A cost of maternal care in the dung beetle Onthophagus taurus?

Parental care theory assumes that investment in current offspring will trade against future investment. A number of field studies on birds have used clutch size manipulations to demonstrate a survival cost to chick rearing. However, such studies do not account for costs accrued during earlier stages of reproduction because not all aspects of reproductive effort are manipulated by varying the number of nestlings. In this study, we investigate the effect of reproductive effort on female survival in the dung beetle, Onthophagus taurus. By experimentally manipulating mating status and dung availability, we demonstrate that virgin females survive longer than mated females and that the survival of mated females was negatively associated with the number of brood masses produced. Using a novel manipulation of the mating system, we separated the effects of egg production and maternal care on female survival. Previously, we have shown that females provisioning with the assistance of a major male provide relatively less care than unassisted females. However, paternal assistance did not alter the number of brood masses produced and hence the amount of reproductive effort that was allocated to egg production. Therefore, our finding that female survival was increased when receiving paternal assistance provides, to our knowledge, the first definitive evidence that maternal care reduces female lifespan. These results are of major importance to theoretical models on the evolution of parental care.     

The evolution of sexual dimorphism in parasitic cuckoos: sexual selection or coevolution?

Sexual dimorphism is ubiquitous in animals and can result from selection pressure on one or both sexes. Sexual selection has become the predominant explanation for the evolution of sexual dimorphism, with strong selection on size-related mating success in males being the most common situation. The cuckoos (family Cuculidae) provide an exceptional case in which both sexes of many species are freed from the burden of parental care but where coevolution between parasitic cuckoos and their hosts also results in intense selection. Here, we show that size and plumage differences between the sexes in parasitic cuckoos are more likely the result of coevolution than sexual selection. While both sexes changed in size as brood parasitism evolved, we find no evidence for selection on males to become larger. Rather, our analysis indicates stronger selection on parasitic females to become smaller, resulting in a shift from dimorphism with larger females in cuckoos with parental care to dimorphism with larger males in parasitic species. In addition, the evolution of brood parasitism was associated with more cryptic plumage in both sexes, but especially in females, a result that contrasts with the strong plumage dimorphism seen in some other parasitic birds. Examination of the three independent origins of brood parasitism suggests that different parasitic cuckoo lineages followed divergent evolutionary pathways to successful brood parasitism. These results argue for the powerful role of parasite-host coevolution in shaping cuckoo life histories in general and sexual dimorphism in particular.     

Male horn dimorphism in the scarab beetle, Onthophagus taurus: do alternative reproductive tactics favour alternative phenotypes?

In a variety of organisms morphological variation is discrete rather than continuous. Discrete variation within a sex has attracted particular interest as it is thought to reflect the existence of alternative adaptations to a heterogeneous selection environment. The beetle Onthophagus taurus shows a dimorphism for male horns: males that exceed a critical body size develop a pair of long, curved horns on their heads, while smaller males remain hornless. In this study we report on the alternative reproductive tactics used by males with these two morphologies, and present experimental and behavioural data suggesting that these alternative tactics selectively favour discretely different male phenotypes. Horned males aggressively defended tunnel entrances containing breeding females. Fights involved the use of horns, and males with longer horns were more likely to win fights. In contrast, hornless males employed nonaggressive sneaking behaviours when faced with competitively superior males. Sneaking behaviours appeared to require high degrees of manoeuvrability inside tunnels to access and mate with females despite the presence of a guarding male. Comparisons of running performances of males with identical body sizes but different horn lengths suggest that the possession of horns reduces male agility inside tunnels. Thus, horn possession confers a clear advantage to males using fighting behaviours to access females, whereas hornlessness may be favoured in males that rely primarily on sneaking behaviours. Combined, the two alternative reproductive tactics used by male O. taurus appear to favour opposite horn phenotypes, which may explain the paucity of intermediate morphologies in natural populations of O. taurus. Copyright 2000 The Association for the Study of Animal Behaviour.     

Trilobite spines and beetle horns: sexual selection in the Palaeozoic?

Raphiophorid trilobites commonly bore median cephalic protuberances such as spines or bulbs, showing a remarkable variety of form. It is unlikely that their primary function was for protection or in hydrodynamics. A case is made that they were secondary sexual features, by comparison with similar morphological structures developed on rhinoceros beetles and other arthropods. This interpretation is supported by four lines of evidence: their ontogeny, their diversity, the existence of plausible examples of sexual dimorphs in some cases and the fact that they show positive allometry.     

Does the timing of attainment of maturity influence sexual size dimorphism and adult sex ratio in turtles?

The attainment of sexual maturity has been shown to affect measures of sexual size dimorphism (SSD) and adult sex ratios in several groups of vertebrates. Using data for turtles, we tested the model that sex ratios are expected to be male‐biased when females are larger than males and female‐biased when males are larger than females because of the relationship of each with the attainment of maturity. Our model is based on the premise that the earlier‐maturing sex remains smaller, on average throughout life, and predominates numerically unless the sexes are strongly affected by differential mortality, differential emigration, and immigration, or biased primary sex ratios. Based on data for 24 species in seven families, SSD and sex ratios were significantly negatively correlated for most analyses, even after the effect of phylogenetic bias was removed. The analyses provide support for the model that SSD and adult sex ratios are correlated in turtles as a result of simultaneous correlation of each with sexual differences in attainment of maturity (bimaturism). Environmental sex determination provides a possible mechanism for the phenomenon in turtles and some other organisms. © 2014 The Authors. Biological Journal of the Linnean Society published by John Wiley & Sons Ltd on behalf of The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 142–149.     

Comparison of members of pro‐ and anti‐abortion organizations in Missouri

Abstract

Comparisons were made between members of Missouri Citizens for Life (MCL) and of the Abortion Rights Alliance (ARA) of Missouri. ARA members were more educated, urbanized, and had fewer children. MCL members were predominantly Catholic, and compared to ARA members, highly religious. ARA members were more inclined to favor equality of the sexes, especially in their approval of the ERA. ARA members were politically more liberal and more committed to free speech for social deviants. MCL members were much more committed to a conservative approach to matters of personal morality. MCL members regarded suicide and euthanasia as more objectionable than did their ARA counterparts, but they were also more militaristic.     

The physical basis of alpha waves in the electroencephalogram and the origin of the “Berger effect”

Synchronised activity, differing in phase in different populations of neurons, plays an important role in existing theories on the function of brain oscillations (e.g., temporal correlation hypothesis). A prerequisite for this synchronisation is that stimuli are capable of affecting (resetting) the phase of brain oscillations. Such a change in the phase of brain waves is also assumed to underlie the Berger effect: when observers open their eyes, the amplitude of EEG oscillations in the alpha band (8–13 Hz) decreases significantly. This finding is usually thought to involve a desynchronisation of activity in different neurons. For functional interpretations of brain oscillations in the visual system, it therefore seems to be crucial to find out whether or not the phase of brain oscillations can be affected by visual stimuli. To answer this question, we investigated whether alpha waves are generated by a linear or a nonlinear mechanism. If the mechanism is linear – in contrast to nonlinear ones – phases cannot be reset by a stimulus. It is shown that alpha-wave activity in the EEG comprises both linear and nonlinear components. The generation of alpha waves basically is a linear process and flash-evoked potentials are superimposed on ongoing alpha waves without resetting their phase. One nonlinear component is due to light adaptation, which contributes to the Berger effect. The results call into question theories about brain-wave function based on temporal correlation or event-related desynchronisation.Electronic Supplementary Material: Supplementary material is available for this article at     

Light participates in the auxin‐dependent regulation of plant growth

Light is the energy source for plant photosynthesis and influences plant growth and development. Through multiple photoreceptors, plant interprets light signals through various downstream phytohormones such as auxin. Recently, Chen et al. (2020) uncover a new layer of regulation in IPyA pathway of auxin biosynthesis by light. Here we highlight recent studies about how light controls plant growth through regulating auxin biosynthesis and signaling.     

Is sexual dimorphism affected by the combined action of prenatal stress and sex ratio?

During embryonic development, offspring are exposed to hormones of both maternal and sibling origin. Maternal stress increases offspring exposure to corticosterone, and, in polytocous animals, the sex ratio or intrauterine position can influence the levels of androgens and estrogens experienced by the offspring. Such hormone exposure has the potential to influence many important morphological and behavioural aspects of offspring, in particular sexually dimorphic traits. Although well known in rodents, the impact of prenatal hormone exposure in other vertebrates is poorly documented. We experimentally investigated the relationship between maternal stress, population density, sex ratio (a surrogate for the degree of exposure to steroids produced by siblings), and sexual dimorphism in a viviparous lizard, Lacerta vivipara. Our results show that prenatal sex ratios have consequences for sexually dimorphic morphology (ventral scale count) in both sexes, but with no effect of maternal stress or any interaction between the two. Embryonic steroid exposure can potentially be an important factor in generating individual variation in natural populations of viviparous animals.     

Arsenic‐induced NFκβ transactivation through Erks‐ and JNKs‐dependent pathways in mouse epidermal JB6 cells

Carnosine, a alanylLhistidine dipeptide with antioxidant properties is present at high concentrations in skeletal muscle tissue. In this study, we report on the antioxidant activity of carnosine on muscle lipid and protein stability from both in vitro and in vivo experiments. Carnosine inhibited lipid peroxidation and oxidative modification of protein in muscle tissue prepared from rat hind limb homogenates exposed to in vitro Fenton reactant (Fe²⁺, H₂O₂)generated free radicals. The minimum effective concentrations of carnosine for lipid and protein oxidation were 2.5 and 1 mM, respectively. Histidine and alanine, active components of carnosine, showed no individual effect towards inhibiting either lipid or protein oxidation. Skeletal muscle of rats fed a histidine supplemented diet for 13 days exhibited a marked increase in carnosine content with a concomitant reduction in muscle lipid peroxidation and protein carbonyl content in skeletal muscle caused by subjecting rats to a Fenitrilotriacetate administration treatment. This significant in vitro result confirms the in vivo antioxidant activity of carnosine for both lipid and protein constituents of muscle under physiological conditions.     

Ethnicity and class identity: The case of French‐ and English‐speaking Canadians*

This study addresses the racial and religious contexts of identity formation among Lebanese immigrants to the United States of America and Somali immigrants to Canada. Each enters with a different racial status: Lebanese as white; Somalis as black/visible minority. Ethnographic interviews explore the strategies of adaptation and identity development within these groups. Specifically, we compare and contrast the Lebanese and Somali experience through an analysis of ethnic relations in the country of origin, the conditions of immigration, and through accounts of their encounters and identity negotiation with the host society. We demonstrate the strategies each group implements to negotiate both race and religion in identity development. Our findings reveal that each group attempts to make their religious identity evident, however, Somali immigrants must negotiate the effects of ‘othering’ processes with both race and religion, while Lebanese immigrants build a religious identity from privileges afforded to them by virtue of their white racial status.     

Time and energy constraints and the evolution of sexual size dimorphism — to eat or to mate?

Summary We present an empirical test of the Ghiselin—Reiss small-male hypothesis for the evolution of sexual size dimorphism (SSD). In mating systems dominated by scramble competition, where male reproductive success is a function of encounter rate with females, small males may be favoured when food is limiting because they require lower absolute amounts of food. Given a trade-off between time and energy devoted to foraging and to mate acquisition, small males should be able to devote more time to the latter. If at the same time larger females are favoured, this mechanism will contribute to the evolution of SSD and may be the major determinant of the female-biased SSDs that characterize most animal taxa. We tested this hypothesis using the water strider,Aquarius remigis (Heteroptera: Gerridae), a scramble competitor which mates many times over a prolonged mating season and which shows female-biased SSD. Laboratory experiments demonstrated that foraging success and giving up times (GUTs) are lower for males than for females during the reproductive season and that male water striders flexibly alter their time budgets under conditions of energy limitation. Controlled feeding experiments showed that male and female longevity, female fecundity and male mating success are positively related to food availability. As predicted, male body size is negatively correlated with several indices of male fitness (longevity, number of mating attempts and mating success), while female body size is positively correlated with longevity. These results are consistent with the hypothesis that scramble competition for mates favours small males in this species and provides empirical support for the Ghiselin—Reiss small-male hypothesis.     

Between‐ vs. within‐family analyses of the correlation of height and intelligence

Abstract

Small but consistently positive correlations between standing height and general intelligence (the unrotated first principal component across the battery of cognitive tests) were found across sexes, racial/ethnic groups (Americans of European vs. Americans of Japanese ancestry), and generations in data from the Hawaii Family Study of Cognition. Sibling data produced significant height‐intelligence correlations for sibling pair means (i.e., between‐family differences) but not for within sibling pair differences. The lack of within‐family height‐intelligence correlations suggested that the two traits were linked due to cross‐assortative mating and/or between‐family environmental influences (e.g., nutrition) affecting both traits. Some evidence for both of these explanations was found.     

Is sexual size dimorphism variable? Data on species of the genus <Emphasis Type="Italic">Martes</Emphasis> in the Urals

Sexual dimorphism in cranial measurements was studied in Ural populations of two species of the genus Martes, M. martes and M. zibellina. The index of sexual dimorphism averaged 8.39% in the former and 9.03% in the latter, being subject to geographic variation. For the first time, temporal variability of sexual dimorphism in dimensional characters was revealed in mammals by analyzing M. zibellina samples collected in different decades of the second half of the 20th century. The majority of corresponding microtrends had reciprocating dynamics.