We present a low-dimensional, continuous model of a multi-agent system motivated by simulation st... more We present a low-dimensional, continuous model of a multi-agent system motivated by simulation studies on dynamics of decision making in animal groups in motion. Each individual moves at constant speed in the plane and adjusts its heading in response to relative headings of others in the population. Two subgroups of the population are informed such that individuals in each subgroup
Phytoplankton growth and stoichiometry depend on the availability of multiple nutrients. We use a... more Phytoplankton growth and stoichiometry depend on the availability of multiple nutrients. We use a mathematical model of phytoplankton with flexible stoichiometry to explain patterns of phytoplankton composition in chemostat experiments and nutrient drawdown dynamics that are found in the field. Exponential growth and equilibrium represent two distinct phases, each amenable to mathematical analysis. In a chemostat at a fixed dilution (growth) rate, phytoplankton stoichiometry matches the nutrient supply stoichiometry over a wide range at low growth rates and over a narrow range at high growth rates. In a chemostat with a fixed nutrient supply stoichiometry, phytoplankton stoichiometry varies with dilution rate nonlinearly, between the supply stoichiometry at low dilution rates and a species-specific optimal ratio at high dilution rates. The flexible-stoichiometry model we study predicts low equilibrium concentrations of two nutrients over a wide range of supply ratios, contrary to the predictions of a traditional fixed-stoichiometry model. The model is in quantitative agreement with experimental data, except at extreme nutrient supply ratios, which require a negative feedback from quota to uptake to fit the data. Our analysis points to the importance of better understanding the regulation of uptake rates in determining phytoplankton stoichiometry and incorporating this knowledge into phytoplankton models. We thank T. Daufresne, P. Falkowski, J. Grover, and two anonymous reviewers for comments and discussion. The authors gratefully acknowledge support from the Andrew W. Mellon Foundation (to S.A.L.) and the National Science Foundation awards DEB-0083566 (to S.A.L.), CHE-9810248 (to F. Morel), and OCE-0084032 (to P. Falkowski).
Evolution; international journal of organic evolution, Jan 22, 2015
Dispersal, whether in the form of a dandelion seed drifting on the breeze, or a salmon migrating ... more Dispersal, whether in the form of a dandelion seed drifting on the breeze, or a salmon migrating upstream to breed in a non-natal stream, transports genes between locations. At these locations, local adaptation modifies the gene frequencies so their carriers are better suited to particular conditions, be those of newly disturbed soil or a quiet river pool. Both dispersal and local adaptation are major drivers of population structure; however, in general, their respective roles are not independent and the two may often be at odds with one another evolutionarily, each one exhibiting negative feedback on the evolution of the other. Here we investigate their joint evolution within a simple discrete-time, metapopulation model. Depending on environmental conditions, their evolutionary interplay leads to either a monomorphic population of highly dispersing generalists or a rarely dispersing, locally adapted, polymorphic population, each adapted to a particular habitat type. A critical valu...
Proceedings of the National Academy of Sciences of the United States of America, Jan 30, 2015
Transitions between regimes with radically different properties are ubiquitous in nature. Such tr... more Transitions between regimes with radically different properties are ubiquitous in nature. Such transitions can occur either smoothly or in an abrupt and catastrophic fashion. Important examples of the latter can be found in ecology, climate sciences, and economics, to name a few, where regime shifts have catastrophic consequences that are mostly irreversible (e.g., desertification, coral reef collapses, and market crashes). Predicting and preventing these abrupt transitions remains a challenging and important task. Usually, simple deterministic equations are used to model and rationalize these complex situations. However, stochastic effects might have a profound effect. Here we use 1D and 2D spatially explicit models to show that intrinsic (demographic) stochasticity can alter deterministic predictions dramatically, especially in the presence of other realistic features such as limited mobility or spatial heterogeneity. In particular, these ingredients can alter the possibility of c...
Journal of the Royal Society, Interface / the Royal Society, Jan 6, 2015
Animal groups in nature often display an enhanced collective information-processing capacity. It ... more Animal groups in nature often display an enhanced collective information-processing capacity. It has been speculated that natural selection will tune this response to be optimal, ensuring that the group is reactive while also being robust to noise. Here, we show that this is unlikely to be the case. By using a simple model of decision-making in a dynamic environment, we find that when individuals behave rationally and are subject to selection based on their accuracy, optimality of collective decision-making is not attained. Instead, individuals overly rely on social information and evolve to be too readily influenced by their neighbours. This is due to a classic evolutionary conflict between individual and collective interest. The result is a sub-optimal system that is poised on the cusp of total unresponsiveness. Individuals in the evolved group exhibit delayed reactions to changes in the environment, before responding with rapid, socially reinforced transitions, reminiscent of fam...
Proceedings of the National Academy of Sciences of the United States of America, Jan 9, 2014
We have a limited understanding of the consequences of variations in microbial biodiversity on oc... more We have a limited understanding of the consequences of variations in microbial biodiversity on ocean ecosystem functioning and global biogeochemical cycles. A core process is macronutrient uptake by microorganisms, as the uptake of nutrients controls ocean CO2 fixation rates in many regions. Here, we ask whether variations in ocean phytoplankton biodiversity lead to novel functional relationships between environmental variability and phosphate (Pi) uptake. We analyzed Pi uptake capabilities and cellular allocations among phytoplankton groups and the whole community throughout the extremely Pi-depleted western North Atlantic Ocean. Pi uptake capabilities of individual populations were well described by a classic uptake function but displayed adaptive differences in uptake capabilities that depend on cell size and nutrient availability. Using an eco-evolutionary model as well as observations of in situ uptake across the region, we confirmed that differences among populations lead to p...
The objective of this study was to examine the association between convulsive status epilepticus ... more The objective of this study was to examine the association between convulsive status epilepticus (CSE) and health-related quality of life (HRQL) during a 24-month follow-up in a multisite incident cohort of children with epilepsy. Data were collected in the Health-Related Quality of Life Study in Children with Epilepsy Study from 374 families of children with newly diagnosed epilepsy. The Quality of Life in Childhood Epilepsy (QOLCE) Questionnaire was used to evaluate parent-reported child HRQL. Hierarchical linear regression was used to examine the relationship between CSE and HRQL at 24 months postepilepsy. A total of 359 families completed the 24-month assessment. Twenty-two children (6.1%) had experienced CSE during the follow-up. Children with and without CSE were similar, except a larger proportion of children with CSE had partial seizures (p < 0.001). Controlling for clinical, demographic, and family characteristics, CSE was significantly associated with poorer HRQL (β = -...
The personal choices affecting the transmission of infectious diseases include the number of cont... more The personal choices affecting the transmission of infectious diseases include the number of contacts an individual makes, and the risk-characteristics of those contacts. We consider whether these different choices have distinct implications for the course of an epidemic. We also consider whether choosing contact mitigation (how much to mix) and affinity mitigation (with whom to mix) strategies together has different epidemiological effects than choosing each separately. We use a set of differential equation compartmental models of the spread of disease, coupled with a model of selective mixing. We assess the consequences of varying contact or affinity mitigation as a response to disease risk. We do this by comparing disease incidence and dynamics under varying contact volume, contact type, and both combined across several different disease models. Specifically, we construct a change of variables that allows one to transition from contact mitigation to affinity mitigation, and vice ...
Oral surgery, oral medicine, and oral pathology, 1962
... Editor RADIATION AND IMAGE DISTORTION IN THE PANOREX XRAY UNIT Owen, W. Kite, DMD,* Lennard T... more ... Editor RADIATION AND IMAGE DISTORTION IN THE PANOREX XRAY UNIT Owen, W. Kite, DMD,* Lennard T. Swanson, DMD,** Samuel Levin,*** and ... roentgenogram will be produced if two of the componentsxray beam, object, or filmhave a stationary center of rota tion in ...
The t-haplotype is a chromosomal region in Mus musculus characterized by meiotic drive such that ... more The t-haplotype is a chromosomal region in Mus musculus characterized by meiotic drive such that heterozygous males transmit t-bearing chromosomes to roughly 90% of their offspring. Most naturally occurring t-haplotypes express a recessive embryonic lethality, preventing fixation of the t-haplotype. Surprisingly, the t-haplotype occurs in nature as a persistent, low-frequency polymorphism. Early modeling studies led LEWONTIN to hypothesize that this low level polymorphism results from a balance between genetic drift in small demes and interdemic migration. Here, we show that while combination of deme size and migration rate that predict natural t-haplotype frequencies exist, the range of such values is too narrow to be biologically plausible, suggesting that small deme size and interdemic migration alone do not explain the observed t-haplotype frequencies. In response, we tested other factors that might explain the observed t-polymorphism. Two led to biologically plausible models: s...
Oral surgery, oral medicine, and oral pathology, 1980
This is a case of Thorotrast-induced carcinoma of the maxillary sinus which was detected inadvert... more This is a case of Thorotrast-induced carcinoma of the maxillary sinus which was detected inadvertently in the course of investigation of associated dental pain and labial paresthesia. Clinical and radiobiologic features are presented. It is likely that similar cases remain undetected and at large in the community.
Proceedings of the National Academy of Sciences of the United States of America, Jan 19, 2015
Demand for animal protein for human consumption is rising globally at an unprecedented rate. Mode... more Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern animal production practices are associated with regular use of antimicrobials, potentially increasing selection pressure on bacteria to become resistant. Despite the significant potential consequences for antimicrobial resistance, there has been no quantitative measurement of global antimicrobial consumption by livestock. We address this gap by using Bayesian statistical models combining maps of livestock densities, economic projections of demand for meat products, and current estimates of antimicrobial consumption in high-income countries to map antimicrobial use in food animals for 2010 and 2030. We estimate that the global average annual consumption of antimicrobials per kilogram of animal produced was 45 mg⋅kg(-1), 148 mg⋅kg(-1), and 172 mg⋅kg(-1) for cattle, chicken, and pigs, respectively. Starting from this baseline, we estimate that between 2010 and 2030, the global consumptio...
Extract: Each year, nosocomial (acquired in hospital) infections affect nearly 2 million patients... more Extract: Each year, nosocomial (acquired in hospital) infections affect nearly 2 million patients and cause over 90,000 deaths in the United States alone. According to the Centers for Disease Control and Prevention (CDC), seventy percent of all nosocomial pathogens are resistant to one or more classes of antibiotics. Antibiotic-resistant bacteria such as vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) are leading causes of hospital acquired infections, and they have proven difficult to eradicate and control. The spread of resistance is ultimately caused by the use and overuse of antibiotics. Antibiotics are effective medicines when used correctly -- as is their purpose. The ability of VRE, MRSA and other antibiotic-resistant bacteria in hospitals to spread is affected by the percentage of people who use antibiotics in a population -- the more that antibiotics are used, the quicker resistance to them appears and the faster the resistant s...
Department of Mathematics and Statistics, University of Victoria, Victoria, BC, Canada V8W 3P4 Ph... more Department of Mathematics and Statistics, University of Victoria, Victoria, BC, Canada V8W 3P4 Phone: 1-250-721-7444, E-mail: jma@math.uvic.ca ... Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA E-mail: lworden@ucdavis.edu
Proceedings of the National Academy of Sciences, 2015
Cellular slime molds, including the well-studied Dictyostelium discoideum, are amoebae whose life... more Cellular slime molds, including the well-studied Dictyostelium discoideum, are amoebae whose life cycle includes both a single-cellular and a multicellular stage. To achieve the multicellular stage, individual amoebae aggregate upon starvation to form a fruiting body made of dead stalk cells and reproductive spores, a process that has been described in terms of cooperation and altruism. When amoebae aggregate they do not perfectly discriminate against nonkin, leading to chimeric fruiting bodies. Within chimeras, complex interactions among genotypes have been documented, which should theoretically reduce genetic diversity. This is however inconsistent with the great diversity of genotypes found in nature. Recent work has shown that a little-studied component of D. discoideum fitness-the loner cells that do not participate in the aggregation-can be selected for depending on environmental conditions and that, together with the spores, they could represent a bet-hedging strategy. We suggest that in all cellular slime molds the existence of loners could resolve the apparent diversity paradox in two ways. First, if loners are accounted for, then apparent genotypic skew in the spores of chimeras could simply be the result of different investments into spores versus loners. Second, in an ecosystem with multiple local environments differing in their food recovery characteristics and connected globally via weak-to-moderate dispersal, coexistence of multiple genotypes can occur. Finally, we argue that the loners make it impossible to define altruistic behavior, winners or losers, without a clear description of the ecology.
We present a low-dimensional, continuous model of a multi-agent system motivated by simulation st... more We present a low-dimensional, continuous model of a multi-agent system motivated by simulation studies on dynamics of decision making in animal groups in motion. Each individual moves at constant speed in the plane and adjusts its heading in response to relative headings of others in the population. Two subgroups of the population are informed such that individuals in each subgroup
Phytoplankton growth and stoichiometry depend on the availability of multiple nutrients. We use a... more Phytoplankton growth and stoichiometry depend on the availability of multiple nutrients. We use a mathematical model of phytoplankton with flexible stoichiometry to explain patterns of phytoplankton composition in chemostat experiments and nutrient drawdown dynamics that are found in the field. Exponential growth and equilibrium represent two distinct phases, each amenable to mathematical analysis. In a chemostat at a fixed dilution (growth) rate, phytoplankton stoichiometry matches the nutrient supply stoichiometry over a wide range at low growth rates and over a narrow range at high growth rates. In a chemostat with a fixed nutrient supply stoichiometry, phytoplankton stoichiometry varies with dilution rate nonlinearly, between the supply stoichiometry at low dilution rates and a species-specific optimal ratio at high dilution rates. The flexible-stoichiometry model we study predicts low equilibrium concentrations of two nutrients over a wide range of supply ratios, contrary to the predictions of a traditional fixed-stoichiometry model. The model is in quantitative agreement with experimental data, except at extreme nutrient supply ratios, which require a negative feedback from quota to uptake to fit the data. Our analysis points to the importance of better understanding the regulation of uptake rates in determining phytoplankton stoichiometry and incorporating this knowledge into phytoplankton models. We thank T. Daufresne, P. Falkowski, J. Grover, and two anonymous reviewers for comments and discussion. The authors gratefully acknowledge support from the Andrew W. Mellon Foundation (to S.A.L.) and the National Science Foundation awards DEB-0083566 (to S.A.L.), CHE-9810248 (to F. Morel), and OCE-0084032 (to P. Falkowski).
Evolution; international journal of organic evolution, Jan 22, 2015
Dispersal, whether in the form of a dandelion seed drifting on the breeze, or a salmon migrating ... more Dispersal, whether in the form of a dandelion seed drifting on the breeze, or a salmon migrating upstream to breed in a non-natal stream, transports genes between locations. At these locations, local adaptation modifies the gene frequencies so their carriers are better suited to particular conditions, be those of newly disturbed soil or a quiet river pool. Both dispersal and local adaptation are major drivers of population structure; however, in general, their respective roles are not independent and the two may often be at odds with one another evolutionarily, each one exhibiting negative feedback on the evolution of the other. Here we investigate their joint evolution within a simple discrete-time, metapopulation model. Depending on environmental conditions, their evolutionary interplay leads to either a monomorphic population of highly dispersing generalists or a rarely dispersing, locally adapted, polymorphic population, each adapted to a particular habitat type. A critical valu...
Proceedings of the National Academy of Sciences of the United States of America, Jan 30, 2015
Transitions between regimes with radically different properties are ubiquitous in nature. Such tr... more Transitions between regimes with radically different properties are ubiquitous in nature. Such transitions can occur either smoothly or in an abrupt and catastrophic fashion. Important examples of the latter can be found in ecology, climate sciences, and economics, to name a few, where regime shifts have catastrophic consequences that are mostly irreversible (e.g., desertification, coral reef collapses, and market crashes). Predicting and preventing these abrupt transitions remains a challenging and important task. Usually, simple deterministic equations are used to model and rationalize these complex situations. However, stochastic effects might have a profound effect. Here we use 1D and 2D spatially explicit models to show that intrinsic (demographic) stochasticity can alter deterministic predictions dramatically, especially in the presence of other realistic features such as limited mobility or spatial heterogeneity. In particular, these ingredients can alter the possibility of c...
Journal of the Royal Society, Interface / the Royal Society, Jan 6, 2015
Animal groups in nature often display an enhanced collective information-processing capacity. It ... more Animal groups in nature often display an enhanced collective information-processing capacity. It has been speculated that natural selection will tune this response to be optimal, ensuring that the group is reactive while also being robust to noise. Here, we show that this is unlikely to be the case. By using a simple model of decision-making in a dynamic environment, we find that when individuals behave rationally and are subject to selection based on their accuracy, optimality of collective decision-making is not attained. Instead, individuals overly rely on social information and evolve to be too readily influenced by their neighbours. This is due to a classic evolutionary conflict between individual and collective interest. The result is a sub-optimal system that is poised on the cusp of total unresponsiveness. Individuals in the evolved group exhibit delayed reactions to changes in the environment, before responding with rapid, socially reinforced transitions, reminiscent of fam...
Proceedings of the National Academy of Sciences of the United States of America, Jan 9, 2014
We have a limited understanding of the consequences of variations in microbial biodiversity on oc... more We have a limited understanding of the consequences of variations in microbial biodiversity on ocean ecosystem functioning and global biogeochemical cycles. A core process is macronutrient uptake by microorganisms, as the uptake of nutrients controls ocean CO2 fixation rates in many regions. Here, we ask whether variations in ocean phytoplankton biodiversity lead to novel functional relationships between environmental variability and phosphate (Pi) uptake. We analyzed Pi uptake capabilities and cellular allocations among phytoplankton groups and the whole community throughout the extremely Pi-depleted western North Atlantic Ocean. Pi uptake capabilities of individual populations were well described by a classic uptake function but displayed adaptive differences in uptake capabilities that depend on cell size and nutrient availability. Using an eco-evolutionary model as well as observations of in situ uptake across the region, we confirmed that differences among populations lead to p...
The objective of this study was to examine the association between convulsive status epilepticus ... more The objective of this study was to examine the association between convulsive status epilepticus (CSE) and health-related quality of life (HRQL) during a 24-month follow-up in a multisite incident cohort of children with epilepsy. Data were collected in the Health-Related Quality of Life Study in Children with Epilepsy Study from 374 families of children with newly diagnosed epilepsy. The Quality of Life in Childhood Epilepsy (QOLCE) Questionnaire was used to evaluate parent-reported child HRQL. Hierarchical linear regression was used to examine the relationship between CSE and HRQL at 24 months postepilepsy. A total of 359 families completed the 24-month assessment. Twenty-two children (6.1%) had experienced CSE during the follow-up. Children with and without CSE were similar, except a larger proportion of children with CSE had partial seizures (p < 0.001). Controlling for clinical, demographic, and family characteristics, CSE was significantly associated with poorer HRQL (β = -...
The personal choices affecting the transmission of infectious diseases include the number of cont... more The personal choices affecting the transmission of infectious diseases include the number of contacts an individual makes, and the risk-characteristics of those contacts. We consider whether these different choices have distinct implications for the course of an epidemic. We also consider whether choosing contact mitigation (how much to mix) and affinity mitigation (with whom to mix) strategies together has different epidemiological effects than choosing each separately. We use a set of differential equation compartmental models of the spread of disease, coupled with a model of selective mixing. We assess the consequences of varying contact or affinity mitigation as a response to disease risk. We do this by comparing disease incidence and dynamics under varying contact volume, contact type, and both combined across several different disease models. Specifically, we construct a change of variables that allows one to transition from contact mitigation to affinity mitigation, and vice ...
Oral surgery, oral medicine, and oral pathology, 1962
... Editor RADIATION AND IMAGE DISTORTION IN THE PANOREX XRAY UNIT Owen, W. Kite, DMD,* Lennard T... more ... Editor RADIATION AND IMAGE DISTORTION IN THE PANOREX XRAY UNIT Owen, W. Kite, DMD,* Lennard T. Swanson, DMD,** Samuel Levin,*** and ... roentgenogram will be produced if two of the componentsxray beam, object, or filmhave a stationary center of rota tion in ...
The t-haplotype is a chromosomal region in Mus musculus characterized by meiotic drive such that ... more The t-haplotype is a chromosomal region in Mus musculus characterized by meiotic drive such that heterozygous males transmit t-bearing chromosomes to roughly 90% of their offspring. Most naturally occurring t-haplotypes express a recessive embryonic lethality, preventing fixation of the t-haplotype. Surprisingly, the t-haplotype occurs in nature as a persistent, low-frequency polymorphism. Early modeling studies led LEWONTIN to hypothesize that this low level polymorphism results from a balance between genetic drift in small demes and interdemic migration. Here, we show that while combination of deme size and migration rate that predict natural t-haplotype frequencies exist, the range of such values is too narrow to be biologically plausible, suggesting that small deme size and interdemic migration alone do not explain the observed t-haplotype frequencies. In response, we tested other factors that might explain the observed t-polymorphism. Two led to biologically plausible models: s...
Oral surgery, oral medicine, and oral pathology, 1980
This is a case of Thorotrast-induced carcinoma of the maxillary sinus which was detected inadvert... more This is a case of Thorotrast-induced carcinoma of the maxillary sinus which was detected inadvertently in the course of investigation of associated dental pain and labial paresthesia. Clinical and radiobiologic features are presented. It is likely that similar cases remain undetected and at large in the community.
Proceedings of the National Academy of Sciences of the United States of America, Jan 19, 2015
Demand for animal protein for human consumption is rising globally at an unprecedented rate. Mode... more Demand for animal protein for human consumption is rising globally at an unprecedented rate. Modern animal production practices are associated with regular use of antimicrobials, potentially increasing selection pressure on bacteria to become resistant. Despite the significant potential consequences for antimicrobial resistance, there has been no quantitative measurement of global antimicrobial consumption by livestock. We address this gap by using Bayesian statistical models combining maps of livestock densities, economic projections of demand for meat products, and current estimates of antimicrobial consumption in high-income countries to map antimicrobial use in food animals for 2010 and 2030. We estimate that the global average annual consumption of antimicrobials per kilogram of animal produced was 45 mg⋅kg(-1), 148 mg⋅kg(-1), and 172 mg⋅kg(-1) for cattle, chicken, and pigs, respectively. Starting from this baseline, we estimate that between 2010 and 2030, the global consumptio...
Extract: Each year, nosocomial (acquired in hospital) infections affect nearly 2 million patients... more Extract: Each year, nosocomial (acquired in hospital) infections affect nearly 2 million patients and cause over 90,000 deaths in the United States alone. According to the Centers for Disease Control and Prevention (CDC), seventy percent of all nosocomial pathogens are resistant to one or more classes of antibiotics. Antibiotic-resistant bacteria such as vancomycin-resistant enterococci (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) are leading causes of hospital acquired infections, and they have proven difficult to eradicate and control. The spread of resistance is ultimately caused by the use and overuse of antibiotics. Antibiotics are effective medicines when used correctly -- as is their purpose. The ability of VRE, MRSA and other antibiotic-resistant bacteria in hospitals to spread is affected by the percentage of people who use antibiotics in a population -- the more that antibiotics are used, the quicker resistance to them appears and the faster the resistant s...
Department of Mathematics and Statistics, University of Victoria, Victoria, BC, Canada V8W 3P4 Ph... more Department of Mathematics and Statistics, University of Victoria, Victoria, BC, Canada V8W 3P4 Phone: 1-250-721-7444, E-mail: jma@math.uvic.ca ... Department of Environmental Science and Policy, University of California, Davis, CA 95616, USA E-mail: lworden@ucdavis.edu
Proceedings of the National Academy of Sciences, 2015
Cellular slime molds, including the well-studied Dictyostelium discoideum, are amoebae whose life... more Cellular slime molds, including the well-studied Dictyostelium discoideum, are amoebae whose life cycle includes both a single-cellular and a multicellular stage. To achieve the multicellular stage, individual amoebae aggregate upon starvation to form a fruiting body made of dead stalk cells and reproductive spores, a process that has been described in terms of cooperation and altruism. When amoebae aggregate they do not perfectly discriminate against nonkin, leading to chimeric fruiting bodies. Within chimeras, complex interactions among genotypes have been documented, which should theoretically reduce genetic diversity. This is however inconsistent with the great diversity of genotypes found in nature. Recent work has shown that a little-studied component of D. discoideum fitness-the loner cells that do not participate in the aggregation-can be selected for depending on environmental conditions and that, together with the spores, they could represent a bet-hedging strategy. We suggest that in all cellular slime molds the existence of loners could resolve the apparent diversity paradox in two ways. First, if loners are accounted for, then apparent genotypic skew in the spores of chimeras could simply be the result of different investments into spores versus loners. Second, in an ecosystem with multiple local environments differing in their food recovery characteristics and connected globally via weak-to-moderate dispersal, coexistence of multiple genotypes can occur. Finally, we argue that the loners make it impossible to define altruistic behavior, winners or losers, without a clear description of the ecology.
Uploads
Papers by Simon Levin