Since its publication in 1953, Henry Hart's famous article, 'The Power of Congress to Limit the Jurisdiction of Federal Courts: An Exercise in Dialectic', subsequently referred to as simply "'The ...Dialogue'," has served as the leading scholarly treatment of congressional control over the federal courts. Now in its seventh decade, much has changed since Hart first wrote. This Article examines what lessons 'The Dialogue' still holds for its readers circa 2020.
Abstract
In some species, permanent curtailment of reproduction part‐way through the lifespan of adult females is a feature of their evolved life history. The existence of such a post‐reproductive ...life stage is apparently rare; reasonably robust evidence for this is confined to only six species (humans, Asian elephants and four whales). That it occurs at all appears to contradict our view of natural selection operating to maximize fitness and special circumstances must exist to explain its occurrence. We evaluate the main hypotheses posited to explain the evolution of this life stage, why it occurs in a restricted group of animals, and why only in females. We bring together literature from multiple biological disciplines and levels of enquiry, ranging through evolutionary ecology, developmental biology, physiology, neuroscience, molecular biology, and human medicine. We conclude that while time‐limited fertility is not in itself adaptive, the duration of subsequent survival is likely to be linked to inclusive fitness benefits. We present a new hypothesis which posits that the duration of female fertility in certain long‐lived, highly encephalised species, with no post‐natal oogenesis, is limited by the need for intense screening of oocyte mitochondria. This is required to support endothermy coupled with the very high energy requirement for the development and maintenance of the exceptionally large brain size required for complex social living. This limits the number and shelf‐life of oocytes, creating an antagonistically pleotropic effect that is beneficial to the production of high performing offspring but carries the later life cost of time‐limited female fertility. But the end of the fertile period is no time to die. Inclusive fitness benefits arising from protracted parental care of offspring, overlapping generations, and kin group structures means that continued survival of post‐reproductive females is favoured by selection. We suggest further lines of research to test these ideas.
Major life history traits, such as fecundity and survival, have been consistently demonstrated to covary positively in nature, some individuals having more resources than others to allocate to all ...aspects of their life history. Yet, little is known about which resources (or state variables) may account for such covariation. Reactive oxygen species (ROS) are natural by-products of metabolism and, when ROS production exceeds antioxidant defenses, organisms are exposed to oxidative stress that can have deleterious effects on their fecundity and survival. Using a wild, long-lived bird, the Alpine Swift (Apus melba), we examined whether individual red cell resistance to oxidative stress covaried with fecundity and survival. We found that males that survived to the next breeding season tended to be more resistant to oxidative stress, and females with higher resistance to oxidative stress laid larger clutches. Furthermore, the eggs of females with low resistance to oxidative stress were less likely to hatch than those of females with high resistance to oxidative stress. By swapping entire clutches at clutch completion, we then demonstrated that hatching failure was related to the production of low-quality eggs by females with low resistance to oxidative stress, rather than to inadequate parental care during incubation. Although male and female resistance to oxidative stress covaried with age, the relationships among oxidative stress, survival, and fecundity occurred independently of chronological age. Overall, our study suggests that oxidative stress may play a significant role in shaping fecundity and survival in the wild. It further suggests that the nature of the covariation between resistance to oxidative stress and life history traits is sex specific, high resistance to oxidative stress covarying primarily with fecundity in females and with survival in males.
God does not exist Monaghan, P. X.
International journal for philosophy of religion,
10/2020, Letnik:
88, Številka:
2
Journal Article
Recenzirano
I often tell my students that the only thing that is not controversial in philosophy is that everything else in it is controversial. While this might be a bit of an exaggeration, it does contain a ...kernel of truth, as many exaggerations do: philosophy is a highly contentious discipline. So it is remarkable the extent to which there is agreement in the philosophy of religion amongst theists, agnostics, and atheists alike that John Mackie’s argument for atheism is either invalid or unsound. As a result, the focus has entirely shifted from the logical problem of evil to the so-called evidential one. But I think that this is a mistake, not necessarily because I think Mackie’s argument is sound, but rather because I reject an assumption made by apparently all parties to the debate, which is that there is only one logical problem of evil. Accordingly, the purpose of this paper is to defend a deductive argument that God* does not exist. As far as I can tell, the basic idea of this argument is a novel one: while Mackie’s argument (and much of the discussion that occurs in its wake) has a more or less consequentialist framework, mine has a deontological one. The evil of which I will speak is that of our having been thrown into the world.
Over the last 20 years the majority of emerging infections which have spread rapidly across the globe have been respiratory infections that are spread via droplets, a trend which is likely to ...continue. Aerosol spray generation in the dental surgery has the potential to spread such infections to staff or other patients. Although the diseases may differ, some common approaches can reduce the risk of transmission. Dental professionals should be aware of areas affected by emerging infections, the incubation period and the recent travel history of patients. Elective dental care for those returning from areas affected by emerging infections should be delayed until the incubation period for the infection is over.
evolutionary ecology of senescence Monaghan, P.; Charmantier, A.; Nussey, D. H. ...
Functional ecology,
June 2008, Letnik:
22, Številka:
3
Journal Article
Recenzirano
Odprti dostop
1. Research on senescence has largely focused on its underlying causes, and is concentrated on humans and relatively few model organisms in laboratory conditions. To understand the evolutionary ...ecology of senescence, research on a broader taxonomic range is needed, incorporating field, and, where possible, longitudinal studies. 2. Senescence is generally considered to involve progressive deterioration in performance, and it is important to distinguish this from other age-related phenotypic changes. We outline and discuss the main explanations of why selection has not eliminated senescence, and summarise the principal mechanisms thought to be involved. 3. The main focus of research on senescence is on age-related changes in mortality risk. However, evolutionary biologists focus on fitness, of which survival is only one component. To understand the selective pressures shaping senescence patterns, more attention needs to be devoted to age-related changes in fecundity. 4. Both genetic and environmental factors influence the rate of senescence. However, a much clearer distinction needs to be drawn between life span and senescence rate, and between factors that alter the overall risk of death, and factors that alter the rate of senescence. This is particularly important when considering the potential reversibility and plasticity of senescence, and environmental effects, such as circumstances early in life. 5. There is a need to reconcile the different approaches to studying senescence, and to integrate theories to explain the evolution of senescence with other evolutionary theories such as sexual and kin selection.
A larger body size confers many benefits, such as increased reproductive success, ability to evade predators and increased competitive ability and social status. However, individuals rarely maximize ...their growth rates, suggesting that this carries costs. One such cost could be faster attrition of the telomeres that cap the ends of eukaryotic chromosomes and play an important role in chromosome protection. A relatively short telomere length is indicative of poor biological state, including poorer tissue and organ performance, reduced potential longevity and increased disease susceptibility. Telomere loss during growth may also be accelerated by environmental factors, but these have rarely been subjected to experimental manipulation in the natural environment. Using a wild system involving experimental manipulations of juvenile Atlantic salmon Salmo salar in Scottish streams, we found that telomere length in juvenile fish was influenced by parental traits and by direct environmental effects. We found that faster‐growing fish had shorter telomeres and there was a greater cost (in terms of reduced telomere length) if the growth occurred in a harsher environment. We also found a positive association between offspring telomere length and the growth history of their fathers (but not mothers), represented by the number of years fathers had spent at sea. This suggests that there may be long‐term consequences of growth conditions and parental life history for individual longevity.
1. Human disturbance has been associated with declines in breeding success in numerous species and is of general concern to conservationists. However, the current framework for predicting and ...minimizing disturbance effects is weak and there is considerable uncertainty about why animals are disturbed by people in the first place. 2. We developed a behavioural model of perceived predation risk as a framework for understanding the effects of disturbance on cliff-nesting birds. This encompassed the concept that the effects of disturbance should increase with increasing numbers of visitors, and decrease with distance from the nest, an insight ignored in current conservation practice. 3. The predictions of this model were tested using field data on nesting success in two species of seabird, kittiwake Rissa tridactyla and guillemot Uria aalge. Statistical models of nesting success in both species suggested that perceived predation risk is a good predictor of the effects of disturbance. 4. Synthesis and applications. Our findings suggest that fixed set-back distances and buffer zones are likely to be inappropriate conservation measures in situations where the numbers of visitors to wildlife areas fluctuates spatially and temporally, as is generally the case. In managing access to wildlife areas there is a need to ensure that larger parties of visitors are kept further away from the nesting areas of vulnerable species or that set-back distances are determined for the largest party likely to visit the site.
Our current understanding of the operation of sexual selection is predicated on a sex difference in parental investment, which favours one sex becoming limiting and choosy over mates, the other ...competitive and nonchoosy. This difference is reflected in the operational sex ratio (OSR), the ratio of sexually receptive males to females, considered to be of fundamental importance in predicting the direction of sexual selection. Difficulties in measuring OSR directly have led to the use of the potential reproductive rates (PRR) as a measure of the level of investment in offspring of males and females. Several recent studies have emphasized that other factors, such as variation in mate quality and sex differences in mortality patterns, also influence the direction of sexual selection. However, as yet there has been no attempt to form a comprehensive theory of sex roles. Here we show that neither OSR nor PRR is the most fundamentally important determinant of sex roles, and that they are not interchangeable. Instead, the cost of a single breeding attempt has a strong direct effect on competition and choosiness as well as consistent relationships to both OSR and PRR. Our life history based approach to mate choice also yields simple, testable predictions on lack of choice in either sex and on mutual mate choice.
PDF
