Population dynamics of wild reindeer (Rangifer tarandus L.) on the Taimyr Peninsula: A simulation model

A simulation model, based on original and published data, has been developed to determine the period and amplitude of natural population cycles of wild reindeer on the Taimyr Peninsula and reveal the role of hunting in these cycles. The results of simulations show that hunting in the late 20th century has smoothed out the cycles. Considering natural factors of population regulation, uncontrolled elimination of part of the population by hunting should maintain the average long-term abundance at a level lower than potentially possible under natural dynamics, leading to negative ecological and economic consequences. © 2013 Pleiades Publishing, Ltd

Decay of free induction in polyvinylchloride in the high elastic state

An experimental study was made of the form of decay of free induction (ID) in PVC samples with different molecular weights in the high elastic state. It was found that the form of ID differs from the form predicted by a model of rotary Brownian motion with a single correlation time. For the theoretical description of the form of ID an attempt was made to use the existing theory, which assumes anisotropic motion of the polymer chain. © 1979

Адаптивные изменения сезонных миграций диких северных оленей на Таймыре

As the largest in the world the Taimyr population of wild reindeer displays pronounced seasonal migrations from forest zone to tundra for fawning in spring and return motion in fall. These motions are characterized with dynamics varying from year to year. Evidences of experience suggest that migration course cannot yet be interrupted or curtailed with artificial constructions or anthropogenic disturbance. By results of long-term observations carried out by one of the authors during 20 years, migration timing and speed were related to current ambient temperature and varied from year to year. As foreseen temperature rise happens more intensively inArcticthan upon an average through the Planet and is higher overland than it is over ocean it must apparently exert influence on the pattern of reindeer migrations. We hold that this phenomenon consists with changes in migration activity for recent decades and manifests increasing all-year-round separate reindeer groups presence in tundra. Some of these groups are registered and presented on the skeleton map. In the light of current climatic trend the ecological mechanism of migrations decrease should be grounded on reindeer bioenergetics and derived from ecological function of their migrations. Energy expenditures for far movements are getting less appropriate and the proportion of total heads staying in tundra zone all-year-round will increase. Available bioenergetics parameters and the simple model let to make a prediction. In the end we propose some preventive conservation arrangements to secure the mass heads of wild reindeer staying in tundra against adverse factors, mainly pending anthropogenic.Обитающая на Таймыре популяция диких северных оленей характеризуется четко выраженными сезонными миграциями, динамика которых варьирует от года к году. На основе многолетних полевых наблюдений показана зависимость начального времени и скорости сезонных миграций от текущей приземной температуры воздуха. Рассмотрено влияние на миграции прогнозируемых климатических изменений, приводится картосхема отмечаемых изменений в миграционной активности популяции за последние десятилетия. В свете наблюдаемой тенденции обоснованы экологические причины сокращения миграций оленей с позиций биоэнергетики. Предлагаются превентивные природоохранные меры, призванные обезопасить поголовье оленей в тундровой зоне от неблагоприятных, прежде всего антропогенных факторов

Female responses to experimental removal of sexual selection components in Drosophila melanogaster

Despite the common assumption that multiple mating should in general be favored in males, but not in females, to date there is no consensus on the general impact of multiple mating on female fitness. Notably, very little is known about the genetic and physiological features underlying the female response to sexual selection pressures. By combining an experimental evolution approach with genomic techniques, we investigated the effects of single and multiple matings on female fecundity and gene expression. We experimentally manipulated the opportunity for mating in replicate populations of Drosophila melanogaster by removing components of sexual selection, with the aim of testing differences in short term post-mating effects of females evolved under different mating strategies

Evolution of sex-specific pace-of-life syndromes: genetic architecture and physiological mechanisms

Sex differences in life history, physiology, and behavior are nearly ubiquitous across taxa, owing to sex-specific selection that arises from different reproductive strategies of the sexes. The pace-of-life syndrome (POLS) hypothesis predicts that most variation in such traits among individuals, populations, and species falls along a slow-fast pace-of-life continuum. As a result of their different reproductive roles and environment, the sexes also commonly differ in pace-of-life, with important consequences for the evolution of POLS. Here, we outline mechanisms for how males and females can evolve differences in POLS traits and in how such traits can covary differently despite constraints resulting from a shared genome. We review the current knowledge of the genetic basis of POLS traits and suggest candidate genes and pathways for future studies. Pleiotropic effects may govern many of the genetic correlations, but little is still known about the mechanisms involved in trade-offs between current and future reproduction and their integration with behavioral variation. We highlight the importance of metabolic and hormonal pathways in mediating sex differences in POLS traits; however, there is still a shortage of studies that test for sex specificity in molecular effects and their evolutionary causes. Considering whether and how sexual dimorphism evolves in POLS traits provides a more holistic framework to understand how behavioral variation is integrated with life histories and physiology, and we call for studies that focus on examining the sex-specific genetic architecture of this integration

Helper Response to Experimentally Manipulated Predation Risk in the Cooperatively Breeding Cichlid Neolamprologus pulcher

Background We manipulated predation risk in a field experiment with the cooperatively breeding cichlid Neolamprologus pulcher by releasing no predator, a medium- or a large-sized fish predator inside underwater cages enclosing two to three natural groups. We assessed whether helpers changed their helping behaviour, and whether within-group conflict changed, depending on these treatments, testing three hypotheses: ‘pay-to-stay’ PS, ‘risk avoidance’ RA, or (future) reproductive benefits RB. We also assessed whether helper food intake was reduced under risk, because this might reduce investments in other behaviours to save energy. Methodology/Principal Findings Medium and large helpers fed less under predation risk. Despite this effect helpers invested more in territory defence, but not territory maintenance, under the risk of predation (supporting PS). Experimentally covering only the breeding shelter with sand induced more helper digging under predation risk compared to the control treatment (supporting PS). Aggression towards the introduced predator did not differ between the two predator treatments and increased with group member size and group size (supporting PS and RA). Large helpers increased their help ratio (helping effort/breeder aggression received, ‘punishment’ by the dominant pair in the group) in the predation treatments compared to the control treatment, suggesting they were more willing to PS. Medium helpers did not show such effects. Large helpers also showed a higher submission ratio (submission/ breeder aggression received) in all treatments, compared to the medium helpers (supporting PS). Conclusions/Significance We conclude that predation risk reduces helper food intake, but despite this effect, helpers were more willing to support the breeders, supporting PS. Effects of breeder punishment suggests that PS might be more important for large compared to the medium helpers. Evidence for RA was also detected. Finally, the results were inconsistent with RB

Parental breeding age effects on descendants' longevity interact over 2 generations in matrilines and patrilines

Individuals within populations vary enormously in mortality risk and longevity, but the causes of this variation remain poorly understood. A potentially important and phylogenetically widespread source of such variation is maternal age at breeding, which typically has negative effects on offspring longevity. Here, we show that paternal age can affect offspring longevity as strongly as maternal age does and that breeding age effects can interact over 2 generations in both matrilines and patrilines. We manipulated maternal and paternal ages at breeding over 2 generations in the neriid fly Telostylinus angusticollis. To determine whether breeding age effects can be modulated by the environment, we also manipulated larval diet and male competitive environment in the first generation. We found separate and interactive effects of parental and grand-parental ages at breeding on descendants' mortality rate and life span in both matrilines and patrilines. These breeding age effects were not modulated by grand-parental larval diet quality or competitive environment. Our findings suggest that variation in maternal and paternal ages at breeding could contribute substantially to intrapopulation variation in mortality and longevity