The dynamics of an ecological community can be described at different focal scales of the species, such as individual states or the population level. More detailed descriptions of ecological dynamics ...offer more information, but produce more complex models that are difficult to analyze. Adequately controlling the model complexity and the availability of multiple descriptions of the concerned dynamics maximizes our understanding of ecological dynamics. One of the central goals of ecological studies is to develop links between multiple descriptions of an ecological community. In this article, starting from a nonlinear state-level description of an ecological community (generalized McKendrick-von Foerster model), role-level and population-level descriptions (Lotka-Volterra model) are derived in a consistent manner. The role-level description covers a wider range of situations than the population-level description. However, using the established connections, it is demonstrated that the population-level description can be used to predict the equilibrium status of the role-level description. This approach connects state-, role-, and population-level dynamics consistently, and offers a justification for the multiple choices of model description.
Marine reserves are an essential component of modern fishery management. Marine reserves, which represent a management tradeoff between harvesting and conservation, are fundamental to maintenance of ...fisheries. Finding optimal reserve sizes that improve fishing yields is not only of theoretical interest, but also of practical importance to facilitate decision making. Also, since the migratory behavior of some species influences the spillover effect of a marine reserve, this is a key consideration when assessing performance of marine reserves. The relationship between optimal reserve size and migration rate/mode has not been well studied, but it is fundamental to management success. Here, I investigate optimal reserve size and its management outcome with different levels of spillover via a simple two-patch mathematical model. In this model, one patch is open to fishing, and the other is closed. The two-patch model is aggregated by single-population dynamics when the migration rate is sufficiently larger than the growth rate of a target species. At this limit, I show that an optimal reserve size exists when pre-reserve fishing occurs at fishing mortality larger than f.sub.MSY , the fishing mortality at the maximum sustainable yield (MSY). Also, the fishing yield at an optimal reserve size becomes as large as MSY at the limit. Numerical simulations at various migration rates between the two patches suggest that the maximum harvest under management with a marine reserve is achieved at this limit. This contrasts with the conservation benefit which is maximized at an intermediate migration rate. Numerical simulations show that the above-mentioned condition for an optimal reserve size to exist derived from the aggregated model is necessary when the migration rate is not sufficiently large, and that a moderate migration rate is further necessary for an optimal reserve size to exist. However, high fishing mortality reduces this requirement.
Terrestrial and marine protected areas are essential tools in mitigating anthropogenic impacts and promoting population persistence and resource sustainability. Adequately implemented protected areas ...(PAs) aim to promote conservation by increasing population size and reducing its variability. To resolve how these effects depend on PA features, I develop and analyze new models of stochastic processes that encompass the fluctuations generated by demographic or environmental stochasticity in PAs management. The stochastic model is built upon individual processes. In the model, density-independent mortality, migration between PAs and non-PAs, organism preference for PAs, and size characterize the features of the PA. The effect of PAs size is also examined. The long-term conservation effects are quantified using the coefficient of variation (CV) of population size in PAs, where a lower CV indicates higher robustness in stochastic variations. The results from this study demonstrate that sufficiently reduced density-independent mortality in PAs and high site preference for PAs and immigration rate into PAs are likely to decrease the CV. However, different types of stochasticity induce rather different consequences: under demographic stochasticity, the CV is always reduced because PAs increase the population size therein, but an increased population size by PAs does not always decrease the CV under environmental stochasticity. The deterministic dynamics of the model are investigated, facilitating effective management decisions.
Overfishing is the main threat to sustainable fisheries and the loss of marine biodiversity. The race-to-fish phenomenon is a central driver of overfishing, and it prevails from small-scale to ...large-scale management regardless of whether spatial-right-based fisheries management has been implemented to ensure the ownership of fishery resources. In practice, the fishing grounds of resource users create complex configurations. Systematic understanding of harvesting competition across these configurations is necessary to promote sustainable fisheries management. Here, we developed a spatially-explicit model to analyze various scenarios of harvesting competition between two user groups using a game-theoretic approach. We found that realized harvesting competition was largely determined by the configuration of fishing grounds and an ecological mechanism where the ecological rescue effect could escalate harvesting competition, leading to a low population size. Our results also suggested that the implementation of voluntary no-take marine protected areas could largely mitigate harvesting competition. This suggests that the coordination of user groups is essential to resolve the race-to-fish.
•Harvesting competition is the central driver of overfishing.•The intensity of harvesting competition depends on fishing ground configuration.•Ecological mechanisms also characterize harvesting competition.•The creation of collaborative no-take MPAs can substantially reduce competition.
Pattern in space and time is central to ecology, and adequately designed ecological sampling is needed to resolve those patterns, pursue ecological questions and design conservation strategies. ...Recently, there has been an explosion of various ecological data due to the proliferation of online data‐sharing platforms, citizen science programs and new technology such as unmanned aerial vehicles (UAVs), but data reliability, consistency and the error properties of the sampling method are usually uncertain. While there are a number of standard survey protocols for different taxa, they often subjectively designed and standardization is meant to facilitate repeatability rather than produce a quantitative evaluation of the data (e.g. error properties). Here, we describe an ecological survey scheme consisting of an ‘algorithm' to be followed in the field that will result in a standard set of data as well as the error properties of the data. While many such sampling schemes could be developed that target different types of organisms, we focus on one case of a moving observer attempting to detect a species in the field (e.g. a birder, UAV, etc.) with the goal of producing a presence–absence map. The multiscale model developed is spatially explicit and accommodates inherent survey tradeoffs such as sampling speed, detectability and map resolution. Given a set of sampling parameters, the model provides estimates of the total sampling time and map accuracy translated into the probability of false negative. Additionally it also provides an actual and sampled occupancy–area curve across mapping resolutions that can be utilized to discuss sampling effects. While the proposed sampling framework is simple, the same general approach could be adapted for other conditions to meet the needs of a particular taxon. If a set of ‘canonical' sampling algorithms could be developed with known mathematical properties, it would enhance reliability and usage of ecological datasets.
Climate extremes affect ecosystems and people’s livelihoods, especially those that depend on them. Increasing extreme events such as droughts due to climate change urgently require the development of ...a framework to assess risks to livelihoods. Using pastoral livelihoods in Mongolia as an example, we develop a mathematical model to assess climate risks to the pastoral socio-ecological system. The study highlights the importance of a support system that ensures the flexibility of herders’ migration in highly variable climates. Risk assessment is essential to mitigate and adapt to climate change and to ensure the sustainability of pastoral livelihoods in the future.
Herein, we discuss the governance implications for emerging protected areas with complexity in the 2020s by analyzing public–private partnership frameworks in Japan’s national parks. First, we ...summarize previous literature to elucidate the characteristics of Japan’s national park management as “weak government” represented by a lack of administrative resources and weak regulatory power. Second, we identify the weak implementation of two legal public–private partnership frameworks from questionnaires and interviews: the Park Management Organization and the Scenic Area Protection Agreement. We discuss the high transaction costs and lack of sufficient benefits to the private sector as the main reasons behind weak implementation. We identify this mismatch as a “governance paradox” and argue that sufficient administrative support and institutional design are indispensable for active partnership implementation.
Intra‐cohort cannibalism is an example of a size‐mediated priority effect. If early life stages cannibalize slightly smaller individuals, then parents face a trade‐off between breeding at the best ...time for larval growth or development and predation risk from offspring born earlier. This game‐theoretic situation among parents may drive adaptive reproductive phenology toward earlier breeding. However, it is not straightforward to quantify how cannibalism affects seasonal egg fitness or to distinguish emergent breeding phenology from alternative adaptive drivers. Here, we devise an age‐structured game‐theoretic mathematical model to find evolutionary stable breeding phenologies. We predict how size‐dependent cannibalism acting on eggs, larvae, or both changes emergent breeding phenology and find that breeding under inter‐cohort cannibalism occurs earlier than the optimal match to environmental conditions. We show that emergent breeding phenology patterns at the level of the population are sensitive to the ontogeny of cannibalism, that is, which life stage is subject to cannibalism. This suggests that the nature of cannibalism among early life stages is a potential driver of the diversity of reproductive phenologies seen across taxa and may be a contributing factor in situations where breeding occurs earlier than expected from environmental conditions.
Cannibalism introduces a trade‐off between breeding at the optimal time in the season and increased predation risk from offspring born earlier. We predict how size‐dependent cannibalism on eggs, larvae, or both changes emergent breeding phenology and find breeding that occurs earlier than the optimal match to environmental conditions. We show that emergent breeding phenology patterns at the level of the population are sensitive to the ontogeny of cannibalism.
The growing availability of high-resolution biodiversity data is enhancing our ability to implement biodiversity conservation more effectively. Spatial planning has widely utilized such fine-scale ...biodiversity data, and proposals of finely-organized protected area networks have been increasing. However, a naive adoption of such fine-scale data for conservation may not only degrade the utility of the data, but may even risk reduction of long-term efficacy of conservation efforts. This is due to inherent tradeoffs between the efficacy of conservation actions over short-term and its persistence over long-term that is characterized by the management scale of spatial planning associated with the resolution of the data used. To demonstrate this argument, the spatiotemporal ecosystem dynamics must be described, but such discussions are limited in the literature. Here, we discuss the potential issues associated with naive uses of fine-scale biodiversity data to establish fine-tuned spatial planning. We then emphasize the importance of matching the data resolution with an appropriate scale of spatial planning that is realized by transforming the data resolution. This method is readily applicable for widely used decision-support tools for spatial planning. A simple worked example is provided to demonstrate its utility with a long-term conservation efficacy in spatial planning. Guided by the recent explosion of biological data, our discussion provides new insights into the ways to maximize the utility of these data, and further improve biodiversity conservation.
Conservation needs adequate support and funding to address our ecological crises. People support conservation in different ways, from social media engagement to donating money. Various factors ...influence how people choose to support conservation, including social norms and ecological status. The rise of social media has provided people with an easy and low‐cost way to support conservation: sharing information online. How valuable is social media engagement and activism for conservation funding and outcomes? Here, we develop an evolutionary game‐theoretic framework to understand the complex interactions between individuals in the context of social media information sharing, conservation philanthropy, and how these interactions ultimately impact ecological outcomes. From a game theory perspective, we can consider donors to be hard‐cooperators, sharers of information on social media to be soft‐cooperators, and those who do nothing to be non‐cooperators. Our model shows that soft‐cooperators can help stabilize conservation funding flows and develop social norms. Supporting conservation through social media sharing can ultimately contribute to conservation success. Our study conceptualizes the complex decision‐making processes of conservation funding and affirms the importance and value of mobilizing all types of supporters in conservation.
In this manuscript, we develop a novel game‐theoretic framework to understand the complex interactions between individuals in the context of information sharing on social media, conservation philanthropy, and how these interactions ultimately impact ecological outcomes. Our results demonstrate the importance of mobilizing people who are weakly engaged in conservation action to stabilize funding flow and ecological status.
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