Browsing by Author "Lima, Mauricio"

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    1000 years of population, warfare, and climate change in pre-Columbian societies of the Central Andes
    (2023) Lima, Mauricio; Gayo, Eugenia M.; Gurruchaga, Andone; Estay, Sergio A.; Santoro, Calogero M.
    Different Andean societies underwent processes of expansion and collapse during propitious or adverse climate conditions, resource boost or depletion along with population variations. Previous studies have emphasized that demographic collapses of polities in the Central Andes Area were triggered by warfare and the negative impacts of fluctuating climate (droughts) on crop productivity. Nevertheless, the interactions between climatic variability, demography and warfare have been less thoroughly evaluated. We develop population dynamic models to test feedback relationships between population growth, climate change and warfare in the Central Andes, where considerable regional hydroclimate variations have occurred over a millennium. Through population models, we found out that the rise and demise of social polities in the northern coast of the Central Andes appear to be a consequence of climate change. In contrast, for the highlands of Peru and the Titicaca basin, population models suggest that warfare intensity has a negative effect on population growth rates.
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    A modeling approach to estimate the historical population size of the Patagonian Kawesqar people
    (2022) Estay, Sergio A.; Lopez, Daniela N.; Silva, Carmen P.; Gayo, Eugenia M.; McRostie, Virginia; Lima, Mauricio
    The study of human-gatherers societies' demography used to be a difficult task due to the lack of direct evidence to support the estimations. This is the case of several human groups from Pacific Patagonia whose historical population size estimations are controversial. This study estimated the historical population size for the Kawesqar people using direct and indirect evidence. Thus, we collated past estimations from experts and encounter rates distribution in time and space to generate a statistical approximation for population size. We used weights to include the reliability of such past estimations under three modeling scenarios. Our results indicate that the historical population ranged roughly between 3700 and 3900 individuals before the massive contact with Chileans and European people. The approach developed here for combining and integrating different evidence for estimating population in Kawesqar people, emerges as a promising and valuable tool to study the demography of other hunter-gatherer societies in South America.
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    Contact tracing-induced Allee effect in disease dynamics
    (2022) Arim, Matias; Herrera-Esposito, Daniel; Bermolen, Paola; Cabana, Alvaro; Fariello, Maria Ines; Lima, Mauricio; Romero, Hector
    Contact tracing, case isolation, quarantine, social distancing, and other non-pharmaceutical interventions (NPIs) have been a cornerstone in managing the COVID-19 pandemic. However, their effects on disease dynamics are not fully understood. Saturation of contact tracing caused by the increase of infected individuals has been recognized as a crucial variable by healthcare systems worldwide. Here, we model this saturation process with a mechanistic and a phenomenological model and show that it induces an Allee effect which could determine an infection threshold between two alternative states-containment and outbreak. This transition was considered elsewhere as a response to the strength of NPIs, but here we show that they may be also determined by the number of infected individuals. As a consequence, timing of NPIs implementation and relaxation after containment is critical to their effectiveness. Containment strategies such as vaccination or mobility restriction may interact with contact tracing-induced Allee effect. Each strategy in isolation tends to show diminishing returns, with a less than proportional effect of the intervention on disease containment. However, when combined, their suppressing potential is enhanced. Relaxation of NPIs after disease containment--e.g. because vaccination--have to be performed in attention to avoid crossing the infection threshold required to a novel outbreak. The recognition of a contact tracing-induced Allee effect, its interaction with other NPIs and vaccination, and the existence of tipping points contributes to the understanding of several features of disease dynamics and its response to containment interventions. This knowledge may be of relevance for explaining the dynamics of diseases in different regions and, more importantly, as input for guiding the use of NPIs, vaccination campaigns, and its combination for the management of epidemic outbreaks. (c) 2022 Elsevier Ltd. All rights reserved.
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    Disentangling the effects of feedback structure and climate on Poaceae annual airborne pollen fluctuations and the possible consequences of climate change
    (2015) Garcia de Leon, David; Garcia-Mozo, Herminia; Galan, Carmen; Alcazar, Purificacion; Lima, Mauricio; Gonzalez-Andujar, Jose L.
    Pollen allergies are the most common form of respiratory allergic disease in Europe. Most studies have emphasized the role of environmental processes, as the drivers of airborne pollen fluctuations, implicitly considering pollen production as a random walk. This work shows that internal self-regulating processes of the plants (negative feedback) should be included in pollen dynamic systems in order to give a better explanation of the observed pollen temporal patterns. This article proposes a novel methodological approach based on dynamic systems to investigate the interaction between feedback structure of plant populations and climate in shaping long-term airborne Poaceae pollen fluctuations and to quantify the effects of climate change on future airborne pollen concentrations. Long-term historical airborne Poaceae pollen data (30 years) from Cordoba city Southern Spain) were analyzed. A set of models, combining feedback structure, temperature and actual evapotranspiration effects on airborne Poaceae pollen were built and compared, using a model selection approach. Our results highlight the importance of first-order negative feedback and mean annual maximum temperature in driving airborne Poaceae pollen dynamics. The best model was used to predict the effects of climate change under two standardized scenarios representing contrasting temporal patterns of economic development and CO2 emissions. Our results predict an increase in pollen levels in southern Spain by 2070 ranging from 28.5% to 44.3%. The findings from this study provide a greater understanding of airborne pollen dynamics and how climate change might impact the future evolution of airborne Poaceae pollen concentrations and thus the future evolution of related pollen allergies. (C) 2015 Elsevier B.V. All rights reserved.
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    Population dynamics and cultural niche construction during the Late Holocene in a mediterranean ecosystem (central Chile, 32°S-36°S)
    (2024) Godoy-Aguirre, Carolina; Frugone-Alvarez, Matias; Gayo, Eugenia M.; Campbell, Roberto; Lima, Mauricio; Maldonado, Antonio; Latorre, Claudio
    Understanding socio-ecological systems over the long term can shed light on past adaptive strategies in environmentally sensitive regions. Central Chile is an emblematic case study for mediterranean ecosystems, where a progressive and sustained population increase began approximately 2000 years ago alongside significant landscape changes. In this work we analyzed regional paleo-demographic trends by compiling a new database of archaeological dates over the last 3000 years, and integrating population dynamics theory with an analysis of the spatio-temporal variation of regional cultural stages. Results show three moments of marked acceleration in population growth: just before agricultural adoption, during the Archaic Period (c. 700-300 BCE); during the second half of the ECP (500-900 CE); and during the Late Intermediate Period (1200-1400 CE). We also identified periods of deceleration in per capita growth rates, although population size continued to increase (300 BCE-500 CE, 900-1200 CE and after 1400 CE). These large shifts in the per capita growth rates coincide with major cultural changes associated with social and economic aspects. The pulses of major occupation show in general terms a more intensive use of the valleys as the population size increased, although the remaining ecosystems never ceased to be occupied with different economic and symbolic emphases.
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    Positive feedbacks in deep-time transitions of human populations
    (2024) Lima, Mauricio; Gayo, Eugenia M.; Estay, Sergio A.; Gurruchaga, Andone; Robinson, Erick; Freeman, Jacob; Latorre, Claudio; Bird, Darcy
    Abrupt and rapid changes in human societies are among the most exciting population phenomena. Human populations tend to show rapid expansions from low to high population density along with increased social complexity in just a few generations. Such demographic transitions appear as a remarkable feature of Homo sapiens population dynamics, most likely fuelled by the ability to accumulate cultural/technological innovations that actively modify their environment. We are especially interested in establishing if the demographic transitions of pre-historic populations show the same dynamic signature of the Industrial Revolution transition (a positive relationship between population growth rates and size). Our results show that population growth patterns across different pre-historic societies were similar to those observed during the Industrial Revolution in developed western societies. These features, which appear to have been operating during most of our recent demographic history from hunter-gatherers to modern industrial societies, imply that the dynamics of cooperation underlay sudden population transitions in human societies.This article is part of the theme issue 'Evolution and sustainability: gathering the strands for an Anthropocene synthesis'.
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    Squeezed from the top: "Social Outburst" (2019) and elite overproduction. A study of the dynamics of Chilean political instability from the approach of Structural Demographic Theory
    (2024) Munoz-Rodriguez, Manuel; Ferrero, Rosana; Luna, Juan Pablo; Lima, Mauricio
    On October 18, 2019, Chile experienced the most important social upheaval since the country regained democracy in the late 1980s. The "Social Outbreak" surprised economic and political elites and seemed paradoxical to the international community who had often praised Chile as a model of successful development. In this paper, we used structural-demographic theory to analyze the interaction between the overproduction of elites and the stagnation in the relative income of the population as the underlying structural cause of Chilean political instability. This theory was able to predict the three most significant instances of political tension in the recent history of Chile: the crisis of the late 1960s that culminated in the coup d'& eacute;tat of 1973, popular mobilizations during the 1980s, and the recent student mobilizations and social upheaval. Our results suggest that, at least during the period 1938-2019, Chilean sociopolitical dynamics is determined by the same structural drivers.
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    Survival and maturation rates of the African rodent, Mastomys natalensis: density-dependence and rainfall
    (2007) Sluydts, Vincent; Crespin, Laurent; Davis, Stephen; Lima, Mauricio; Leirs, Herwig
    Survival and maturation rates of female Mastomys natalensis were analysed based on a ten-year monthly capture-recapture data set. We investigated whether direct and delayed density dependent and independent (rainfall) variables accounted for the considerable variation in demographic traits. It was estimated that seasonal and annual covariates accounted for respectively 29 and 26% of the total variation in maturation rates and respectively 17 and 11% of the variation in survival rates. Explaining the between-year differences in maturation rates with annual past rainfall or density did not improve the model fit. On the other hand we showed that maturation rates were correlated negatively with density the previous month and positively to cumulative rainfall over the past three months. Survival estimates of both adults and subadults varied seasonally, with higher estimates during the increase phase (dry season). The subadults were characterised by a very high survival rate (> 0.95) during this phase. In the decrease phase only minor differences were found between survival rates of subadults and adults. We found that 39% of the between-year variation in survival can be explained by accumulated rainfall over the past year.
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    Temporal variation on the diet of the South American Tern (Sterna hirundinacea, Charadriiformes: Laridae) on its wintering grounds
    (2011) Alfaro, Matilde; Mauco, Laura; Norbis, Walter; Lima, Mauricio
    The diet of the South American Tern (Sterna hirundinacea) and its seasonal variation during the 2005 and 2006 non-reproductive seasons in the Uruguayan Atlantic coast was analyzed. Diet was assessed by the analysis of pellets collected in the Rocha lagoon sandbar, a major tern roosting area in Uruguay, aiming to analyze the hypothesis that terns feed mainly on the Argentine Anchovy (Engraulis anchoita) during the wintering period. A total of 844 pellets were collected, 442 in 2005 and 402 in 2006. Diet was composed of fish (88 %), insects (9 %) and crustaceans (3 %). The main fish species consumed was the Argentine Anchovy (77.7 %), followed by Marini's Anchovy (Anchoa marinii) (7.9 %) and the Striped Weakfish (Cynoscion guatucupa) (3.6 %). Insects and crustaceans were the main items in two of the groups of pellets collected during the study period. Despite this temporal variation in the diet, the Argentine Anchovy was the main prey item consumed during both seasons. These results support the hypothesis that South American Terns strongly depend on anchovies as trophic resource.
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    The Interaction Between Stock Dynamics, Fishing and Climate Caused the Collapse of the Jack Mackerel Stock at Humboldt Current Ecosystem
    (2020) Lima, Mauricio; Mariella Canales, T.; Wiff, Rodrigo; Montero, Jose
    The collapse of marine fisheries had caused a cascade of ecological, social and economic consequences. Recognizing the complex nature of the fisheries collapses is essential for understanding the impact of human activities on natural systems. The rapid and abrupt shifts in abundance exhibited by some marine fish populations can be driven by the fishing fleet behaving like generalist predators. Here, we propose that fishing fleet has a s-shaped functional predator function that, combined with economic factors and ENSO variability could cause rapid and abrupt transitions in the of jack mackerel (Trachurus murphyi) fishery in the south-eastern Pacific. Our results showed that fishing fleet predator functional response is well described by a s-shaped function, where ENSO variability (El Nino/La Nina years) appears to decrease/increase the fishing rate. Our model predictions were able to accurately forecast independent data of jackmackerel acoustic survey estimates. We show that the population trend and collapse of jack mackerel stock at the Humboldt Current Ecosystem (HCE) can be explained by the changes in fishing effort, which seem to be driven by economic forces and El Nino climatic variability. Our simple model allows us to explore some management responses in a heuristic manner. The most critical element seems to be the combination of an n-shaped isocline for fish stock growth, modulated by ENSO variability, and a horizontal isocline of fishing effort which is highly sensitive to changes in the profitability of the fishery. Therefore, the implementation of management policies based on simple theoretical models will be increasingly required to harvest fish stocks in these times of growing demographic demands and climate change.
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    The link between human population dynamics and energy consumption during the Anthropocene
    (2024) Lima, Mauricio
    Our present world is the consequence of the size of the human population and its domination of the biosphere through the combustion of fossil fuels. Since similar to 1950, there has been a sudden increase in the rate of human global energy consumption, economic productivity, and population growth. This abrupt departure of the system dynamics has been defined as the "Great Acceleration." The accelerated population and economic expansion during the past 70 years would have been impossible without using fossil fuels. However, no studies have made an explicit connection between human population dynamics on a global scale and historical changes in energy consumption growth rates, economic growth, and the energy return on investment of fossil fuels (EROI). In this study, I apply a simple population dynamic model of cooperation/competition to decipher the effects of changes in these factors on the dynamics of the human population during the period (1800-2020).
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    Towards understanding human-environment feedback loops: the Atacama Desert case
    (2024) Gayo, Eugenia M.; Lima, Mauricio; Gurruchaga, Andone; Estay, Sergio A.; Santoro, Calogero M.; Latorre, Claudio; Mcrostie, Virginia
    The overall trajectory for the human-environment interaction has been punctuated by demographic boom-and-bust cycles, phases of growth/overshooting as well as of expansion/contraction in productivity. Although this pattern has been explained in terms of an interplay between population growth, social upscaling, ecosystem engineering and climate variability, the evoked demographic-resource-complexity mechanisms have not been empirically tested. By integrating proxy data for population sizes, palaeoclimate and internal societal factors into empirical modelling approaches from the population dynamic theory, we evaluated how endogenous (population sizes, warfare and social upscaling) and exogenous (climate) variables module the dynamic in past agrarian societies. We focused on the inland Atacama Desert, where populations developed agriculture activities by engineering arid and semi-arid landscapes during the last 2000 years. Our modelling approach indicates that these populations experienced a boom-and-bust dynamic over the last millennia, which was coupled to structure feedback between population sizes, hydroclimate, social upscaling, warfare and ecosystem engineering. Thus, the human-environment loop appears closely linked with cooperation, competition, limiting resources and the ability of problem-solving.This article is part of the theme issue 'Evolution and sustainability: gathering the strands for an Anthropocene synthesis'.
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    Variable interspecific competition under megadrought conditions: rodent population dynamics in semiarid Chile
    (2023) Lima, Mauricio; Correa Cuadros, Jennifer Paola; Henríquez, Sergio; Jaksic, Fabian
    Deciphering how climatic variability modulates the interspecific interactions in natural systems is one of the most interesting and least studied ecological processes. Rodent outbreaks or irruptions in semiarid Chile are associated with rainfall pulses driven by the El Niño Southern Oscillation (ENSO). During the last decade, north-central Chile has experienced an almost uninterrupted sequence of > 10 dry years, the so-called megadrought, which had led to a new ecological benchmark in this region. We employ a diagnostic approach to analyze abundance data regarding two rodent species, Phyllotis darwini and Abrothrix olivacea, using a 33 year time series spanning from 1987 to 2019. Our population dynamic models provide evidence of competitive interactions within and between both species. This result is novel because we show that rainfall variability influences the degree of interspecific competition and that it is asymmetric. The diagnostic approach used here offers a way to develop simple population models that are useful for understanding the causes of population fluctuations and for predicting population changes under a climate change scenario.