Domestication in the silver fox (Vulpes fulvus Desm): Changes in physiological boundaries of the sensitive period of primary socialization

The physiological boundaries of the sensitive period of primary socialization were studied in the silver fox (Vulpes fulvus Desm). A total of 273 farm-bred foxes from 59 litters were observed from 1976 to 1978; pups were produced by vixens from two populations, one selected for domesticated behaviour and the other unselected. Results indicate that the age when the eyes are fully open, when the response to sound first appears and when exploratory behaviour is first shown in strange surroundings is 3 weeks, on average. The age when the socialization period starts appears to be 20–25 days old. The optimum period of the formation of primary social bonds appears to be 30–35 days, when maximum exploration in a novel situation is shown. The 40–45 days period appears to be the upper boundary of primary socialization in unselected foxes because pups show fear in response to novel stimuli, which prevents exploration. In pups from the population of domesticated foxes, the sensitive period of socialization is prolonged to over 60–65 days old.     

Song and brain development in canaries raised under different conditions of acoustic and social isolation over two years

Early isolation experiments indicate that male songbirds learn their songs during an early sensitive period, although later work has shown that some open-ended learners modify songs in later years. Recent isolation experiments suggest that in some species song has a stronger genetic basis than previously thought. This study raised domestic canaries under different combinations of acoustic and social isolation and followed song development into the second year. Males raised alone in acoustic isolation developed songs with normal syllables, but larger repertoires and also produced syllables with lower repetition rates when compared to controls. The smallest repertoire occurred in males raised in a peer group. Isolate males had a smaller song control nucleus HVC than controls, but there was no effect on nucleus RA or on brain weight in general. In the second year, after introduction into a large normal colony, isolate and peer group males adjusted their syllable repertoire to normal size. In particular, the isolates reduced their repertoire even though the size of HVC showed a significant increase in volume. However, songs of isolate and peer group males still differ in repetition rate and number of single syllables in the common aviary. In contrast, control males showed low syllable turnover and no significant change in repertoire size. Nor did they show any significant change in the volumes of song control nuclei. It seems that complete isolation affects only some aspects of song and brain development, and later socialization corrects some but not all of these in the second year.     

Migration and mental illness: What role do traditional childhood socialization practices play?

Interpretations of studies which show a correlation between migration and mental illness generally focus on sociocultural variables while giving scant attention to determinants of cognitive-personality orientations. This article examines childhood socialization practices as a key variable for comparing points of psychological stress between the traditional rural culture and the post-industrial urban culture. The hypothesis that harsh and restrictive childhood socialization practices foster the development of a cognitivepersonality orientation which increases the likelihood of maladaptive responses to culture change is illustrated by anthropological and psychological data obtained from Sicilians living in Sicily, the U.S.A. and Australia. Suggestions are given for minimizing the mental health risks involved during the critical transition period following migration.     

Participation of the fear reaction in limiting the period of primary socialization in silver foxes

Administration of chloditan, an inhibitor of adrenal cortex function, at the terminal stage of the sensitive period of socialization of foxes reduced the cortisol concentration in blood as compared with control and intact animals aged 45 and 60 days. Simultaneously, the weakening of fear reaction and an enhancement of exploratory and motor activities in an unknown surrounding were observed. However, administration of chloditan did not affect the duration of the sensitive period of socialization, since the aggressive defensive reactions changed neither at the age of 45 and 60 days, nor at the age of 7 months.     

The effects of neonatal social isolation on the behavior and endocrine function of Holstein calves

A link between neonatal isolation and increased milk production has been reported for Holstein dairy cattle (Donaldson, 1970; Arave et al., 1985). This research proposes and investigates four mechanisms that might underlie this effect.Three hypotheses were unsupported: neonatal isolation did not affect social dominance, reproductive maturation or socialization to humans.A fourth hypothesis proposes that neonatal isolation, by imposing stress, has organizational effects on hypothalamo-hypophyseal-adrenal axis function. This was supported by behavioral and endocrine evidence. Isolated calves stood more (P < 0.02) and tended to vocalize and investigate more than controls, evidence of discontent or stress. As yearling heifers, isolates had a higher mean serum cortisol concentration than controls (P < 0.01) following short-term stressors. Differences in adrenocortical function may, therefore, underlie the effects of neonatal isolation on milk yield, by affecting cows' ability to maintain homeostasis when stressed.     

The Politics of Crime: Aggression and Control in a Colonial Context

Political resistance to colonial rule poses particular problems of control and political socialization during the initial period of occupation. The strategy of early British intervention in Uganda reveals the recurrent use of legislative and judicial reform rather than direct police action to repress local unrest. In this paper, the history of administrative action with regard to two imputed offenses, arson and witchcraft, is examined as well as the factors which underlay the failure or success of such measures.     

Quantifying patterns in the evolution of reproductive isolation

We present a likelihood-based statistical method for examining the pattern or rate of evolution of reproductive isolation. The method uses large empirical datasets to estimate, for a given clade, the average duration of two phases in the divergence of populations. The first phase is a lag phase and refers to the period during which lineages diverge but no detectable reproductive isolation evolves. The second is an accumulation phase, referring to the period during which the magnitude of reproductive isolation between diverging lineages increases. The pattern of evolution is inferred from the relative durations of these two phases. Results of analyses of postzygotic isolation data indicate significant differences among taxa in the pattern of evolution of postzygotic isolation that are consistent with predictions based on genetic differences among these groups. We also examine whether the evolution of postzygotic isolation is best explained by either of two models for the rate of accumulation: a linear model or a quadratic function as may be suggested by recent studies. Our analysis indicates that the appropriateness of either model varies among taxa.     

Social life of captive Asian elephants (Elephas maximus) in Southern India: implications for elephant welfare

Asian elephants in the wild live in complex social societies; in captivity, however, management often occurs in solitary conditions, especially at the temples and private places of India. To investigate the effect of social isolation, this study assessed the social group sizes and the presence of stereotypies among 140 captive Asian elephants managed in 3 captive systems (private, temple, and forest department) in Tamil Nadu, India, between 2003 and 2005. The majority of the facilities in the private (82%) and temple (95%) systems held a single elephant without opportunity for social interaction. The forest department managed the elephants in significantly larger groups than the private and temple systems. Among the 3 systems, the proportion of elephants with stereotypies was the highest in temple (49%) followed by private system (26%) and the forest department facility (6%); this correlates with the social isolation trend observed in the 3 systems and suggests a possible link between social isolation and abnormal elephant behavior separate from other environmental factors. The results of this study indicate it would be of greater benefit to elephant well being to keep the patchily distributed solitary temple and private elephants who are socially compatible and free from contagious diseases in small social groups at "common elephant houses" for socialization.     

稻绿核菌(稻曲病菌)分离方法的比较研究

作者对不同情况下稻曲病菌的分离方法进行了比较研究。结果表明成熟早期稻曲球上的绝大多数新鲜的厚垣孢子具有萌发能力,及时进行分离培养是病原菌成功分离的关键。随保存时间的延长,厚垣孢子萌发能力急剧下降;消毒处理可杀死大部分的厚垣孢子。菌核可长期保存并保持极高的萌发生长能力,是稻曲病菌分离最为理想的材料。稻曲球中部的致密菌丝组织分离难度较大,只能作为稻曲病菌分离的一种补救方法。     

A few days of social separation affects yearling horses' response to emotional reactivity tests and enhances learning performance

Learning performance is influenced by emotional reactivity, low reactivity being generally beneficial. Previous experiments show that emotional reactivity can be modified after a period of social isolation. We hypothesized that eleven days of isolation would affect yearlings' emotional reactivity and improve their learning abilities. Twenty-five yearlings were divided into two groups: 12 were continuously isolated for 11 days (isolated) and 13 stayed together (control). During the period of isolation, all yearlings underwent two learning tasks: a habituation procedure in which a novel object was presented for 120 s every day, either when the horse was alone (isolated) or with conspecifics (control); an instrumental learning task in which the yearling had to walk forwards or backwards to obtain a food reward. At the end of the isolation period, animals performed tests to assess aspects of emotional reactivity: reactivity to novelty, to humans, to social separation, to suddenness and to sensory stimuli. Results showed that isolated yearlings habituated more to the novel object than controls and performed better in the instrumental task. Moreover, they were less reactive to novelty, to social separation and to suddenness than controls. Overall, these data suggest that the better performance of isolated yearlings could be explained by a decrease in their emotional reactivity. This article is part of a Special Issue entitled: insert SI title.     

Adolescent vulnerability to cardiovascular consequences of chronic social stress: Immediate and long‐term effects of social isolation during adolescence

It has been demonstrated that disruption of social bonds and perceived isolation (loneliness) are associated with an increased risk of cardiovascular morbidity and mortality. Adolescence is proposed as a period of vulnerability to stress. Nevertheless, the impact of chronic social stress during this ontogenic period in cardiovascular function is poorly understood. Therefore, the purpose of this study was to compare the impact in cardiovascular function of social isolation for 3 weeks in adolescent and adult male rats. Also, the long‐term effects of social isolation during adolescence were investigated longitudinally. Social isolation reduced body weight in adolescent, but not in adult animals. Disruption of social bonds during adolescence increased arterial pressure without affecting heart rate and pulse pressure (PP). Nevertheless, social isolation in adulthood reduced systolic arterial pressure and increased diastolic arterial pressure, which in turn decreased PP without affecting mean arterial pressure. Cardiovascular changes in adolescents, but not adults, were followed by facilitation of both baroreflex sensitivity and vascular reactivity to the vasodilator agent acetylcholine. Vascular responsiveness to either the vasodilator agent sodium nitroprusside or the vasoconstrictor agent phenylephrine was not affected by social isolation. Except for the changes in body weight and baroreflex sensitivity, all alterations evoked by social isolation during adolescence were reversed in adulthood after moving animals from isolated to collective housing. These findings suggest a vulnerability of adolescents to the effects of chronic social isolation in cardiovascular function. However, results indicate minimal cardiovascular consequences in adulthood of disruption of social bonds during adolescence. © 2015 Wiley Periodicals, Inc. Develop Neurobiol 76: 34–46, 2016     

Reproductive isolation and the period gene of Drosophila

The identification of genes of large effect on ecologically important traits is an important aim of molecular ecology. The period gene of Drosophila is a candidate for a gene with a large influence on premating isolation between Drosophila species, as it determines species specific aspects of courtship behaviour. Strains of D. melanogaster are available which have been genetically transformed with the period gene of either D. melanogaster or D. simulans. Here we show that D. melanogaster females do not discriminate between two such strains. This suggests that period may only make a small contribution to total premating isolation between these species. We discuss the use of genetically transformed strains in assessing the influence of single genes on complex traits.     

青藏高原东缘同域分布的2种橐吾属杂草的合子前生殖隔离

生殖隔离是阻止种间杂交、保持物种完整性和独立性的关键,对生物多样性的产生和维持有重要意义.不同物种间的生殖隔离形成阶段、方式和强度不完全相同,因而对物种间隔离机制的研究有助于揭示物种形成和维持机制.对青藏高原东缘同域分布的2种橐吾属杂草黄帚橐吾和箭叶橐吾的花期物候观察、访花昆虫观察及花粉-柱头亲和性进行研究,分析了2种橐吾多种合子前生殖隔离机制的特点及其在生殖隔离中的作用.结果表明: 黄帚橐吾种群花期比箭叶橐吾早20 d左右,虽然盛花期存在差异,但是2种群花期存在10 d左右的重叠期,并且在重叠期内2种橐吾花粉和柱头均具有活性.2种橐吾共享传粉昆虫,为泛化传粉模式,并且传粉者对2种植物的访花行为相似,存在2种植物间交叉访问.尽管2种橐吾花期不存在完全的时间隔离,也不存在完全的传粉者隔离,但2种橐吾柱头对异源花粉的亲和性差,表现为柱头对异源花粉有明显的排斥反应,异源花粉管在柱头上的生长过程明显受阻.这种花粉-柱头排异形式很有可能是2种橐吾属植物重要的合子前隔离机制,从而避免了种间的自然杂交,更好地维持了自然种群的多样性和遗传结构的稳定性.     

The release of primordia of marginal buds onbryophyllum crenatum leaves from growth inhibition in relationship to the level of endogenous IAA

The growth of primordia of marginal buds (marginals) which differentiate on leaf margins is correlatively inhibited on intactBryophyllum crenatum plants. Following leaf isolation, the marginals are released from this correlative inhibition, which process is accompanied within 2 to 10 h after leaf isolation with a decrease in the content of endogenous IAA in the leaf blade. This decrease can be enhanced by transversal cutting of the leaf blade into three parts which also results in enhanced subsequent growth of the marginals. The growth which follows after the release of the marginals from correlative inhibition is accompanied in cut leaf blades with an increased content of endogenous IAA in the period from 12 h to 7 d after leaf isolation when compared with uncut leaf blades. The highest content of endogenous IAA was recorded in the middle section, and the lowest IAA content in the basal section of the leaf blade.     

Involvement of GABA-A receptor chloride channel complex in isolation stress-induced free choice ethanol consumption in rats

The present study revealed the effect of diazepam, a benzodiazepine, and progesterone, a pregnane precursor of neurosteroids, which act via modulating GABA-A chloride channel complex on the isolation stress-induced free choice ethanol consumption in adult rats. Isolation stress for 24 hr over a period of 6 days produced a significant increase in ethanol consumption, which persisted during the 6-day recovery period. Pretreating the animals with diazepam (5 mg/kg, i.p.), or progesterone (5 mg/kg, i.p.), blocked the isolation stress-induced increase in ethanol consumption. Bicuculline (2 mg/kg, i.p.), a GABA-A receptor antagonist significantly attenuated the effect of both diazepam and progesterone on stress-induced modulation of ethanol consumption. Isolation stress also caused an increase in total fluid consumption, which was antagonised by both diazepam and progesterone. Like ethanol consumption, this effect of diazepam and progesterone on isolation stress-induced increase in total fluid consumption was attenuated by bicuculline. Neither diazepam nor progesterone produced an increase in ethanol consumption in non-stressed rats. However, unlike diazepam, progesterone administration to non-stressed rats caused a significant increase in total fluid consumption. Results of the present study thus show that GABAergic mechanisms may be playing an important role in isolation stress-induced increase in ethanol consumption.     

The effects of short-term isolation on systolic blood pressure and heart rate in rats

The effect of short-term isolation on the systolic blood pressure and heart rate of rats has been studied. Five days continuous isolation in glass metabolic cages caused systolic arterial hypertension in all animals. Isolation in standard cages for this time period caused hypertension, but only in 55% of the animals. Both forms of isolation caused an initial tachycardia. Handling and contact with other animals for 1 hr daily prevented the development of hypertension in some animals but did not alter the blood pressure once the hypertension had developed. Group-housing of animals after a 3 week period of isolation restored blood pressure to control levels within 24 hr. It is possible that stress imposed by isolation activated the sympatho-adrenal system and thereby caused these changes.     

Effects of a short period of isolation in adulthood on the aggressive behavior of dominant and subordinate male mice

Male ddY mice were used to investigate the effect of a short period of isolation in adulthood on aggressive behavior. The relationship between the dominance status previous to isolation and the effect of isolation was investigated. The mice were kept in isolation for 3 weeks from 9 weeks of age, during which intruder tests were conducted once a week. They the went through an encounter test, in which the mice encountered dominant or subordinate mice in a neutral space. The number of the formerly-dominant isolated mice that attacked the intruder mice decreased at first and then increased. The latency to attack also lengthened at first and then shortened. Seven former-dominants continued to show aggression throughout the intruder The number of the formerly-subordinate isolated mice that attacked the intruder mice increased linearly. But 3 former-subordinates did not show aggression through the entire experiment. After 3 weeks isolation, the number of mice that showed aggression and the amount of aggression did not differ between the former-dominants and subordinatcs. Isolation housing was concluded to differentially affect the dominant and subordinate mice during the 3 weeks of isolation. It was also concluded to differentially affect the mice of absolute dominance and relative dominance differentially. The aggressive behavior of the isolated mice appears to occur independently of site.     

Distinguishing Migration from Isolation Using the Variance of Pairwise Differences

Two demographic scenarios are considered: two populations with migration and two populations that have been completely isolated from each other for some period of time. The variance of the number of differences between pairs of sequences in a single sample is studied and forms the basis of a test of the isolation model. The migration model is one possible alternative to isolation. The isolation model is rejected when the proposed test statistic, which involves the variances of pairwise difference within and between populations, is larger than some critical value. The power and realized significance of the test are investigated using simulations, and an example using mitochondrial DNA illustrates its application.     

Impact of ancestral populations on postzygotic isolation in allopatric speciation

Postzygotic isolation evolves due to an accumulation of substitutions (potentially deleterious alleles in hybrids) in populations that have become geographically isolated. These potentially deleterious alleles might also be maintained in ancestral populations before geographic isolation. We used an individual-based model to examine the effect of the genetic state of an ancestral population on the evolution of postzygotic isolation after geographic isolation of a population. The results showed that the number of loci at which degenerative alleles are fixed in an ancestral population at equilibrium significantly affects the evolutionary rates of postzygotic isolation between descendant allopatric populations. Our results suggest that: (1) a severe decrease in population size (e.g., less than ten individuals) is not necessary for the rapid evolution of postzygotic isolation (e.g., <10,000 generation); (2) rapid speciation can occur when there is a large difference in the equilibrium number of accumulated degenerative alleles between ancestral and descendant populations; and (3) in an ancestral population maintained at a small effective population size for a long period of time, postzygotic isolation rarely evolves if back mutations that restore the function of degenerative alleles are limited.