Determinants Of Population Growth Research Articles

Determinants of suboptimal birth spacing among reproductive-age women in Adama district, Ethiopia: a community-based unmatched case-control study

BackgroundBirth spacing is crucial for ensuring the health of mothers and their children, as well as determining population growth. Short birth intervals represent a universal public health problem associated with adverse maternal, fetal, neonatal, and child outcomes. However, there is limited information in the study area regarding the determinants of suboptimal birth spacing. Thus, this study aimed to identify the determinants of suboptimal spacing among women of reproductive age in the Adama district, Ethiopia.MethodsA community-based unmatched case-control study was conducted among 568 randomly selected reproductive-age women using the multi-stage sampling technique. Data were collected using an interviewer-administered, structured questionnaire. The collected data were entered into Epi Info version 7.2 and analyzed using SPSS version 26. Binary logistic regression analysis was used to model the association between suboptimal birth spacing and independent variables. Adjusted odds ratios with their 95% confidence intervals were calculated to determine the strength of the association. A p-value < 0.05 was considered to declare statistical significance.ResultEducational status (no formal education) (AOR = 2.40; 95% CI: 1.23–1.75), inadequate knowledge of optimal birth space (AOR = 2.60; 95% CI; 1.80–3.90), non-use of modern contraceptives (AOR = 3.00; CI: 1.90–4.20), short breastfeeding duration (AOR = 2.30; 95% CI: 1.50–3.40), and having female index child (AOR = 1.60; 95% CI: 1.13–2.50) were independent determinants of suboptimal birth spacing practice.ConclusionEncouraging women’s education, contraceptive use, and breastfeeding is crucial for birth spacing. Community health initiatives should also focus on preventing sex-based birth intervals.

Acclimation to warmer temperatures can protect host populations from both further heat stress and the potential invasion of pathogens.

Thermal acclimation can provide an essential buffer against heat stress for host populations, while acting simultaneously on various life-history traits that determine population growth. In turn, the ability of a pathogen to invade a host population is intimately linked to these changes via the supply of new susceptible hosts, as well as the impact of warming on its immediate infection dynamics. Acclimation therefore has consequences for hosts and pathogens that extend beyond simply coping with heat stress-governing both population growth trajectories and, as a result, an inherent propensity for a disease outbreak to occur. The impact of thermal acclimation on heat tolerances, however, is rarely considered simultaneously with metrics of both host and pathogen population growth, and ultimately fitness. Using the host Daphnia magna and its bacterial pathogen, we investigated how thermal acclimation impacts host and pathogen performance at both the individual and population scales. We first tested the effect of maternal and direct thermal acclimation on the life-history traits of infected and uninfected individuals, such as heat tolerance, fecundity, and lifespan, as well as pathogen infection success and spore production. We then predicted the effects of each acclimation treatment on rates of host and pathogen population increase by deriving a host's intrinsic growth rate (rm) and a pathogen's basic reproductive number (R0). We found that direct acclimation to warming enhanced a host's heat tolerance and rate of population growth, despite a decline in life-history traits such as lifetime fecundity and lifespan. In contrast, pathogen performance was consistently worse under warming, with within-host pathogen success, and ultimately the potential for disease spread, severely hampered at higher temperatures. Our results suggest that hosts could benefit more from warming than their pathogens, but only by linking multiple individual traits to population processes can the full impact of higher temperatures on host and pathogen population dynamics be realised.

Spatial differences in recruit density, survival, and size structure prevent population growth of stony coral assemblages in southeast Florida

The size structure of stony coral populations can reveal underlying demographic barriers to population growth or recovery. Recent declines in coral cover from acute disturbances are well documented, but few studies have assessed size structure and the demographic processes that determine population growth. Vital rates, such as recruitment and survival, vary spatially and temporally in response to environmental conditions, in turn influencing assemblage composition. The Southeast Florida Coral Reef Ecosystem Conservation Area (Coral ECA) is a high-latitude reef system offshore of a heavily urbanized coastline. Consecutive heat stress events, stony coral tissue loss disease (SCTLD), and Hurricane Irma caused significant declines in stony coral cover and density from 2014 to 2018. The recovery potential of stony coral assemblages is influenced by their composition, the size structure of the remnant populations, and population growth during inter-disturbance periods. To assess the viability of the remaining stony coral assemblages in the Coral ECA, we quantified variation in stony coral recruit density, abundance, size structure, and assemblage composition across depth and latitude at permanent sites over 3 years (2019–2022) when no disturbances occurred. We found spatial decoupling in recruit density, adult colony density, and cover that maintains a preponderance of small colonies and skewed size structure. At sites close to shore where recruit density was higher, there was limited evidence of survival and growth of recruits, while at sites where large colonies were sampled or cover was relatively high, there was limited recruitment. The majority (&amp;gt;75%) of recruits sampled were Siderastrea siderea, but size frequency distributions were positively skewed and the coefficient of variation was high, suggesting high recruit/juvenile colony mortality and little growth into larger size classes. Porites astreoides size structure was generally lognormal and mesokurtic, particularly closer to shore, suggesting a transition between size classes. Skewness decreased moving offshore in Montastraea cavernosa and S. siderea, suggesting a transition between size classes. Recruit and adult diversity also increased moving offshore, but recruits of most species were uncommon throughout the study area. We suggest that low recruitment and high mortality, particularly in small colonies and inshore, even during inter-disturbance periods, limit the population growth of stony coral assemblages in southeast Florida.

Migration View on the Demographic Development of the Almaty City

To characterize the demographic development of a particular region, it is necessary not only to determine population growth, but also to expand the subject area of statistical demography and conduct research to identify patterns of natural renewal of the structure of the age composition of the population. For the completeness of the study, methods of statistical and mathematical analysis were used. Official long-term statistical data for Almaty were collected and analyzed. A mathematical model was developed to determine the share of influence of each factor. It is substantiated that the demographic development of the city of Almaty cannot be characterized as a process of reproduction. Causeand-effect relationships of population growth from migration processes are revealed. It is noted that in the city of Almaty there were demographic phenomena typical for large cities of the modern world. It is substantiated that the growth of the population of Almaty does not have a positive impact on the demographic development of the country, but leads to negative consequences (high population density of the city, infrastructure, traffic jams, temporary labor migrants) of the development of the metropolis and the country as a whole. The significance of the results of the study lies in the recommendations for taking measures to limit the movement of internal migration in Almaty and aimed at natural demographic reproduction.

High survival promotes persistence in a reintroduced population of Common Crane (Grus grus)

Reintroductions are increasingly used for re‐establishing populations, though the documented success rates are variable. Success is typically measured by the survival and breeding success of released individuals and subsequent establishment and growth of the population. However, few studies quantify demographic rates of reintroduced populations of long‐lived species, with slower dynamics and lower reproductive rates, and the demographic rates of subsequent generations, which determine population growth and persistence, are often unknown. We document the success of the reintroduction of the Common Crane Grus grus to south‐west England in the UK, using survival analysis and population modelling to determine whether the overarching aim of establishing a self‐sustaining population is likely to be achieved. Between 2010 and 2014, 93 Common Cranes were hatched from wild eggs, custom‐reared and soft‐released into suitable habitat. Survival of all age‐classes was apparently higher than survival of healthy wild individuals, particularly in juvenile age‐classes, and was higher in females than in males. Productivity was relatively low, but increased with age. Assuming that the demographic rates of subsequent generations are at the levels estimated for the captive‐reared population, slow positive population growth is predicted over the next 30 years. Sensitivity analyses showed that the persistence of this population is sensitive to even a slight decrease in values of adult survival, and growth is impacted to a lesser extent by juvenile survival and levels of productivity. This study highlights the ability to achieve persistence in a reintroduced population despite low levels of productivity when survival is exceptionally high. It also illustrates the need for long‐term monitoring to establish reintroduction success in animals that have slow life histories: 9 years after initial releases, the Common Crane population remains dominated by first‐generation birds and productivity is skewed by transient age‐structure and the late onset of reproductive success.

A synthesis of Eurasian Curlew (Numenius arquata arquata) demography and population viability to inform its management

The European population of Eurasian Curlew Numenius arquata arquata, a near‐threatened wader subspecies, has undergone pronounced population declines over the past 30 years. To assess the demography and viability of its global population, we surveyed studies quantifying demographic rates (productivity and survival) and complemented this review with new estimates of survival probability at the flyway scale. Then, using a demographic model, we estimated population growth rates while accounting for the range of variation of demographic parameters, and compared these estimates (expected based on demographic rates) with those observed based on population censuses. Both observed and expected average growth rates were negative but the observed rates were higher than estimates from demographic models (λ = 0.98–0.99 compared with 0.85–0.95). This discrepancy implies that there is geographical variation in the demography of different populations that is not fully covered by current demographic data, namely unstudied regions with higher productivity. According to our calculations, at the flyway scale, productivity is currently c. 0.57 fledglings per pair per year, higher than the average reported productivity of 0.29, but lower than the 0.68 needed to achieve a stable global population size (λ = 1). Adult survival, estimated at 0.90, was the most sensitive parameter determining population growth rates, but the low productivity levels over the last few decades seems to be the most probable cause of population declines. The negative population growth rates require immediate conservation actions to preserve adult survival and increase the extremely low productivity in western and northern European populations to values above 0.68 fledglings per pair per year. We hope our synthesis on the demographic status of Curlew in Europe will encourage the collection of more demographic data and allow concrete management goals at the flyway scale to be established in order to recover the global population of this iconic species.

Review of range-wide vital rates quantifies eastern wild Turkey population trajectory.

Recent declines in eastern wild turkeys (Meleagris gallopavo silvestris) have prompted increased interest in management and research of this important game species. However, the mechanisms underlying these declines are unclear, leaving uncertainty in how best to manage this species. Foundational to effective management of wildlife species is understanding the biotic and abiotic factors that influence demographic parameters and the contribution of vital rates to population growth. Our objectives for this study were to (1) conduct a literature review to collect all published vital rates for eastern wild turkey over the last 50 years, (2) perform a scoping review of the biotic and abiotic factors that have been studied relative to wild turkey vital rates and highlight areas that require additional research, and (3) use the published vital rates to populate a life-stage simulation analysis (LSA) and identify the vital rates that make the greatest contribution to population growth. Based on published vital rates for eastern wild turkey, we estimated a mean asymptotic population growth rate (λ) of 0.91 (95% CI=0.71, 1.12). Vital rates associated with after-second-year (ASY) females were most influential in determining population growth. Survival of ASY females had the greatest elasticity (0.53), while reproduction of ASY females had lower elasticity (0.21), but high process variance, causing it to explain a greater proportion of variance in λ. Our scoping review found that most research has focused on the effects of habitat characteristics at nest sites and the direct effects of harvest on adult survival, while research on topics such as disease, weather, predators, or anthropogenic activity on vital rates has received less attention. We recommend that future research take a more mechanistic approach to understanding variation in wild turkey vital rates as this will assist managers in determining the most appropriate management approach.

Non-linear relationships between density and demographic traits in three Aedes species

Understanding the relationship of population dynamics to density is central to many ecological investigations. Despite the importance of density-dependence in determining population growth, the empirical relationship between density and per capita growth remains understudied in most systems and is often assumed to be linear. In experimental studies of interspecific competition, investigators often evaluate the predicted outcomes by assuming such linear relationships, fitting linear functions, and estimating parameters of competition models. In this paper, we experimentally describe the shape of the relationship between estimated population rate of change and initial density using laboratory-reared populations of three mosquito species. We estimated per capita growth rate for these experimental populations over a 30-fold range of larval densities at a standard resource abundance. We then compared fits of linear models and several different nonlinear models for the relationship of estimated rate of change and density. We find that that the relationship between density and per capita growth is strongly non-linear in Aedes aegypti (Linnaeus), Aedes albopictus (Skuse), and Aedes triseriatus (Say) mosquitoes. Components of population growth (survivorship, development time, adult size) are also nonlinearly related to initial density. The causes and consequences of this nonlinearity are likely to be important issues for population and community ecology.

On population growth with catastrophes

In this article, we study a particular class of Piecewise deterministic Markov processes (PDMP’s) which are semi-stochastic catastrophe versions of deterministic population growth models. In between successive jumps the process follows a flow describing deterministic population growth. Moreover, at random jump times, governed by state-dependent rates, the size of the population shrinks by a random amount of its current size, an event possibly leading to instantaneous local (or total) extinction. A special separable shrinkage transition kernel is investigated in more detail, including the case of total disasters. We discuss conditions under which such processes are recurrent (positive or null) or transient. To do so, we introduce a modified scale function which is used to compute, when relevant, the law of the height of excursions and to decide if the process is recurrent or not. The question of the finiteness of the time to extinction is investigated together with the evaluation of the mean time to extinction when the last one is finite. Some information on the embedded jump chain of the PDMP is also required when dealing with the classification of states 0 and that we exhibit.

Density dependence and spatial heterogeneity limit the population growth rate of invasive pines at the landscape scale

Determining population growth across large scales is difficult because it is often impractical to collect data at large scales and over long timespans. Instead, the growth of a population is often only measured at a small, plot‐level scale and then extrapolated to derive a mean field estimate. However, this approach is prone to error since it simplifies spatial processes such as the neighbourhood effects of density and dispersal. We present a novel approach that estimates how spatial processes derived from the effects of density and dispersal affect population growth between plot scales and landscape scales. The method is based on a scale transition theory and calculates a transition term to measure the spatial scaling of population growth, which we extend to unstable, expanding populations in order to assess whether landscape‐scale population dynamics are different from those estimated at smaller spatial scales. We illustrate this approach using aerial imagery of eight locations in New Zealand experiencing non‐native pine invasions. Analyses examined the dynamics at a plot scale (1 ha) and compared this to estimates across entire landscapes (between 24 and 1600 ha), in several cases for more than one time period. We used a Bayesian spatial random effects model to examine population growth and to account for neighbourhood effects and dispersal between plots in a rapidly changing system.We found that the estimates of the scale transition term were typically 10–25% of the mean field estimates, which led to mean field estimates of population growth extrapolated from plots being considerably higher than landscape estimates. The approach we have developed will not only have applications for predicting the populations' growth of invasive species, but also for studies examining the scaling of landscape‐scale phenomena.

Plunging floater survival causes cryptic population decline in the Common Loon.

Populations of many vertebrates are declining and geographic ranges contracting, largely as a consequence of anthropogenic threats. Many reports of such decline, however, lack the breadth and detail to narrow down its causes. Here we describe population decline in the Common Loon (Gavia immer), a charismatic aquatic bird, based on systematic resighting and measurement of a marked population. During our 27-year investigation, age-adjusted chick mass has fallen by 11%, mortality among young and old chicks has increased by 31% and 82%, respectively, and fledging success has declined by 26%. Meanwhile, the return rate of marked nonbreeders ("floaters") has plunged by 53%, and the adult population overall has declined by 22%. Consistent with the thinning ranks of floaters, the rate of territory eviction has decreased by 52% during the study. Despite the decline in floaters, territory occupancy remains unchanged. However, a matrix model, updated with recent estimates for breeding success, juvenile survival, and senescence, yields a recalculated deterministic population growth rate (λ) of 0.94 for our study population, which suggests that declines in vital rates could lead to a loss of 52% of the current population and a decline of 37% in territory occupancy by 2031. Lack of data on floaters in other upper Midwest and New England loon populations leaves their status in doubt.

Determinants of Sub-Optimal Birth Spacing in Gedeo Zone, South Ethiopia: A Case-Control Study.

BackgroundBirth spacing is key in ensuring the health of mothers and their children as well as determining population growth. Most of the mothers in developing nations including Ethiopia have been practicing short inter-birth intervals. There is a paucity of studies concerned with suboptimal birth spacing among women in reproductive age in the study area.PurposeThis study aims to identify the determinants of sub-optimal birth spacing among reproductive-age women in Gedeo zone, South Ethiopia.Materials and MethodsA community-based unmatched case–control study was undertaken among 814 reproductive-age women in Gedeo zone, South Ethiopia from October 1 to November 30, 2018. Cases were women practiced suboptimal/short birth intervals (<33 months), whereas controls were women practiced inter-birth intervals of 33 months and more. A structured interviewer-administered questionnaire was used. A stratified, two-stage cluster sampling technique was used. EpiData version 3.1 and SPSS version 22 were used for data entry and analysis, respectively. Bivariate and multivariable logistic regression analyses were computed. P-value <0.05 was considered as statistically significant. All ethical procedures were considered.ResultsWomen’s educational status, AOR (95% CI) =0.6 (0.43, 0.96), age at first marriage, AOR (95% CI) = 0.9 (0.85, 0.99), distance from the nearest health facility, AOR (95% CI) = 1.4 (1.04, 1.94), wealth index, AOR (95% CI) = 4.1 (2.66, 6.19), and postnatal care utilization after the previous birth, AOR (95% CI) = 0.4 (0.25, 0.53) were statistically significant with suboptimal birth spacing.ConclusionWomen’s educational status age at first marriage, distance from the nearest health facility, wealth index and postnatal care utilization after the previous birth were the determinants of suboptimal birth spacing.

Landscape context mediates the physiological stress response of birds to farmland diversification

Abstract Farmland diversification practices are increasingly adopted to help reverse biodiversity declines in agroecosystems. However, evidence for the effectiveness of this approach often comes from documenting the species attracted to particular farming systems or landscapes, rather than their underlying physiological states that ultimately determine population growth or decline over the longer term. Across 38 organic, mixed‐produce farms spanning the US west coast, we quantified three physiological biomarkers that are widely used to capture variation in short‐ and long‐term stress responses for nine bird species with diverse life‐history traits. While controlling for other potentially confounding variables, we used multilevel models to examine the association between bird physiological conditions, landscape context and local farm management practices, including the integration of livestock, and cropland composition and configuration. Birds generally had lower stress responses on more‐locally diverse farms and in landscapes with higher amounts of semi‐natural cover. However, interactions between farm diversity and landscape context suggested birds were less stressed on more diverse farms in simpler landscapes, but more stressed and in poorer condition on more diverse farms embedded within complex landscapes. We found no differences in stress responses among birds in relation to their degree of human association (synanthropy), which suggests generality in our findings. Synthesis and applications. Birds were often less stressed on more diverse farms. However, these patterns were mediated by landscape context: birds were less stressed on more diverse farms in simplified landscapes, but more stressed on more diverse farms within complex landscapes. This means land managers might not see uniform effects of local diversification schemes across different landscape contexts. Our results underscore the need to consider responses related to physiological health status, in addition to species richness and abundance, to determine the effectiveness of farm management for biodiversity conservation.

Inference of Bacterial Pathogen Instantaneous Population Growth Dynamics.

Although bacterial host colonization is a dynamic process that requires population growth, studies often focus on comparing bacterial populations at a given time point. However, this may not reflect the dynamics of the colonization process. Time-course assays provide important insights into the dynamics of host colonization but are laborious and may still lack resolution for immediate processes affecting populations. An alternative way to address this issue, using widely accessible tools (such as quantitative PCR [qPCR]), is to take advantage of the relationship between bacterial chromosomal replication and cell division to determine population growth status at the sampling time. Conceptually, the ratio between the number of copies at the origin of replication and that at the terminus of replication should be correlated with the measured bacterial growth rate. This peak-to-trough ratio (PTR) to estimate instantaneous population growth status was tested with the slow-growing plant-pathogenic bacterium Xylella fastidiosa. We found no correlation between PTR and the measured growth rate when using genome-level data but overall sequencing depth of coverage trends matched theoretical expectations. On the other hand, the population growth status of X. fastidiosa was predicted by PTR when using qPCR data, which was improved by the pretreatment of cells with a photoreactive DNA-binding dye. Our results suggest that PTR could be used to determine X. fastidiosa growth status both in planta and in insect vectors. We expect PTR will perform better with fast-growing bacterial pathogens, potentially becoming a powerful tool for easily and quickly assessing population growth status.

NicheMapR – an R package for biophysical modelling: the ectotherm and Dynamic Energy Budget models

Mechanistic niche models characterise the fundamental niche of an organism by determining thermodynamic constraints on its heat, water and nutritional budget, and the consequences of this for growth, development and reproduction. They can thus quantify constraints on survival, activity and, ultimately, the vital rates that determine population growth, given a sequence of environmental conditions and the key morphological, physiological and behavioural functional traits.Here we introduce and document the ectotherm model of NicheMapR, an R package that includes a suite of programs for the mechanistic modelling of heat, water, energy and mass exchange between any kind of ectothermic organism and its environment. The NicheMapR ectotherm model is based on a Fortran program originally developed by Porter, Mitchell and Beckman for predicting core body temperature and evaporative water loss as a function of microclimatic conditions and behavioural thermoregulation. The model includes routines for computing steady state body temperature and evaporative water loss given two extreme microclimates (minimum and maximum shade) as computed by the NicheMapR microclimate model. Behavioural options include posture and colour change, shade‐seeking, panting, climbing and retreating underground.Here we configure the program to be called from R as part of the NicheMapR package and describe the model in detail including new functionality for modelling whole life‐cycle energy and water budgets using Dynamic Energy Budget theory. We include scripts for core operation of the ectotherm model as well as stand‐alone R scripts for running the DEB model. Example applications are provided in the paper and in the associated vignettes. The integrated microclimate and ectotherm models should provide a strong thermodynamic basis for determining the effects of environmental change on the behaviour, distribution and abundance of ectothermic organisms.

Rainfall and temperature change drive Arnica montana population dynamics at the Northern distribution edge.

Plant species of semi-natural grasslands are threatened by several simultaneous global change drivers, most notably land-use and climate change. In this study, we explore spatiotemporal variation and changes in deterministic (λ) and stochastic population growth rates (λs), and the underlying vital rates of eight populations of Arnica montana at the species' north-western range margin in Norway. We assess to what extent variation in the demographic rates could be attributed to environmental correlates of the key global change drivers likely to operate at the range edge, including population size, surrogates of habitat quality, temperature and precipitation. We found no relationship between λ and population size or habitat quality, but λ declined in response to both increasing precipitation and increasing temperature. Life-table response experiments revealed that the temporal variability was driven by survival and clonality, whereas the spatial variation was driven by clonality. Our results suggest that A. montana has a threshold response to increasing precipitation, likely due to adaptations to local climatic conditions. Growth and flowering were both negatively affected by increasing temperature, but these effects had a low influence on the spatiotemporal variability in λ. In contrast, the stochastic growth rate was negatively influenced by climate change, indicating an increased extinction risk for marginal populations, possibly leading to range contraction of A. montana as climate change proceeds. Altogether, our study illustrates how the fates of peripheral populations, which are critically important in species range dynamics, may be affected by both deterministic and stochastic effects of multiple coinciding global change drivers.

Consequences of neglecting cryptic life stages from demographic models

Information on individuals from all stages of life is crucial to explore their ecology, evolution and conservation biology. However, the life cycles of many species contain cryptic life stages that are difficult to detect and track over time and are therefore omitted from demographic models. One example is the dormant seed bank, an evolutionary bet-hedging mechanism that buffers plant populations in variable environments. To evaluate this methodological oversight, we conduct simulations to explore the effect of seed bank parameter uncertainties on demographic outputs such as the deterministic (λ1) and stochastic population growth rate (λS), and extinction probabilities of 12 plant species. We have used uninformed and informed priors for seed bank parameters based on literature estimates, and reconstructed published models in which the seed bank was excluded without justification. Trials on removing the seed stage from models (6 species) explored the worst-case scenario for ignoring the seed bank. Inclusion of a seed bank and demographic uncertainty in seed bank parameters have little impact on stable populations (λ1 ≈ 1) with high post-seedling survival. When populations deviate from stability or demonstrate temporal demographic variation, greater changes in λ1 and the range of possible growth rates caused by demographic uncertainty are observed. As expected, decreasing populations (λ1 < 1) benefit from the inclusion of a seed bank through increases in the growth rate and extinction times, whereas increasing populations (λ1 > 1) are slowed down. While germination estimates from the literature cannot accurately reflect those obtained in the field, they provide a starting point to assess the relative importance of a seed bank. The exclusion of the seed bank must be justified by confirming that dormancy is either non-existent or not important. Accounting for cryptic stages in demographic models will produce better informed management decisions for threatened or invasive species.

Range expansion is associated with increased survival and fecundity in a long-lived bat species.

The speed and dynamics of range expansions shape species distributions and community composition. Despite the critical impact of population growth rates for range expansion, they are neglected in existing empirical studies, which focus on the investigation of selected life-history traits. Here, we present an approach based on non-invasive genetic capture-mark-recapture data for the estimation of adult survival, fecundity and juvenile survival, which determine population growth. We demonstrate the reliability of our method with simulated data, and use it to investigate life-history changes associated with range expansion in 35 colonies of the bat species Rhinolophus hipposideros. Comparing the demographic parameters inferred for 19 of those colonies which belong to an expanding population with those inferred for the remaining 16 colonies from a non-expanding population reveals that range expansion is associated with higher net reproduction. Juvenile survival was the main driver of the observed reproduction increase in this long-lived bat species with low per capita annual reproductive output. The higher average growth rate in the expanding population was not associated with a trade-off between increased reproduction and survival, suggesting that the observed increase in reproduction stems from a higher resource acquisition in the expanding population. Environmental conditions in the novel habitat hence seem to have an important influence on range expansion dynamics, and warrant further investigation for the management of range expansion in both native and invasive species.

Analytical expressions for the eigenvalues, demographic quantities, and extinction criteria arising from a three‐stage wildlife population matrix

AbstractWe used the symbolic solution for the roots of a cubic polynomial to derive expressions for the eigenvalues of a three‐stage population projection matrix. As well, we obtained expressions for eigenvectors, moduli, damping ratios, sensitivities, and elasticities. The equations reveal the existence of “superparameters;” natural groupings of vital rates that drive population dynamics. We show that growth rates can be calculated using (at most) three superparameters in place of as many as nine original vital rates, potentially simplifying data collection. Necessary and sufficient conditions for extinction can be summarized equivalently by three superparameter inequalities. For a common life history (Noon &amp; Biles, 1990, J Wildl Manag, 54, 18–27) four vital rate parameters are reduced to two superparameters. The results are applicable to population viability and recovery analysis and harvest planning.Two recommendations for resource managers Superparameters can be estimated to determine population growth rates. Superparameters can be used to conduct rapid assessments of extinction risk.

From fish physiology to ecosystems management: Keys for moving through biological levels of organization in detecting environmental changes and anticipate their consequences

Tackling environmental problems not only requires the detection of harmful agents or the drivers that induce changes in ecosystems and their effects, but also knowledge of their action mechanisms and the processes involved in order to design solutions, recover the damaged systems and, above all, prevent any deterioration before it occurs. In recent years conservation physiology has been proposed as a discipline that could play an important role in this context. However, the main problem in generalizing physiological indicators in order to assess ecological status is the leap in scale from the internal physiology of an individual to its relevance for ecosystem functioning. In this paper, we propose that the study of the physiological bases and epigenetic mechanisms that determine the allocation of energy resources, in the context of Dynamic Energy Budget theory, can be the hinge that allows us to pass from the physiology of the individual to the scale of population dynamics, the structure of populations and ecosystems. This proposal is based on the strong relationship shown by the parameters of the life story of individuals, such as body growth rate, maximum size, life expectancy or generation time, with the parameters that determine population growth and the ecological strategies of the species. There is growing evidence that the relationship between these parameters is not completely fixed and does not only respond to evolutionary scales, but may be flexible within certain limits throughout ontogeny and the life of individuals, producing consequences in populations in response to environmental conditions, environmental stress and, in the case of fish, the effects of fishing. Lay summaryBiological index to detect environmental impacts can be applied from cell to ecosystem scale. However, at lower levels, although they give important information on the mechanisms involved it is difficult to infer the real consequences of the detected changes on the ecosystems. The review of the regularities existing in ecological guilds relationships of fishes suggests that the study of the physiological and epigenetic bases that determine the allocation of energy resources in the context of Dynamic Energy Budget theory can be the hinge that allows us to pass from the effects on the physiology of the individual to the scale of population dynamics and ecosystems when modelling the consequences of changes in environmental stress.