Ontogenetic Dynamics Research Articles

COMPLEX INOCULATION OF SOYBEANS WITH NODULE BACTERIA BRADYRHIZOBIUM JAPONICUM AS A MEASURE TO OPTIMIZE SYMBIOTIC NITROGEN FIXATION

Objective. Establish effective mixed inoculants for soybeans based on new active strains of Bradyrhizobium japonicum with different intensity and dynamics of nitrogen-fixing activity to improve nodulation processes and functional activity of legume-rhizobia symbiosis. Methods. Microbiological, physiological, statistical, gas chromatography. Legume-rhizobia systems based on Glycine max L. (Merill) soybean, variety Samorodok, were studied using recombinant strains of B. japonicum: B199, B201, Д47, Д48, Д52, Д60, Д63. Monoinoculation of soybean with B. japonicum 634б served as the control. Results. Mixed inoculation of B. japonicum ensured positive ontogenetic dynamics of root nodule formation in soybean. The indicator of the number of root nodules in experimental plants was 1.2–1.9 times higher versus the control plants from Day 18 to 45 of soybean vegetation. When soybeans were inoculated with B. japonicum 634б + B201 and 634б + Д 52, the mass of nodules at Day 45 of vegetation increased by 30.0–35.3 % versus the control and was the highest (1.10–1.15 g/plant) among the studied variants, as a result of the strengthening effect of complex bacterization. A positive synergistic effect of the combined use of strains was obtained — intensification of the nitrogen-fixing activity of soybean root nodules. In the phase of budding/beginning of flowering and full flowering under combined inoculation with active strains of B. japonicum 634б + Д47, 634б + Д52 and 634б + В201, nitrogen fixation of soybean nodules increased by 10.7–25.5 % (at Day 32), by 13.2–30.9 % (at Day 38), and was also 2.3–2.8 times higher in the phase of full flowering (Day 45 of soybean vegetation) versus the similar indicator of control plants. In the phase of full flowering of plants (Day 45 of vegetation), under mixed inoculation with strains of B. japonicum 634б + Д47, 634б + В201, 634б + Д52 and В201 + Д52, the aboveground mass of plants exceeded that of control plants by 8.3–17.2 % variant, which was probably provided by improved conditions of their nitrogen nutrition, due to enhanced assimilation of N2 by root nodules. The most developed root system was in soybeans inoculated with strains B. japonicum 634б and B. japonicum 634б + Д52, B. japonicum 634б + В201 and B. japonicum Д48 + Д52. Conclusion. Symbiotic features of active recombinant strains of B. japonicum and their variability in functional activity at different stages of soybean ontogenesis should be taken into account when creating complex nitrogen-fixing bacterial preparations for soybeans with the effect of microbiological synergy.

Ontogenetic dynamics of the nudibranch epithelium in Onchidoris muricata (O.F. Müller, 1776)

The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the epithelium, muscles, and elements of connective and nerve tissue. The integument acts as a physical barrier between the external environment and the internal environment that serves to protect and maintain the body of the animal. The body of nudibranch mollusks undergo significant changes during ontogenesis, with the subepidermal space changing as the mollusk grows. As the extracellular subepidermal matrix is modified, the number of collagen fibers increases, muscles and nerves develop, and calcite spicules appear and grow. Yet, specific knowledge pertaining to the transformation of the epithelium is absent. In the present work, the ontogenetic dynamics of the surface epithelium of nudibranch mollusks are traced for the first time using Onchidoris muricata (O. F. Müller, 1776) during the postlarval stages of development. Ontogenetic changes in the epithelium of O. muricata were studied using a complex set of morphological methods. According to our data, the degree of modification to the epithelium in ontogenesis depends on individual body parts and is not consistent throughout. First x-cells were recognized as the probable precursors to sclerocytes.

Features of the Ontogenetic Dynamics of Protective-Couping Behavior

Introduction. The theme of ontogenetic dynamics of defense mechanisms and coping strategies is one of the least explored areas in the psychology of defense-coping behavior. A detailed and thorough analysis of this area will contribute to a clearer understanding of the ways to overcome stress and the mechanisms of their formation in different age periods. Understanding the age-related features of defense-coping behavior will lead to the emergence of more effective methods of psychological counseling, psychotherapy, and psychocorrection of various age groups. Such individualization of therapy will increase the well-being of both the individual personality and various social groups and society as a whole.Purpose. This research conducts a theoretical analysis of research dedicated to ontogenetic changes in coping behavior, analyzes protective psychological mechanisms, and strategies for overcoming stress inherent in different ages. The aim is to identify the patterns of age dynamics of defense-coping behavior and to define its characteristics inherent in different age groups.Materials and Methods. The study was conducted through a theoretical-methodological analysis of literature dedicated to defense-coping behavior within the framework of its age changes. Methods of analysis, synthesis, comparison, and generalization were applied. Monographs and publications of domestic and foreign authors describing cross-sectional and longitudinal studies of the ontogenetic dynamics of defense-coping behavior served as the material for the study.Results. The characteristics of the defense-coping sphere of personality at different age periods were noted. The similarities and contradictions of longitudinal and cross-sectional studies in this sphere were analyzed and summarized. An attempt was made to explain the ontogenetic features of defense-coping behavior from the perspective of age psychology. The results obtained can serve as a basis for developing and conducting experimental studies and applying their data in the field of education, health care, and other areas of social life.Conclusion. The authors have identified general patterns that provide a basis for further experimental study of the stated problem.

Self-image of children with parents working abroad

Like other countries, Romania exports labour permanently or seasonally. In the secondscenario, the question of the psychological price paid by children left at home arises. A number of answers have already been accumulated, but this natural experiment of occupational migration still off ers much room for investigation. Can the ontogenetic dynamics of childhood self-image act as a protective factor? Does the constellation of parental absence matter? How do the two variables interfere on global self-image/on sub-components? These are the stakes of the present study, carried out on a group of 175 preschoolers and young schoolchildren from the cities of Galați and Iași. We opted for one of the multidimensional paradigms of self-identity [11] and a 2x3 research design. There are two novelties, relatively counterintuitive, compared to other similar researches in terms of topic: - in the case of self-image, there are no diff erences between children with one absent parent and those with both parents present; - identification of the fact that participants with both parents present have a self-image centred on aggressive behaviour more accentuated than children with absent parents.

3D models related to the publication: Deciphering the morphological variation and its ontogenetic dynamics in the Late Devonian conodont Icriodus alternatus

3D models related to the publication: Deciphering the morphological variation and its ontogenetic dynamics in the Late Devonian conodont Icriodus alternatus

Deciphering the morphological variation and its ontogenetic dynamics in the Late Devonian conodont Icriodus alternatus

Identification of relevant taxonomic and evolutionary units is a recurrent issue in the fossil record, and all the more for ancient fossils devoid of modern equivalents such as conodonts. Extensive morphological variation has often led to the description of numerous species, subspecies or morphotypes, which may correspond to end-member morphologies reached through ontogeny. The platform elements of the Late Devonian conodont speciesIcriodus alternatuswere characterized by rows of denticles coming into occlusion between opposite elements; each element grew by the incremental addition of lamellae and by the addition of successive triads during ontogeny. During the late Frasnian and the early Famennian, the important morphological variation within this species led to the description of three subspecies. An extensive sample of early FamennianIcriodus alternatuswas quantified using 2D biometric measurements and denticle counts on 2D pictures, showing that the subspecies mainly differed in their size range but not in their general morphology. A 3D morphometric analysis was further performed on a subsample to characterize the shape of the ontogenetically older part of the elements. During ontogeny, early valleys between denticles tended to be filled, and the asymmetry between the inner and outer side of the element increased. These ontogenetic trends are responsible for the morphologies formerly described as the subspeciesIc. alt. mawsonaeandIc. alt. helmsi. Slight discrepancies between temporal ranges of the subspecies may be achieved through variations in range of size reached by the elements as a response to environmental changes. Disparity along ontogeny seems to follow an “hourglass model” suggesting a shift from relatively loose developmental constraints to a pattern of growth modulated by functional constraints during occlusion.

Canalization and developmental stability of the yellow-necked mouse (Apodemus flavicollis) mandible and cranium related to age and nematode parasitism

BackgroundMammalian mandible and cranium are well-established model systems for studying canalization and developmental stability (DS) as two elements of developmental homeostasis. Nematode infections are usually acquired in early life and increase in intensity with age, while canalization and DS of rodent skulls could vary through late postnatal ontogeny. We aimed to estimate magnitudes and describe patterns of mandibular and cranial canalization and DS related to age and parasite intensity (diversity) in adult yellow-necked mice (Apodemus flavicollis).ResultsWe found the absence of age-related changes in the levels of canalization for mandibular and cranial size and DS for mandibular size. However, individual measures of mandibular and cranial shape variance increased, while individual measures of mandibular shape fluctuating asymmetry (FA) decreased with age. We detected mandibular and cranial shape changes during postnatal ontogeny, but revealed no age-related dynamics of their covariance structure among and within individuals. Categories regarding parasitism differed in the level of canalization for cranial size and the level of DS for cranial shape. We observed differences in age-related dynamics of the level of canalization between non-parasitized and parasitized animals, as well as between yellow-necked mice parasitized by different number of nematode species. Likewise, individual measures of mandibular and cranial shape FA decreased with age for the mandible in the less parasitized category and increased for the cranium in the most parasitized category.ConclusionsOur age-related results partly agree with previous findings. However, no rodent study so far has explored age-related changes in the magnitude of FA for mandibular size or mandibular and cranial FA covariance structure. This is the first study dealing with the nematode parasitism-related canalization and DS in rodents. We showed that nematode parasitism does not affect mandibular and cranial shape variation and covariance structure among and within individuals. However, parasite intensity (diversity) is related to ontogenetic dynamics of the levels of canalization and DS. Overall, additional studies on animals from natural populations are required before drawing some general conclusions.

Maternal cradling bias in baboons: The first environmental factor affecting early infant handedness development?

The most emblematic behavioral manifestation of human brain asymmetries is handedness. While the precise mechanisms behind the development of handedness are still widely debated, empirical evidences highlight that besides genetic factors, environmental factors may play a crucial role. As one of these factors, maternal cradling behavior may play a key role in the emergence of early handedness in the offspring. In the present study we followed 41 Papio anubis infants living in social groups with their mother for which direction (e.g., left- or right-arm) and degree of maternal cradling-side bias were available from a previous published study. We assessed hand preferences for an unimanual grasping task at three developmental stages: (A) 0-4, (B) 4-6, and (C) 9-10 months of age. We found that individual hand preferences for grasping exist as soon as the first months of age, with a population-level left-handedness predominance, being stable until 6months; to wit the period during which juveniles are mainly carried by their mothers. More importantly, this early postnatal handedness is positively correlated with maternal cradling lateralization. Interestingly, hand preferences assessed later in the development, once juveniles are no longer carried (i.e., from 9 to 10 months of age), are less dependent from the maternal cradling bias and less consistent with the earlier developmental stages, especially in infants initially cradled on the right maternal side. Our findings suggest that the ontogenetic dynamics of the infant's hand preference and its changes might ultimately rely on the degree of infant dependence from the mother across development.

Genetic changes involving the coral gastrovascular system support the transition between colonies and bailed-out polyps: evidence from a Pocillopora acuta transcriptome

BackgroundA coral colony is composed of physiologically integrated polyps. In stony corals, coloniality adopts a wide diversity of forms and involves complex ontogenetic dynamics. However, molecular mechanisms underlying coloniality have been little studied. To understand the genetic basis of coloniality and its contribution to coral ecology, we induced polyp bail-out in a colonial coral, Pocillopora acuta, and compared transcription profiles of bailed-out polyps and polyps in normal colonies, and their responses to heat shock and hyposalinity.ResultsConsistent with morphological formation of a gastrovascular system and its neural transmission and molecular transport functions, we found genetic activation of neurogenesis and development of tube-like structures in normal colonies that is absent in bailed-out polyps. Moreover, relative to bailed-out polyps, colonies showed significant overexpression of genes for angiotensin-converting enzymes and endothelin-converting enzymes. In response to hyperthermal and hyposaline treatments, a high proportion of genetic regulation proved specific to either bailed-out polyps or colonies. Elevated temperatures even activated NF-κB signaling in colonies. On the other hand, colonies showed no discernible advantage over bailed-out polyps in regard to hyposalinity.ConclusionsThe present study provides a first look at the genetic basis of coloniality and documents different responses to environmental stimuli in P. acuta colonies versus those in bailed-out polyps. Overexpression of angiotensin-converting enzymes and endothelin-converting enzymes in colonies suggests possible involvement of these genes in development of the gastrovascular system in P. acuta. Functional characterization of these coral genes and further investigation of other forms of the transition to coloniality in stony corals should be fruitful areas for future research.

Ontogenetic dynamics of the subepidermal spicule complex in Nudibranchia (Gastropoda): the case of Onchidoris muricata

Spicules are mineral-based biocomposites skeletal structures that are widely distributed among phylogenetically distant groups of invertebrates (Porifera, Cnidaria, Mollusca, Echinodermata). Subepidermal spicules are formed under the ectodermal epithelium and are characterized for all groups except mollusks (Aplacophora, Polyplacophora, Bivalvia), their spicules are located on the surface of the body. However, one group of mollusks (Gastropoda: Heterobranchia) have unique subepidermal spicules that have never been detected above the ectodermal epithelium and similarly to those characterized for Porifera, Cnidaria and Echinodermata. Understanding subepidermal spicule formation in mollusks could help solve the question on the origin of spicules. Spicules in nudibranchs have been described for more than 150 years, yet ontogenetic dynamics of spicules have never been studied and the full mechanism of their formation remains unknown. Herein we investigate the spicule formation in different stages of postlarval development of the nudibranch Onchidoris muricata (O.F. Müller, 1776). For the first time, ontogenetic transformations of the spicule complex are described using experiments and different morphological methods. Our studies demonstrate that spicules of O. muricata form in the subepidermal space in early developmental stages immediately after veliger settlement. A single spicule forms inside a huge vacuole within a sclerocyte and remains there throughout the entire life of the specimen. Signs of spicule or sclerocyte migration under the epithelium in postlarval development was not found. Spicules only form during larval settlement, increasing only in size as development furthers. For the first time, spicule mineralization zones were detected at the tips of the spicules as well as the presence of collagen I in the overall composition of the spicules. Thus, our findings suggest that spicules form by an ectodermal cell that emerged under the ectodermal epithelium during the earliest stages of postlarval development.

The importance of educating prospective dog owners on best practice for acquiring a puppy

The urgent need to reduce the number of dogs that are abandoned or relinquished to shelters is now widely recognised by the scientific community, veterinarians, dog trainers and breeders. The...

Ontogeny of the facial phenotypic variability in Mexican patients with 22q11.2 deletion syndrome

Background22q11.2 deletion syndrome is a medical condition that results from genomic loss at chromosome 22. Affected patients exhibit large variability that ranges from a severe condition to mild symptoms. In addition, the spectrum of clinical features differs among populations and even within family members. The facial features related to this syndrome are not an exception, and although part of its variation arises through development, few studies address this topic in order to understand the intra and inter-population heterogeneities. Here, we analyze the ontogenetic dynamics of facial morphology of Mexican patients with del22q11.2 syndrome.MethodsFrontal facial photographs of 37 patients (mean age = 7.65 ± 4.21 SE) with del22q11.2DS and 200 control subjects (mean age = 7.69 ± 4.26 SE) were analyzed using geometric morphometric methods. Overall mean shape and size differences between patients and controls were analyzed, as well as differences in ontogenetic trajectories (i.e. development, growth, and allometry).ResultsWe found that Mexican patients show typical traits that have been reported for the Caucasian population. Additionally, there were significant differences between groups in the facial shape and size when all the ontogenetic stages were considered together and, along ontogeny. The developmental and allometric trajectories of patients and controls were similar, but they differed in allometric scaling. Finally, patients and controls showed different growth trajectories.ConclusionThe results suggest that the typical face of patients with del22q11.2DS is established prenatally; nonetheless, the postnatal ontogeny could influence the dysmorphology and its variability through size-related changes.

Generalising from a regional case study: A dialogue with a hill

In this article, I propose a sociocultural psychological and dialogical approach of a Czech hill. I first briefly present how I came to study and built it into a dialogical case study. I then explore sociogenetic dynamics at stake – the historical and mythical existence of the hill, and how it reflects in its appearances and its uses – microgenetic dynamics – everyday encounters around the hill – and ontogenetic dynamics – the lives of people under the hill. Drawing on a series of sociocultural theoretical tools and on dialogical authors, I try to show how phenomena at each level of analysis are deeply affected by, or affecting, phenomena at other levels, and I highlight specific dialogical dynamics and patterns. I then discuss the more fundamental dialogical encounter that takes place between a researcher and such complex dialogical case study in terms of dialogical ethics. I finally reflect on issues of generalisation that may follow from as such case study, and on the dialogue it engages with current scientific debates.

Influence of l-type slow calcium channels blockers on cardiac, respiratory and motor activity at the intact and poisoned by physostigmine (eserine) of rats during the early ontogeny

The effects of calcium-channel blockers (CCBs) (verapamil, nifedipine) on heart rate, respiration rate and motor activity were studied in 3-30-day-old rats. The role of calcium channels in development of disturbances of a heart and respiratory rhythms after introduction to newborn rats of acetylcholinesterase (AChE) inhibitor of physostigmine was revealed. Parameters of functional activity of heart, respiratory and somatomotor systems in case of blockade of calcium channels were studied also under conditions of the activation of cholinoceptive structures caused by an injection to infant rats of AChE inhibitor after premedication by CCBs. It is shown that use of calcium channels blockers leads to development of bradycardia, and verapamil causes more expressed disturbance of a heart rhythm in rats of younger age, while blockade of dihydropyridinic receptors by nifedipine has no ontogenetic specifics. Similar ontogenetic dynamics concerns also reaction of respiratory system. Verapamil have a detrimental effect on respiration, up to a stop, in 3-7-day-old and to a lesser extent in 16-30-day-old infant rats. Nifedipine slightly reduces a respiration rate at younger infant rats, but raises it at the mature rats. The nifedipine injection more in comparison with verapamil changes the level and a pattern of motor activity. Preliminary blockade of calcium channels does not render significant change of reaction at the subsequent introduction of physostigmin.

Integrating transcriptomic network reconstruction and eQTL analyses reveals mechanistic connections between genomic architecture and Brassica rapa development.

Plant developmental dynamics can be heritable, genetically correlated with fitness and yield, and undergo selection. Therefore, characterizing the mechanistic connections between the genetic architecture governing plant development and the resulting ontogenetic dynamics of plants in field settings is critically important for agricultural production and evolutionary ecology. We use hierarchical Bayesian Function-Valued Trait (FVT) models to estimate Brassica rapa growth curves throughout ontogeny, across two treatments, and in two growing seasons. We find genetic variation for plasticity of growth rates and final sizes, but not the inflection point (transition from accelerating to decelerating growth) of growth curves. There are trade-offs between growth rate and duration, indicating that selection for maximum yields at early harvest dates may come at the expense of late harvest yields and vice versa. We generate eigengene modules and determine which are co-expressed with FVT traits using a Weighted Gene Co-expression Analysis. Independently, we seed a Mutual Rank co-expression network model with FVT traits to identify specific genes and gene networks related to FVT. GO-analyses of eigengene modules indicate roles for actin/cytoskeletal genes, herbivore resistance/wounding responses, and cell division, while MR networks demonstrate a close association between metabolic regulation and plant growth. We determine that combining FVT Quantitative Trait Loci (QTL) and MR genes/WGCNA eigengene expression profiles better characterizes phenotypic variation than any single data type (i.e. QTL, gene, or eigengene alone). Our network analysis allows us to employ a targeted eQTL analysis, which we use to identify regulatory hotspots for FVT. We examine cis vs. trans eQTL that mechanistically link FVT QTL with structural trait variation. Colocalization of FVT, gene, and eigengene eQTL provide strong evidence for candidate genes influencing plant height. The study is the first to explore eQTL for FVT, and specifically do so in agroecologically relevant field settings.

Internal disorder pattern in mental development disorder: features and dynamics in childhood and adolescence

The article presents the results of theoretical and empirical analysis of the ontogenetic dynamics of the internal disorder pattern in mental development disorder. It is revealed that the self-attitude and self-esteem of children with mental development disorder depends on the form of education, has a special pace, goes from dependence to independence, from unconditional positivity to criticality. The study on 60 children and adolescents revealed an increase in the level of awareness of qualities, the development of gender and family identity, maintaining a high and medium level of self-relationship. The age dynamics of the cognitive and physical component of the internal disorder pattern is determined. Recognition of the violation and the level of knowledge increases in primary school, in adolescence decreases. It is suggested that the denial of their own violations occur. In adolescents with mental retardation there is a decrease in sensitivity, suggestibility, fixation on their own bodily sensations.

The benefits of the third dimension – What can we learn from the z-axis in 3D geometric morphometrics based on sailfin silversides (Telmatherinidae)?

The benefits of the third dimension – What can we learn from the z-axis in 3D geometric morphometrics based on sailfin silversides (Telmatherinidae)?

Age-Related Dynamics of Structural Organization of the Metacognitive Processes and Traits of Personality

Introduction. The paper: (a) considers theoretical and empirical studies on the age-related dynamics of structural organization of the metacognitive processes and traits of personality; (b) focuses on quantitative indices of structural organization of the metacognitive processes and traits of personality for various age groups; and (c) describes general ontogenetic dynamics of metacognitive and meta-regulative processes and traits.
 Methods. An empirical study was carried out at two levels that mutually reinforced each other. Specific patterns of the dynamics of certain parameters of metacognitive processes and traits of personality were identified and interpreted at the analytical level. The structural level of the study included two large methodological modules—namely, the diagnostic and statistical module, and the structural and psychological one.
 Results. The study revealed specific characteristics and patterns underlying the genetic and ontogenetic dynamics of metacognitive and meta-regulative personality traits and processes. The indices of structural organization of parameters of the metacognitive processes and traits of personality changed depending on age. Research findings are presented in tables, structuregrams, and graphs.
 Discussion. The results of the empirical study were considered in the context of the main approaches to studying the metacognitive processes and traits of personality, including the author’s approach. The parameters of the main metacognitive and meta-regulative processes do not change significantly between the age of 20 and 62. However, there is a significant age-related increase in the degree of structural organization of the main parameters of the metacognitive traits and processes of personality. With the increase in participants’ age the general dynamics of the index of coherence of the parameters structure of the metacognitive processes and traits is most pronounced. Besides, the dynamics of the divergence index is significantly less pronounced in all the age groups. It is established that the index of overall organization, which is based on the interaction and mutual co-organization of meta-regulative and metacognitive processes, has the most prominent dynamics.
 Highlights
 
 Given the lack of critical attention to the relationships among basic provisions of metacognitivism, developmental, and genetic psychology, studying the patterns of age-related dynamics of the metacognitive processes and traits of personality is an imperative.
 The individual measures of the extent of manifestation of main metacognitive and meta-regulatory processes do not change substantially in ontogenetic development.
 The general increase in the degree of the structural organization of metacognitive and meta-regulative processes and traits of personality underlies their genetic dynamics, which essentially enables the implementation of two main cognitive functions—the compensatory and the resource supplying.
 All the discovered structural changes in the metacognitive processes and traits of personality during ontogenetic development represent a specific variation of a systemic genetic development, as the general increase in the degree of its structural organization serves the purpose of its systemic manifestation, which is basic for the psyche as a whole.

Regeneration of the skin pigment system during larval development of the clawed frog

We demonstrate regeneration capability of the skin pigment system of clawed frog larvae after local damage to melanophores without skin rupture. The contribution to recovery of pigmentation of the injured area of de novo differentiation of melanophores is compared to contribution of mitotic division of undamaged melanophores localized on the boundaries of the injured area. The regeneration process is observed during various stages of pigment system development of larvae. We establish that, compared to ontogenetic dynamics, pigmentation development in animals is more intense during the regeneration.

Dynamics of the fecal corticosterone content in males of red, gray-sided, and bank voles (Myodes, Rodentia, Cricetidae) upon sexual maturation

The dynamics of the corticosterone content in feces of males are analyzed in red (M. rutilis), graysided (M. rufocanus), and bank (M. glareolus) voles. The ontogenetic dynamics of the corticosterone content in feces of these species collected on the 20th and 40th days are shown to depend differently on the month of their birth. At the same time, the fecal corticosterone content is similar in males of all species that originated from litters with various sizes and shares of males in it. The fecal corticosterone content in the 40-day-old animals is related to the month of birth for all three species. The species-specific features of adrenal activity are found on the 20 and 40 days after the birth of animals. The males of the May and August generations have the highest corticosterone level in feces. The fecal corticosterone content in the red vole males also correlates with the social environs; in addition, socially isolated single males have a higher rate of maturation. The fecal corticosterone in the gray-sided vole males related to the season of start maturation and to the date of birth negatively correlates with sexual maturation. The mature males of those species are found only among the spring–early summer generation. Thus, population factors are important only for maturing males that were born in the current year. Moreover, sexual maturation at a high population density is accompanied by a smaller decrease in the adrenocortical activity.