Abstract Evolutionary theory predicts that once an individual reaches an age of sufficiently low ... more Abstract Evolutionary theory predicts that once an individual reaches an age of sufficiently low Darwinian fitness,(s) he will have reduced chances of keeping cancerous lesions in check.
A central problem in ecology is predicting the diversity of communities. Insect parasitoids may e... more A central problem in ecology is predicting the diversity of communities. Insect parasitoids may encompass 20 percent of all insect species; hence, establishing the mechanisms that drive parasitoid species richness represents a major step in understanding the diversity of terrestrial communities.
Both theoretical and empirical evidence suggest that infectious disease can be a major determinan... more Both theoretical and empirical evidence suggest that infectious disease can be a major determinant of the dynamics of host populations and, more broadly, of the species composition of plant and animal communities. Previous studies of host-parasite systems have, for the most part, laid emphasis on epidemiological interpretations of the host-parasite interactions. In this article, we extend previous models of multiparasite systems and relate these models to general concepts of predator-prey and competitive interactions.
We compiled life tables for 78 holometabolous herbivorous insect species to quantify levels of ap... more We compiled life tables for 78 holometabolous herbivorous insect species to quantify levels of apparent enemy-induced mortality of immature insects. Enemies were classified by type (predator, parasitoid, or pathogen), and mortalities caused by each type in each herbivore immature stage were tested with Analysis of Deviance for differences associated with four ecological characteristics of preadult herbivores: feeding biology, invasion status, and the cultivation status and latitudinal zone of the habitat.
Summary We have investigated the theoretical consequences of character evolution for the populati... more Summary We have investigated the theoretical consequences of character evolution for the population dynamics of a host—parasitoid interaction, assuming a monophagous parasitoid. In the purely ecological model it is assumed that hosts can escape parasitism by being in absolute refuges. A striking property of this model is a threshold effect in control of the host by the parasitoid, when host density dependence is weak.
The growing importance of pathogens in biological control warrants an investigation into the like... more The growing importance of pathogens in biological control warrants an investigation into the likely effects of disease on the widely successful class of biological-control agents, the parasitoid. Our models consider a parasitoid that can exhibit a range of attack behaviors ranging from clumped to random. The pathogen is assumed to be transmitted by external stages that can span periods when the host is rare or absent.
Abstract Introduction: According to the empirical regularity called Taylor's law, the variance of... more Abstract Introduction: According to the empirical regularity called Taylor's law, the variance of population density in samples of populations is a power of the mean population density. The exponent is often between 1 and 2. Our experiments investigated how genetics, evolution, and environment shape Taylor's law.
abstract: Species interactions commonly coevolve as complex geographic mosaics of populations sha... more abstract: Species interactions commonly coevolve as complex geographic mosaics of populations shaped by differences in local selection and gene flow. We use a haploid matching-alleles model for coevolution to evaluate how a pair of species coevolves when fitness interactions are reciprocal in some locations (“hot spots”) but not in others (“cold spots”). Our analyses consider mutualistic and antagonistic interspecific interactions and a variety of gene flow patterns between hot and cold spots.
Abstract The 'high-dose-refuge'(HDR) strategy is widely recommended by the biotechnology industry... more Abstract The 'high-dose-refuge'(HDR) strategy is widely recommended by the biotechnology industry and regulatory authorities to delay pest adaptation to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. This involves cultivating nontoxic plants (refuges) in close proximity to crops producing a high dose of Bt toxin. The principal cost associated with this strategy is due to yield losses suffered by farmers growing unprotected, refuge plants.
Abstract Despite knowledge about microbial responses to abiotic stress, few studies have investig... more Abstract Despite knowledge about microbial responses to abiotic stress, few studies have investigated stress responses to antagonistic species, such as competitors, predators and pathogens. While it is often assumed that interacting populations of bacteria and phage will coevolve resistance and exploitation strategies, an alternative is that individual bacteria tolerate or evade phage predation through inducible responses to phage presence.
Summary. Previous studies have synthesized life-table data from herbivore species to identify gen... more Summary. Previous studies have synthesized life-table data from herbivore species to identify general trends in the demography of herbivorous insects.
Abstract Although very common under natural conditions, the consequences of multiple enemies (par... more Abstract Although very common under natural conditions, the consequences of multiple enemies (parasites, predators, herbivores, or even 'chemical'enemies like insecticides) on investment in defence has scarcely been investigated. In this paper, we present a simple model of the joint evolution of two defences targeted against two enemies. We illustrate how the respective level of each defence can be influenced by the presence of the two enemies.
Abstract Since the mid 1970s, cancer has been described as a process of Darwinian evolution, with... more Abstract Since the mid 1970s, cancer has been described as a process of Darwinian evolution, with somatic cellular selection and evolution being the fundamental processes leading to malignancy and its many manifestations (neoangiogenesis, evasion of the immune system, metastasis, and resistance to therapies). Historically, little attention has been placed on applications of evolutionary biology to understanding and controlling neoplastic progression and to prevent therapeutic failures.
Despite the abundance of studies on the evolution of specialization in trophic interactions (Bere... more Despite the abundance of studies on the evolution of specialization in trophic interactions (Berenbaum 1996), experimental work on the evolution of generalists versus specialists and their coexistence have usually assumed an abiotic heterogeneous (Reboud and Bell 1997; Barrett et al. 2005) or a biotic homogeneous (Crill et al. 2000; Turner and Elena 2000) environment.
Abstract Plants are known to maintain fitness despite herbivore attack by a variety of damage-ind... more Abstract Plants are known to maintain fitness despite herbivore attack by a variety of damage-induced mechanisms. These mechanisms are said to confer tolerance, which can be measured as the slope of fitness over the proportion of plant biomass removed by herbivore damage. It was recently supposed by Stowe et al.(2000) that another plant property, general vigor, has little effect on tolerance.
I employ a mathematical model integrating the population and co-adaptive dynamics of an insect ho... more I employ a mathematical model integrating the population and co-adaptive dynamics of an insect host and its specialist parasitoiod wasp to investigate the competitive evolution of two forms of host resistance: concealment from adult parasitoid location and encapsulation of parasitoid eggs. When only one form of resistance is permitted to evolve, concealment always evolves to frequencies equal to or higher than encapsulation.
Background Like conventional crops, some GM cultivars may readily hybridize with their wild or we... more Background Like conventional crops, some GM cultivars may readily hybridize with their wild or weedy relatives. The progressive introgression of transgenes into wild or weedy populations thus appears inevitable, and we are now faced with the challenge of determining the possible evolutionary effects of these transgenes. The aim of this study was to gain insight into the impact of interspecific hybridization between transgenic plants and weedy relatives on the evolution of the weedy phenotype.
Summary We lest the ability of a complex spatial model to predict the size of M. rebeli populatio... more Summary We lest the ability of a complex spatial model to predict the size of M. rebeli populations in two mountain ranges. The published model was based on nineteen parameters that described the population dynamic interactions between the butterfly, its initiai food plant Gentiana cruciata, its subsequen! host Myrmica schenckL and other competing non-host species of Myrmica.
Abstract Resistance to chemotherapies, particularly to anticancer treatments, is an increasing me... more Abstract Resistance to chemotherapies, particularly to anticancer treatments, is an increasing medical concern. Among the many mechanisms at work in cancers, one of the most important is the selection of tumor cells expressing resistance genes or phenotypes.
Abstract Evolutionary theory predicts that once an individual reaches an age of sufficiently low ... more Abstract Evolutionary theory predicts that once an individual reaches an age of sufficiently low Darwinian fitness,(s) he will have reduced chances of keeping cancerous lesions in check.
A central problem in ecology is predicting the diversity of communities. Insect parasitoids may e... more A central problem in ecology is predicting the diversity of communities. Insect parasitoids may encompass 20 percent of all insect species; hence, establishing the mechanisms that drive parasitoid species richness represents a major step in understanding the diversity of terrestrial communities.
Both theoretical and empirical evidence suggest that infectious disease can be a major determinan... more Both theoretical and empirical evidence suggest that infectious disease can be a major determinant of the dynamics of host populations and, more broadly, of the species composition of plant and animal communities. Previous studies of host-parasite systems have, for the most part, laid emphasis on epidemiological interpretations of the host-parasite interactions. In this article, we extend previous models of multiparasite systems and relate these models to general concepts of predator-prey and competitive interactions.
We compiled life tables for 78 holometabolous herbivorous insect species to quantify levels of ap... more We compiled life tables for 78 holometabolous herbivorous insect species to quantify levels of apparent enemy-induced mortality of immature insects. Enemies were classified by type (predator, parasitoid, or pathogen), and mortalities caused by each type in each herbivore immature stage were tested with Analysis of Deviance for differences associated with four ecological characteristics of preadult herbivores: feeding biology, invasion status, and the cultivation status and latitudinal zone of the habitat.
Summary We have investigated the theoretical consequences of character evolution for the populati... more Summary We have investigated the theoretical consequences of character evolution for the population dynamics of a host—parasitoid interaction, assuming a monophagous parasitoid. In the purely ecological model it is assumed that hosts can escape parasitism by being in absolute refuges. A striking property of this model is a threshold effect in control of the host by the parasitoid, when host density dependence is weak.
The growing importance of pathogens in biological control warrants an investigation into the like... more The growing importance of pathogens in biological control warrants an investigation into the likely effects of disease on the widely successful class of biological-control agents, the parasitoid. Our models consider a parasitoid that can exhibit a range of attack behaviors ranging from clumped to random. The pathogen is assumed to be transmitted by external stages that can span periods when the host is rare or absent.
Abstract Introduction: According to the empirical regularity called Taylor's law, the variance of... more Abstract Introduction: According to the empirical regularity called Taylor's law, the variance of population density in samples of populations is a power of the mean population density. The exponent is often between 1 and 2. Our experiments investigated how genetics, evolution, and environment shape Taylor's law.
abstract: Species interactions commonly coevolve as complex geographic mosaics of populations sha... more abstract: Species interactions commonly coevolve as complex geographic mosaics of populations shaped by differences in local selection and gene flow. We use a haploid matching-alleles model for coevolution to evaluate how a pair of species coevolves when fitness interactions are reciprocal in some locations (“hot spots”) but not in others (“cold spots”). Our analyses consider mutualistic and antagonistic interspecific interactions and a variety of gene flow patterns between hot and cold spots.
Abstract The 'high-dose-refuge'(HDR) strategy is widely recommended by the biotechnology industry... more Abstract The 'high-dose-refuge'(HDR) strategy is widely recommended by the biotechnology industry and regulatory authorities to delay pest adaptation to transgenic crops that produce Bacillus thuringiensis (Bt) toxins. This involves cultivating nontoxic plants (refuges) in close proximity to crops producing a high dose of Bt toxin. The principal cost associated with this strategy is due to yield losses suffered by farmers growing unprotected, refuge plants.
Abstract Despite knowledge about microbial responses to abiotic stress, few studies have investig... more Abstract Despite knowledge about microbial responses to abiotic stress, few studies have investigated stress responses to antagonistic species, such as competitors, predators and pathogens. While it is often assumed that interacting populations of bacteria and phage will coevolve resistance and exploitation strategies, an alternative is that individual bacteria tolerate or evade phage predation through inducible responses to phage presence.
Summary. Previous studies have synthesized life-table data from herbivore species to identify gen... more Summary. Previous studies have synthesized life-table data from herbivore species to identify general trends in the demography of herbivorous insects.
Abstract Although very common under natural conditions, the consequences of multiple enemies (par... more Abstract Although very common under natural conditions, the consequences of multiple enemies (parasites, predators, herbivores, or even 'chemical'enemies like insecticides) on investment in defence has scarcely been investigated. In this paper, we present a simple model of the joint evolution of two defences targeted against two enemies. We illustrate how the respective level of each defence can be influenced by the presence of the two enemies.
Abstract Since the mid 1970s, cancer has been described as a process of Darwinian evolution, with... more Abstract Since the mid 1970s, cancer has been described as a process of Darwinian evolution, with somatic cellular selection and evolution being the fundamental processes leading to malignancy and its many manifestations (neoangiogenesis, evasion of the immune system, metastasis, and resistance to therapies). Historically, little attention has been placed on applications of evolutionary biology to understanding and controlling neoplastic progression and to prevent therapeutic failures.
Despite the abundance of studies on the evolution of specialization in trophic interactions (Bere... more Despite the abundance of studies on the evolution of specialization in trophic interactions (Berenbaum 1996), experimental work on the evolution of generalists versus specialists and their coexistence have usually assumed an abiotic heterogeneous (Reboud and Bell 1997; Barrett et al. 2005) or a biotic homogeneous (Crill et al. 2000; Turner and Elena 2000) environment.
Abstract Plants are known to maintain fitness despite herbivore attack by a variety of damage-ind... more Abstract Plants are known to maintain fitness despite herbivore attack by a variety of damage-induced mechanisms. These mechanisms are said to confer tolerance, which can be measured as the slope of fitness over the proportion of plant biomass removed by herbivore damage. It was recently supposed by Stowe et al.(2000) that another plant property, general vigor, has little effect on tolerance.
I employ a mathematical model integrating the population and co-adaptive dynamics of an insect ho... more I employ a mathematical model integrating the population and co-adaptive dynamics of an insect host and its specialist parasitoiod wasp to investigate the competitive evolution of two forms of host resistance: concealment from adult parasitoid location and encapsulation of parasitoid eggs. When only one form of resistance is permitted to evolve, concealment always evolves to frequencies equal to or higher than encapsulation.
Background Like conventional crops, some GM cultivars may readily hybridize with their wild or we... more Background Like conventional crops, some GM cultivars may readily hybridize with their wild or weedy relatives. The progressive introgression of transgenes into wild or weedy populations thus appears inevitable, and we are now faced with the challenge of determining the possible evolutionary effects of these transgenes. The aim of this study was to gain insight into the impact of interspecific hybridization between transgenic plants and weedy relatives on the evolution of the weedy phenotype.
Summary We lest the ability of a complex spatial model to predict the size of M. rebeli populatio... more Summary We lest the ability of a complex spatial model to predict the size of M. rebeli populations in two mountain ranges. The published model was based on nineteen parameters that described the population dynamic interactions between the butterfly, its initiai food plant Gentiana cruciata, its subsequen! host Myrmica schenckL and other competing non-host species of Myrmica.
Abstract Resistance to chemotherapies, particularly to anticancer treatments, is an increasing me... more Abstract Resistance to chemotherapies, particularly to anticancer treatments, is an increasing medical concern. Among the many mechanisms at work in cancers, one of the most important is the selection of tumor cells expressing resistance genes or phenotypes.
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Papers by Michael Hochberg