Life has been awesomely busy recently, with various weekends away (karate course and Sonisphere being the main ones recently) but I’ve also got rather into MOOCs again. These are Massive Open Online Courses i.e. free courses available to everyone. You may have heard some of the big names: FutureLearn, Coursera and Khan Academy are a few examples.
Currently my main one (there were others but they’ve forcibly fallen by the wayside due to time constraints, but I dearly hope they’ll run again) is Animal Behaviour, run by the University of Melbourne and available on Coursera. It’s an 8 week course with a suggested 6-8 hours weekly input.
As well as weekly video lectures, quizzes and extra reading, there are two main assigments which I hope are interesting enough to warrant sharing. The first assignment is a blog project. You choose any wild animal species you like, study it’s behaviour over a period of time and write notes in a blog. Thankfully you are not restricted to animals “in the flesh” and many people like myself have chosen webcams. I found a fantastic cam looking at osprey chicks which were about a week old when I started the project in the second half of June. I’m in my final week now and I think the blog’s looking good enough to show y’all, so here it is.
I hope you find the chicks as adorably goofy looking as I do. They’ve grown up so much in the last month! They are very well cared for by gorgeous parents Iris and Stanley (not my choice of name!) and even the runt is doing well… I wasn’t so sure a couple of weeks ago.
The second assignment was to write an article that might be used by the Conversation or similar outlet about one of fifteen scientific papers on animal behaviour. This assignment has now been submitted, peer-marked and released, was a written communication piece based on our choice out of 15 papers. They change the papers with each course iteration (check here to register interest in future sessions, they’re free!) so I’m allowed to republish here.
The sights and smells of fish family life; kin recognition in zebrafish
When it comes to survival, getting on with your family can really pay off. Many animals live in social groups for increased protection against predators and competitors. More often than not, these groups have strong blood ties. It’s well established that animals which share a genetic legacy are more likely to form social groups and behave co-operatively than with unrelated peers.
What’s not so well understood is how exactly different animals learn to recognise their kin. This process is important because in order to stick with your family, you need to know who its members are! In many species this is done using “imprints”, sort of mental images which form very early in life but last forever.
For goslings, imprinting is almost comically straightforward. It’s not much more complex than “The thing that I spend time with 12-16 hours after I hatch is my mummy”. Whether that thing is actually mummy or a scientist or even a boot is immaterial to the goslings, and the bond lasts a lifetime.
The rules of imprinting vary greatly between species, and the underlying learning process is not well understood at all. Cornelia Hind from Carl von Ossietzky University in Germany and her team of researchers wanted to see how important the senses of sight and smell were in forming these bonds.
Their animals they studied were young zebrafish, known as larvae. Zebrafish are popular choices among both tropical fish owners and all sorts of scientists. Their conveniently small size and see-through embryos make them lab favourites for studying diseases and physical development. But Hind and her team wanted to get to know the workings of their young minds.
They had two main questions in mind. Firstly, how important is sight and smell in learning to recognise kin? Is only one of these necessary, both or neither? Secondly, can you trick the zebrafish larvae into imprinting on unrelated fish, like the goslings did to “mummy-scientist”?
The researchers isolated random larvae from their egggroup before hatching and raised them on their own in glass beakers surrounded by different environments. Beakers were placed in shallow tanks containing either their siblings, or unrelated fish. That was the “sight” portion of the experiment. For the “smell” part, the water in the beakers came from tanks which had contained either related or unrelated fish, so the young fish were literally bathed in their scent. The four groups are shown in Figure 3 below.
When the fish were older, they were placed in a special new tank and given a choice. Do you prefer (and therefore swim towards) water that smells like your family, non-family or neither? After testing many fish multiple times, their results brought up some interesting findings that helps answer their original questions.
It turns out that zebrafish need to be surrounded by both the sights and smells of their brethren in order to form an imprint. The imprint of these larvae was strong enough that they were even drawn towards scents of fish-relatives they’d never encountered before. That’s like a toddler looking round a mixed congregation of a large wedding and knowing immediately who was related to them and who wasn’t.
Just like the goslings, the imprinting only worked at very specific time periods – five days old for sight and six days old for smells in this case. Fish raised with only sight or smell of kin showed no particular preference for their genetic relatives.
This is the first study to show the importance of timing in two different senses in a fish species forming a kin imprint, and it raises some important questions. For example, what substances does a fish detect that allows it to find their family, and what happens in its brain to form and reinforce the imprint? Hopefully future work will shed light on the mechanisms here.
As to whether the fish could be tricked into treating unrelated fish like family, the answer was a surprising “no”. The zebrafish that were surrounded by the sight and smell of unrelated fish showed no preference to these fish when given a choice. This seems to suggest an inbuilt ability to detect family members in addition to imprinting – very different to the gullible goslings.
This is the first reporting of a genetic predisposition to kin recognition in any species, and claims a significant paradigm shift that must be treated with caution. After all, if zebrafish hatch with the knowledge of who their siblings are, what would be the point of imprinting?
To compound the problem, and by the admission of the authors, “in the wild, very little is known about zebrafish behaviour”. This doesn’t matter much if you’re studying something like eye development, but in behavioural research this could lead to misleading results. There may well be big differences in how fish raised in lab environments behave compared to wild fish, thanks to the complex interactions between genes and their environment over many generations.
This conundrum can only be resolved by more research. If other groups cannot also find an inbuilt predisposition, then the original experiment was probably flawed in some way. The tests should be carried out on fish and other animals whose natural behaviour is better known. However if they find the same results in zebrafish or even in other animals, then this could be the first sign of a whole new way young animals understand and react to the world around them.
Primary source and original paper: Cornelia Hinz et al, Kin recognition in zebrafish, Danio rario, is based on imprinting of olfactory and visual stimuli.