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We consider different anti-symmetric Lotka-Volterra systems governing the pairwise interactions among the same n species inhabiting m spatially discrete habitat patches, with each patch having infinitely many equilibria. In the absence of inter-patch species migration, the species densities in each isolated patch evolve in periodic orbits. A central idea of this work is to design a control action to make the trajectories of the system asymptotically converge to a desired coexistence equilibrium among the infinitely many equilibrium points. We propose a scheme to simultaneously control different anti-symmetric Lotka-Volterra systems in multiple habitat patches by designing a metapopulation model. By introducing a suitable inter-patch migration of species, we prove that the trajectories of the resulting metapopulation model are effectively asymptotically converging to the desired coexistence equilibrium. The stability of the coexistence equilibrium is proved using Lyapunov methods coupled with LaSalle's invariance principle.
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Ecosistema , Modelos Biológicos , Dinámica Poblacional , AnimalesRESUMEN
Matsuda and Abrams (Theor Popul Biol 45(1):76-91, 1994) initiated the exploration of self-extinction in species through evolution, focusing on the advantageous position of mutants near the extinction boundary in a prey-predator system with evolving foraging traits. Previous models lacked theoretical investigation into the long-term effects of harvesting. In our model, we introduce constant-effort prey and predator harvesting, along with individual logistic growth of predators. The model reveals two distinct evolutionary outcomes: (i) Evolutionary suicide, marked by a saddle-node bifurcation, where prey extinction results from the invasion of a lower forager mutant; and (ii) Evolutionary reversal, characterized by a subcritical Hopf bifurcation, leading to cyclic prey evolution. Employing an innovative approach based on Gröbner basis computation, we identify various bifurcation manifolds, including fold, transcritical, cusp, Hopf, and Bogdanov-Takens bifurcations. These contrasting scenarios emerge from variations in harvesting parameters while keeping other factors constant, rendering the model an intriguing subject of study.
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Evolución Biológica , Cadena Alimentaria , Conceptos Matemáticos , Modelos Biológicos , Dinámica Poblacional , Conducta Predatoria , Animales , Dinámica Poblacional/estadística & datos numéricos , Extinción Biológica , Simulación por Computador , Mutación , EcosistemaRESUMEN
The dynamics of soil arthropod communities in annual monoculture grasslands is still unclear, which restricts the understanding of the degradation mechanism of cultivated grasslands. We cultivated two annual gramineae species, Lolium multiflorum and Avena sativa, separately in Hongyuan County, located on the eastern edge of the Qinghai-Tibet Plateau, in April 2019. We investigated soil arthropods, plant communities and soil properties in the cultivated grasslands and natural grassland in the late September every year from 2019 to 2022. The results showed that: 1) The taxonomic composition of soil arthropod communities differed significantly among three grasslands and sampling years. 2) There was no significant difference in the density, taxonomic richness, Shannon index and evenness index of soil arthropod communities among three grasslands. 3) The density of soil arthropod communities significantly fluctuated across years in three grasslands, and the taxonomic richness and Shannon index decreased significantly in the L. multiflorum and A. sativa grasslands, with the evenness index declining significantly only in the fourth year. The Shannon index fluctuated significantly and the evenness index varied little in natural grassland. 4) The above- and below-ground biomass, the contents of soil total P, total K and available N were the main factors influencing the taxonomic composition, density and diversity indices of soil arthropod communities. The results suggested that the cultivation of annual gramineae grasslands have significant effects on taxonomic composition, but not on density and diversity of soil arthropod communities, and those variables change significantly across different years.
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Artrópodos , Pradera , Suelo , Animales , Artrópodos/clasificación , Artrópodos/crecimiento & desarrollo , Suelo/química , China , Biodiversidad , Dinámica Poblacional , Lolium/crecimiento & desarrollo , Lolium/clasificación , Poaceae/crecimiento & desarrollo , Poaceae/clasificación , Avena/crecimiento & desarrollo , Avena/clasificación , AltitudRESUMEN
We studied the population characteristics of Caragana microphylla and related soil factors across diffe-rent stages of shrub encroachment (i.e., light, moderate, and severe) on the Xilingol Grassland of Inner Mongolia. The results showed that the density and height of C. microphylla gradually increased during the process of grassland shrub-encroachment from light to moderate to severe. The density and height were increased by 196.0% and 34.5% from light to moderate stage of shrub encroachment, and were increased by 25.4% and 17.6% from moderate to severe stage. Crown size, basal diameter, tiller number per clump, and aboveground productivity of C. microphylla tented to decrease first and then increase, while the proportion of aboveground biomass allocation to leaves decreased across the stages of shrub encroachment. The competition between C. microphylla and herbaceous species was strongest in the moderate encroachment stage. C. microphylla reduced its lateral growth (such as crown size, basal diameter, and tiller number per clump) and increased density and height to get competitive advantage. Limi-ting soil factors for C. microphylla varied significantly at different stages of shrub encroachment. In the light encroachment stage, soil factors had little effect on the growth of C. microphylla. In the moderate encroachment stage, soil moisture in the deep layer (20-50 cm) and soil pH were the key factors limiting shrub density. In the severe encroachment stage, soil moisture in the deep layer and pH limited the vertical growth of C. microphylla, while soil moisture of shallow layer (0-20 cm) and nutrients were the limiting factors for the lateral expansion of shrubs.
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Caragana , Pradera , Suelo , China , Caragana/crecimiento & desarrollo , Suelo/química , Ecosistema , Dinámica PoblacionalRESUMEN
We analyzed age structure and dynamics, spatial distribution patterns, and reproductive capabilities of four Rosa persica populations in Xinjiang, to evaluate the survival status of the species and explore the reasons behind its endangerment. The results showed that the populations had fewer individuals in the youngest (â ) and oldest (â ¥-â §) age classes, with a predominance of middle-aged individuals, resulting in an irregular pyramid-shaped distribution, described as "high in the middle, low on both sides". The populations were generally growing, but were susceptible to external environmental disturbances (Vpi'ï¼0, Pmaxï¼0). The mortality rate (qx) and vanish rate (Kx) peaked at age â ¤, leading to a sharp decline in plant abundance. The life expectancy (ex) decreased progressively with the increases of age class, reaching its lowest at age â §, which indicated minimal vitality at this stage. A time sequence analysis predicted a future dominance of individuals at age â ¤-â §, suggesting an aging trend. Spatially, the four populations were predominantly clumped, with the intensity of clumping ranked from highest to lowest as P4, P3, P1, and P2. P3 and P4 exhibited better reproductive capabilities than P1 and P2. There was a significant positive correlation between hundred-fruit weight and plant height and crown width, and between total seed number and crown width and hundred-fruit weight.
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Dinámica Poblacional , Rosa , Rosa/crecimiento & desarrollo , China , Frutas/crecimiento & desarrollo , Reproducción , Ecosistema , Conservación de los Recursos NaturalesRESUMEN
The warming of the Arctic had lead to a diverse range of impacts on local biota, including northward shifts of some species range. Here, we report past and present distribution and abundance of an Arctic zooplanktivorous seabird, the little auk Alle alle in West Greenland south of 74° N, and examine the changes in sea surface temperature (SST) and sea ice concentration (SIC) in the birds foraging areas in 1850-2007. We estimated the little auk population in the studied region to be 5,200 pairs in the 1930s, 6,000-6,500 pairs in the 1940-1970s and 70-80 pairs by the 2000s. We found that periods with increased SST and reduced SIC, especially in the last few decades, coincided with little auk population declines. Besides, years with little auk presence in breeding sites were characterized by either low SST and low to moderate SIC or higher SST but moderate to high SIC. Observed contraction of the breeding range and a decrease in abundance of the little auk may be attributed to more complex climate-driven changes in the marine ecosystem at finer spatial and temporal scales and/or cannot be easily detected given the coarseness of data used. It is possible that the population in this region has never been very numerous being subjected to local impacts such as disease, bycatch, predation, etc. The climate warming that is currently being observed, along with corresponding shifts in zooplankton communities, may lead to extirpation of the studied little auk populations.
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Ecosistema , Animales , Groenlandia , Regiones Árticas , Cambio Climático , Cubierta de Hielo , Dinámica Poblacional , Temperatura , Charadriiformes/fisiologíaRESUMEN
Chemical pollution, land cover change, and climate change have all been established as important drivers of amphibian reproductive success and phenology. However, little is known about the relative impacts of these anthropogenic stressors, nor how they may interact to alter amphibian population dynamics. Addressing this gap in our knowledge is important, as it allows us to identify and prioritise the most needed conservation actions. Here, we use long-term datasets to investigate landscape-scale drivers of variation in the reproductive success and phenology of UK Common frog (Rana temporaria) populations. Consistent with predictions, we found that increasing mean temperatures resulted in earlier initialisation of spawning, and earlier hatching, but these relationships were not consistent across all sites. Lower temperatures were also linked to increased spawn mortality. However, temperature increases were also strongly correlated with increases in urban area, arable area, and nitrate levels in the vicinity of spawning grounds. As with spawning and hatching, there was marked spatial variation in spawn mortality trends, where some sites exhibited steady increases over time in the proportion of dead or diseased spawn. These findings support previous work linking warming temperatures to shifts in timing of amphibian breeding, but also highlight the importance of assessing the effect of land use change and pollution on wild amphibian populations. These results have implications for our understanding of the response of wild amphibian populations to climate change, and the management of human-dominated landscapes for declining wildlife populations.
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Cambio Climático , Rana temporaria , Reproducción , Temperatura , Animales , Reproducción/fisiología , Dinámica PoblacionalRESUMEN
Incorporating a weak Allee effect in a two-dimensional biological model in â2, the study delves into the application of bifurcation theory, including center manifold and Ljapunov-Schmidt reduction, normal form theory, and universal unfolding, to analyze nonlinear stability issues across various engineering domains. The focus lies on the qualitative dynamics of a discrete-time system describing the interaction between prey and predator. Unlike its continuous counterpart, the discrete-time model exhibits heightened chaotic behavior. By exploring a biological Mmdel with linear functional prey response, the research elucidates the local asymptotic properties of equilibria. Additionally, employing bifurcation theory and the center manifold theorem, the analysis reveals that, for all α1 (i.e., intrinsic growth rate of prey), ð1Ë (i.e., parameter that scales the terms yn), and m (i.e., Allee effect constant), the model exhibits boundary fixed points A1 and A2, along with the unique positive fixed point A∗, given that the all parameters are positive. Additionally, stability theory is employed to explore the local dynamic characteristics, along with topological classifications, for the fixed points A1, A2, and A∗, considering the impact of the weak Allee effect on prey dynamics. A flip bifurcation is identified for the boundary fixed point A2, and a Neimark-Sacker bifurcation is observed in a small parameter neighborhood around the unique positive fixed point A∗=(mð1Ë-1,α1-1-α1mð1Ë-1). Furthermore, it implements two chaos control strategies, namely, state feedback and a hybrid approach. The effectiveness of these methods is demonstrated through numerical simulations, providing concrete illustrations of the theoretical findings. The model incorporates essential elements of population dynamics, considering interactions such as predation, competition, and environmental factors, along with a weak Allee effect influencing the prey population.
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Modelos Biológicos , Conducta Predatoria , Conducta Predatoria/fisiología , Animales , Dinámicas no Lineales , Simulación por Computador , Dinámica Poblacional , Factores de TiempoRESUMEN
The spatial availability of social resources is speculated to structure animal movement decisions, but the effects of social resources on animal movements are difficult to identify because social resources are rarely measured. Here, we assessed whether varying availability of a key social resource-access to receptive mates-produces predictable changes in movement decisions among bighorn sheep in Nevada, the United States. We compared the probability that males made long-distance 'foray' movements, a critical driver of connectivity, across three ecoregions with varying temporal duration of a socially mediated factor, breeding season. We used a hidden Markov model to identify foray events and then quantified the effects of social covariates on the probability of foray using a discrete choice model. We found that males engaged in forays at higher rates when the breeding season was short, suggesting that males were most responsive to the social resource when its existence was short lived. During the breeding season, males altered their response to social covariates, relative to the non-breeding season, though patterns varied, and age was associated with increased foray probability. Our results suggest that animals respond to the temporal availability of social resources when making the long-distance movements that drive connectivity. This article is part of the theme issue 'The spatial-social interface: a theoretical and empirical integration'.
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Borrego Cimarrón , Animales , Borrego Cimarrón/fisiología , Masculino , Nevada , Conducta Social , Estaciones del Año , Femenino , Conducta Sexual Animal/fisiología , Dinámica Poblacional , MovimientoRESUMEN
Density-dependent population dynamic models strongly influence many of the world's most important harvest policies. Nearly all classic models (e.g. Beverton-Holt and Ricker) recommend that managers maintain a population size of roughly 40-50 percent of carrying capacity to maximize sustainable harvest, no matter the species' population growth rate. Such insights are the foundational logic behind most sustainability targets and biomass reference points for fisheries. However, a simple, less-commonly used model, called the Hockey-Stick model, yields very different recommendations. We show that the optimal population size to maintain in this model, as a proportion of carrying capacity, is one over the population growth rate. This leads to more conservative optimal harvest policies for slow-growing species, compared to other models, if all models use the same growth rate and carrying capacity values. However, parameters typically are not fixed; they are estimated after model-fitting. If the Hockey-Stick model leads to lower estimates of carrying capacity than other models, then the Hockey-Stick policy could yield lower absolute population size targets in practice. Therefore, to better understand the population size targets that may be recommended across real fisheries, we fit the Hockey-Stick, Ricker and Beverton-Holt models to population time series data across 284 fished species from the RAM Stock Assessment database. We found that the Hockey-Stick model usually recommended fisheries maintain population sizes higher than all other models (in 69-81% of the data sets). Furthermore, in 77% of the datasets, the Hockey-Stick model recommended an optimal population target even higher than 60% of carrying capacity (a widely used target, thought to be conservative). However, there was considerable uncertainty in the model fitting. While Beverton-Holt fit several of the data sets best, Hockey-Stick also frequently fit similarly well. In general, the best-fitting model rarely had overwhelming support (a model probability of greater than 95% was achieved in less than five percent of the datasets). A computational experiment, where time series data were simulated from all three models, revealed that Beverton-Holt often fit best even when it was not the true model, suggesting that fisheries data are likely too small and too noisy to resolve uncertainties in the functional forms of density-dependent growth. Therefore, sustainability targets may warrant revisiting, especially for slow-growing species.
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Conservación de los Recursos Naturales , Explotaciones Pesqueras , Peces , Conceptos Matemáticos , Modelos Biológicos , Densidad de Población , Dinámica Poblacional , Explotaciones Pesqueras/estadística & datos numéricos , Animales , Conservación de los Recursos Naturales/estadística & datos numéricos , Dinámica Poblacional/estadística & datos numéricos , Peces/crecimiento & desarrollo , Biomasa , Simulación por ComputadorRESUMEN
Seabird colonies with long-term monitoring records, i.e., > 50 years, are rare. The population data for northern gannets (Morus bassanus) in Cape St. Mary's (CSM) Ecological Reserve (Newfoundland and Labrador, Canada) is robust, extending back to 1883 when the colony was presumed established. We inferred the colony's historical population shifts by measuring ornithogenic proxies in a dated sediment record collected from a nearby pond. Our record extended to the early eighteenth century, but the proxy data only began to show significant signs of seabird presence between ca. 1832 and 1910, aligning with the period gannets were first observed at CSM. Through the twentieth century, we observed significant increases in δ15N, P, Zn, Cd, and chlorophyll a, coeval with a shift in the dominant diatom species, indicating rapid colony growth. The proxies were overall highest in ca. 2005, corresponding to the reported historical maximum of the gannet colony in 2009. Our results validate that paleo-reconstructions using ornithogenic proxies can accurately reflect population trends and provide a stronger understanding of the colony's establishment and growth. This study highlights the value of applying paleolimnological methods in seabird population studies to frame the history of a colony's dynamics and inform conservation efforts.
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Aves , Animales , Terranova y Labrador , Censos , Diatomeas/crecimiento & desarrollo , Dinámica Poblacional , Clorofila A/análisis , Sedimentos Geológicos/análisis , Historia del Siglo XXRESUMEN
Rabies is a neglected disease primarily related to dog-mediated transmission to humans. Accurate dog demographic and dynamic data are essential for effectively planning and evaluating population management strategies when designing interventions to prevent rabies. However, in Thailand, longitudinal survey data regarding dog population size are scarce. A school-based participatory research (SBPR) approach was conducted to survey owned dogs for one year in four high-risk provinces (Chiang Rai, Surin, Chonburi, and Songkhla) of Thailand, aiming to understand dog population dynamics and raise awareness about rabies. 'Pupify' mobile application was developed to collect data on dog population and observe the long-term population dynamics in this study. At the end of the data collection period, telephone interviews were conducted to gain insight into contextual perceptions and awareness regarding both animal and human rabies, as well as the social responsibility of dog owners in disease prevention and control. Among 303 high school students who registered in our study, 218 students reported at least one update of their dog information throughout the one-year period. Of 322 owned dogs from our survey, the updates of dog status over one year showed approximately 7.5 newborns per 100-dog-year, while deaths and missing dogs were 6.2 and 2.7 per 100-dog-year, respectively. The male to female ratio was approximately 1.8:1. Twenty-three students (10%) voluntarily participated and were interviewed in the qualitative study. The levels of rabies awareness and precautions among high-school students were relatively low. The high dropout rate of the survey was due to discontinuity in communication between the researcher and the students over the year. In conclusion, this study focused on using the SBPR approach via mobile application to collect data informing dog population dynamics and raising awareness regarding rabies in Thailand Other engaging platforms (e.g. Facebook, Instagram, Twitter, and other popular applications) is necessary to enhance communication and engagement, thereby sustaining and maintaining data collection. Further health education on rabies vaccination and animal-care practices via social media platforms would be highly beneficial. For sustainable disease control, engaging communities to raise awareness of rabies and increase dog owners' understanding of their responsibilities should be encouraged.
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Enfermedades de los Perros , Conocimientos, Actitudes y Práctica en Salud , Dinámica Poblacional , Rabia , Perros , Rabia/prevención & control , Rabia/epidemiología , Rabia/veterinaria , Animales , Tailandia/epidemiología , Humanos , Masculino , Femenino , Enfermedades de los Perros/prevención & control , Enfermedades de los Perros/epidemiología , Enfermedades de los Perros/virología , Instituciones Académicas , Adolescente , Investigación Participativa Basada en la Comunidad , Estudiantes/psicología , Encuestas y CuestionariosRESUMEN
Many conservation actions must be implemented with limited data. This is especially true when planning recovery efforts for extirpated populations, such as grizzly bears (Ursus arctos) within the Bitterroot Ecosystem (BE), where strategies for reestablishing a resident population are being evaluated. Here, we applied individual-based movement models developed for a nearby grizzly bear population to predict habitat use in and near the BE, under scenarios of natural recolonization, reintroduction, and a combination. All simulations predicted that habitat use by grizzly bears would be higher in the northern half of the study area. Under the natural recolonization scenario, use was concentrated in Montana, but became more uniform across the northern BE in Idaho over time. Use was more concentrated in east-central Idaho under the reintroduction scenario. Assuming that natural recolonization continues even if bears are reintroduced, use remained widespread across the northern half of the BE and surrounding areas. Predicted habitat maps for the natural recolonization scenario aligned well with outlier and GPS collar data available for grizzly bears in the study area, with Spearman rank correlations of ≥0.93 and mean class values of ≥9.1 (where class 10 was the highest relative predicted use; each class 1-10 represented 10% of the landscape). In total, 52.4% of outlier locations and 79% of GPS collar locations were in class 10 in our predicted habitat maps for natural recolonization. Simulated grizzly bears selected habitats over a much larger landscape than the BE itself under all scenarios, including multiple-use and private lands, similar to existing populations that have expanded beyond recovery zones. This highlights the importance of recognizing and planning for the role of private lands in recovery efforts, including understanding resources needed to prevent and respond to human-grizzly bear conflict and maintain public acceptance of grizzly bears over a large landscape.
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Conservación de los Recursos Naturales , Ecosistema , Ursidae , Ursidae/fisiología , Animales , Idaho , Conservación de los Recursos Naturales/métodos , Montana , Dinámica PoblacionalRESUMEN
Traditional assays for counting bacteriophages and their lysogens are labor-intensive and perturbative to the host cells. Here, we present a high-throughput infection method in a microplate reader, where the growth dynamics of the infected culture is measured using the optical density (OD). We find that the OD at which the culture lyses scales linearly with the logarithm of the initial phage concentration, providing a way of measuring phage numbers over nine orders of magnitude and down to single-phage sensitivity. Interpreting the measured dynamics using a mathematical model allows us to infer the phage growth rate, which is a function of the phage-cell encounter rate, latent period, and burst size. Adding antibiotic selection provides the ability to measure the rate of host lysogenization. Using this method, we found that when E. coli growth slows down, the lytic growth rate of lambda phages decreases, and the propensity for lysogeny increases, demonstrating how host physiology influences the viral developmental program.
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Escherichia coli , Lisogenia , Escherichia coli/virología , Escherichia coli/crecimiento & desarrollo , Bacteriófagos/fisiología , Bacteriófago lambda/fisiología , Bacteriófago lambda/genética , Modelos Biológicos , Dinámica Poblacional , Antibacterianos/farmacología , Modelos TeóricosRESUMEN
BACKGROUND: Antananarivo, the capital city of Madagascar, is experiencing a steady increase in population growth. Due to the abundance of mosquito vectors in this locality, the population exposed to mosquito-borne diseases is therefore also increasing, as is the risk of epidemic episodes. The aim of the present study was to assess, in a resource-limited setting, the information on mosquito population dynamics and disease transmission risk that can be provided through a longitudinal entomological study carried out in a multi-host single site. METHODS: Mosquitoes were collected every 15 days over 16 months (from January 2017 to April 2018) using six CDC-light traps in a peri-urban area of Antananarivo. Multivariable generalised linear models were developed using indoor and outdoor densities of the predominant mosquito species as response variables and moon illumination, environmental data and climatic data as the explanatory variables. RESULTS: Overall, 46,737 mosquitoes belonging to at least 20 species were collected, of which Culex antennatus (68.9%), Culex quinquefasciatus (19.8%), Culex poicilipes (3.7%) and Anopheles gambiae sensu lato (2.3%) were the most abundant species. Mosquito densities were observed to be driven by moon illumination and climatic factors interacting at different lag periods. The outdoor models demonstrated biweekly and seasonal patterns of mosquito densities, while the indoor models demonstrated only a seasonal pattern. CONCLUSIONS: An important diversity of mosquitoes exists in the peri-urban area of Antananarivo. Some well-known vector species, such as Cx. antennatus, a major vector of West Nile virus (WNV) and Rift-Valley fever virus (RVFV), Cx. quinquefasciatus, a major vector of WNV, Cx. poicilipes, a candidate vector of RVFV and An. gambiae sensu lato, a major vector of Plasmodium spp., are abundant. Importantly, these four mosquito species are present all year round, even though their abundance declines during the cold dry season, with the exception of Cx. quinquefasciatus. The main drivers of their abundance were found to be temperature, relative humidity and precipitation, as well as-for outdoor abundance only-moon illumination. Identifying these drivers is a first step towards the development of pathogen transmission models (R0 models), which are key to inform public health stakeholders on the periods of most risk for vector-borne diseases.
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Culex , Mosquitos Vectores , Dinámica Poblacional , Animales , Madagascar/epidemiología , Mosquitos Vectores/virología , Mosquitos Vectores/fisiología , Estudios Longitudinales , Culex/virología , Culex/fisiología , Culex/clasificación , Estaciones del Año , Culicidae/virología , Culicidae/fisiología , Culicidae/clasificación , Anopheles/fisiología , Anopheles/virología , Anopheles/clasificación , Humanos , Densidad de Población , Virus del Nilo Occidental , FemeninoRESUMEN
Introduction: Community-level changes in population mobility can dramatically change the trajectory of any directly-transmitted infectious disease, by modifying where and between whom contact occurs. This was highlighted throughout the COVID-19 pandemic, where community response and nonpharmaceutical interventions changed the trajectory of SARS-CoV-2 spread, sometimes in unpredictable ways. Population-level changes in mobility also occur seasonally and during other significant events, such as hurricanes or earthquakes. To effectively predict the spread of future emerging directly-transmitted diseases, we should better understand how the spatial spread of infectious disease changes seasonally, and when communities are actively responding to local disease outbreaks and travel restrictions. Methods: Here, we use population mobility data from Virginia spanning Aug 2019-March 2023 to simulate the spread of a hypothetical directly-transmitted disease under the population mobility patterns from various months. By comparing the spread of disease based on where the outbreak begins and the mobility patterns used, we determine the highest-risk areas and periods, and elucidate how seasonal and pandemic-era mobility patterns could change the trajectory of disease transmission. Results and discussion: Through this analysis, we determine that while urban areas were at highest risk pre-pandemic, the heterogeneous nature of community response induced by SARS-CoV-2 cases meant that when outbreaks were occurring across Virginia, rural areas became relatively higher risk. Further, the months of September and January led to counties with large student populations to become particularly at risk, as population flows in and out of these counties were greatly increased with students returning to school.
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COVID-19 , SARS-CoV-2 , Estaciones del Año , Humanos , COVID-19/epidemiología , COVID-19/transmisión , Virginia/epidemiología , Pandemias , Viaje/estadística & datos numéricos , Dinámica Poblacional , Brotes de EnfermedadesRESUMEN
Climatic oscillations affect fish population dynamics, ecological processes, and fishing operations in maritime habitats. This study examined how climatic oscillations affect catch rates for striped, blue, and silver marlins in the Atlantic Ocean. These oscillations are regarded as the primary factor influencing the abundance and accessibility of specific resources utilized by fishers. Logbook data were obtained from Taiwanese large-scale fishing vessels for climatic oscillations during the period 2005-2016. The results indicated that the effect of the Subtropical Indian Ocean Dipole on marlin catch rates did not have a lag, whereas those of the North Atlantic Oscillation, Atlantic Multidecadal Oscillation, Pacific Decadal Oscillation, and Indian Ocean Dipole had various lags. Pearson's correlation analysis was conducted to examine the correlations between atmospheric oscillation indices and marlin catch rates, and wavelet analysis was employed to describe the influences of the most relevant lags. The results indicated that annual atmospheric fluctuations and their lags affected the abundance and catchability of striped, blue, and silver marlins in the study region. This, in turn, may affect the presence of these species in the market and lead to fluctuations in their prices in accordance with supply and demand. Overall, understanding the effects of climatic oscillations on fish species are essential for policymakers and coastal communities seeking to manage marine resources, predict changes in marine ecosystems, and establish appropriate methods for controlling the effects of climate variability.
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Explotaciones Pesqueras , Animales , Peces/fisiología , Cambio Climático , Océano Atlántico , Ecosistema , Dinámica Poblacional , Taiwán , ClimaRESUMEN
Demographic processes that ensure the recovery and resilience of marine populations are critical as climate change sends an increasing proportion on a trajectory of decline. Yet for some populations, recovery potential remains high. We conducted annual monitoring over 9 years (2012-2020) to assess the recovery of coral populations belonging to the genus Pocillopora. These populations experienced a catastrophic collapse following a severe typhoon in 2009. From the start of the monitoring period, high initial recruitment led to the establishment of a juvenile population that rapidly transitioned to sexually mature adults, which dominated the population within 6 years after the disturbance. As a result, coral cover increased from 1.1% to 20.2% during this time. To identify key demographic drivers of recovery and population growth rates (λ), we applied kernel-resampled integral projection models (IPMs), constructing eight successive models to examine annual change. IPMs were able to capture reproductive traits as key demographic drivers over the initial 3 years, while individual growth was a continuous key demographic driver throughout the entire monitoring period. IPMs further detected a pulse of reproductive output subsequent to two further Category 5 typhoon events during the monitoring period, exemplifying key mechanisms of resilience for coral populations impacted by disturbance. Despite rapid recovery, (i.e., increased coral cover, individual colony growth, low mortality), IPMs estimated predominantly negative values of λ, indicating a declining population. Indeed, while λ translates to a change in the number of individuals, the recovery of coral populations can also be driven by an increase in the size of surviving colonies. Our results illustrate that accumulating long-term data on historical dynamics and applying IPMs to extract demographic drivers are crucial for future predictions that are based on comprehensive and robust understandings of ecological change.
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Antozoos , Crecimiento Demográfico , Antozoos/fisiología , Animales , Tormentas Ciclónicas , Arrecifes de Coral , Modelos Biológicos , Cambio Climático , Dinámica Poblacional , Conservación de los Recursos NaturalesRESUMEN
Studying the mechanisms shaping age-related changes in behavior ("behavioral aging") is important for understanding population dynamics in our changing world. Yet, studies that capture within-individual behavioral changes in wild populations of long-lived animals are still scarce. Here, we used a 15-y GPS-tracking dataset of a social obligate scavenger, the griffon vulture (Gyps fulvus), to investigate age-related changes in movement and social behaviors, and disentangle the role of behavioral plasticity and selective disappearance in shaping such patterns. We tracked 142 individuals for up to 12 y and found a nonlinear increase in site fidelity with age: a sharp increase in site fidelity before sexual maturity (<5 y old), stabilization during adulthood (6 to 15 y), and a further increase at old age (>15 y). This pattern resulted from individuals changing behavior throughout their life (behavioral plasticity) and not from selective disappearance. Mature vultures increased the predictability of their movement routines and spent more nights at the most popular roosting sites compared to younger individuals. Thus, adults likely have a competitive advantage over younger conspecifics. These changes in site fidelity and movement routines were mirrored in changes to social behavior. Older individuals interacted less with their associates (decreasing average strength with age), particularly during the breeding season. Our results reveal a variety of behavioral aging patterns in long-lived species and underscore the importance of behavioral plasticity in shaping such patterns. Comprehensive longitudinal studies are imperative for understanding how plasticity and selection shape the persistence of wild animal populations facing human-induced environmental changes.
Asunto(s)
Envejecimiento , Conducta Animal , Animales , Envejecimiento/fisiología , Conducta Animal/fisiología , Dinámica Poblacional , Conducta Social , Falconiformes/fisiología , Femenino , MasculinoRESUMEN
The non-Mendelian transmission of sex chromosomes during gametogenesis carries significant implications, influencing sex ratios and shaping evolutionary dynamics. Here we focus on known mechanisms that drive non-Mendelian inheritance of X chromosomes during spermatogenesis and their impact on population dynamics in species with different breeding systems. In Drosophila and mice, X-linked drivers targeting Y-bearing sperm for elimination or limiting their fitness, tend to confer unfavourable effects, prompting the evolution of suppressors to mitigate their impact. This leads to a complex ongoing evolutionary arms race to maintain an equal balance of males and females. However, in certain insects and nematodes with XX/X0 sex determination, the preferential production of X-bearing sperm through atypical meiosis yields wild-type populations with highly skewed sex ratios, suggesting non-Mendelian transmission of the X may offer selective advantages in these species. Indeed, models suggest X-meiotic drivers could bolster population size and persistence under certain conditions, challenging the conventional view of their detrimental effects. Furthering our understanding of the diverse mechanisms and evolutionary consequences of non-Mendelian transmission of X chromosomes will provide insights into genetic inheritance, sex determination, and population dynamics, with implications for fundamental research and practical applications.