Laurent Keller | University of Lausanne (original) (raw)
Papers by Laurent Keller
F1000 - Post-publication peer review of the biomedical literature, 2006
F1000 - Post-publication peer review of the biomedical literature, 2005
Scientific reports, Feb 28, 2024
Division of labour is widely thought to increase the task efficiency of eusocial insects. Workers... more Division of labour is widely thought to increase the task efficiency of eusocial insects. Workers can switch their task to compensate for sudden changes in demand, providing flexible task allocation. In combination with automated tracking technology, we developed a robotic system to precisely control and spatiotemporally manipulate floor temperature over days, which allowed us to predictably drive brood transport behaviour in colonies of the ant Camponotus floridanus. Our results indicate that a small number of workers, usually minors belonging to the nurse social group, are highly specialised for brood transport. There was no difference in the speed at which workers transported brood, suggesting that specialisation does not correlate with efficiency. Workers often started to transport the brood only after having identified a better location. There was no evidence that workers shared information about the presence of a better location. Notably, once brood transporters had been removed, none of the remaining workers performed this task, and the brood transport completely stopped. When brood transporters were returned to their colony, brood transport was immediately restored. Taken together, our study reveals that brood transport is an inflexible task, achieved through the synchronous actions of a few privately informed specialist workers.
The American Naturalist, 2012
Classical epidemic theory focuses on directly transmitted pathogens, but many pathogens are inste... more Classical epidemic theory focuses on directly transmitted pathogens, but many pathogens are instead transmitted when hosts encounter infectious particles. Theory has shown that for such diseases pathogen persistence time in the environment can strongly affect disease dynamics, but estimates of persistence time, and consequently tests of the theory, are extremely rare. We consider the consequences of persistence time for the dynamics of the gypsy moth baculovirus, a pathogen transmitted when larvae consume foliage contaminated with particles released from infectious cadavers. Using field-transmission experiments, we are able to estimate persistence time under natural conditions, and inserting our estimates into a standard epidemic model suggests that epidemics are often terminated by a combination of pupation and burnout rather than by burnout alone, as predicted by theory. Extending our models to allow for multiple generations, and including environmental transmission over the winter, suggests that the virus may survive over the long term even in the absence of complex persistence mechanisms, such as environmental reservoirs or covert infections. Our work suggests that estimates of persistence times can lead to a deeper understanding of environmentally transmitted pathogens and illustrates the usefulness of experiments that are closely tied to mathematical models.
Cambridge University Press eBooks, Mar 14, 2017
The striking differences in lifespan observed among some social insect castes offer unique opport... more The striking differences in lifespan observed among some social insect castes offer unique opportunities to study ageing and have therefore attracted increasing attention. While evolutionary theories of ageing can explain the long lifespan of social insect queens, experimental evidence to support them is lacking or contradictory. Furthermore, how social insects age is still poorly understood. Senescence patterns vary between behavioural worker castes and senescence in honeybee workers can even be reversed by inducing a caste transition, but explicit comparisons between queens and workers are needed to understand how queen longevity is linked to senescence. The ability of queens in advanced insect societies to combine long lifespans with high investment into reproduction presents a physiological puzzle, which may be solved in honeybees by the unique relationship between Juvenile Hormone and Vitellogenin. How this is achieved in other species remains unclear. We finish with a consideration of the challenges facing research into social insect ageing and discuss how these can best be met.
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Jul 10, 2006
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Mar 26, 2009
APS March Meeting Abstracts, 2019
Journal of Evolutionary Biology, May 1, 1997
有色金属：冶炼部分, 2008
目前金属基材料的原材料成本对热喷涂涂层的经济性造成压力。特别是材料挥发和近期铼、钨、钴和镍基材料的价格增长,对各应用领域的许多涂层的经济性造成严重威胁。由于沉积效率的限制,喷涂中未沉积物问题变得... more 目前金属基材料的原材料成本对热喷涂涂层的经济性造成压力。特别是材料挥发和近期铼、钨、钴和镍基材料的价格增长,对各应用领域的许多涂层的经济性造成严重威胁。由于沉积效率的限制,喷涂中未沉积物问题变得越来越重要,不仅只是减少浪费,还可以从材料自身价值角度去看。回收是解决这个问题的一个措施,特别是当废料中含有高价值金属时。欧洲执行的REACH(化学制品的注册、评估、授权)将会逐步强制淘汰标有有毒的材料和物质的使用。在热喷涂中使用这些有毒物质或使用热喷涂产品可能暂时是安全的,然而,从法律限制和从其他工业领域得到的指示表明,像WC-Co粉末这样的化学制品对人体有害。要想在将来的涂层工厂中保持竞争性,必须符合不断提高的更严格的环保和安全规程。
Evolutionary Ecology Research, 2009
Background: The sexually selected sperm hypothesis predicts that selection will favour female mul... more Background: The sexually selected sperm hypothesis predicts that selection will favour female multiple mating by increasing the sperm competitive abilities of their sons. Hypothesis: Sons of multiply mated females should have higher sperm competitive abilities than sons of singly mated females. Organism: The bulb mite, Rhizoglyphus robini (Acari: Acaridae). Methods: Rhizoglyphus is a highly promiscuous species in which females gain no direct benefits from multiple matings. Virgin females were mated to one or six males. Sons of singly and multiply mated females were allowed to compete with each other for access to females' ova. Sperm competitiveness was estimated by the sterile male method. Results: Contrary to the predictions of the hypothesis, we found no difference in sperm competitiveness between sons of singly and multiply mated females. We suggest that non-genetic effects could explain this result.
PLOS Biology, Jul 24, 2023
AU : Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly: The physiology and behavior of soc... more AU : Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly: The physiology and behavior of social organisms correlate with their social environments. However, because social environments are typically confounded by age and physical environments (i.e., spatial location and associated abiotic factors), these correlations are usually difficult to interpret. For example, associations between an individual's social environment and its gene expression patterns may result from both factors being driven by age or behavior. Simultaneous measurement of pertinent variables and quantification of the correlations between these variables can indicate whether relationships are direct (and possibly causal) or indirect. Here, we combine demographic and automated behavioral tracking with a multiomic approach to dissect the correlation structure among the social and physical environment, age, behavior, brain gene expression, and microbiota composition in the carpenter ant Camponotus fellah. Variations in physiology and behavior were most strongly correlated with the social environment. Moreover, seemingly strong correlations between brain gene expression and microbiota composition, physical environment, age, and behavior became weak when controlling for the social environment. Consistent with this, a machine learning analysis revealed that from brain gene expression data, an individual's social environment can be more accurately predicted than any other behavioral metric. These results indicate that social environment is a key regulator of behavior and physiology.
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Oct 22, 2007
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Feb 17, 2006
F1000 - Post-publication peer review of the biomedical literature, 2006
F1000 - Post-publication peer review of the biomedical literature, 2005
Scientific reports, Feb 28, 2024
Division of labour is widely thought to increase the task efficiency of eusocial insects. Workers... more Division of labour is widely thought to increase the task efficiency of eusocial insects. Workers can switch their task to compensate for sudden changes in demand, providing flexible task allocation. In combination with automated tracking technology, we developed a robotic system to precisely control and spatiotemporally manipulate floor temperature over days, which allowed us to predictably drive brood transport behaviour in colonies of the ant Camponotus floridanus. Our results indicate that a small number of workers, usually minors belonging to the nurse social group, are highly specialised for brood transport. There was no difference in the speed at which workers transported brood, suggesting that specialisation does not correlate with efficiency. Workers often started to transport the brood only after having identified a better location. There was no evidence that workers shared information about the presence of a better location. Notably, once brood transporters had been removed, none of the remaining workers performed this task, and the brood transport completely stopped. When brood transporters were returned to their colony, brood transport was immediately restored. Taken together, our study reveals that brood transport is an inflexible task, achieved through the synchronous actions of a few privately informed specialist workers.
The American Naturalist, 2012
Classical epidemic theory focuses on directly transmitted pathogens, but many pathogens are inste... more Classical epidemic theory focuses on directly transmitted pathogens, but many pathogens are instead transmitted when hosts encounter infectious particles. Theory has shown that for such diseases pathogen persistence time in the environment can strongly affect disease dynamics, but estimates of persistence time, and consequently tests of the theory, are extremely rare. We consider the consequences of persistence time for the dynamics of the gypsy moth baculovirus, a pathogen transmitted when larvae consume foliage contaminated with particles released from infectious cadavers. Using field-transmission experiments, we are able to estimate persistence time under natural conditions, and inserting our estimates into a standard epidemic model suggests that epidemics are often terminated by a combination of pupation and burnout rather than by burnout alone, as predicted by theory. Extending our models to allow for multiple generations, and including environmental transmission over the winter, suggests that the virus may survive over the long term even in the absence of complex persistence mechanisms, such as environmental reservoirs or covert infections. Our work suggests that estimates of persistence times can lead to a deeper understanding of environmentally transmitted pathogens and illustrates the usefulness of experiments that are closely tied to mathematical models.
Cambridge University Press eBooks, Mar 14, 2017
The striking differences in lifespan observed among some social insect castes offer unique opport... more The striking differences in lifespan observed among some social insect castes offer unique opportunities to study ageing and have therefore attracted increasing attention. While evolutionary theories of ageing can explain the long lifespan of social insect queens, experimental evidence to support them is lacking or contradictory. Furthermore, how social insects age is still poorly understood. Senescence patterns vary between behavioural worker castes and senescence in honeybee workers can even be reversed by inducing a caste transition, but explicit comparisons between queens and workers are needed to understand how queen longevity is linked to senescence. The ability of queens in advanced insect societies to combine long lifespans with high investment into reproduction presents a physiological puzzle, which may be solved in honeybees by the unique relationship between Juvenile Hormone and Vitellogenin. How this is achieved in other species remains unclear. We finish with a consideration of the challenges facing research into social insect ageing and discuss how these can best be met.
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Jul 10, 2006
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Mar 26, 2009
APS March Meeting Abstracts, 2019
Journal of Evolutionary Biology, May 1, 1997
有色金属：冶炼部分, 2008
目前金属基材料的原材料成本对热喷涂涂层的经济性造成压力。特别是材料挥发和近期铼、钨、钴和镍基材料的价格增长,对各应用领域的许多涂层的经济性造成严重威胁。由于沉积效率的限制,喷涂中未沉积物问题变得... more 目前金属基材料的原材料成本对热喷涂涂层的经济性造成压力。特别是材料挥发和近期铼、钨、钴和镍基材料的价格增长,对各应用领域的许多涂层的经济性造成严重威胁。由于沉积效率的限制,喷涂中未沉积物问题变得越来越重要,不仅只是减少浪费,还可以从材料自身价值角度去看。回收是解决这个问题的一个措施,特别是当废料中含有高价值金属时。欧洲执行的REACH(化学制品的注册、评估、授权)将会逐步强制淘汰标有有毒的材料和物质的使用。在热喷涂中使用这些有毒物质或使用热喷涂产品可能暂时是安全的,然而,从法律限制和从其他工业领域得到的指示表明,像WC-Co粉末这样的化学制品对人体有害。要想在将来的涂层工厂中保持竞争性,必须符合不断提高的更严格的环保和安全规程。
Evolutionary Ecology Research, 2009
Background: The sexually selected sperm hypothesis predicts that selection will favour female mul... more Background: The sexually selected sperm hypothesis predicts that selection will favour female multiple mating by increasing the sperm competitive abilities of their sons. Hypothesis: Sons of multiply mated females should have higher sperm competitive abilities than sons of singly mated females. Organism: The bulb mite, Rhizoglyphus robini (Acari: Acaridae). Methods: Rhizoglyphus is a highly promiscuous species in which females gain no direct benefits from multiple matings. Virgin females were mated to one or six males. Sons of singly and multiply mated females were allowed to compete with each other for access to females' ova. Sperm competitiveness was estimated by the sterile male method. Results: Contrary to the predictions of the hypothesis, we found no difference in sperm competitiveness between sons of singly and multiply mated females. We suggest that non-genetic effects could explain this result.
PLOS Biology, Jul 24, 2023
AU : Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly: The physiology and behavior of soc... more AU : Pleaseconfirmthatallheadinglevelsarerepresentedcorrectly: The physiology and behavior of social organisms correlate with their social environments. However, because social environments are typically confounded by age and physical environments (i.e., spatial location and associated abiotic factors), these correlations are usually difficult to interpret. For example, associations between an individual's social environment and its gene expression patterns may result from both factors being driven by age or behavior. Simultaneous measurement of pertinent variables and quantification of the correlations between these variables can indicate whether relationships are direct (and possibly causal) or indirect. Here, we combine demographic and automated behavioral tracking with a multiomic approach to dissect the correlation structure among the social and physical environment, age, behavior, brain gene expression, and microbiota composition in the carpenter ant Camponotus fellah. Variations in physiology and behavior were most strongly correlated with the social environment. Moreover, seemingly strong correlations between brain gene expression and microbiota composition, physical environment, age, and behavior became weak when controlling for the social environment. Consistent with this, a machine learning analysis revealed that from brain gene expression data, an individual's social environment can be more accurately predicted than any other behavioral metric. These results indicate that social environment is a key regulator of behavior and physiology.
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Oct 22, 2007
Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature, Feb 17, 2006