Sink Patches Research Articles

DISPERSAL IN PREY–PREDATOR SYSTEMS WITH PREY’S FEAR AND PREDATOR’S ADAPTIVE SEARCH

This paper considers predator–prey systems in which the predator adapts the search speed to prey’s density. The prey admits the cost of fear because of the predator and moves between source–sink patches to escape from predation. Using dynamical systems theory, we demonstrate equilibrium stability, uniform persistence and bifurcations in the system. It is shown that enhancing the search speed of predator and/or decreasing prey’s dispersal from the source to sink could promote persistence of the system, while increasing the fear cost would stabilize the system. Moreover, dispersal could make the prey persist in both source–sink patches, even drive the predator into extinction. The dispersal could also make the prey reach a total population abundance larger than that without dispersal, even larger than the carrying capacity. Asymmetry in dispersal plays a role in the persistence and abundance. A novel finding of this work is that dispersal may lead to results reversing those without dispersal. Numerical simulations illustrate and extend our results. This work is important in understanding complexity in predation systems.

Spatial dispersal in chemostat systems with agent-based asymmetry

This paper considers chemostat consumer-resource systems in which the consumer disperses between spatial patches and acts as an agent. Using the theory of dynamical systems and the method of graphs, we demonstrate global stability of steady states in the model. It is shown that dispersal of the consumer and clustering mode of patches are important for persistence of the consumer, while asymmetry in the dispersal determines the final distribution of consumer in the system. Moreover, appropriate asymmetry could make the consumer persist in sink patches, and could make the consumer approach a total population abundance higher than that without dispersal. A novel finding of this work is that agent-based selection on asymmetry could make the consumer evolve to the maximal abundance. Numerical simulations on the model reproduce radiograph/CT of COVID-19 patients in both figures and animations. Our research has potential applications in computer-aided diagnosis and treatment.

Agent-based diffusion in predation systems with Beddington–DeAngelis response

Understanding dynamical behavior of a spatially distributed population is crucial to conservation and management of endangered species. This paper considers predator–prey systems with Beddington–DeAngelis functional response, where the predator moves between source–sink patches asymmetrically and acts as an agent. Our aim is to show how agent-based diffusion affects dynamics of the system and total population abundance of the species. Using dynamical systems theory, we demonstrate stability of positive equilibria in the system, which implies coexistence of the species and change of abundance by diffusion. Moreover, we show Hopf and Bautin bifurcations with multiple limit cycles, which implies multiple oscillations of populations and even extinction of species. Furthermore, this work demonstrates that diffusion in the system may lead to results reversing those without diffusion. The diffusion could change dynamics of the system between coexistence at a steady state and persistence in periodic oscillation, while evolution in asymmetry of diffusion could make the predator reach a total abundance larger than that without diffusion, even reach the maximal abundance. Our results are consistent with experimental observations and are important in studying conservation of biodiversity.

Coevolution of Patch Selection in Stochastic Environments.

AbstractSpecies interact in landscapes where environmental conditions vary in time and space. This variability impacts how species select habitat patches. Under equilibrium conditions, evolution of this patch selection can result in ideal free distributions where per capita growth rates are zero in occupied patches and negative in unoccupied patches. These ideal free distributions, however, do not explain why species occupy sink patches, why competitors have overlapping spatial ranges, or why predators avoid highly productive patches. To understand these patterns, we solve for coevolutionarily stable strategies (coESSs) of patch selection for multispecies stochastic Lotka-Volterra models accounting for spatial and temporal heterogeneity. In occupied patches at the coESS, we show that the differences between the local contributions to the mean and the variance of the long-term population growth rate are equalized. Applying this characterization to models of antagonistic interactions reveals that environmental stochasticity can partially exorcize the ghost of competition past, select for new forms of enemy-free and victimless space, and generate hydra effects over evolutionary timescales. Viewing our results through the economic lens of modern portfolio theory highlights why the coESS for patch selection is often a bet-hedging strategy coupling stochastic sink populations. Our results highlight how environmental stochasticity can reverse or amplify evolutionary outcomes as a result of species interactions or spatial heterogeneity.

Using a settlement connectivity‐based framework to map the farmland abandonment risk: A case study on the World Heritage of Honghe Hani Rice Terraces

AbstractFarmland abandonment is a gradual, complex, and fragmented process that varied with time and space. How to identify the abandonment‐risk of farmland with a spatial explicit way is a challenge and a key step toward the efficient management and sustainability of regional agriculture. This paper introduced the quantification method of connectivity from landscape ecology, took the rural settlements as the source patches that farmers moved out with materials and energies into the sink patches of farmlands, and during the moving process the least‐cost path among settlements means the highest connectivity and the lowest risk of farmland abandonment. Then the new integrated framework for spatially quantifying the abandonment‐risk of farmland based on settlement connectivity combined with the least‐cost model (namely the FARBSC framework) was put forward and validated at the Honghe Hani Rice Terraces (HHRT) in Southwestern China. The verification and accuracy comparison of the FARBSC framework to the composite indicators and the buffer zone analysis of settlement were all indicated the efficiency of the new method. For the HHRT region, according to the FARBSC framework, the risky, weakly stable, stable, and highly stable zone is occupied 13.5%, 43.3%, 36.7%, and 6.5% of the land, respectively. The FARBSC framework had provided a quick and convenient way to mapping the risk area of farmland abandonment, especially for data‐lack remote rural mountainous areas, such rice terrace heritage sites in mountainous Asia. More detailed spatial data can be used to improve its accuracy in future studies.

Metacommunity stability and persistence for predation turnoff in selective patches

Predation as an important trophic interaction of ecological communities controls the large-scale patterns of species distribution, population abundance and community structure. Numerous studies address that predation can mediate diversity and regulate the ecological community and food web stability through changes in the behavior, morphology, development, and abundance of prey. Since predation has large effects on persistence and diversity, the local loss or removal of predation in a community can trigger a cascade of extinctions. In ecological theory, the effect of predation removal has been well studied in foodwebs, but it remains unclear in the case of a spatially distributed community connected by dispersal. In this study, the interaction between local and spatial processes is taken into account, we present how a predation turnoff in selective patches affects the synchronized oscillatory dynamics of a metacommunity. Using a simple predator–prey metacommunity with a diffusive dispersal, we show the impact of predation on synchronized, asynchronized and source–sink dynamics. Our results reveal that predation turnoff in very few patches stabilizes the metacommunity by damping the perfectly synchronized oscillatory state into multicluster equilibrium (i.e., steady) states. In a source–sink behavior, predation turnoff in a source patch reduces the number of sink patches and changes the clusters. In general, predation turnoff in low number of patches shows non-zero equilibrium states in both prey and predator populations, whereas predation turnoff in a larger number of patches can lead to the complete extinction of predators. Moreover, prey density from the patches where predation is absent goes to a saturating state near the carrying capacity. Thus, this study stresses that predation turnoff in selective patches acts as a stabilizing mechanism to promote the metacommunity persistence.

Assessing the effects of nurse shrubs, sink patches and plant water-use strategies for the establishment of late-successional tree seedlings in Mediterranean reclaimed mining hillslopes

The use of ecohydrologically suitable microsites, such as sink patches (i.e. zones intercepting and infiltrating runoff) and nurse shrubs, have largely been proposed as tools to improve the establishment of late-successional trees in Mediterranean reclaimed landscapes. Nonetheless, this technique needs to be accurately tested along with the influence of seedling water-use strategy. To that purpose, we monitored the short- and mid-term (i.e. 4 and 8 years, respectively) influence of sink patches and nurse shrubs (Genista scorpius) on seedlings of two species with contrasted water-use strategies, Pinus nigra, a more drought avoider and isohydric species, and Quercus ilex, a more drought tolerant and anisohydric species. In the short term, G. scorpius shrubs enhanced the establishment of seedlings planted in shaded spots under its canopy. This positive interaction was more relevant for Q. ilex in drier years, while P. nigra was more facilitated in wetter years. Sink patches ameliorated the survival of both species, but only promoted greater growth during wetter years. P. nigra seedlings showed a high sensitivity to precipitation reduction. Their survival and growth were strongly constrained in dry years, resulting in a very high cumulative mortality at the end of the 8-year study period regardless of the microsite the seedlings were planted in. Q. ilex showed better seedling performance than P. nigra in the mid-term, keeping also the positive effects of suitable microsites on plant survival in the mid-term, after 8 years of plantation. Our results support the use of suitable microsites that ameliorate ecohydrological conditions as key spots for enhancing ecological succession in reclaimed mining sites, particularly the use of G. scorpius as nurse shrub for improving Q. ilex seedling establishment and growth. Our results also suggest that seedling functional strategy to cope with drought is a critical factor conditioning the overall plantation performance in the mid-term. Thus, seedling water-use strategy should constitute a key species selection criteria in future restoration programs focused on Mediterranean ecosystems, especially under climate change.

Modeling Potential Dispersal Routes for Giant Pandas in Their Key Distribution Area of the Qinling Mountains, China

The national surveys on giant panda (Ailuropoda melanoleuca) population and habitat quality have shown a high-density population of this species in the Qinling Mountains, China. We investigated five adjacent nature reserves (NR), i.e., the key distribution area of giant pandas in the Qinling Mountains, to model and identify the potential dispersal routes for giant pandas. We hypothesized that giant pandas will spread to neighboring areas when the population of the species keeps increasing. Habitat suitability was firstly evaluated based on environmental and disturbance factors. We then identified source and sink patches for giant pandas’ dispersal. Further, Minimum Cumulative Resistance (MCR) model was applied to calculate cost of movement. Finally, the Current Theory was adopted to model linkages between source and sink patches to explore potential dispersal routes of giant pandas. Our results showed that (1) the three large source patches and eight potential sink patches were identified; (2) the 14 potential corridors were predicted for giant pandas dispersing from source patches to the neighboring areas; (3) through the predicted corridors, the giant pandas in the source patches could disperse to the west, the south and the east sink patches. Our research revealed possible directional patterns for giant pandas’ dispersal in their key distribution area of the Qinling Mountains, and can provide the strong recommendations in policy and conservation strategies for improving giant panda habitat management in those identified sink patches and also potential dispersal corridors.

Dynamics of Competitive Systems with Diffusion Between Source-Sink Patches.

This paper considers two-species competitive systems with one-species' diffusion between patches. Each species can persist alone in the corresponding patch (a source), while the mobile species cannot survive in the other (a sink). Using the method of monotone dynamical systems, we give a rigorous analysis on persistence of the system, prove local/global stability of the equilibria and show new types of bi-stability. These results demonstrate that diffusion could lead to results reversing those without diffusion, which extend the principle of competitive exclusion: Diffusion could lead to persistence of the mobile competitor in the sink, make it reach total abundance larger than if non-diffusing and even exclude the opponent. The total abundance is shown to be a distorted function (surface) of diffusion rates, which extends both previous theory and experimental observations. A novel strategy of diffusion is deduced in which the mobile competitor could drive the opponent into extinction, and then approach the maximal abundance. Initial population density and diffusive asymmetry play a role in the competition. Our work has potential applications in biodiversity conservation and economic competition.

Effects of Prey's Diffusion on Predator-Prey Systems with Two Patches.

This paper considers predator-prey systems in which the prey can move between source and sink patches. First, we give a complete analysis on global dynamics of the model. Then, we show that when diffusion from the source to sink is not large, the species would coexist at a steady state; when the diffusion is large, the predator goes to extinction, while the prey persists in both patches at a steady state; when the diffusion is extremely large, both species go to extinction. It is derived that diffusion in the system could lead to results reversing those without diffusion. That is, diffusion could change species' coexistence if non-diffusing, to extinction of the predator, and even to extinction of both species. Furthermore, we show that intermediate diffusion to the sink could make the prey reach total abundance higher than if non-diffusing, larger or smaller diffusion rates are not favorable. The total abundance, as a function of diffusion rates, can be both hump-shaped and bowl-shaped, which extends previous theory. A novel finding of this work is that there exist diffusion scenarios which could drive the predator into extinction and make the prey reach the maximal abundance. Diffusion from the sink to source and asymmetry in diffusion could also lead to results reversing those without diffusion. Meanwhile, diffusion always leads to reduction of the predator's density. The results are biologically important in protection of endangered species.

Dynamics of consumer-resource systems with consumer's dispersal between patches

<p style='text-indent:20px;'>This paper considers consumer-resource systems with Holling II functional response. In the system, the consumer can move between a source and a sink patch. By applying dynamical systems theory, we give a rigorous analysis on persistence of the system. Then we show local/global stability of equilibria and prove Hopf bifurcation by the Kuznetsov Theorem. It is shown that dispersal in the system could lead to results reversing those without dispersal. Varying a dispersal rate can change species' interaction outcomes from coexistence in periodic oscillation, to persistence at a steady state, to extinction of the predator, and even to extinction of both species. By explicit expressions of stable equilibria, we prove that dispersal can make the consumer reach overall abundance larger than if non-dispersing, and there exists an optimal dispersal rate that maximizes the abundance. Asymmetry in dispersal can also lead to those results. It is proven that the overall abundance is a ridge-like function (surface) of dispersal rates, which extends both previous theory and experimental observation. These results are biologically important in protecting endangered species.</p>

A consumer–resource system with source–sink populations and asymmetric dispersal

In this paper, we consider a two-patch system with source–sink populations and asymmetric dispersal, which includes exploitable resources and extends a recent model describing experiments. Applying dynamical systems theory, we reveal uniform persistence of the system and exhibit existence of stable positive equilibria. Based on rigorous analysis, we demonstrate that dispersal can lead to survival of species in both patches, and asymmetric dispersal can make the species reach higher density than that with symmetric dispersal or with no dispersal. A new prediction of this paper is that in source–sink populations, the species with asymmetric dispersal can approach a density higher than that in the corresponding homogeneous resource-distributions with or without dispersal, which extends previous theory. It is shown that small asymmetry to the sink patch can increase total population abundance, while extremely large asymmetry would result in extinction of species. Our findings are consistent with experimental results and provide new predictions. Numerical computations confirm and extend the findings.

Insect infestation sources in stored maize grain; what is more important resident versus incoming infestation?

Most studies targeted pest control inside stores; incognisant of the population dynamics in the store vicinity; leading to product re-infestation. Distinction between storage insect pest source and sink grain patches is important for effective pest management strategies. We examined the role of resident versus incoming insect infestation in phosphine-fumigated closed or open and unfumigated closed or open maize farm stores. Grain quality measurements were recorded over 32 weeks for two storage seasons. Whether open or closed, fumigated grain had significantly lower (p < 0.001) grain damage and lower grain weight loss (p < 0.05) than unfumigated grain. Fumigated open stores had significantly higher (p= 0.004) grain damage and weight loss than closed ones. Grain damage was higher in unfumigated-closed than fumigated-open, evidence that resident infestation inflicted higher food loss than incoming infestation. Prostephanus truncatus, Cryptolestes ferrugineus and Tribolium castaneum had significantly higher populations (p < 0.001, p = 0.018 and p = 0.001; respectively) at bottom levels of unfumigated and fumigated grain (T. castaneum). Sitotroga cerealella and Sitophilus zeamais were significantly higher (p < 0.001) at the top of closed than open unfumigated compartments. Grain suffers less infestation and quality loss when it is a sink patch than when it is a source patch. Population build-up and ‘settling’ to inflict significant food loss takes longer for incoming compared to resident infestation. These results have ecological implications on postharvest IPM.

Linking Heat Source–Sink Landscape Patterns with Analysis of Urban Heat Islands: Study on the Fast-Growing Zhengzhou City in Central China

Globally, the urban heat island (UHI) effect is a major problem which leads to urban residents suffering from adverse urban ecological environments and serious health risks. Understanding the impacts of urban landscape features on the thermal environment has been an important focus across various fields of research. The purpose of this study is to analyze the impacts of urban heat source–sink landscape patterns on urban heat islands, using the fast-growing Zhengzhou City in central China as the case study. Landsat data (captured in 1996, 2006, and 2014), various geospatial approaches, and correlation analysis were applied to facilitate the analysis. Based on the contributions of the urban landscape to land surface temperature (LST), we empirically identified the heat sources and heat sinks. Then, the composition and configurations of heat source and sink landscapes were estimated by a series of spatial metrics at the landscape and class levels. The results showed that the overall mean land surface temperature (LST) in the study area increased by 2.72 °C from 1996 to 2014. This observed increasing trend in overall mean LST is consistent with the process of rapid urbanization in the study area, which was evidenced by the dramatic increase in impervious surfaces and the substantial loss in vegetation cover. Generally, as observed, landscape composition has a stronger influence on LST than does landscape configuration. For heat sources, the proportion, size, aggregation, and density of patches have positive effects on LST, while adjusting the spatial distribution and abundance of urban landscape are effective ways to control the UHI effects. In contrast, the percentage, size, density, and aggregation of heat sink patches have negative effects on LST. Additionally, the effects of increasing total patch edges and shape complexity should be considered when mitigating the UHI effect. These findings are beneficial for furthering our understanding of how urban landscape patterns affect UHI, and they can help optimize urban landscape patterns to alleviate the UHI effect and enhance sustainable development in the study area.

Age-structure density-dependent fertility and individuals dispersal in a population model

In this work, we analyze the interplay between general age structured density-dependent fertility functions and age classes dispersal in a patchy environment. As novelties, (i) the fertility function depends on age classes (instead of on the total population size) and (ii) dispersal patterns are also allowed to be different for individuals belonging to different age classes.Our results highlight the interplay between the shape of the age structured density-dependent fertility function and the age classes dispersal patterns. We analyze this interaction from an environmental management point of view by exploring the consequences of connecting patches that can sustain a population (source patch) or cannot (sink patch), as well as its relation to component Allee effects and strong Allee effects.In particular, we have found scenarios such that the metapopulation goes extinct when two isolated source patches are connect due to heterogeneous age classes distribution. On the contrary, there are settings such that heterogeneous age classes distribution enables two isolated sink patches to be sustainable when connected. Besides, we discuss what kind of local interventions are helpful to manage component Allee effect and its impact at the metopopulation level.The source code used to simulations is fully available. The code is presented as a knitr reproducible document in the open source R computing system. Thus, free access and usability of the code are granted.

Stochastic population growth in spatially heterogeneous environments: the density-dependent case

This work is devoted to studying the dynamics of a structured population that is subject to the combined effects of environmental stochasticity, competition for resources, spatio-temporal heterogeneity and dispersal. The population is spread throughout n patches whose population abundances are modeled as the solutions of a system of nonlinear stochastic differential equations living on [0,infty )^n. We prove that r, the stochastic growth rate of the total population in the absence of competition, determines the long-term behaviour of the population. The parameter r can be expressed as the Lyapunov exponent of an associated linearized system of stochastic differential equations. Detailed analysis shows that if r>0, the population abundances converge polynomially fast to a unique invariant probability measure on (0,infty )^n, while when r<0, the population abundances of the patches converge almost surely to 0 exponentially fast. This generalizes and extends the results of Evans et al. (J Math Biol 66(3):423–476, 2013) and proves one of their conjectures. Compared to recent developments, our model incorporates very general density-dependent growth rates and competition terms. Furthermore, we prove that persistence is robust to small, possibly density dependent, perturbations of the growth rates, dispersal matrix and covariance matrix of the environmental noise. We also show that the stochastic growth rate depends continuously on the coefficients. Our work allows the environmental noise driving our system to be degenerate. This is relevant from a biological point of view since, for example, the environments of the different patches can be perfectly correlated. We show how one can adapt the nondegenerate results to the degenerate setting. As an example we fully analyze the two-patch case, n=2, and show that the stochastic growth rate is a decreasing function of the dispersion rate. In particular, coupling two sink patches can never yield persistence, in contrast to the results from the non-degenerate setting treated by Evans et al. which show that sometimes coupling by dispersal can make the system persistent.

Linking potential heat source and sink to urban heat island: Heterogeneous effects of landscape pattern on land surface temperature.

Rapid urbanization has significantly contributed to the development of urban heat island (UHI). Regulating landscape composition and configuration would help mitigate the UHI in megacities. Taking Shenzhen, China, as a case study area, we defined heat source and heat sink and identified strong and weak sources as well as strong and weak sinks according to the natural and socioeconomic factors influencing land surface temperature (LST). Thus, the potential thermal contributions of heat source and heat sink patches were differentiated. Then, the heterogeneous effects of landscape pattern on LST were examined by using semiparametric geographically weighted regression (SGWR) models. The results showed that landscape composition has more significant effects on thermal environment than configuration. For a strong source, the percentage of patches has a positive impact on LST. Additionally, when mosaicked with some heat sink, even a small improvement in the degree of dispersion of a strong source helps to alleviate UHI. For a weak source, the percentage and density of patches have positive impacts on LST. For a strong sink, the percentage, density, and degree of aggregation of patches have negative impacts on LST. The effects of edge density and patch shape complexity vary spatially with the fragmentation of a strong sink. Similarly, the impacts of a weak sink are mainly exerted via the characteristics of percent, density, and shape complexity of patches.

The downward spiral: eco‐evolutionary feedback loops lead to the emergence of ‘elastic’ ranges

In times of severe environmental changes and resulting shifts in the geographical distribution of animal and plant species it is crucial to unravel the mechanisms responsible for the dynamics of species’ ranges. Without such a mechanistic understanding, reliable projections of future species distributions are difficult to derive. Species’ ranges may be highly dynamic. One particularly interesting phenomenon is range contraction following a period of expansion, referred to as ‘elastic’ behaviour. It has been proposed that this phenomenon occurs in habitat gradients, which are characterized by a negative cline in selection for dispersal from the range core towards the margin, as one may find, for example, with increasing patch isolation. Using individual‐based simulations and numerical analyses we show that Allee effects are an important determinant of range border elasticity. If only intra‐specific processes are considered, Allee effects are even a necessary condition for ranges to exhibit elastic behavior. The eco‐evolutionary interplay between dispersal evolution, Allee effects and habitat isolation leads to lower colonization probability and higher local extinction risk after range expansions, which result in an increasing amount of marginal sink patches and consequently, range contraction. We also demonstrate that the nature of the gradient is crucial for range elasticity. Gradients which do not select for lower dispersal at the margin than in the core (especially gradients in patch size, demographic stochasticity and extinction rate) do not lead to elastic range behavior. Thus, we predict that range contractions are likely to occur after periods of expansion for species living in gradients of increasing patch isolation, which suffer from Allee effects.

Protected polymorphisms and evolutionary stability of patch-selection strategies in stochastic environments.

We consider a population living in a patchy environment that varies stochastically in space and time. The population is composed of two morphs (that is, individuals of the same species with different genotypes). In terms of survival and reproductive success, the associated phenotypes differ only in their habitat selection strategies. We compute invasion rates corresponding to the rates at which the abundance of an initially rare morph increases in the presence of the other morph established at equilibrium. If both morphs have positive invasion rates when rare, then there is an equilibrium distribution such that the two morphs coexist; that is, there is a protected polymorphism for habitat selection. Alternatively, if one morph has a negative invasion rate when rare, then it is asymptotically displaced by the other morph under all initial conditions where both morphs are present. We refine the characterization of an evolutionary stable strategy for habitat selection from Schreiber (Am Nat 180:17-34, 2012) in a mathematically rigorous manner. We provide a necessary and sufficient condition for the existence of an ESS that uses all patches and determine when using a single patch is an ESS. We also provide an explicit formula for the ESS when there are two habitat types. We show that adding environmental stochasticity results in an ESS that, when compared to the ESS for the corresponding model without stochasticity, spends less time in patches with larger carrying capacities and possibly makes use of sink patches, thereby practicing a spatial form of bet hedging.

Zoonotic disease in a peripheral population: persistence and transmission of Leishmania major in a putative sink-source system in the Negev Highlands, Israel.

Populations at the edge of their geographic distributions are referred to as peripheral populations. Very little attention has been given to this topic in the context of persistence of infectious disease in natural populations. In this study, we examined this question using zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major in the Negev Desert of Israel as a model system. Here, we suggest that the regional persistence of Phlebotomus papatasi populations and L. major transmission in the Sede Boqer region could be explained through processes akin to sink-source and/or mainland-island metapopulation dynamics. Given its potentially enzootically superior ecological conditions, we hypothesize that the Zin Valley ecotope constitutes the "mainland" or the "source" patch for the Sede Boqer area where L. major transmission is persistent and resistant to local extinctions (die-outs) whereas the local sand fly populations on the Zin Plateau ("island patch" or "sink patch") are more prone to local extinctions. Between 2007 and 2008, we trapped sand flies and sand rats in the two areas and compared sand fly abundance and L. major infection prevalence in both. In both 2007 and 2008, sand fly abundance was high and continuous in the Zin Wadi but low and discontinuous in the Zin Plateau. Infection prevalence of sand rats was significantly higher in the Wadi (13%) compared with the Zin Plateau (3%). Minimum infection rate in sand flies did not differ significantly between the two areas. Overall, our results are consistent with the premise that the Zin Valley population is relatively robust in terms of L. major transmission, whereas transmission is potentially more tenuous in the plateau. Understanding the biotic and abiotic processes enabling the persistence of L. major and other vector-borne diseases in peripheral disease foci is important for predicting the effect of anthropogenic land use and climate change.