Overview
My broad research interest is in social behavior, how the interactions between individuals combine to affect their fitness and life-history. From ants to human’s individuals interact in complex social systems, these social systems can have important effects on an individual’s behavior, and their ability to survive and reproduce. I’m interested the interaction between these broad global effects, the behavior of individuals, and evolution.
My current work focused on social behaviors in Killer Whales working with Darren Croft. Using data from a 40 years of observation in we’re investigating in how the complex social systems of Killers Whales affect their behavior and survival. We are also interested in post-reproductive lifespans in Killer Whales and other animals.
Broad research specialisms:
Social behaviour, animal behaviour, behavioural ecology, network analysis
Qualifications
2007-2010 BSc(Hons) Zoology Univerity of Bristol
2011-2015 PhD Biology University of York
Career
2007-2010 BSc(Hons) Zoology, University of Bristol
2011-2015 PhD Biology, University of York
2016-Present PostDoc, University of Exeter
Links
Research group links
Research
Research interests
Social behaviour, animal behaviour, behavioural ecology, network analysis
Research projects
- The Evolution of a prolonged post-reproductive lifespan in a non-human mammal.
Publications
Key publications | Publications by category | Publications by year
Key publications
Ellis S, Robinson EJH (2016). Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Behav Ecol,
27(2), 660-668.
Abstract:
Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Resource sharing is an important cooperative behavior in many animals. Sharing resources is particularly important in social insect societies, as division of labor often results in most individuals including, importantly, the reproductives, relying on other members of the colony to provide resources. Sharing resources between individuals is therefore fundamental to the success of social insects. Resource sharing is complicated if a colony inhabits several spatially separated nests, a nesting strategy common in many ant species. Resources must be shared not only between individuals in a single nest but also between nests. We investigated the behaviors facilitating resource redistribution between nests in a dispersed-nesting population of wood ant Formica lugubris. We marked ants, in the field, as they transported resources along the trails between nests of a colony, to investigate how the behavior of individual workers relates to colony-level resource exchange. We found that workers from a particular nest "forage" to other nests in the colony, treating them as food sources. Workers treating other nests as food sources means that simple, pre-existing foraging behaviors are used to move resources through a distributed system. It may be that this simple behavioral mechanism facilitates the evolution of this complex life-history strategy.
Abstract.
Author URL.
Ellis S, Robinson EJH (2015). The role of non-foraging nests in polydomous wood ant colonies.
PLoS ONE,
10(10).
Abstract:
The role of non-foraging nests in polydomous wood ant colonies
© 2015 Ellis, Robinson. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas. Copyright:
Abstract.
Ellis S, Robinson EJH (2014). Polydomy in red wood ants.
Insectes Sociaux,
61(2), 111-122.
Abstract:
Polydomy in red wood ants
Polydomy, a single colony spread between multiple nests, is a widespread life history strategy in ants. The mechanisms by which a polydomous colony functions, and the fitness benefits this nesting strategy provides, are poorly understood. Here we review what is known about polydomy in the well-studied and ecologically important Formica rufa group. We focus particularly on the ecological fitness benefits polydomy may provide to members of the F. rufa group. We discuss the well-documented association in this group between polygyny (multiple queens in a colony) and polydomy, and how this relationship may favour colony reproduction by budding. We argue that although polygyny and reproduction by budding may drive a colony to spread between multiple nests, the maintenance of prolonged communication between these nests needs further explanation in terms of fitness benefits. The potential benefits of polydomy in the F. rufa group are discussed, specifically how polydomy may help a colony: exploit resources, dominate spaces, or lower the cost of stochastic nest destruction. The potential consequences of polydomy for the social organisation of a colony are explored. We also highlight gaps in current knowledge, and suggest future research directions. © 2014 International Union for the Study of Social Insects (IUSSI).
Abstract.
Ellis S, Franks DW, Robinson EJH (2014). Resource redistribution in polydomous ant nest networks: Local or global?.
Behavioral Ecology,
25(5), 1183-1191.
Abstract:
Resource redistribution in polydomous ant nest networks: Local or global?
© 2014 © the Author 2014. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. An important problem facing organisms in a heterogeneous environment is how to redistribute resources to where they are required. This is particularly complex in social insect societies as resources have to be moved both from the environment into the nest and between individuals within the nest. Polydomous ant colonies are split between multiple spatially separated, but socially connected, nests. Whether, and how, resources are redistributed between nests in polydomous colonies is unknown. We analyzed the nest networks of the facultatively polydomous wood ant Formica lugubris. Our results indicate that resource redistribution in polydomous F. lugubris colonies is organized at the local level between neighboring nests and not at the colony level. We found that internest trails connecting nests that differed more in their amount of foraging were stronger than trails between nests with more equal foraging activity. This indicates that resources are being exchanged directly from nests with a foraging excess to nests that require resources. In contrast, we found no significant relationships between nest properties, such as size and amount of foraging, and network measures such as centrality and connectedness. This indicates an absence of a colony-level resource exchange. This is a clear example of a complex behavior emerging as a result of local interactions between parts of a system.
Abstract.
Robinson EJH, Franks NR, Ellis S, Okuda S, Marshall JAR (2011). A Simple Threshold Rule is Sufficient to Explain Sophisticated Collective Decision-Making.
PLOS ONE,
6(5).
Author URL.
Publications by category
Journal articles
Ellis S, Franks D, Nattrass S, Currie T, Cant M, Giles D, Balcomb K, Croft D (In Press). Analyses of ovarian activity reveal repeated evolution of post-reproductive lifespans in toothed whales.
Scientific Reports Full text.
Ellis S, Franks DW, Nattrass S, Cant MA, Weiss MN, Giles D, Balcomb KC, Croft DP (In Press). Mortality risk and social network position in resident killer whales: sex differences and the importance of resource abundance.
Proceedings of the Royal Society B: Biological Sciences Full text.
Ellis S, Robinson EJH (2016). Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Behav Ecol,
27(2), 660-668.
Abstract:
Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Resource sharing is an important cooperative behavior in many animals. Sharing resources is particularly important in social insect societies, as division of labor often results in most individuals including, importantly, the reproductives, relying on other members of the colony to provide resources. Sharing resources between individuals is therefore fundamental to the success of social insects. Resource sharing is complicated if a colony inhabits several spatially separated nests, a nesting strategy common in many ant species. Resources must be shared not only between individuals in a single nest but also between nests. We investigated the behaviors facilitating resource redistribution between nests in a dispersed-nesting population of wood ant Formica lugubris. We marked ants, in the field, as they transported resources along the trails between nests of a colony, to investigate how the behavior of individual workers relates to colony-level resource exchange. We found that workers from a particular nest "forage" to other nests in the colony, treating them as food sources. Workers treating other nests as food sources means that simple, pre-existing foraging behaviors are used to move resources through a distributed system. It may be that this simple behavioral mechanism facilitates the evolution of this complex life-history strategy.
Abstract.
Author URL.
Ellis S, Robinson EJH (2015). The role of non-foraging nests in polydomous wood ant colonies.
PLoS ONE,
10(10).
Abstract:
The role of non-foraging nests in polydomous wood ant colonies
© 2015 Ellis, Robinson. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas. Copyright:
Abstract.
Ellis S, Robinson EJH (2014). Polydomy in red wood ants.
Insectes Sociaux,
61(2), 111-122.
Abstract:
Polydomy in red wood ants
Polydomy, a single colony spread between multiple nests, is a widespread life history strategy in ants. The mechanisms by which a polydomous colony functions, and the fitness benefits this nesting strategy provides, are poorly understood. Here we review what is known about polydomy in the well-studied and ecologically important Formica rufa group. We focus particularly on the ecological fitness benefits polydomy may provide to members of the F. rufa group. We discuss the well-documented association in this group between polygyny (multiple queens in a colony) and polydomy, and how this relationship may favour colony reproduction by budding. We argue that although polygyny and reproduction by budding may drive a colony to spread between multiple nests, the maintenance of prolonged communication between these nests needs further explanation in terms of fitness benefits. The potential benefits of polydomy in the F. rufa group are discussed, specifically how polydomy may help a colony: exploit resources, dominate spaces, or lower the cost of stochastic nest destruction. The potential consequences of polydomy for the social organisation of a colony are explored. We also highlight gaps in current knowledge, and suggest future research directions. © 2014 International Union for the Study of Social Insects (IUSSI).
Abstract.
Ellis S, Franks DW, Robinson EJH (2014). Resource redistribution in polydomous ant nest networks: Local or global?.
Behavioral Ecology,
25(5), 1183-1191.
Abstract:
Resource redistribution in polydomous ant nest networks: Local or global?
© 2014 © the Author 2014. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. An important problem facing organisms in a heterogeneous environment is how to redistribute resources to where they are required. This is particularly complex in social insect societies as resources have to be moved both from the environment into the nest and between individuals within the nest. Polydomous ant colonies are split between multiple spatially separated, but socially connected, nests. Whether, and how, resources are redistributed between nests in polydomous colonies is unknown. We analyzed the nest networks of the facultatively polydomous wood ant Formica lugubris. Our results indicate that resource redistribution in polydomous F. lugubris colonies is organized at the local level between neighboring nests and not at the colony level. We found that internest trails connecting nests that differed more in their amount of foraging were stronger than trails between nests with more equal foraging activity. This indicates that resources are being exchanged directly from nests with a foraging excess to nests that require resources. In contrast, we found no significant relationships between nest properties, such as size and amount of foraging, and network measures such as centrality and connectedness. This indicates an absence of a colony-level resource exchange. This is a clear example of a complex behavior emerging as a result of local interactions between parts of a system.
Abstract.
Robinson EJH, Franks NR, Ellis S, Okuda S, Marshall JAR (2011). A Simple Threshold Rule is Sufficient to Explain Sophisticated Collective Decision-Making.
PLOS ONE,
6(5).
Author URL.
Publications by year
In Press
Ellis S, Franks D, Nattrass S, Currie T, Cant M, Giles D, Balcomb K, Croft D (In Press). Analyses of ovarian activity reveal repeated evolution of post-reproductive lifespans in toothed whales.
Scientific Reports Full text.
Ellis S, Franks DW, Nattrass S, Cant MA, Weiss MN, Giles D, Balcomb KC, Croft DP (In Press). Mortality risk and social network position in resident killer whales: sex differences and the importance of resource abundance.
Proceedings of the Royal Society B: Biological Sciences Full text.
2016
Ellis S, Robinson EJH (2016). Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Behav Ecol,
27(2), 660-668.
Abstract:
Internest food sharing within wood ant colonies: resource redistribution behavior in a complex system.
Resource sharing is an important cooperative behavior in many animals. Sharing resources is particularly important in social insect societies, as division of labor often results in most individuals including, importantly, the reproductives, relying on other members of the colony to provide resources. Sharing resources between individuals is therefore fundamental to the success of social insects. Resource sharing is complicated if a colony inhabits several spatially separated nests, a nesting strategy common in many ant species. Resources must be shared not only between individuals in a single nest but also between nests. We investigated the behaviors facilitating resource redistribution between nests in a dispersed-nesting population of wood ant Formica lugubris. We marked ants, in the field, as they transported resources along the trails between nests of a colony, to investigate how the behavior of individual workers relates to colony-level resource exchange. We found that workers from a particular nest "forage" to other nests in the colony, treating them as food sources. Workers treating other nests as food sources means that simple, pre-existing foraging behaviors are used to move resources through a distributed system. It may be that this simple behavioral mechanism facilitates the evolution of this complex life-history strategy.
Abstract.
Author URL.
2015
Ellis S, Robinson EJH (2015). The role of non-foraging nests in polydomous wood ant colonies.
PLoS ONE,
10(10).
Abstract:
The role of non-foraging nests in polydomous wood ant colonies
© 2015 Ellis, Robinson. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas. Copyright:
Abstract.
2014
Ellis S, Robinson EJH (2014). Polydomy in red wood ants.
Insectes Sociaux,
61(2), 111-122.
Abstract:
Polydomy in red wood ants
Polydomy, a single colony spread between multiple nests, is a widespread life history strategy in ants. The mechanisms by which a polydomous colony functions, and the fitness benefits this nesting strategy provides, are poorly understood. Here we review what is known about polydomy in the well-studied and ecologically important Formica rufa group. We focus particularly on the ecological fitness benefits polydomy may provide to members of the F. rufa group. We discuss the well-documented association in this group between polygyny (multiple queens in a colony) and polydomy, and how this relationship may favour colony reproduction by budding. We argue that although polygyny and reproduction by budding may drive a colony to spread between multiple nests, the maintenance of prolonged communication between these nests needs further explanation in terms of fitness benefits. The potential benefits of polydomy in the F. rufa group are discussed, specifically how polydomy may help a colony: exploit resources, dominate spaces, or lower the cost of stochastic nest destruction. The potential consequences of polydomy for the social organisation of a colony are explored. We also highlight gaps in current knowledge, and suggest future research directions. © 2014 International Union for the Study of Social Insects (IUSSI).
Abstract.
Ellis S, Franks DW, Robinson EJH (2014). Resource redistribution in polydomous ant nest networks: Local or global?.
Behavioral Ecology,
25(5), 1183-1191.
Abstract:
Resource redistribution in polydomous ant nest networks: Local or global?
© 2014 © the Author 2014. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. An important problem facing organisms in a heterogeneous environment is how to redistribute resources to where they are required. This is particularly complex in social insect societies as resources have to be moved both from the environment into the nest and between individuals within the nest. Polydomous ant colonies are split between multiple spatially separated, but socially connected, nests. Whether, and how, resources are redistributed between nests in polydomous colonies is unknown. We analyzed the nest networks of the facultatively polydomous wood ant Formica lugubris. Our results indicate that resource redistribution in polydomous F. lugubris colonies is organized at the local level between neighboring nests and not at the colony level. We found that internest trails connecting nests that differed more in their amount of foraging were stronger than trails between nests with more equal foraging activity. This indicates that resources are being exchanged directly from nests with a foraging excess to nests that require resources. In contrast, we found no significant relationships between nest properties, such as size and amount of foraging, and network measures such as centrality and connectedness. This indicates an absence of a colony-level resource exchange. This is a clear example of a complex behavior emerging as a result of local interactions between parts of a system.
Abstract.
2011
Robinson EJH, Franks NR, Ellis S, Okuda S, Marshall JAR (2011). A Simple Threshold Rule is Sufficient to Explain Sophisticated Collective Decision-Making.
PLOS ONE,
6(5).
Author URL.
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