looks at the drawing and image of the uomo universale and explores the distinction between presence and representation, between the visibility of the image, its content and detail and the symbolic role of the image as constitutive of a canon of architecture. Though we are not meant to “see” the human figure as corporeal presence and rather focus our attention on the image as a geometric schema, my argument is that only through the figure is the uomo universale engendered as an image of the highest form of nature.

Molting and reproduction in portunus pelagicus

This investigation describes ovarian maturation stages in the female reproductive system, evidence for histones in sperm nuclei and novel morphological changes that occur during spermiogenesis in the male blue swimming crab, portunus pelagicus. It also identifies dual functionality of the molt inhibiting hromone on molting and vitellogenesis through RNA inteference.

Invitation to the feed: the body and the environment in a selection of dystopian YA science fictions

 In an analysis of Monica Hughes’ Invitation to the Game and M. T. Anderson’s Feed, this paper explores the nexus between nature and the artificial, and how that both empowers and disempowers young adults in two highly technological futuristic dystopias.

The effect of repeated boar exposure on cortisol secretion and reproduction in gilts

It has been proposed that short-term activation of the hypothalamo-pituitary adrenal axis, with a consequent increase in the secretion of cortisol, amy disrupt the endocrine events prior to ovulation and thereby impair reproduction in females. We investigated this concept in gilts in which oestrus was detected by introduction to boars, where intense physical contact is possible, or by applying pressure to the back of gilts (back-pressure test) during fence-line exposure to boars, where intense physical contact is prohibited. We expected that there would be a greater release of cortisol and that reproduction would be inhibited in gilts introduced to boars compared to gilts in which the back-pressure test was used. As expected, introduction of gilts to boars resulted in a significant transient increase in plasma concentrations of cortisol while there was no significant effect of using the back-pressure test on plasma cortisol. Nevertheless, introduction of gilts to boars did not impair reproduction and there was no effect of method of detecting oestrus on duration of oestrus, sexual receptivity, fertility or fecundity. The length of the oestrous cycle was decreased and ovulation rate increased in gilts that were introduced to boars compared to gilts that underwent the back-pressure test, indicating that introduction of gilts to boars may have stimulated these aspects of reproduction. These stimulatory effects may have been due to an increased exposure of gilts to sexual behaviour and stimuli from boars when introduced to boars and/or to stimulatory effects of the hypothalamo-pituitary adrenal axis on some aspects of reproduction.

Stress and reproduction: central mechanisms and sex differences in non-rodent species

Despite extensive research, the mechanisms by which stress affects reproduction are unknown. Activation of stress systems could potentially influence reproduction at any level of the hypothalamo-pituitary gonadal axis. Nonetheless, the predominant impact is on the secretion of gonadotrophin releasing hormone (GnRH) from the brain and the secretion of the gonadotrophins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), from the gonadotrophs of the anterior pituitary gland. When stress is prolonged, it is likely that secretion of the gonadotrophins will be suppressed but the effects of acute stress or repeated acute stress are not clear. Different stressors activate different pathways for varying durations, and the actions of stress vary with sex and are influenced by the predominance of particular sex steroids in the circulation. The mechanisms by which stress influences reproduction are likely to involve complex interactions between a number of central and peripheral pathways and may be different in males and females. To understand these mechanisms, it is important to determine the stress pathways that are activated by particular stressors and to establish how these pathways affect the secretion and actions of GnRH. Furthermore, there is a need to know how stress influences the feedback actions of gonadal steroids and inhibin.

Diderot’s body and cognitive science: sensation, impulse and action in performer training

This essay places Diderot's materialist philosophy articulated in Paradox of the Actor in the late Nineteenth century, alongside emerging thinking from neurobiology. Taking Diderot’s pursuit for the recognition acting as an art as a point of departure, it reflects on the labour of the actor as awareness within multiple cognitions: impulse, sensation, and action. The discussion maps various examples including Stanislavsky in the early 1900s through to contemporary more regulated techniques like Susana Bloch’s Alba Emoting method and Phillip Zarrilli’s psychophysical approach. It considers the language of neuroscience in explicating the nuances of technique in acting and proposes that good acting requires a mastery of self at a neural level. ​

Body image and body change techniques among young adolescent boys

The aim of the present study was to examine the level of body image disturbance among adolescent boys and to determine how body image disturbance was related to body change techniques. Twenty boys from year 7 (mean age = 12.55 years, SD = 0.61) and 20 boys from year 9 (mean age = 14.85 years, SD = 0.59) were interviewed individually about their body image and body change strategies. The boys were questioned about the importance and their satisfaction with their weight, body size, body shape, muscle tone and parts of their body and the frequency with which they used the following techniques: eating less to lose weight, eating more to gain weight, and exercise to change body size, shape or muscle tone. The results demonstrated that of those boys who wanted to change their body (50 per cent), 12 wanted to lose weight and eight wanted to gain weight. The most frequent strategy used to change body size or shape was exercise, rather than changing eating patterns. Year 7 boys were more satisfied with their weight than year 9 boys, and boys with a larger body mass index (BMI) were less satisfied with their muscle tone and more likely to change their eating habits to decrease their body size or shape than boys with a smaller BMI. The implications of these findings for obtaining a better understanding of how male body image and body change strategies are different from girls are discussed.