[MUSIC] We have now moved to the beach because many of the most permanent members of the next super kingdom live in the oceans. The group we're going to talk about is called Chromalveolata, and it's a group consisting of many different single-celled organisms. But also large and multicellular ones such as the brown algae or kelp. Again, the group is mainly supported by molecular data. And the taxa in the group have no general morphological traits in common. However, it seems like many of them have one thing in common. Those that are able to make photosynthesis all developed their plastids through secondary endosymbiosis. And the eukaryotic cells were part of this endosymbiosis. All seem to be red algae. So, let's take a look at some of the members of the Chromalveolates. We could, for instance, start with the multicellular ones and look for some brown algae. Let's see. for instance, we have this quite typical one in Danish water called the bladderwrack. It's a brown algae, looking like this. But we also have many other different kinds of brown algae, like, for instance, the Laminaria that can reach gigantic sizes, for instance, the big kelp forests that we have off the U.S. west coast. If we take a look at the microscopic taxa of the group, we have several groups that occur in very high abundances, and are important in the ecosystems. One example is the dinoflagellates that exist in both freshwater and marine waters. They are interesting in many ways. For instance, they have cyclomorphosis, meaning that they can change shape over time. If you look at this dinoflagellate on the photo you can see that it has spines or spikes. They will change in length and shape over the year depending on the water temperature, which has to do with their ability to float in the water. We all know that the water viscosity changes with the temperature, and when the dinoflagellates change shape, they are able to adapt to the changes in water viscosity. Their changing spines can also be a reaction to predators. Experiments have shown that if you add predators such as copepods or maybe rotifers to a population of dinoflagellates, their spines will get longer, which probably will make them more difficult to handle for the predator. The dinoflagellates have this heavy armor as you see also. It means that it fossilizes very well, and we have a pretty rich fossil dinoflagellate fauna going all the way back to the Silurian. Two other ecological important chromalveolate groups are the Diatoms and the ciliates. The diatoms have these two hard silicon shells, which again mean that we have a very rich fossil record going back to the Jurassic. So when dinosaurs started to develop on land, these little organisms evolved in the lakes and the oceans. They are very common and very important photoautotrophic organisms and you find them in the plankton as well as in the benthic communities. The ciliates are also very abundant aquatic organisms. Opposed to the diatoms, they are relatively soft and then they are often covered with cilia. Despite the softness they are actually able to leave fossil traces, and we have certain traces of ciliates from the Ordovician, and it's not unlikely that they are much older and maybe even existed in the Ediacaran. They can take many shapes, and as you see on the photo if you have been working with aquatic plankton, you must have come across them, as they are very common. But perhaps you also met them in the lab. Many experiments about transport across membranes have for instance been carried out on the ciliate Paramecium, the oval one that you see on the graphic. The last chromalveolate groups I'm going to show you are some more algal groups, namely the yellow algae and the golden algae. Both are single celled organisms but they may form large colonies and they may even occur in so high numbers that they'll color the water yellow. For instance if any of you have visited the Yellowstone National Park in Wyoming you probably know the amazing Morning Glory Pool. Some of the fantastic coloring you see here is actually made by the yellow algae. I said earlier that we have pretty good phylogenetic support for our six Eukaryotic super kingdoms. If we have one exception from this it might be the Chromalveolates. We truly have molecular data that supports Chromalveolate monophyly, but then again, other molecular data is conflicting and suggests that some chromalveolates are actually more closely related with Rhizaria. We are not still certain what's correct here but until this has been clarified we operate with an alternative group that tentatively is named the S-A-R or the SAR group. The SAR group is an acronym for the groups Stramenopilis, which is kelp and diatoms, Alveolates which are ciliates and dinoflagellates, and finally, Rhizaria that's you'll remember was the super kingdom with the radiolarians and the forams. Hence if this alternative phylogeny is correct, the Chromalveolates would be left with only yellow algae and golden algae and a few other minor groups. But that is for the future to show us. [MUSIC]
