Types Of Population Dynamics Research Articles

Insights into drivers of mobility and cultural dynamics of African hunter-gatherers over the past 120 000 years.

Humans have a unique capacity to innovate, transmit and rely on complex, cumulative culture for survival. While an important body of work has attempted to explore the role of changes in the size and interconnectedness of populations in determining the persistence, diversity and complexity of material culture, results have achieved limited success in explaining the emergence and spatial distribution of cumulative culture over our evolutionary trajectory. Here, we develop a spatio-temporally explicit agent-based model to explore the role of environmentally driven changes in the population dynamics of hunter-gatherer communities in allowing the development, transmission and accumulation of complex culture. By modelling separately demography- and mobility-driven changes in interaction networks, we can assess the extent to which cultural change is driven by different types of population dynamics. We create and validate our model using empirical data from Central Africa spanning 120 000 years. We find that populations would have been able to maintain diverse and elaborate cultural repertoires despite abrupt environmental changes and demographic collapses by preventing isolation through mobility. However, we also reveal that the function of cultural features was also an essential determinant of the effects of environmental or demographic changes on their dynamics. Our work can therefore offer important insights into the role of a foraging lifestyle on the evolution of cumulative culture.

Microbial population dynamics decouple growth response from environmental nutrient concentration

How the growth rate of a microbial population responds to the environmental availability of chemical nutrients and other resources is a fundamental question in microbiology. Models of this response, such as the widely used Monod model, are generally characterized by a maximum growth rate and a half-saturation concentration of the resource. What values should we expect for these half-saturation concentrations, and how should they depend on the environmental concentration of the resource? We survey growth response data across a wide range of organisms and resources. We find that the half-saturation concentrations vary across orders of magnitude, even for the same organism and resource. To explain this variation, we develop an evolutionary model to show that demographic fluctuations (genetic drift) can constrain the adaptation of half-saturation concentrations. We find that this effect fundamentally differs depending on the type of population dynamics: Populations undergoing periodic bottlenecks of fixed size will adapt their half-saturation concentrations in proportion to the environmental resource concentrations, but populations undergoing periodic dilutions of fixed size will evolve half-saturation concentrations that are largely decoupled from the environmental concentrations. Our model not only provides testable predictions for laboratory evolution experiments, but it also reveals how an evolved half-saturation concentration may not reflect the organism's environment. In particular, this explains how organisms in resource-rich environments can still evolve fast growth at low resource concentrations. Altogether, our results demonstrate the critical role of population dynamics in shaping fundamental ecological traits.

Boom-bust population dynamics increase diversity in evolving competitive communities

The processes and mechanisms underlying the origin and maintenance of biological diversity have long been of central importance in ecology and evolution. The competitive exclusion principle states that the number of coexisting species is limited by the number of resources, or by the species’ similarity in resource use. Natural systems such as the extreme diversity of unicellular life in the oceans provide counter examples. It is known that mathematical models incorporating population fluctuations can lead to violations of the exclusion principle. Here we use simple eco-evolutionary models to show that a certain type of population dynamics, boom-bust dynamics, can allow for the evolution of much larger amounts of diversity than would be expected with stable equilibrium dynamics. Boom-bust dynamics are characterized by long periods of almost exponential growth (boom) and a subsequent population crash due to competition (bust). When such ecological dynamics are incorporated into an evolutionary model that allows for adaptive diversification in continuous phenotype spaces, desynchronization of the boom-bust cycles of coexisting species can lead to the maintenance of high levels of diversity.

Составление карты субрегиональных типов динамики населения Иркутской области

In the article the results of research of specifics of digital mapping of spatial and temporal dynamics of the population in a sparsely populated region (on the example of Irkutsk region). The study area is mainly inhomogeneously populated, with a sparse network of settlements (mainly spatially contiguous). The exception is the south territory along the Trans-Siberian Railway. To identify subregional and local characteristics of distribution of the population, the famous dazimetric method of V.P. Semyonov-Tyan-Shansky was used (adjusted for the features of sparsely populated regions). The boundaries of the areal inhabited territory are defined by the method of spots with a buffer radius of 3 km from the borders of populated locality. The overlapping spots, form a solidly populated space, from which depart linear-band elements of settlement, formed on the base of settlements dislocated along the paths of old communications (rivers and roads). The article presents a geoinformation methodology for collecting and processing available statistical data about population movement. In contrast to usual mapping, the calculation of general population dynamics, growth component and subsequent mapping were implemented not in municipal districts, urban and rural settlements, but within localities and settlement areas formed by them, ignoring official boundaries. The mapping allowed to identify patterns and detailing of the dynamics of the population considering the features of real distribution of the population in Irkutsk region. There is a discrepancy between the tendencies of demographic and economic development. The growth of resource complex comes at the expense of the northern periphery of the region, and the general direction of the population system development—growth of demographic potential around the regional center in conditions of depopulation of the periphery. The experience of mapping subregional types of population dynamics in Irkutsk region can be used in mapping similar regions.

Is There a Relationship between the Chitty Effect and the Types of Population Dynamics?

Thirty-year studies of populations of eight shrew species in the Middle Yenisei taiga have shown that at the late 20th century the population dynamics had a pronounced cyclic character, but in the 21st century cyclic dynamics changed with fluctuating one. The analysis of the dependence of the animal body weight on the population density have revealed that under cyclic dynamics at the peaks of the population, the animal's body weight is significantly higher than that at population decline, i.e., the corollary from the Chitty hypothesis (the Chitty effect) is observed. In populations with fluctuating dynamics such regularity has not been observed.

Neutral and niche forces as drivers of species selection

The evolutionary and ecological processes behind the origin of species are among the most fundamental problems in biology. In fact, many theoretical hypothesis on different type of speciation have been proposed. In particular, models of sympatric speciation leading to the formation of new species without geographical isolation, are based on the niche hypothesis: the diversification of the population is induced by the competition for a limited set of available resources. Interestingly, neutral models of evolution have shown that stochastic forces are sufficient to generate coexistence of different species. In this work, we put forward this dichotomy within the context of species formation, studying how neutral and niche forces contribute to sympatric speciation in a model ecosystem. In particular, we study the evolution of a population of individuals with asexual reproduction whose inherited characters or phenotypes are specified by both niche-based and neutral traits. We analyze the stationary state of the dynamics, and study the distribution of individuals in the whole phenotypic space. We show, both numerically and analytically, that there is a non-trivial coupling between neutral and niche forces induced by stochastic effects in the evolution of the population allowing the formation of clusters, that is, species in the phenotypic space. Remarkably, our framework can be generalized also to sexual reproduction or other type of population dynamics.

Identification of the Type of Population Dynamics of the Green Oak Tortrix with a Generalized Discrete Logistic Model

Identification of the Type of Population Dynamics of the Green Oak Tortrix with a Generalized Discrete Logistic Model

Seasonal changes in the Phrynocephalus Guttatus Guttatusgmel. population age and sex structure

The autumn studies of the Phrynocephalus guttatus guttatus Gmel. population in the Astrakhan semideserts (August 2011 and August - September 2016) revealed the following features of its age and sex structure. The autumn settlement of the species reliably splits into several age groups: 1-2 group of young, 2-4 groups of females and 2-5 group of males. In the fall season the settlement is dominated by males, especially great was the numerical superiority of the males in the fall season of 2016.The lack of immature individuals, the significant prevalence of older age groups and the predominance of males among adult animals in the autumn 2016 create the picture of the population depression. The unsustainable type of population dynamics, typical for short-living species, may be one of the characteristics that stimulates the processes of population depression. Almost complete replacement of the population is likely to occur both in two or 3-4 years.

Plant population processes in the course of forest succession in abandoned meadows. II. Demography of succession promotors

The studies on populations in the course of forest succession in abandoned meadows (15 ha) were conducted for 15 years (1974-1988). It was found that the population size of species which took part in the successional process either changed directionally, i.e. developmental phases of populations conformed to the succession stages, or fluctuated, when no direct relationship between both was determined. Three types of population dynamics were distinguished: 1) developmental cycle (increase, decrease and equilibrium in population size) lasted as long as forest comeback; 2) developmental cycle accompanied one successional phase; 3) species appeared in cycles, as a series of populations in the course of long-term succession. Following species groups were distinguished regarding their role in the vegetation transformation in unmown meadows: 1) long-term promotors, present throughout succession and affecting both, changes in meadow vegetation, and initiation of tall-herb and brushwood communities; 2) short-term promotors, present in the first successional phases, especially at the stage of transformation of meadow phytocoenoses; 3) stenoecious promotors, confined to various depressions, periodically or permanently overlogged. All succession promotors were characterized by: high fecundity, ability to form polycormones and clones, strong and long-lived underground organs, modification of lifecycles, dual reproductive mode.

Population Dynamics of Metastable Growth-Rate Phenotypes

Neo-Darwinian evolution has presented a paradigm for population dynamics built on random mutations and selection with a clear separation of time-scales between single-cell mutation rates and the rate of reproduction. Laboratory experiments on evolving populations until now have concentrated on the fixation of beneficial mutations. Following the Darwinian paradigm, these experiments probed populations at low temporal resolution dictated by the rate of rare mutations, ignoring the intermediate evolving phenotypes. Selection however, works on phenotypes rather than genotypes. Research in recent years has uncovered the complexity of genotype-to-phenotype transformation and a wealth of intracellular processes including epigenetic inheritance, which operate on a wide range of time-scales. Here, by studying the adaptation dynamics of genetically rewired yeast cells, we show a novel type of population dynamics in which the intracellular processes intervene in shaping the population structure. Under constant environmental conditions, we measure a wide distribution of growth rates that coexist in the population for very long durations (>100 generations). Remarkably, the fastest growing cells do not take over the population on the time-scale dictated by the width of the growth-rate distributions and simple selection. Additionally, we measure significant fluctuations in the population distribution of various phenotypes: the fraction of exponentially-growing cells, the distributions of single-cell growth-rates and protein content. The observed fluctuations relax on time-scales of many generations and thus do not reflect noisy processes. Rather, our data show that the phenotypic state of the cells, including the growth-rate, for large populations in a constant environment is metastable and varies on time-scales that reflect the importance of long-term intracellular processes in shaping the population structure. This lack of time-scale separation between the intracellular and population processes calls for a new framework for population dynamics which is likely to be significant in a wide range of biological contexts, from evolution to cancer.

Population dynamics and utilitarian criteria in the Lucas–Uzawa Model

This paper introduces population growth in the Uzawa–Lucas model, analyzing the implications of the choice of the welfare criterion on the model's outcome. Traditional growth theory assumes population growth to be exponential, but this is not a realistic assumption (see Brida and Accinelli, 2007). We model exogenous population change by a generic function of population size. We show that a unique non-trivial equilibrium exists and the economy converges towards it along a saddle path, independently of population dynamics. What is affected by the type of population dynamics is the dimension of the stable manifold, which can be one or two, and when the equilibrium is reached, which can happen in finite time or asymptotically. Moreover, we show that the choice of the utilitarian criterion will be irrelevant on the equilibrium of the model, if the steady state growth rate of population is null, as in the case of logistic population growth. Then, we show that a closed-form solution for the transitional dynamics of the economy (both in the case population dynamics is deterministic and stochastic) can be found for a certain parameter restriction.

Types of population dynamics in settlements of Zaplanje area

The aim of this article is to present the main directions of changes in the spatial-demographic settlements organization of Zaplanje, which, due to rapid demographic recession since the 60s of the 20th century, is the strongest depopulation area with the oldest population in Serbia. This research aims is to determine the main types of changes in demographic development of the settlements and indirectly reveals key issues of the sustainable development of Zaplanje settlements and revitalization of villages.

Simulation of population dynamics using continuous-time finite-state Markov chains

This paper is concerned with the simulation of certain types of population dynamics using Markov chains. A brief review of the Markovian property, the Chapman–Kolmogorov equation, and the forward equation together with its solution is given. The essentials in simulating continuous-time Markov chains are provided and two case studies are presented for demonstration. The first is a process of drug delivery for which a closed-form solution of the forward equation can also be obtained. The second one deals with cell population dynamics, for which a Markovian model capturing birth, death, and growth is developed and simulated. The key to such simulation studies is to specify the generator Q, which in turn requires a thorough understanding of the properties of the underlying system. In return, one obtains not only the means and variances, but also the entire probability distributions, and the evolution of the random processes of interest.

Capital Breeders and Income Breeders among Lepidoptera: Consequences to Population Dynamics

Among Lepidoptera, populations of some species display outbreaks at irregular intervals, some show regular cycles, whereas densities of most species never reach extremely high values. In recent years, researchers have looked for correlations between life-history traits and different types of population dynamics (Nothnagle and Schultz 1987, Hunter 1991, Hunter 1995a) while others have generalized based on relatively few but well-studied cases (Price et al. 1990, Price 1994). The proximate reasons of changes in population density presumably are in the environment (Ruohomiki and Haukioja 1992) but these kinds of observations may have masked the importance of life-history x environment interactions. Here we emphasize the importance of adult feeding, a correlate of eruptive (sensu Price et al. 1990) and cyclic population dynamics among Lepidoptera which has deserved almost no attention until very recently (Miller 1996). Furthermore, we propose ecological and evolutionary explanations for the correlation.