Korallkompatibilitet

I wonder how much relatedness is a component in whether a coral will burn another. Two corals of the same species is not expected to burn eachother (that's why a colonial animal like most of our corals do not die as the various polyps make war on eachother), and possible also not two corals of the same genus. This follows from the assumption that burning is a behaviour intended to drive off would be competitors for resources like light and water current, and that thus only "others" would be burnt, whereas "self" would be spared. If so, would the severity of the burn be proportional to fylogenetic distance between the species? In other words, would two rather distantly related species be more expected to burn eachother than two closely related species? If we assume that one coral will not burn another as a result of recognizing some molecular markers that signals they are closely related, then I would assume that distantly related corals would share less such markers (because they are evolutonary distant) and hence be more prone to burn eachother.

I hope the data we are collecting will help to test this hypothesis. Below is a figure from Budd et al (2012) which displays the fylogenetic tree of various corals based on rRNA analyses. The tree shows how related the corals are. The closer they are located in the tree (the shorter the distance between them when following the connecting lines), the more closely related they are, and the more similar (both when looking at the shame of the coloni, its polyps, coenesteum, corallites, septa, as well as, internal structures like DNA sequences and, in this case more importantly, the molecular structures that other corals would come in contact with upon touching) they will be.



So I will glance to this figure as more and more data come in.

As a sidenote: It is these data that are causing huge revisions in corals taxonomy these days. An example being the Favia genus. Originally coral species found both in the Atlantic and the Pacific were assigned to the Favia genus based on morphological similarities. New studies, including molecular studies like the one above (one can see that F. leptophyllia is quite distant from F. fragum), have shown that, as expected, corals from the Pacific and the Atlantic show sufficient differences, particularly on the molecular level, to deserve placement in separete genuses. Because of this, only Atlantic corals are now kept in the Favia genus (actually only F. fragum) while Pacific species have been moved to the Dipsastraea genus. Another genus that has been thoroughly shook up lately is Scolymia (just look how corals named Scolymia in the figure above are located in various places and not clustered together as one would expect from corals in the same genus).