Shy Sticklebacks & Social Structure - Planet Earth Online

If you've ever walked with hundreds of other people to a football match - or the recent Olympics perhaps - then you will have been part of a group dynamic.  Studying group behaviour has a number of important applications so Planet Earth podcast presenter Richard Hollingham joined behavioural ecologist Dr Andrew King at the Royal Veterinary College in Hertfordshire.  They met inside one of the rooms that is part of the Structure and Motion laboratory. It was filled with tanks of stickleback fish to find out how personality and group decisions as a group, such as in shoals, tell us more than you ever thought possible.

Andrew -   We take individual fish and we put them in this arena, which we have to our left here and this arena has individual tanks with lanes in it in which we can test how bold each fish is.  So, the tank has a very scary shallow end and a very friendly deeper end and what the fish tend to do is stay in the safe end.  The number of occasions and how long they spend at the scary end gives us an indication of how bold those fish are.  And so what we then do is we get an order of how bold fish are from 1 to 100, for example.

Richard -   Each one is, what, about, 3 or 4 centimetres along, lovely glinting shiny colour. They have different personalities?

Andrew -   Yes, so what we find is that when we put them in these lanes in which we're looking at how much exploration they do, that they do vary considerably according to the identity of the fish.  The important thing is that this variability is consistent within an individual.  So fish A will be bold on day 1 and if we retest him one week later he will also be bold on day 7, and the great thing is that we've found that when we collect the fish from the tank, the order which we catch the fish correlates with their boldness score in the tank. So, if they are caught first they are extremely bold in the tank and if they're caught last they don't go anywhere in the tank, they are extremely shy, so it's a really nice indication that what we're measuring is something real.

Richard -   So you've got these categories of, quite scared, quite bold?

Andrew -   Yeah, it's called a bold/shy continuance so it varies according to the fish. Once we have that we put them in these tanks which we have to our right-hand side.

Richard -   So these are much smaller individual tanks all numbered in a rack of shelves...

Andrew -   Each tank is in the same water system, the same filtration, and each fish stays in here during the behavioural tests and we feed each fish so we know every fish gets the same amount of food and we control their social environment so they can see each other, they are very social animals so we don't want to deprive them of that, so they can see one another and we rotate them so they don't get used to being next to certain neighbours.  What this means then is that we have individual fish that we know how bold they are, we know how much food they've been getting, we know they haven't been interacting with any males or females recently and we combine these fish into different categories of bold or shy individuals and we make up shoals composed of mostly shy, mostly bold and a mix of the above.  And what the idea is to try and test what combination of these different personality types creates a "winning team" if you like.  What combination of these personalities creates the best shoal?

Richard -   So, a shoal might consist of all bold, or all a little scared or a mix of the two?

Andrew -   Yes, exactly. And in the wild what we find if you try and catch a population - it's hard to catch a whole population, but if you catch a sample - then what you tend to find is that you get lots of shy individuals and relatively few bold individuals.  So what we try and do is try and work out why on Earth that combination would be a crucial or optimal combination of fish to have.  So we make these different shoals and we give them tests like try and find food in this new novel environment or try and avoid this predator and then we see which of these different shoals perform best.

Richard -   Now is this really just to understand shoaling and understand the process by which fish move as a mass?

Andrew -   One aim is to understand exactly those individual shoals and what rules they are using, how do they follow fish - are they following all their neighbours, one, two, four, five neighbours?  That relates to a lot of working flocking animals and shoaling fish and flocking birds.  But the other thing that we want to try and work out is if animals have this personality why on Earth is it adaptive, why should you vary?  So this is trying to get to the grips of it might be beneficial when you combine all these individuals, individuals do better by paring up with those which are different from them.

Richard -   Why do this - I mean it's interesting - but what's the point of it?

Andrew -   From a pure behavioural ecology perspective, we wanted to understand the evolution of these personality differences.  But from a broader perspective I also do work with human groups and different ungulates and primates as well.  And to try and work out what combination of personality types and characteristics make a winning team is of interest for economists, basically anyone who is interested in information-sharing group societies. Maybe it's a little bit of a jump but it works surprisingly well across these species.

Richard -   That's incredible that there are basic rules or this suggests that there are basic rules underlying the way fish or higher animals or us interact.

Andrew -   Definitely and one of the things that keeps emerging from my research is leadership and followership - there are two social roles that these individuals adopt and there are surprisingly common principles across many different species from fish to birds to humans to ants.