FOOD AS A CONTROL OF A POPULATION OF WHITE-FOOTED MICE, PEROMYSCUS LEUCOPUS NOVEBORACENSIS (FISCHER)

This study examined the impact of the COVID-19 pandemic on marriage, divorce, birth, and death rates using the Poisson regression model and an interrupted time-series Poisson regression model. Before the pandemic, marriage and birth rates were decreasing, while divorce and death rates were increasing, with only the trend in birth rates being statistically significant. The immediate effect of the pandemic was a significant decrease in the divorce rate, but there were non-significant effects on birth and marriage rates. However, in the months following the onset of the pandemic, there was a statistically significant sustained effect on increasing death and divorce rates. Forecasts based on pre-pandemic data showed that by the end of 2020, marriage, divorce, death, and birth rates were higher compared to pre-pandemic levels. In conclusion, the pandemic has greatly impacted society, particularly in terms of death and divorce rates. Birth rates were not immediately affected to the time lag between decisions and actual births. Fear of COVID-19 may have increased death rates as people avoided seeking medical help. Vaccination and effective treatment strategies are vital in reducing the pandemic's impact on mortality. Supporting families financially is important due to the role of economic issues in couples’ decisions.

The authors show that the dynamics of the birth rate of the BSSR population is characterized by a gradual drop from the mid-1920s to mid-1930s to a minimum in 1933–1934, with fluctuations within the limits of the trend; the death rate is generally stable with the similar fluctuation within the trend. The dynamics of the birth and death rates in 1933–1934 are shown as population waves with a maximum (fall) in seasonal birth (death) rate is compensated by its seasonal increase (drop). The death rate increase and negative natural growth of the population in the urban environment are localized and insignificant. For the majority of the BSSR, its demographic indicators are not pointing to a demographic crisis: either a high birth rate with a relatively low death rate was prevailing, or a drop in the birth rate didn’t result in the abrupt natural growth decrease, which remained positive. A lower birth rate and a higher death rate can be attributed to different causes other than famine. The only two regions with a high death rate and a negative natural growth of population were Narovlyansk and Elsk — two districts on the border with Ukraine. This is the exact area of the BSSR affected by the famine as confirmed by the official papers and the demographic indicators. The loss of the BSSR population due to the drop in birth rate in 1932–1934 is approximately 64,000 people; the direct decrease due to the death rate is 4,100 people; both are within the limits of the trend fluctuations and cannot be considered as a demographic crisis. In general, the indicators in the BSSR do not point to the demographic catastrophe.

Every important process in population ecology ultimately influences either fecundity or survival, so reliable methods for estimating birth and death rates in the field are key to understanding what features of the environment regulate population dynamics. In 1960 W. T. Edmondson, after visiting the Istituto Italiano de Idrobiologia in Pallanza while on sabbatical leave from the University of Washington, published a remarkably simple method for estimating zooplankton instantaneous birth rate, b, based on females’ mean clutch size and egg development time as a function of temperature (Edmondson 1960). He further pointed out that, taken together with population instantaneous rate of change, r, calculated from the population sizes on consecutive dates, instantaneous death rate could be calculated as d = r − b.

Implementation of the "Concept of demographic policy of the Russian Federation for the period until 2025" and Priority national projects in health and demography helped to reduce mortality and increase birth rate. However, these processes in rural areas had their own characteristics due to the long-term systemic crisis. Purpose: to assess the state and trends in demographic development of the rural district of the Krasnoyarsk region. Material and methods. The paper uses data of the State statistics for the period 2010-2018. The main demographic indicators of the Nizhneingashsky district of the Krasnoyarsk region were studied: population size, population structure by age and gender, birth and death rates. Results. The district population has a long-term sustainable tendency towards decreasing (15.9% during the study period). It is mainly due to the migration outflow of the working – age population, the size of which decreased by 24.6 %. The district mortality rate is high (16.7‰), however, during the study period it has dropped by 30.3 %. There is an ongoing tendency towards reduction in the share of people of working ages (up to 55.9%) in the population structure, primarily due to moving to other territories, and increase in the share of the elderly and senile (up to 23.9%), which makes it possible to classify this area as the one with a very high level of demographic old age population. Analysis of indicators of the special birth rate F allows us to characterize it as low (˂ 64‰). The growth rate of this indicator added up to 20.9 % in 2013 compared to 2010, while it decreased by 45.9% from 2013 to 2018. From 2010 to 2017, the total birth rate in the Nizhneingashsky district decreased by -1.02‰ (∆b), or 7.5 %. Conclusion. The ongoing decline in the share of fertile females is the main demographic factor that has spurred the decline in the birth rate since 2013. Opening new jobs in the district will stimulate the influx of people from other territories as well as reduce the migration outflow of the working-age population, rather increasing the population then just preserving its size. Increase in the share of the working-age population of reproductive age will contribute to the increased birth rate, because it is traditionally higher in rural areas. Improving demographic situation in the district requires development of socio-economic measures aimed at stimulating the birth of the third and subsequent children.

This article provides a brief characterization of the dynamics of population size and age structure in the Arkhangelsk and Murmansk regions, the Nenets Autonomous Okrug, and the republics of Komi and Karelia. The main aspects of natural and migration movements of the population are examined. The mortality rates from major groups of diseases (circulatory system diseases, neoplasms) and conditions (external causes of death) are analyzed. The aim of the study is to analyze the demographic indicators of the Arkhangelsk and Murmansk regions, the Nenets Autonomous Okrug, and the republics of Komi and Karelia to assess the dynamics of demographic prospects. Materials and methods. Data from the Federal State Statistics Service databases for the Arkhangelsk and Murmansk regions, the Nenets Autonomous Okrug, and the republics of Komi and Karelia, as well as the Unified Interdepartmental Information and Statistical System for the period from 2013 to 2022, were used as materials. To assess demographic processes, values of general birth and death rates (per 1,000 permanent population), natural increase (or decrease) coefficients, and migration increase (or decrease) coefficients (per 1,000 permanent population) were calculated. Results. In the regions under consideration, a clear trend towards depopulation has been observed from 2013 to 2022 due to declining birth rates, increasing mortality, and migration. This trend has most strongly affected the Republic of Komi and the Arkhangelsk region, with a combined demographic loss of –17.5 and –16.77, respectively. Until 2019, there was an increase in the proportion of pensioners, followed by a decrease, indicating an aging population «from below.» The Nenets Autonomous Okrug stands out with positive natural growth and a high birth rate (11.6 per 1,000 in 2022 compared to 8.9 nationwide). The Arctic zone is characterized by a lower life expectancy than the national average. From 2012 to 2022, a steady decline in birth rates was noted. The total fertility rate in the Arkhangelsk and Murmansk regions is close to the national average, while in the Nenets Autonomous Okrug it is significantly higher: in 2022 it was 11.6 per 1,000 population compared to 8.9 per 1,000 nationwide. Mortality among the population showed a declining trend since 2012; however, after 2019, this indicator began to rise. The main causes of death in the Arctic regions are diseases of the circulatory system, with rates exceeding the national averages. In 2020 and 2021, due to the COVID-19 pandemic, there was an increase in the standardized mortality rate. The Arkhangelsk region and the Nenets Okrug have high mortality rates from external causes, related to unfavorable living conditions. Mortality rates from neoplasms are close to national averages, with the highest rates in the Republic of Karelia and Arkhangelsk region (254.8 and 248.3 per 1,000 respectively in 2022). Conclusions. All studied regions face a clear trend towards depopulation caused by declining birth rates, increasing mortality, and migration processes, which have particularly affected the Republic of Komi and the Arkhangelsk region. There is an increase in the proportion of pensioners, indicating an aging population. However, the Nenets Autonomous Okrug stands out with positive natural growth and an increase in the number of older individuals due to attractive living conditions. Mortality in the region showed a declining trend until 2019, after which it began to rise, especially as a result of the COVID-19 pandemic. The main causes of death are related to diseases of the circulatory system, neoplasms, and other external factors. Thus, the issue of demographic crisis requires a comprehensive approach to improving living conditions, increasing birth rates, and reducing mortality in these regions

Reply to evolutionary flux of canonical microRNAs and mirtrons in Drosophila.

Birth and death rates are two major components of population growth. A time series analysis of birth and death rates in Tripura state was conducted during 1971-89 using rates taken from the Basic Statistics of Northeastern Region, Northeastern Council Secretariat, Shillong. The analysis found that both birth and death rates in the state were changing over time in both urban and rural areas. The birth rate, however, is declining more slowly than the death rate. Birth rates in the state over the period for the overall population, rural areas, and urban centers are more than twice as large as the death rates in any given year, one of the main reasons for population growth in Tripura state. A high rate of immigration from the neighboring country is another likely reason for rapid population growth in the state.

Vital rate in India being problematic from past many years, which is affected by many factors prevailing in the country, the study attempts to find out the effect of economic growth on the death and birth rate of the country. GDP is considered as an indicator of economic growth rate of the country for the study. The data regarding GDP, death rate, birth rate have been collected from the secondary sources which are authenticated by the organization of India like RBI which is the foundation from where we had taken the data of death and birth rate. NITIAYOG is the intermediate for the data regarding GDP of the nation. The correlation and regression analysis have been used to find out the temperament for both the death and birth rate correspondingly. A strapping negative correlation is established for in cooperation of death and birth rate with admiration to GDP. Financial statement for GDP is a foundation of revolutionize in the death rate of the motherland which is 95% and for nativity rate of the nation state is 97% that sandwiched between the periods of 2011-2018. KEYWORDS: GDP, Birth Rate, Death Rate, Nitiayog, RBI

1. In the Klostersee in southern Federal Republic of Germany, Daphnia hyalina (H) and D. cucullata (C) have coexisted for at least 50 years. in 1971/72 they exhibited seasonal density fluctuations which are in accord with predictions from a model based on alternative adaptations of two competitors to natality (food utilization) and mortality (escape from enemies) in an environment that fluctuates with respect to food and intensity of predation. 2. In general, both species fluctuate in a similar fashion. Birth (b), death (m) and growth rates (r) are correlated between both species. Furthermore, in either species birth and death rates are positively correlated. But the birth and death rates of H are about 1.7 times as large as those of C, resulting in stronger density fluctuations of H. This fact, in combination with the seasonal course of the b/m-ratio produces a marked seasonal segregation of the abundances of both species, with H dominating in early summer and C dominating in autumn and winter. 3. In both species, the fluctuations of the growth rate are mainly determined by fluctuations of the death and not the birth rate. 4. Birth and death rates are much higher in the warm season than in the cold season, but births dominate in the cold, deaths in the warm season. Evidence is presented that mortality is mainly due to predation by fish. 5. The differences of natality and mortality which cause the seasonal segregation between the two species, exist independent of seasonal temperature fluctuations. But, there is an additional temperature effect accentuating the differences. 6. A partial correlation analysis shows that by measuring the density of one species and lake temperature, the density difference between both species and, hence, the density of the second species can be predicted with good precision. 7. The importance of the observed temporal segregation and other factors for the stabilized coexistence of both species is discussed.

Four theoretical types of population growth cycles are presented. Growth cycles from lower death rates in combination with stationary birth rates seem to have characterized preindustrial societies. A growth cycle resulting from a lag of the birth rate behind the death rate while both are declining appears to have accompanied industrialization. Future growth cycles in industrialized societies will probably depend upon increased birth rates in combination with "sticky" death rates. The fourth theoretical cycle in which death rates lag behind birth rates while both increase has neither precedent nor prospect.

The article presents an ethno-demographic characteristic of the population of Chukotka from the 18th century to the present. Until now. The source base of the study is statistical materials, published documents concerning the number and characteristics of settlement, the way of life of the indigenous people of Chukotka, scientific literature on the problems of ethnic demography. The paper presents a comparative analysis of the results of surveys and censuses of the population of Chukotka for 1897, 1926/27, 1939, 1959, 1970, 1979, 1989, 2002, 2010 (and partly 2020) The main components of the change in the population and the national composition of the region (natural, general, migration population growth) in the Soviet and post-Soviet periods are characterized. According to the data of the 2002 and 2010 censuses, the number of Chukchi, Koryaks, and Yukagirs increased during the intercensal period; the number of Eskimos, Evens, Chuvans and Kereks decreased. The ambiguous demographic picture among indigenous peoples is connected, on the one hand, with the real processes of depopulation in some of them, and, on the other hand, with the qualitative side of the census. The main reasons for the decline in the number of indigenous people of Chukotka: problems with natural growth against the background of high birth and death rates. The decline in the birth rate is associated with a change in traditional attitudes towards having many children, a decrease in marriage rates and an increase in the proportion of single-parent families. Although the Chukchi, Eskimos, Evens and Yukagirs are classified by demographers as a group with an increased birth rate. The demographic situation is also influenced by the increase in the number of mixed marriages. It should be noted that despite the decline in the birth rate among the indigenous inhabitants of Chukotka, its rates are still higher than among the visiting population of the region. The increase in mortality rates in Chukotka is due to a change in the age structure of the inhabitants, since in the 1990s a significant part of the able-bodied population left the district, the growth in the share of indigenous people in the structure of total mortality increased. The life expectancy of indigenous peoples is significantly lower than the national and regional indicators. The current ethno-demographic situation in Chukotka will become clear after the publication of the results of the 2020 All-Russian Population Census. It can be stated with confidence that there is a significant decrease in the number of permanent residents of the region, and the number of indigenous people in the total population of the ChAO continues to increase.

The importance of stochastic processes in relation to problems of population growth was pointed out by W. Feller [1] in 1939. He considered among other examples the "birth-and-death" process in which the expected birth and death rates (per head of population per unit of time) were constants, $\lambda_o$ and $\mu_o$, say. In this paper, I shall give the complete solution of the equations governing the generalised birth-and-death process in which the birth and death rates $\lambda(t)$ and $\mu(t)$ may be any specified functions of the time. The mathematical method employed starts from M. S. Bartlett's idea of replacing the differential-difference equations for the distribution of the population size by a partial differential equation for its generating function. For an account of this technique,$^1$ reference may be made to Bartlett's North Carolina lectures [2]. The formulae obtained lead to an expression for the probability of the ultimate extinction of the population, and to the necessary and sufficient condition for a birth-and-death process to be of "transient" type. For transient processes the distribution of the cumulative population is also considered, but here in general it is not found possible to do more than evaluate its mean and variance as functions of $t$, although a complete solution (including the determination of the asymptotic form of the distribution as $t$ tends to infinity) is obtained for the simple process in which the birth and death rates are independent of the time. It is shown that a birth-and-death process can be constructed to give an expected population size $\bar n_t$ which is any desired function of the time $t$, and among the many possible solutions the unique one is determined which makes the fluctuation, Var$(n_t)$, a minimum for all. The general theory is illustrated with reference of two examples. The first of these is the $(\lambda_0, \mu_1t)$ process introduced by N. Arley [3] in his study of the cascade showers associated with cosmic radiation; here the birth rate is constant and the death rate is a constant multiple of the "age, $t$, of the process. The $\bar n_t$-curve is then Gaussian in form, and the process is always of transient type. The second example is provided by the family of "periodic" processes, in which the birth and death rates are periodic functions of the time $t$. These appear well adapted to describe the response of population growth (or epidemic spread) to the influence of the seasons.

We examined the population dynamics and seasonal change in body size of a population of Daphnia galeata mendotae experiencing strong vertebrate predation. The intensity of food limitation was quantified seasonally by in situ food addition. We also collected live animals early and late in the summer for laboratory studies designed to estimate genetic variation and seasonal change in life‐history traits for the population.The population was characterized by nearly equal short‐term birth and death rates that were strongly correlated with population density, suggesting density dependence. The population generally exhibited very high birth and death rates and no significant response to experimental food addition. The one exception was June 1988, when the population achieved high densities and exhibited strong food limitation. Throughout both summers, minimal and average body sizes of adults decreased.Laboratory studies document substantial genetic variation for body size and other life‐history traits among animals collected early in summer. By late summer, however, there was little genetic variation for these same traits. Furthermore, clones collected early in summer were genetically larger in body size at birth and maturity than clones collected in late summer. We interpret these results as indicating natural selection for body size.

In this article we contemplate the dynamics of an additional food-provided prey-predator system. We assume that the behavior of cooperative predators induces fear in prey, which radically affects the prey's birth and death rates. We observe that the structural instability imposed by strong cooperative hunting among predators goes away with higher intensities of fear levels affecting the prey's reproductive output and mortality. High levels of prey refuge are not conducive to the survival of predators. In such a situation, adequate supply of high-quality additional food is favorable regarding the persistence and stability of the system. Interestingly, the system potentially exhibits two stable configurations under identical ecological conditions by allowing different bifurcation scenarios, including saddle-node and backward bifurcations, and associated hysteresis effects with prey refuge along with additional food quantity and quality. In the stochastic environment, the system experiences critical transitions through bifurcation-induced tipping events with time-varying additional food for predators. Enhanced disturbance events promote noise-induced switching and tipping events. Finally, our investigation explores whether impending population crashes resulting from the variability of additional food quantity and quality can reliably be predicted using early warning signals in the context of redshifted noise. Overall, our results may provide insights for finding control strategies in the context of community ecology.

The relationship of the demographic parameters of a population to its ecological niche constitutes one of the central problems of population biology. A most interesting theoretical notion pertinent to this problem is r- and K-selection (MacArthur 1962; Cody 1966; MacArthur and Wilson 1967; Hairston, Tinkle, and Wilbur 1970; Roughgarden 1971). The central idea of r- and K-selection is that populations living in environments imposing high density-independent (D.I.) mortality (r-strategists) will be selectively favored to allocate a greater proportion of resources to reproductive activities at the cost of their capabilities to propagate under crowded conditions, and conversely, populations living in environments imposing high density-dependent (D.D.) regulation (K-strategists) will be selectively favored to allocate a greater proportion of resources to nonreproductive activities, at the cost of their capabilities to propagate under conditions of high D.I. mortality. From the argument just stated, it may be deduced that the birth rate of an r-strategist will be greater than that of a related K-strategist. However, increased birth rate under conditions of high D.I. mortality is not sufficient evidence for an r-strategy, because, as demonstrated later in this paper, any increase in D.I. mortality must by itself produce a new equilibrium of birth and death rates at higher values of both. The crucial evidence needed for r- and K-selection is whether an organism is allocating a greater proportion of its resources to reproductive activities (r-strategists) than another related one (K-strategist) under any and all D.D. and D.I. mortality conditions.