This post is really inspired by two things that happened on the same day. Firstly, one of my old office mates has a paper published in American Naturalist (possibly the most fuddy-duddy, old school journal I have come across). Secondly, the Times reported on dolphins having a social network, because no one knew that....
So the Am Nat paper, it's about how the social structure that cichlids are born into shapes their development. This is interesting because all social species have to interact with other members of their group, and so they have to constantly deal with aggression, hierarchies and recognising other individuals. This stuff has to be learned, and there is a potential cost to that. What Stefan Fischer et al. found was that being reared in a large group means that you have better social skills later in life. Not only did they find behaviour differences between individuals from small groups but also structural changes to their brains. What this study hints at, is that the costs of learning how to behave in a group might mean that it only pays to invest in these behaviours and developmental changes if you need to. This adds a further cost to sociality, one that had not been measured before.
Fischer et al. (2015) Rearing-group size determines social competence and brain structure in a cooperatively breeding cichlid. Am. Nat.
The second new bit of research is on dolphins. These marine mammals live in cool fusion-fission societies, where group compositions constantly change and groups can be subsets of much larger units. From what I can gather from the abstract, I no longer have any university affiliations and so can't access non-open access journals, one of the cool things they found was that the habitat "narrowness" influenced the level of sociality observed. They found that dolphins spent more time with certain individuals than with others, much like humans. This type of social network is important for things that range from disease transmission to social learning. But finding a link to the environment is really interesting, as scientist have theorized that some environments are more likely to select for group living species but this finding might hint that environments may select for the type of social organisation within those groups. But having been unable to read the paper this could be wild speculation!!
Here is the abstract so you can make up your own mind:
Titcomb et al. (2015) Social communities and spatiotemporal dynamics of association patterns in estuarine bottlenose dolphins. Marine Mammal Science, DOI: 10.1111/mms.12222
Network analysis has recently been used to delve into the dynamics of cetacean sociality. Few studies, however, have addressed how habitat shape influences sociality, specifically how linear water bodies constrain the space where individuals might interact. We utilized network and spatiotemporal analyses to investigate association patterns and community structure in a bottlenose dolphin population in a linear estuarine system, the Indian River Lagoon (IRL), Florida. Using sighting histories from a multiyear photo-identification study we examined association patterns for 185 individuals collected over a 6.5 yr period (2002–2008). The population was highly differentiated (S = 0.723) and organized into six distinct social communities (Q = 0.544), spread in an overlapping pattern along the linear system. Social organization differed between communities, with some displaying highly interconnected networks and others comprising loosely affiliated individuals with more ephemeral associations. Temporal patterns indicated short-term associations were a significant feature of the fission-fusion dynamics of this population. Spatial analyses revealed that social structure was shaped by an individual's ranging patterns and by social processes including preference and avoidance behavior. Finally, we found that habitat “narrowness” may be a major driving force behind the sociality observed.
So the Am Nat paper, it's about how the social structure that cichlids are born into shapes their development. This is interesting because all social species have to interact with other members of their group, and so they have to constantly deal with aggression, hierarchies and recognising other individuals. This stuff has to be learned, and there is a potential cost to that. What Stefan Fischer et al. found was that being reared in a large group means that you have better social skills later in life. Not only did they find behaviour differences between individuals from small groups but also structural changes to their brains. What this study hints at, is that the costs of learning how to behave in a group might mean that it only pays to invest in these behaviours and developmental changes if you need to. This adds a further cost to sociality, one that had not been measured before.
Fischer et al. (2015) Rearing-group size determines social competence and brain structure in a cooperatively breeding cichlid. Am. Nat.
The second new bit of research is on dolphins. These marine mammals live in cool fusion-fission societies, where group compositions constantly change and groups can be subsets of much larger units. From what I can gather from the abstract, I no longer have any university affiliations and so can't access non-open access journals, one of the cool things they found was that the habitat "narrowness" influenced the level of sociality observed. They found that dolphins spent more time with certain individuals than with others, much like humans. This type of social network is important for things that range from disease transmission to social learning. But finding a link to the environment is really interesting, as scientist have theorized that some environments are more likely to select for group living species but this finding might hint that environments may select for the type of social organisation within those groups. But having been unable to read the paper this could be wild speculation!!
Here is the abstract so you can make up your own mind:
Titcomb et al. (2015) Social communities and spatiotemporal dynamics of association patterns in estuarine bottlenose dolphins. Marine Mammal Science, DOI: 10.1111/mms.12222
Network analysis has recently been used to delve into the dynamics of cetacean sociality. Few studies, however, have addressed how habitat shape influences sociality, specifically how linear water bodies constrain the space where individuals might interact. We utilized network and spatiotemporal analyses to investigate association patterns and community structure in a bottlenose dolphin population in a linear estuarine system, the Indian River Lagoon (IRL), Florida. Using sighting histories from a multiyear photo-identification study we examined association patterns for 185 individuals collected over a 6.5 yr period (2002–2008). The population was highly differentiated (S = 0.723) and organized into six distinct social communities (Q = 0.544), spread in an overlapping pattern along the linear system. Social organization differed between communities, with some displaying highly interconnected networks and others comprising loosely affiliated individuals with more ephemeral associations. Temporal patterns indicated short-term associations were a significant feature of the fission-fusion dynamics of this population. Spatial analyses revealed that social structure was shaped by an individual's ranging patterns and by social processes including preference and avoidance behavior. Finally, we found that habitat “narrowness” may be a major driving force behind the sociality observed.
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