Using stationary vital rates in impact assessments may underestimate potential threat

Population viability analysis (PVA) is commonly used to assess future potential risks to threatened species. These models are typically based on mean vital rates, such as survival and fecundity, with some level of environmental stochasticity. However, the vital rates of wild populations, especially those already exhibiting declining trajectories, may be nonstationary, such that the mean or variance changes over time. In this study, we examined whether including observed temporal trends in vital rates affects the predictive accuracy of PVA, as well as the projected impact associated with a hypothetical threat. To achieve this, we ran a series of simulations using Leslie matrix PVA models that included different combinations of environmental stochasticity, temporal trends in vital rates, and threat. We found that including observed temporal trends in vital rates was (i) crucial for the accurate reconstruction of observed population dynamics and (ii) had a dramatic effect on the projected impact from the hypothetical threat. In an era when many animal and plant populations are declining due to long-term trends in their vital rates, we conclude that this demographic structure is essential for robustly evaluating potential threats using PVA models. Omitting observed temporal trends in vital rates from impact assessments is highly likely to yield unreliable results that could misinform conservation and management decision making.

Age-Grouping, Time-Specific Life-Tables, and Predictive Population Models

This chapter describes techniques to create life-tables for animals whose generations overlap widely. Age-grouping is a prerequisite for these methods, which have been most widely applied to vertebrate populations. Age cannot be inferred from the developmental stage without reference to the environment. The speed of development may be temperature-dependent or influenced by factors such as oxygen and food availability. The methods for ageing animal groups, including invertebrates, fish, reptiles, amphibians, birds, and mammals, are reviewed. Time-specific life-tables, population modelling, and Leslie matrices are described. R code to analyze Leslie matrix dynamics is presented.

Towards a replicator dynamics model of age structured populations

We present a new modelling framework combining replicator dynamics, the standard model of frequency dependent selection, with an age-structured population model. The new framework allows for the modelling of populations consisting of competing strategies carried by individuals who change across their life cycle. Firstly the discretization of the McKendrick von Foerster model is derived. We show that the Euler–Lotka equation is satisfied when the new model reaches a steady state (i.e. stable frequencies between the age classes). This discretization consists of unit age classes where the timescale is chosen so that only a fraction of individuals play a single game round. This implies a linear dynamics and individuals not killed during the round are moved to the next age class; linearity means that the system is equivalent to a large Bernadelli–Lewis–Leslie matrix. Then we use the methodology of multipopulation games to derive two, mutually equivalent systems of equations. The first contains equations describing the evolution of the strategy frequencies in the whole population, completed by subsystems of equations describing the evolution of the age structure for each strategy. The second contains equations describing the changes of the general population’s age structure, completed with subsystems of equations describing the selection of the strategies within each age class. We then present the obtained system of replicator dynamics in the form of the mixed ODE-PDE system which is independent of the chosen timescale, and much simpler. The obtained results are illustrated by the example of the sex ratio model which shows that when different mortalities of the sexes are assumed, the sex ratio of 0.5 is obtained but that Fisher’s mechanism, driven by the reproductive value of the different sexes, is not in equilibrium.

Application of the Leslie Matrix to Predict the Number and Growth Rate of Women in West Java 2021

Data from the Central Statistics Agency 2019 collected that the total population of women in Indonesia is less than male, which is 131.48 million people if compared to the total male population, which is 132.68 million population. This matter is directly relation to the total female population in West Java which is also less than the male population around 24031252.0 female and 24652609.0 male population(Badan Pusat Statistika, 2019).This should be the focus of the government to balance the population growth of women and men in West Java because of the role of women being central in the population growth of the people of West Java. The targets of the development plan contained in the RPJM 2005-2025 is to improve the quality of human resources, including the role of women in development. The growth of the female population is an important thing that must be observed, considering the role of women is determining the development of the human population in the future, because without the role of women the population will not be able to develop. This encourages researchers to predict the number and rate of female population growth in West Java in 2021. The Leslie matrix is a matrix used to predict the number and growth rate of a population. By applying the Leslie matrix to predict the number and growth rate of women in West Java in 2021, it can be concluded that the number of female populations in West Java is around tends to increase.

Human Cost of Tyranny in Kurdistan Region of Iraq

BackgroundThe 2003 liberation/invasion of Iraq and the resulting casualties from civilians and armed forces attracted researchers publishing in high prestigious journals but little was mentioned about the events that led to the armed intervention. This paper assesses the human cost of successive Iraqi governments’ tyrannical rule in Kurdistan Region of Iraq over three decades.MethodThe two most recent and reliable census datasets of 1947 and 1957 were used to estimate fertility and survival rates by age group under normal circumstances. These were used in the classical Leslie Matrix to predict the 2007 Kurdistan Region of the Iraqi population. Results were contrasted with estimates for the same year that were obtained by the World Food Programme as part of their Food Security Analysis for Iraq to arrive at estimates that would indicate the scale of the loss in human capital from Saddam Hussein’s tyranny. FindingsThe Kurdistan Region has lost around 1,911,479 people of which 1,043,549 were male and 867,930 female of different age groups. These include the direct victims of past genocide actions of successive Iraqi governments as well as those who sought refuge beyond the boundaries of the Kurdistan Region during past decades. InterpretationSaddam Hussein’s actions were directed to all indigenous inhabitants irrespective of gender and age. As such, any possible offspring, had life continued as normal, is counted as human loss. Demographical, socio-political and the environmental impact of Saddam Hussien’s tyrannical rule are worthy of further investigation.

Human Cost of Tyranny in Kurdistan Region of Iraq

Background The 2003 liberation/invasion of Iraq and the resulting casualties from civilians and armed forces attracted researchers publishing in high prestigious journals but little mentioned about the events that led to the armed intervention. This paper is assessing the human cost of successive Iraqi governments tyrannical rule in Kurdistan Region of Iraq over three decades.Method The two most recent and reliable census datasets of 1947 and 1957 were used to estimate fertility and survival rates by age group under normal circumstances. These were used in the classical Leslie Matrix to predict 2007 Kurdistan Region of Iraq population. Results were contrasted with estimates for the same year that were obtained by the World Food Programme as part of their Food Security Analysis for Iraq to arrive at estimates that would indicate the scale of the loss in human capital from Saddam’s tyranny that was imposed on the region. Findings Kurdistan Region has lost around 1,911,479 of which 1,043,549 were male and 867,930 female of different age groups. These include direct victims of the past genocide actions of successive Iraqi governments as well as those who thought refuge beyond the boundaries of Kurdistan Region during the past decades. Interpretation Saddam’s actions were directed to all indigenous inhabitants irrespective of gender and age. As such, any possible offspring, had life continued as normal, is counted as human loss. Impacts of changes in demography, socio-political and the environment of Saddam’s tyrannical rule are worth further investigation.Funding None