Eloy Revilla - Academia.edu (original) (raw)
Papers by Eloy Revilla
Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting ... more Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting effects on metapopulation dynamics by contributing to patch isolation in nontrivial ways. We analyze the movement properties during interpatch dispersal in a metapopulation of Iberian lynx (Lynx pardinus). On a daily temporal scale, lynx habitat selection defines two types of matrix habitats where individuals may move: open and dispersal habitats (avoided and used as available, respectively). There was a strong and complex impact of matrix heterogeneity on movement properties at several temporal scales (hourly and daily radiolocations and the entire dispersal event). We use the movement properties on the hourly temporal scale to build a simulation model to reconstruct individual dispersal events. The two most important parameters affecting model predictions at both the individual (daily) and metapopulation scales were related to the movement capacity (number of movement steps per day and autocorrelation in dispersal habitat) followed by the parameters representing the habitat selection in the matrix. The model adequately $15.00. All rights reserved.
Interactions among species, which range from competition to facilitation, have profound effects o... more Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta-analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and diet overlap, intraguild predation and kleptoparasitism), we underline some mechanisms facilitating their coexistence (different prey-age selection and scavenging opportunities). We stress the fact that prey abundance is key to their coexistence and that hyaenas forming very large groups in rich ecosystems could have a negative impact on lions. We show that the coexistence of spotted hyaenas and lions is a complex balance between competition and facilitation, and that prey availability within the ecosystem determines which predator is dominant. However, there are still many gaps in our knowledge such as the spatio-temporal dynamics of their interactions. As both species' survival becomes increasingly dependent on protected areas, where their densities can be high, it is critical to understand their interactions to inform both reintroduction programs and protected area management.
Anim Conserv, 2014
Several studies suggest that species' mortality rates are positively related with local populatio... more Several studies suggest that species' mortality rates are positively related with local population abundances. Because owls have shown both high road mortality rates and road avoidance behaviours, we hypothesize that road-kill likelihood is not always directly linked to their occurrence. In this study, we examined the relationship between the likelihood of species occurrence in the vicinity of major roads and the road-kill risk for barn owls Tyto alba, tawny owls Strix aluco and little owls Athene noctua. Specifically, we address: (1) the role of road-related features on spatial patterns of species' occurrence and road kills; (2) the composition of road kills and their distribution throughout the year; (3) the relationship between species' occurrence likelihood and mortality risk. Our findings show that changes in movement patterns is probably the main behavioural mechanism that threatens owls in roaded landscapes. The high mortality risk of barn owls in autumn and winter seasons, after the peak of dispersal period, provides support for the hypotheses of expanding movements because of lack of food. However, mortality because of high occurrence likelihood seems to also explain tawny owls' response towards roads. The high occurrence likelihood of little owls combined with low mortality rate also suggests avoidance of road crossings. Although, it is clear that within species there is variation according to age-and territory-holding status, closely related species have different sensitivities to roads as a function of their varying food preferences. We believe that linking species distribution with mortality risk may be more effective in focus conservation efforts. Therefore, we suggest measures should be applied to reduce prey availability close to roads and in road verges. This is particularly important for barn owls, for which foraging in the vicinity of roads during the cold season is especially risky.
Biological reviews of the Cambridge Philosophical Society, Jan 20, 2014
Interactions among species, which range from competition to facilitation, have profound effects o... more Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta-analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and die...
Nature, 2014
The user has requested enhancement of the downloaded file.
Dispersal Ecology and Evolution, 2012
Oryx, 2012
Although the Near Threatened Eurasian otter Lutra lutra has been recovering in Europe since the 1... more Although the Near Threatened Eurasian otter Lutra lutra has been recovering in Europe since the 1980s nothing is known about population trends of the species in northern Africa. Ninety sites was searched for signs of otters in northern and western Morocco in 1983 and we repeated this survey in 2011. At each site we searched for otter spraints (faeces) or clear footprints along a maximum of 600 m of river bank, ending the search when the first sign was found.
Trends in Ecology & Evolution, 2003
In a recent article in TREE [1], Johnson et al. review the evidence showing that, when resources ... more In a recent article in TREE [1], Johnson et al. review the evidence showing that, when resources are patchily distributed, the economics of exploiting these patches enable individuals to share resources over a common area, satisfying their needs without imposing large costs on each other. This resource dispersion hypothesis (RDH) is presented as a causal mechanism of group living, especially when individuals obtain no apparent benefits from such living. There are two points on which I would like to comment.
The American Naturalist, 2004
Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting ... more Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting effects on metapopulation dynamics by contributing to patch isolation in nontrivial ways. We analyze the movement properties during interpatch dispersal in a metapopulation of Iberian lynx (Lynx pardinus). On a daily temporal scale, lynx habitat selection defines two types of matrix habitats where individuals may move: open and dispersal habitats (avoided and used as available, respectively). There was a strong and complex impact of matrix heterogeneity on movement properties at several temporal scales (hourly and daily radiolocations and the entire dispersal event). We use the movement properties on the hourly temporal scale to build a simulation model to reconstruct individual dispersal events. The two most important parameters affecting model predictions at both the individual (daily) and metapopulation scales were related to the movement capacity (number of movement steps per day and autocorrelation in dispersal habitat) followed by the parameters representing the habitat selection in the matrix. The model adequately $15.00. All rights reserved.
Science, 2005
Agent-based complex systems are dynamic networks of many interacting agents; examples include eco... more Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.
Proceedings of the National Academy of Sciences, 2008
The dynamics of spatially structured populations is characterized by within- and between-patch pr... more The dynamics of spatially structured populations is characterized by within- and between-patch processes. The available theory describes the latter with simple distance-dependent functions that depend on landscape properties such as interpatch distance or patch size. Despite its potential role, we lack a good mechanistic understanding of how the movement of individuals between patches affects the dynamics of these populations. We used the theoretical framework provided by movement ecology to make a direct representation of the processes determining how individuals connect local populations in a spatially structured population of Iberian lynx. Interpatch processes depended on the heterogeneity of the matrix where patches are embedded and the parameters defining individual movement behavior. They were also very sensitive to the dynamic demographic variables limiting the time moving, the within-patch dynamics of available settlement sites (both spatiotemporally heterogeneous) and the response of individuals to the perceived risk while moving. These context-dependent dynamic factors are an inherent part of the movement process, producing connectivities and dispersal kernels whose variability is affected by other demographic processes. Mechanistic representations of interpatch movements, such as the one provided by the movement-ecology framework, permit the dynamic interaction of birth-death processes and individual movement behavior, thus improving our understanding of stochastic spatially structured populations.
Proceedings of the National Academy of Sciences, 2008
Movement is important to all organisms, and accordingly it is addressed in a huge number of paper... more Movement is important to all organisms, and accordingly it is addressed in a huge number of papers in the literature. Of nearly 26,000 papers referring to movement, an estimated 34% focused on movement by measuring it or testing hypotheses about it. This enormous amount of information is difficult to review and highlights the need to assess the collective completeness of movement studies and identify gaps. We surveyed 1,000 randomly selected papers from 496 journals and compared the facets of movement studied with a suggested framework for movement ecology, consisting of internal state (motivation, physiology), motion and navigation capacities, and external factors (both the physical environment and living organisms), and links among these components. Most studies simply measured and described the movement of organisms without reference to ecological or internal factors, and the most frequently studied part of the framework was the link between external factors and motion capacity. Few studies looked at the effects on movement of navigation capacity, or internal state, and those were mainly from vertebrates. For invertebrates and plants most studies were at the population level, whereas more vertebrate studies were conducted at the individual level. Consideration of only population-level averages promulgates neglect of between-individual variation in movement, potentially hindering the study of factors controlling movement. Terminology was found to be inconsistent among taxa and subdisciplines. The gaps identified in coverage of movement studies highlight research areas that should be addressed to fully understand the ecology of movement.
Proceedings of the National Academy of Sciences, 2008
CITATIONS 674 READS 263 7 authors, including:
PLoS ONE, 2012
Background: Climate change is affecting many physical and biological processes worldwide. Anticip... more Background: Climate change is affecting many physical and biological processes worldwide. Anticipating its effects at the level of populations and species is imperative, especially for organisms of conservation or management concern. Previous studies have focused on estimating future species distributions and extinction probabilities directly from current climatic conditions within their geographical ranges. However, relationships between climate and population parameters may be so complex that to make these high-level predictions we need first to understand the underlying biological processes driving population size, as well as their individual response to climatic alterations. Therefore, the objective of this study is to investigate the influence that climate change may have on species population dynamics through altering breeding season.
PLoS ONE, 2011
Background: Domestic cats ranging freely in natural areas are a conservation concern due to compe... more Background: Domestic cats ranging freely in natural areas are a conservation concern due to competition, predation, disease transmission or hybridization with wildcats. In order to improve our ability to design effective control policies, we investigate the factors affecting their numbers and space use in natural areas of continental Europe.
Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting ... more Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting effects on metapopulation dynamics by contributing to patch isolation in nontrivial ways. We analyze the movement properties during interpatch dispersal in a metapopulation of Iberian lynx (Lynx pardinus). On a daily temporal scale, lynx habitat selection defines two types of matrix habitats where individuals may move: open and dispersal habitats (avoided and used as available, respectively). There was a strong and complex impact of matrix heterogeneity on movement properties at several temporal scales (hourly and daily radiolocations and the entire dispersal event). We use the movement properties on the hourly temporal scale to build a simulation model to reconstruct individual dispersal events. The two most important parameters affecting model predictions at both the individual (daily) and metapopulation scales were related to the movement capacity (number of movement steps per day and autocorrelation in dispersal habitat) followed by the parameters representing the habitat selection in the matrix. The model adequately $15.00. All rights reserved.
Interactions among species, which range from competition to facilitation, have profound effects o... more Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta-analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and diet overlap, intraguild predation and kleptoparasitism), we underline some mechanisms facilitating their coexistence (different prey-age selection and scavenging opportunities). We stress the fact that prey abundance is key to their coexistence and that hyaenas forming very large groups in rich ecosystems could have a negative impact on lions. We show that the coexistence of spotted hyaenas and lions is a complex balance between competition and facilitation, and that prey availability within the ecosystem determines which predator is dominant. However, there are still many gaps in our knowledge such as the spatio-temporal dynamics of their interactions. As both species' survival becomes increasingly dependent on protected areas, where their densities can be high, it is critical to understand their interactions to inform both reintroduction programs and protected area management.
Anim Conserv, 2014
Several studies suggest that species' mortality rates are positively related with local populatio... more Several studies suggest that species' mortality rates are positively related with local population abundances. Because owls have shown both high road mortality rates and road avoidance behaviours, we hypothesize that road-kill likelihood is not always directly linked to their occurrence. In this study, we examined the relationship between the likelihood of species occurrence in the vicinity of major roads and the road-kill risk for barn owls Tyto alba, tawny owls Strix aluco and little owls Athene noctua. Specifically, we address: (1) the role of road-related features on spatial patterns of species' occurrence and road kills; (2) the composition of road kills and their distribution throughout the year; (3) the relationship between species' occurrence likelihood and mortality risk. Our findings show that changes in movement patterns is probably the main behavioural mechanism that threatens owls in roaded landscapes. The high mortality risk of barn owls in autumn and winter seasons, after the peak of dispersal period, provides support for the hypotheses of expanding movements because of lack of food. However, mortality because of high occurrence likelihood seems to also explain tawny owls' response towards roads. The high occurrence likelihood of little owls combined with low mortality rate also suggests avoidance of road crossings. Although, it is clear that within species there is variation according to age-and territory-holding status, closely related species have different sensitivities to roads as a function of their varying food preferences. We believe that linking species distribution with mortality risk may be more effective in focus conservation efforts. Therefore, we suggest measures should be applied to reduce prey availability close to roads and in road verges. This is particularly important for barn owls, for which foraging in the vicinity of roads during the cold season is especially risky.
Biological reviews of the Cambridge Philosophical Society, Jan 20, 2014
Interactions among species, which range from competition to facilitation, have profound effects o... more Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta-analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and die...
Nature, 2014
The user has requested enhancement of the downloaded file.
Dispersal Ecology and Evolution, 2012
Oryx, 2012
Although the Near Threatened Eurasian otter Lutra lutra has been recovering in Europe since the 1... more Although the Near Threatened Eurasian otter Lutra lutra has been recovering in Europe since the 1980s nothing is known about population trends of the species in northern Africa. Ninety sites was searched for signs of otters in northern and western Morocco in 1983 and we repeated this survey in 2011. At each site we searched for otter spraints (faeces) or clear footprints along a maximum of 600 m of river bank, ending the search when the first sign was found.
Trends in Ecology & Evolution, 2003
In a recent article in TREE [1], Johnson et al. review the evidence showing that, when resources ... more In a recent article in TREE [1], Johnson et al. review the evidence showing that, when resources are patchily distributed, the economics of exploiting these patches enable individuals to share resources over a common area, satisfying their needs without imposing large costs on each other. This resource dispersion hypothesis (RDH) is presented as a causal mechanism of group living, especially when individuals obtain no apparent benefits from such living. There are two points on which I would like to comment.
The American Naturalist, 2004
Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting ... more Mounting theoretical and empirical evidence shows that matrix heterogeneity may have contrasting effects on metapopulation dynamics by contributing to patch isolation in nontrivial ways. We analyze the movement properties during interpatch dispersal in a metapopulation of Iberian lynx (Lynx pardinus). On a daily temporal scale, lynx habitat selection defines two types of matrix habitats where individuals may move: open and dispersal habitats (avoided and used as available, respectively). There was a strong and complex impact of matrix heterogeneity on movement properties at several temporal scales (hourly and daily radiolocations and the entire dispersal event). We use the movement properties on the hourly temporal scale to build a simulation model to reconstruct individual dispersal events. The two most important parameters affecting model predictions at both the individual (daily) and metapopulation scales were related to the movement capacity (number of movement steps per day and autocorrelation in dispersal habitat) followed by the parameters representing the habitat selection in the matrix. The model adequately $15.00. All rights reserved.
Science, 2005
Agent-based complex systems are dynamic networks of many interacting agents; examples include eco... more Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.
Proceedings of the National Academy of Sciences, 2008
The dynamics of spatially structured populations is characterized by within- and between-patch pr... more The dynamics of spatially structured populations is characterized by within- and between-patch processes. The available theory describes the latter with simple distance-dependent functions that depend on landscape properties such as interpatch distance or patch size. Despite its potential role, we lack a good mechanistic understanding of how the movement of individuals between patches affects the dynamics of these populations. We used the theoretical framework provided by movement ecology to make a direct representation of the processes determining how individuals connect local populations in a spatially structured population of Iberian lynx. Interpatch processes depended on the heterogeneity of the matrix where patches are embedded and the parameters defining individual movement behavior. They were also very sensitive to the dynamic demographic variables limiting the time moving, the within-patch dynamics of available settlement sites (both spatiotemporally heterogeneous) and the response of individuals to the perceived risk while moving. These context-dependent dynamic factors are an inherent part of the movement process, producing connectivities and dispersal kernels whose variability is affected by other demographic processes. Mechanistic representations of interpatch movements, such as the one provided by the movement-ecology framework, permit the dynamic interaction of birth-death processes and individual movement behavior, thus improving our understanding of stochastic spatially structured populations.
Proceedings of the National Academy of Sciences, 2008
Movement is important to all organisms, and accordingly it is addressed in a huge number of paper... more Movement is important to all organisms, and accordingly it is addressed in a huge number of papers in the literature. Of nearly 26,000 papers referring to movement, an estimated 34% focused on movement by measuring it or testing hypotheses about it. This enormous amount of information is difficult to review and highlights the need to assess the collective completeness of movement studies and identify gaps. We surveyed 1,000 randomly selected papers from 496 journals and compared the facets of movement studied with a suggested framework for movement ecology, consisting of internal state (motivation, physiology), motion and navigation capacities, and external factors (both the physical environment and living organisms), and links among these components. Most studies simply measured and described the movement of organisms without reference to ecological or internal factors, and the most frequently studied part of the framework was the link between external factors and motion capacity. Few studies looked at the effects on movement of navigation capacity, or internal state, and those were mainly from vertebrates. For invertebrates and plants most studies were at the population level, whereas more vertebrate studies were conducted at the individual level. Consideration of only population-level averages promulgates neglect of between-individual variation in movement, potentially hindering the study of factors controlling movement. Terminology was found to be inconsistent among taxa and subdisciplines. The gaps identified in coverage of movement studies highlight research areas that should be addressed to fully understand the ecology of movement.
Proceedings of the National Academy of Sciences, 2008
CITATIONS 674 READS 263 7 authors, including:
PLoS ONE, 2012
Background: Climate change is affecting many physical and biological processes worldwide. Anticip... more Background: Climate change is affecting many physical and biological processes worldwide. Anticipating its effects at the level of populations and species is imperative, especially for organisms of conservation or management concern. Previous studies have focused on estimating future species distributions and extinction probabilities directly from current climatic conditions within their geographical ranges. However, relationships between climate and population parameters may be so complex that to make these high-level predictions we need first to understand the underlying biological processes driving population size, as well as their individual response to climatic alterations. Therefore, the objective of this study is to investigate the influence that climate change may have on species population dynamics through altering breeding season.
PLoS ONE, 2011
Background: Domestic cats ranging freely in natural areas are a conservation concern due to compe... more Background: Domestic cats ranging freely in natural areas are a conservation concern due to competition, predation, disease transmission or hybridization with wildcats. In order to improve our ability to design effective control policies, we investigate the factors affecting their numbers and space use in natural areas of continental Europe.