Sometimes you see a couple of animals or plants and you think to yourself ‘wow they are really similar – they must be related’. And sometimes (but not always) its true. Sometimes you look at some fish larvae and adults and think ‘no way are those guys the same – they are too different! Must be separate species’. But they aren’t always.
It all comes down to adapting to your environment, and your current needs. Generally speaking, when your a small larvae, you really want to grow quick and avoid predation. When your an adult, you want to ‘sow your wild oats’ and avoid predation. These two life stages require often different body plans (shape, size, colouration, etc.) to maximise survival and (eventually) reproduction chances. In marine teleost fish the colouration between juvenile and adults of the same species is often very different…the mechanisms behind this aren’t fully understood. These differences got Dr Carole Baldwin from the Smithsonian’s National Museum of Natural History thinking. Can the colour patterns of the larval stages give us any information about phylogenetic relationships – who is related to who, and how far back is that common ancestor?
Analysing colour photographs of fish larvae collected off Belize, Carole found some remarkable similarities in the colouration of many species known to be related. Interestingly, she also found colouration similarities in species thought to be unrelated. It may be that such species do in fact have a very very distant common ancestor, but as Carole notes it’s too early to tell just how good an indicator larval colouration is of evolutionary relationships really is.
The paper is open access – freely available to all! You can find it (and more images of larvae here: http://dx.doi.org/10.1111/zoj.12033
If you want to know more about phylogenetic relationships in general, check out this little site http://evolution.berkeley.edu/evosite/evo101/IIHistory.shtml
Image: Percomorphacea (Ophidiiformes). Top, Brotulataenia sp. and bottom, Lampogrammus sp., Hawaii. Photos by Joshua Lambus.
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