Population Dynamics Research Articles

Reproductive Potential and Population Growth of the Worm Enchytraeus buchholzi (Clitellata: Enchytraeidae) Under Laboratory Conditions as Well as Regression Models

The worm Enchytraeus buchholzi is a new pest injuring American ginseng Panax quinquefolium. To explore its reproductive potential and then estimate its population dynamics, the authors conducted two related experiments: (1) measuring individual fecundity in its lifetime by rearing each of the parent adults alone in a wet sandy dish at 18 and 21 °C indoors; (2) testing population growth by rearing each of the parent adults together with its offspring for a time longer than two generations at 21 °C. In Experiment I, five dependent variables, namely daily mean cocoons (DMC), cumulative cocoons (CC), eggs per cocoon (EPC), daily mean eggs (DME) and cumulative eggs (CE), were extracted, with each of them subject to a stepwise regression analysis on rearing time (T) and its power series as independent variables. Equaling to the net reproductive rate (R0), the generational adult equivalent (GAE) was calculated via a conversion of F1 generational eggs into adult equivalents (AE). In Experiment II, both an exponential and a logistic function were applied to construct regression equations. The results indicated that (1) a parent adult of E. buchholzi was able to live for a period as long as 10 and 13 full generations at the two temperatures tested and lay 84.8 and 110.6 cocoons containing 545 and 714 eggs, respectively; (2) DMC reached its maximum between 7 and 9 days of rearing and then declined slowly along a straight regression line; (3) CC rose steadily along a quadratic curve; (4) both EPC and DME varied following a cubic curve; (5) CE increased steadily along a cubic curve; (6) the new polynomial models suitably reflected the numerical growth trends of cocoons and eggs in the F1 generation in a broad sense, while corresponding derivative equations quantified both the daily reproductive potential and resistance of the worm, thus revealed its daily reproductive capacity; (7) R0 was 41.2 AE at 21 °C and 42.5 AE at 18 °C when a population of E. buchholzi lived in a niche with unlimited ambient resources; (8) this kind of temporal population generated by individual reproduction had fully demonstrated its significant, generational reproductive potential; and (9), through living in such a limited area as the wet sandy dish, bypassing an exponential growth process, the laboratory population grew up along a logistic curve from the F1 to F3 generations. The statistical relationships help to comprehend the individual reproduction of E. buchholzi, understand deeply the logical sequence and the difference between individual and population reproductions, predict population dynamics of the worm, and provide its integrated pest management with a solid basis. The experimental study has expanded theories on bionomics and population ecology, opening up a new area for research work in related fields.

Nonconsumptive effects of the predator Hippodamia convergens reduce probing behavior of Diaphorina citri on Citrus sinensis

AbstractNonconsumptive effects (NCEs) impact predator–prey interactions when the presence of a predator affects behavior, physiology, or population dynamics of the prey species without resulting in consumption. NCEs are critical to understanding ecological interactions broadly and in an applied manner, when addressing the efficacy of biological control within agroecosystems. In this study, we explore the impact of cues from the predator, Hippodamia convergens Guérin‐Méneville (Coleoptera: Coccinellidae), on the probing and feeding behavior of Diaphorina citri Kuwayama (Hemiptera: Psyllidae), the Asian citrus psyllid (ACP), which transmits the causal bacteria of Huanglongbing (HLB) disease of citrus (Rutaceae). Due to wide‐spread HLB incidence and insecticide resistance, it has become critical to better understand the activity of biological control agents within the HLB–ACP pathosystem. Utilizing electropenetrography (EPG), we investigated the feeding behavior of ACP exposed to the predator H. convergens or exposed to the chemical trails H. convergens produce while foraging. Overall, ACP detected H. convergens cues and responded by avoiding probing, although the extent of this response varied depending on the type of cue perceived. When H. convergens was present in the leaf but unable to reach the psyllid, ACP were slower to initiate probing and spent less time overall on probing and feeding from the xylem. In contrast, when exposed to H. convergens foraging cues without the beetle present, ACP initiated probing quicker than when the beetle was present and had a shorter total probing time compared to the control, with no other parameters being affected. Interestingly, the H. convergens chemical trail extracts, at two dosages, did not significantly influence ACP probing and feeding, except for a lower proportion of salivation and ingestion events into the phloem at the lower test dose. Our results suggest ACP exhibits avoidance behaviors in response to H. convergens cues, leading to a reduction in feeding, which suggests the maintenance of agroecosystem health through preservation of insect community diversity may be overlooked as an additive factor in vector management.

What matters for environmental concerns among university students in Bangladesh? An empirical study

IntroductionExperts have a well-established consensus regarding the detrimental effects of human activities on the environment, including extreme temperature events, rainfall variability, pollution, deforestation, biodiversity loss, and flood occurrences—all of which significantly stress Earth’s natural systems. This study investigates the level of environmental concern among university students in Bangladesh, considering their socio-demographic factors.MethodsA comprehensive survey was conducted using a self-administered questionnaire targeting 380 final-year bachelor and master’s students from various academic disciplines at Shahjalal University of Science and Technology (SUST) Sylhet, Bangladesh. The analysis involved variables such as gender, completion of university courses related to the environment or climate change, disciplinary background, and vulnerability to climate change or extreme weather events in their home locality. Relationships between these variables and the students’ environmental concerns were examined using cross-tabulation with the Chi-square test and mean difference with the ANOVA test.ResultsThe findings indicate a high level of knowledge and significant concern among students regarding environmental issues, with disciplinary background being the primary determinant of environmental concern level. Additionally, completing university courses on environmental or climate change topics and experiencing vulnerability to such events in one’s hometown are significant predictors of environmental concerns.DiscussionThis study highlights the growing environmental concerns among university students and underscores the need for further scientific research to comprehensively understand their impact on population dynamics.

Establishing an IPM System for Tarnished Plant Bug (Hemiptera: Miridae) in North Carolina

Prior to 2010, Lygus lineolaris Palisot de Beauvois was a minor pest in North Carolina cotton, Gossypium hirsutum L., but became one of the top pests by 2017. This insect was already a persistent pest in other US cotton-producing regions. Initial work focused on addressing near-term management needs and documenting locally relevant ecology and population dynamics of the pest in North Carolina. Landscape factors were found that correlated with tarnished plant bug incidence. Adult numbers tended to be higher in fragmented fields (more field edges) and nymph numbers were higher near field edges. The minimum required sample for estimating tarnished plant bug populations was studied. Thresholds developed in the Midsouth were proven to be useful in a study between both southeastern Virginia and northeastern North Carolina. Furthermore, an insecticide application sequence was recommended based on efficacy trials, number of expected insecticides, and preserving beneficial insects early in the season. These were evaluated in a study investigating IPM systems approaches. Finally, new management tactics for tarnished plant bug, such as ThryvOn cotton, are being evaluated. As new management strategies and tactics are developed, they will need to be evaluated for their fit in this IPM system.

Thirty years of ‘strange bedmates’: The ICPD and the nexus of population control, feminism, and family planning

Widely credited with ending population control and ushering in a new era of reproductive rights, the 1994 International Conference on Population and Development (ICPD) Programme of Action also included some important compromises. The commemoration of ICPD+30 presents an opportune moment to reflect critically on those compromises and their implications for family planning programmes in the three decades since. Here, we critically examine how these compromises have enabled population control logics to flourish within global family planning programmes and the ways that neo-Malthusian concerns still motivate contraceptive programming under co-opted feminist rhetoric. We argue that rather than binary stances of ‘pro’ or ‘anti’ contraception, the post-ICPD landscape includes multiple contested positions, including: (1) concern for reproductive rights and autonomy; (2) concern over fertility or population dynamics; and (3) opposition to biomedical contraception and abortion. Setting out the intersecting and diverging tenets of these ideologies, we call for more critical reflection on these tangled histories and engagement with reproductive justice during ICPD+30.

Pathogenic bacterial taxa constitute a substantial portion of fecal microbiota in common migratory bats and birds in Europe.

The understanding of gut microbiota composition and dynamics in wild vertebrate populations, especially in highly mobile vertebrates, birds and bats, remains limited. Our study sheds light on the critical knowledge gap in how common pathogenic bacterial taxa of fecal microbiota are in migratory bats and birds in Europe. We found out that bacterial genera having species pathogenic to human or animals constituted a substantial portion of the fecal microbiota in all the studied host taxa. Most importantly, we identified asymptomatic individuals that were dysbiotic with bacterial pathogen overgrowth. These previously unknown pathogen bloomers appear as potent Europe-wide transmitters of bacterial pathogens, which cause, for example, diarrhea and bacteremia in human. Our findings may contribute to better understanding of seasonal disease hotspots and pathogen spillover risks related to migratory vertebrates.

Museomics and morphological analyses of historical and contemporary peninsular Italian wolf (Canis lupus italicus) samples.

After centuries of decline and protracted bottlenecks, the peninsular Italian wolf population has naturally recovered. However, an exhaustive comprehension of the effects of such a conservation success is still limited by the reduced availability of historical data. Therefore, in this study, we morphologically and genetically analyzed historical and contemporary wolf samples, also exploiting the optimization of an innovative bone DNA extraction method, to describe the morphological variability of the subspecies and its genetic diversity during the last 30 years. We obtained high amplification and genotyping success rates for tissue, blood and also petrous bone DNA samples. Multivariate, clustering and variability analyses confirmed that the Apennine wolf population is genetically and morphologically well-distinguishable from both European wolves and dogs, with no natural immigration from other populations, while its genetic variability has remained low across the last three decades, without significant changes between historical and contemporary specimens. This study highlights the scientific value of well-maintained museum collections, demonstrates that petrous bones represent reliable DNA sources, and emphasizes the need to genetically long-term monitor the dynamics of peculiar wolf populations to ensure appropriate conservation management actions.

Active- and Allosteric-Site Cyclic Peptide Inhibitors of Secreted M. tuberculosis Chorismate Mutase.

The secreted Chorismate mutase enzyme of Mycobacterium tuberculosis (*MtbCM) is an underexplored potential target for the development of new antitubercular agents that are increasingly needed as antibiotic resistance rises in prevalence. As an enzyme suspected to be involved in virulence and host-pathogen interactions, disruption of its function could circumvent the difficulty of treating tuberculosis-infected granulomas. Drug development, however, is limited by novel ligand discovery. Currently, *MtbCM activity is measured by using a low throughput acid/base-mediated product derivatization absorbance assay. Here, we utilized an RNA-display affinity selection approach enabled by the Random Peptides Integrated Discovery (RaPID) system to screen a vast library of macrocyclic peptides (MCP) for novel *MtbCM ligands. Peptides identified from the RaPID selection, and analogs thereof identified by analyzing the selection population dynamics, produced a new class of *MtbCM inhibiting MCPs. Among these were two noteworthy "chorismides", whose binding modes were elucidated by X-ray crystallography. Both were potent inhibitors of the CM enzyme activity. One was identified as an allosteric binding peptide revealing a novel inhibition approach, while the other is an active-site binding peptide that when conjugated to a fluorescent probe allowed for the development of a series of alternative fluorescence-based ligand-displacement assays that can be utilized for the assessment of potential *MtbCM inhibitors.

Periodic solutions in a class of periodic switching delay differential equations

In this paper, we explore the dynamical properties of a class of nonlinear systems governed by delay differential equations with multitime periodic switching. The systems incorporate piecewise-smooth birth and death functions to capture complex population dynamics under seasonal variations. Assuming monotonicity for both birth and death functions, we obtain a novel equivalence result: when the delay is a positive integer multiple of the switching period, the existence and stability of periodic solutions for the systems are equivalent to those in the nondelay case. To illustrate and validate the theoretical findings, a logistic model with seasonal switching is presented. Numerical simulations further confirm that the system exhibits consistent dynamical behaviors across varying delay values.

Human-environment interaction during the Holocene in Eastern South America: Rapid climate changes and population dynamics.

About 15 years ago, we suggested that the low frequency of archaeological sites dating from the mid-Holocene in several regions of Lowland South America (which was then called the "Archaic Gap") was due to an increase in the magnitude of dry periods related to the mid-Holocene hypsithermal. Since then, data regarding paleoenvironmental reconstructions for this vast area, coupled with an increase in the archaeological knowledge, allow us to reassess the idea of the "Archaic Gap" and redefine both the spatial extent of the phenomenon and its possible causes. Our present analysis aims to present a broader picture of the relations between humans and the environment in Eastern South America since the Late Pleistocene. The obtained results suggest that the extent of the areas that were somewhat depopulated during the mid-Holocene is larger than previously thought; not only Central Brazil, but parts of the Amazon and the Pantanal (close to the Bolivian border) seem to show the same pattern. However, as expected when larger datasets are available, it is possible to perceive oscillations in the archaeological signal that suggest reoccupation of some areas. Although we maintain that the main reasons underlying these patterns are related to climate, they are most probably related to an increase in climatic variability, and not necessarily to an increase in dryness. These observations are of interest to the current debate about the effects of the global warming on human populations.

An integrative framework to combine migratory connectivity and demographic data

Abstract Migratory species experience various conditions and events throughout their annual cycle that influence their spatial and demographic dynamics. To understand these dynamics, it is essential to describe the origin and destination of individuals. Migratory connectivity, which is defined as the geographic linkage between populations across the annual cycle, is increasingly incorporated in population models to relate population trends to environmental variables at different stages of the cycle. However, such information on migratory movements is obtained independently from the study of population dynamics despite the interaction between both processes. Expanding on the growing use of integrated modelling approaches, we developed an integrated framework that allows the sharing of information between migratory connectivity and population data. We first assembled an integrated migratory connectivity model and an integrated population model to join the analysis of GPS, live‐reencounter, dead‐recovery, capture–mark–recapture, and population count data within a unified framework. Based on simulated data, we assessed the ability of the resulting integrated connectivity and population model to produce unbiased and precise connectivity and demographic estimates. We then applied the same assessment to real data using the Eurasian Curlew (Numenius arquata) as a case study. On simulated data, the integrated connectivity and population model estimated connectivity and survival parameters with no bias and similar precision to the connectivity model alone. However, it outperformed the population model in estimating fecundity in the absence of explicit productivity data. When applied to the Eurasian Curlew, the integrated connectivity and population model produced overall similar migratory connectivity and more accurate demographic estimates than the connectivity model alone, consistent with previous studies. Additionally, the model was able to estimate fecundity, whereas the data were too sparse for the population model alone to disentangle juvenile survival and fecundity. The sharing of information between migratory connectivity and population data improved the estimation of demographic parameters by the population model and improved connectivity parameter estimates when data were scarce. This flexible framework can be generalised to include diverse data on migration movements, population structure, individual heterogeneity or environmental variables, allowing further investigation of the interaction between migration patterns and population dynamics.

Environment-driven trends in larval abundance predict fishery recruitment in two saltwater basses

Abstract Environmental and biological factors influencing fish larvae can drive fishery cohort strength, yet larval abundance is typically a better indicator of spawning biomass. Under a changing ocean, studies that explore the relationships between environmental variables, larval abundance, and fishery recruitment remain valuable areas for ongoing research. We focus on a popular, recreational-only, multispecies saltwater bass fishery (genus Paralabrax) whose population status and recovery potential are uncertain. We resolved Paralabrax spp. larval data to species over a 54-year period (1963–2016) and used species distribution models to (i) generate and test species-specific standardized indices of larval abundance as indicators of adult stock status and fishery recruitment and (ii) evaluate long-term spatiotemporal trends in their population dynamics relative to environmental variables and climate forcing. Contrary to initial hypotheses, species-specific larval abundance predicted future catches, with higher recent larval abundances suggesting potential for fishery recovery. Temperature, zooplankton biomass, and isothermal depth were important predictors of bass larval abundance, indicating these variables could also be valuable for predicting fishery recruitment and anticipating population change. Our findings paint a path forward towards a more ecosystem-based fishery management approach for this important fishery and may serve as a template for data- or assessment-limited fisheries.

Mathematical Modeling of Host-Parasitoid Dynamics for Sustainable Pest Management

Aims: The management of agricultural pest populations represents a critical challenge in sustainable crop production, particularly for challenging species like the tomato fruit borer, Helicoverpa armigera. The research work aimed in developing and analysing a novel mathematical model describing the interaction between the tomato fruit borer and its egg parasitoid, Trichogramma chilonis. The main objective of this study to analyze the stability of the proposed system of differential equations. Model Formulation: The model incorporates stage-structured population dynamics and impulsive control measures, providing insights into biological pest control strategies. In this model the tomato borer is represented by the egg and larval stages, and the parasitoid is considered in terms of the parasitized eggs. This model assumes uniform spatial distribution of both host and parasitoid populations, constant environmental conditions affecting parameters like reproduction and mortality rates, and idealized parasitoid release conditions where the released amount p remains consistent across interventions. Methodology: We used existing secondary data from research articles' instead of conducting primary field experiments for parameter identification for this mathematical model. The use of secondary data from peer-reviewed literature not only provides validated parameter values that have been rigorously tested and verified by multiple researchers, but also allows for the incorporation of findings from diverse geographical locations and climatic conditions. Results: Stability analysis identified three equilibrium points: the trivial, host-only E0,coexistence equilibria E1, and E2. The coexistence equilibirium E2 found to be locally stable under optimal parasitoid release intervals and quantities. The equilibrium point E2= (9.14,0.02,5.71) represents a coexistence state in the host-parasitoid dynamics, where the tomato fruit borer's egg density stabilizes at 9.14, the density of parasitized eggs at 0.02, and the larval density stabilizes at 5.71. This equilibrium is analyzed through its associated eigenvalues. This stability provides a reliable basis for implementing successful biological pest control strategies in tomato cultivation, ensuring a resilient and sustainable ecosystem.

Impact of Temperature Variation on the Biological Traits and Lifecycle of Spodoptera exigua (Lepidoptera: Noctuidae): A Meta-Analysis Approach

Spodoptera exigua is a pest of considerable economic importance; however, detailed research into its ecological adaptability in newly invaded habitats is limited. This research performed a comprehensive analysis of the life history characteristics of S. exigua under varying temperature, photoperiod, and humidity conditions. A total of 264 studies that met the inclusion criteria were included in the analysis, and the data were examined using random-effects model, fixed-effects model, and meta-regression analysis techniques. The findings reveal that when temperatures exceed 20 °C, several biological parameters of S. exigua significantly increase, with the highest biological activity observed at 33 °C. As temperature rises, the duration of each developmental phase significantly decreases, accompanied by a reduction in the average number of eggs produced by females and a shorter pre-oviposition period. In addition, the pupal development period is shortened, resulting in a longer adult lifespan. By considering environmental variables such as temperature, photoperiod, and relative humidity, we identified the optimal conditions for the survival of each developmental stage of S. exigua. These results provide a foundation for predicting the population dynamics of this pest and contribute to the development of more effective pest control strategies.

Genetic Differentiation of Abies alba Outside Its Main Range Under Warm Meso- and Sub-Mediterranean Conditions in Italy and Switzerland.

Abies alba is an important European tree species currently mostly found at cool and humid sites in the montane zone. In the past, it grew under markedly warmer and drier climates during the Eemian and mid-Holocene, and cryptic Mediterranean populations confirm the species' capacity to grow under warm, summer-dry conditions. However, it is unknown if warm-loving Mediterranean occurrences are related to specific genetic properties (e.g., subspecies or ecotypes). Investigating the genetics of cryptic warm-loving populations is crucial for a better understanding of past and future population dynamics of A. alba. We genotyped 478 A. alba samples at 174 single-nucleotide polymorphisms (SNP), covering a broad latitudinal range from Southern Italy to Switzerland while accounting for local altitudinal gradients, and combined these newly introduced genotypes with those of other European Abies populations from the literature. Population genetic structure analyses grouped the warm-loving meso- and sub-Mediterranean populations into the same genetic cluster as the mountain populations of each region. The occurrence of three genetic clusters from Northern to Southern Italy is in line with the glacial refugia history. The inferred evolutionary and demographic history suggests a northward expansion of A. alba after glaciation, as well as a trans-Adriatic gene flow between Balkan and Southern Italian populations. Collectively, the combined genotypic data from individuals across the species' range demonstrate that cryptic Mediterranean populations of A. alba align with the local and large-scale genetic structure of populations from its main range, suggesting that the species is able to thrive in a warmer and drier environmental range than hitherto anticipated. This finding implies that it is unneeded to postulate extinct subspecies or ecotypes to explain the occurrence of meso- and sub-Mediterranean Eemian or mid-Holocene silver fir forests, with important implications for future A. alba population dynamics.

Macrofauna community structure and population dynamics in the Flemish bank region: Assessing long-term change in the Anthropocene

Macrofauna community structure and population dynamics in the Flemish bank region: Assessing long-term change in the Anthropocene

Systematic shifts in the variation among host individuals must be considered in climate-disease theory.

To make more informed predictions of host-pathogen interactions under climate change, studies have incorporated the thermal performance of host, vector and pathogen traits into disease models to quantify effects on average transmission rates. However, this body of work has omitted the fact that variation in susceptibility among individual hosts affects disease spread and long-term patterns of host population dynamics. Furthermore, and especially for ectothermic host species, variation in susceptibility is likely to be plastic, influenced by variables such as environmental temperature. For example, as host individuals respond idiosyncratically to temperature, this could affect the population-level variation in susceptibility, such that there may be predictable functional relationships between variation in susceptibility and temperature. Quantifying the relationship between temperature and among-host trait variation will therefore be critical for predicting how climate change and disease will interact to influence host-pathogen population dynamics. Here, we use a model to demonstrate how short-term effects of temperature on the distribution of host susceptibility can drive epidemic characteristics, fluctuations in host population sizes and probabilities of host extinction. Our results emphasize that more research is needed in disease ecology and climate biology to understand the mechanisms that shape individual trait variation, not just trait averages.

Ecological Traits and Intraguild Competition Mediate Spatial and Temporal Overlaps Among Sympatric Mesocarnivores

In terrestrial mammalian carnivore guilds, interspecific competitions (interferences and resource competitions) among sympatric species induce their ecological and behavioral patterns and population dynamics, thereby shaping community structures. Competitive species must partition their ecological niches for sympatry, while the extent of niche overlaps is mediated by either the ecological traits (e.g., body size differences) or environmental features. We aimed to elucidate the patterns of spatial and temporal niche overlaps in mesocarnivore guilds, which are mediated by their ecological traits, regional environments, and anthropogenic disturbances. We investigated the spatial occurrence and diel activities of six mesocarnivore species and estimated their spatial and temporal overlap indices in various landscapes with different anthropogenic disturbances in central Bulgaria. Statistical modeling demonstrated that spatial overlap among mesocarnivores declined when mesocarnivore pairs were within the same family and when large carnivores (particularly wolves, Canis lupus) were present. Furthermore, we found that the extent of their temporal overlaps was associated with taxonomic and body size differences in mesocarnivore pairs as well as their trophic competitions. Our findings indicated that the intensity of interferences among mesocarnivore species was key for the decline of spatial or temporal niche overlap to relax antagonistic interactions.

Seasonal and Spatial Distribution of Fall Armyworm Larvae in Maize Fields: Implications for Integrated Pest Management

The fall armyworm (FAW), Spodoptera frugiperda, a major pest in maize production, was assessed for its temporal and spatial distribution in maize fields during both the dry and rainy seasons of 2021 and 2022 in two agroecological regions in Benin (zone 6 and 8). Zone 6 (AEZ 6) “called zone of terre de barre” (Southern and Central Benin) consisted of ferralitic soils, a Sudano-Guinean climate (two rainy seasons alternating with two dry seasons) with a rainfall ranging between 800 and 1400 mm of rainfall per year; while zone 8 (AEZ 8) called “fisheries region” (Southern Benin” is characterized by coastal gleysols and arenosols with a Sudano-Guinean climate and a rainfall of 900–1400 mm of rainfall per year. In this study, 30 and 50 maize plants were randomly sampled using a “W” pattern during the dry and rainy seasons, respectively. Larval density, larval infestation rates, and damage severity were monitored over time. Taylor’s power law and the mean crowding aggregation index were applied to evaluate the dispersion patterns of the larvae. The results indicate a higher larval infestation rate and larval density in AEZ 8 compared to AEZ 6 during the dry season. In the rainy season, while the percentage of damaged plants was higher in AZE 8, no significant differences in larval density between the two zones were observed. The dispersion analysis revealed moderate aggregation (aggregation index = 1.25) with a basic colony of 2.08 larvae, i.e., an average initial cluster of 2.08 larvae observed per plant, reflecting the aggregation oviposition behavior of FAW. This study provides valuable monitoring data on the FAW’s distribution, offering insights for further research on population dynamics and developing predictive models for integrated pest management strategies.

Dynamics analysis of a reaction-diffusion-advection benthic-drift model with logistic growth.

This paper aims to investigate the benthic-drift population model in both open and closed advective environments, focusing on the logistic growth of benthic populations. We obtain the threshold dynamics using the monotone iteration method, and show that the zero solution is globally attractive straightforward when linearly stable. When unstable, limits from monotonic iteration of upper and lower solutions are upper and lower semi-continuous, respectively. By employing a part metric, we prove these limits are equal and continuous, leading to a positive steady state. In the critical case, we establish that the limit function from the upper solution iteration must be the zero solution by analyzing an algebraic equation. Furthermore, we conduct a quantitative analysis of the principal eigenvalue for a non-self-adjoint eigenvalue problem to examine how the diffusion rate, advection rate, and population release rates influence the dynamics. The results suggest that the diffusion rate and advection rate have distinct effects on population dynamics in open and closed advective environments, depending on the population release rates.