Evolved Relationships: Symbiosis in the natural world

Co-evolution between symbionts can not only lead to the development of new organs but also potentially the evolution of a whole new phylum. This can be seen in the evolution from sub social Cockroaches to Eusocial Termites.  Termites were once thought to have evolved as a sister group to cockroaches but thanks to recent research into their obligate gut symbionts, there is mounting evidence that termites have evolved from cockroaches (Nalepa 2017). Although the main ancestor is not known, (Nalepa 2017) believes that termites may have evolved from sub-social termites such as the family Cryptocercus. Termites & Cryptocercus both tend to live in logs and have wood as their main food source which they cannot digest without their symbionts. Both share an obligate symbiotic relationship with a diverse array of gut microbiota that digest plant fibres and convert them into a bioaccessable form for their hosts to eat (Ohkuma & Brune 2010: Nalepa 2017). As a result, both the h...

New symbiotic relationships can be hard to identify and understand especially when they occur inside another organism. Holobiont relationships can have a broad range of effects on the host and it's microbial communities.  One organism well known for its diversity and complexity in symbiotic partners is coral. Just this year five new types of endosymbiotic algae have been discovered in coral in the red sea (Osman et al. 2020). While coral algae symbiosis were originally thought to be mutualistic, studies have found that coral – algae symbiosis runs on a spectrum between mutualism and parasitism depending on the species involved and the level of stress on the coral (Baker et al. 2018). Other Cnidarians such as some species of jellyfish and anemones also hold mutualistic cyanobacteria within their surface mucus layer for energy exchange. It is believed that they also play a role in host immune responses however, their role in this is still varied and unclear (Ortega ...

Have you ever wondered why so many animals live in perfect harmony with each other? Sometimes it is because they can rely on each other for resources. Although the majority of symbiotic interactions occur at the microscopic level (Gilbert et al. 2015), there are symbiotic relationships that we can appreciate without the microscope. Some of the best known examples of these relationships are cleaning symbiosis where one species will pick the parasites off another for food. This is particularly common in birds and fish for example, the cattle and egret commensalism. Cattle egrets Bubulcus ibis with a cow (Dupont 2016) The cattle egret Bubulcus ibis is known to live among various animals such as deer and cattle to pick off and eat parasites such as ticks that may live on them (Palmer et al. 2019; Chaskda et al. 2018). Although Egrets are not obligatory symbionts, Chaskda et al. 2018 found that egrets that feed of flock parasites do spend less time looking for fo...