The Evolution of Social Behavior
Natural selection states that selection acts on individuals leading to population level changes in allele frequencies. Colonies of individuals, such as honey bees, have often been likened to a single organism: the queen and drones being the reproductive organs and the workers making up the other systems. As such, it is possible to imagine selection acting on the colony as a whole leading to emergent traits that may be selected against at the level of the individual but selected for at the level of the group.
Within a honey bee colony conflict abounds. One such conflict is that over the production of male offspring. Workers, although they never mate, are able to produce male offspring due to their haplodiploid sex determination system (here, unfertilized eggs develop into males whilst fertilized eggs develop into females). As such, a worker can produce her own offspring. At the individual level all workers should want to produce their own offspring. However, because the queen mates multiply, the other workers in a colony should prefer that the queen produces all of the male and female offspring. Indeed workers eat the eggs laid by other workers in a queen right colony, a behavior known as worker policing behavior. It is this conflict over the production of male offspring that I am using to study levels of selection.
Ultimately, selection could be acting at 3 different levels:
1. The Individual Level - Workers police eggs laid by other workers as they are less related to the sons of their half sisters than their mothers and therefore, gain increased indirect fitness benefits through helping their mother to produce more offspring than their sisters.
2. The Colony Level - Worker laying inflicts a productivity cost upon the colony. As such, a colony with laying workers would put less reproductives (drones and queens) into the mating pool than a colony where the workers do not lay. Over time this would select for colonies where workers do not lay eggs.
3. The Intragenomic Level - Intragenomic conflict would occur within the genome of worker honey bees. Workers get half of their genes from their mother and half from their father. The likelihood that these genes will enter the next generation differ depending on the behavior of the worker. From the mothers perspective her genes will enter the next generation in both her female and male offspring. From the fathers perspective his genes will enter the next generation in females through his mating with the queen, however, because males are haploid and get all of their genetic information from their mother the only way his genes can be found in males is if his daughters reproduce. Therefore, there should be selection on the male portion of the genome for worker laying. Worker laying would decrease the queens reproductive success and therefore it is expected that worker policing would be selected for on the maternal genome.
I am using a combination of mathematical modelling and experimental manipulation to examine how this conflict is resolved at all of these levels of selection.
Within a honey bee colony conflict abounds. One such conflict is that over the production of male offspring. Workers, although they never mate, are able to produce male offspring due to their haplodiploid sex determination system (here, unfertilized eggs develop into males whilst fertilized eggs develop into females). As such, a worker can produce her own offspring. At the individual level all workers should want to produce their own offspring. However, because the queen mates multiply, the other workers in a colony should prefer that the queen produces all of the male and female offspring. Indeed workers eat the eggs laid by other workers in a queen right colony, a behavior known as worker policing behavior. It is this conflict over the production of male offspring that I am using to study levels of selection.
Ultimately, selection could be acting at 3 different levels:
1. The Individual Level - Workers police eggs laid by other workers as they are less related to the sons of their half sisters than their mothers and therefore, gain increased indirect fitness benefits through helping their mother to produce more offspring than their sisters.
2. The Colony Level - Worker laying inflicts a productivity cost upon the colony. As such, a colony with laying workers would put less reproductives (drones and queens) into the mating pool than a colony where the workers do not lay. Over time this would select for colonies where workers do not lay eggs.
3. The Intragenomic Level - Intragenomic conflict would occur within the genome of worker honey bees. Workers get half of their genes from their mother and half from their father. The likelihood that these genes will enter the next generation differ depending on the behavior of the worker. From the mothers perspective her genes will enter the next generation in both her female and male offspring. From the fathers perspective his genes will enter the next generation in females through his mating with the queen, however, because males are haploid and get all of their genetic information from their mother the only way his genes can be found in males is if his daughters reproduce. Therefore, there should be selection on the male portion of the genome for worker laying. Worker laying would decrease the queens reproductive success and therefore it is expected that worker policing would be selected for on the maternal genome.
I am using a combination of mathematical modelling and experimental manipulation to examine how this conflict is resolved at all of these levels of selection.
Group Coordination
Any animal group must coordinate its behaviors in order to efficiently carry out tasks. One situation in which this is crucial is the finding and exploitation of food. Food sources are often dispersed unevenly across environments. Food sources are often temporary, changing location with the day, week, month, season and year. Sometimes, within the hour. Communication has long been assumed to be essential in improving task performance e.g. ant trails, honey bee waggle dance.
Humans are no exception. Early hominids had to hunt across just such a patchy environment and even today we face similar spatial-temporal uncertainties in our daily lives. To exchange information we use a complex mosaic of non-verbal and verbal communication allowing us to discern what others perceive, intend, desire, know and believe. As such, in human groups, group decision-making is generally based on mutual discussion.
We used a simple foraging task and automated data collection method to examine how communication enhances performance of human groups in a social foraging context. We found that gestures (e.g. pointing and waving) are crucial for group coordination.
Humans are no exception. Early hominids had to hunt across just such a patchy environment and even today we face similar spatial-temporal uncertainties in our daily lives. To exchange information we use a complex mosaic of non-verbal and verbal communication allowing us to discern what others perceive, intend, desire, know and believe. As such, in human groups, group decision-making is generally based on mutual discussion.
We used a simple foraging task and automated data collection method to examine how communication enhances performance of human groups in a social foraging context. We found that gestures (e.g. pointing and waving) are crucial for group coordination.