Think of yourself in a situation with no one around you, complete isolated with no signs of another living organism except you. Sounds scary, right? This is because we live in an environment where we interact with each other. This interaction between different species or between individuals of the same species is what helps us survive. The ultimate goal of a species is to increase its population and establish a community. This increase in population can only be possible with the least competition with the other species. Here comes the role of mutualistic relationships between organisms.
“Species select their mutualistic partners to maximise their population,” said Filippo Simini.
Filippo Simini is a postdoctoral research associate at the Center for Complex Network Research in the Northeastern University.
Species forms links with other species based on the fact that which one is nearby. These links become progressively more organised, with less favourable interactions being cast aside for more favourable ones, the community becomes more stable. Simini was stuck to the fact that why is this happening? In a paper which was released in the journal “Nature”, Simini and his colleagues Samir Suweis and Amos Maritan of the University of Padova and Jayanth Banavar of the University of Maryland presented a so-called variational principle. The principle was known to explain the unexpected, though commonly observed, the topology of mutualistic networks.
“Nestedness”- this type of architecture looks like a set of Russian Matryoshka dolls. Metaphorically, the smallest doll comprises the most specialised species. Let me explain it giving an example, the bacteria that can only survive inside a cow’s stomach, where it pays rent by keeping the cow’s gut clean and healthy. However, the outermost dolls, are considered to be made up of the links between more generalist species—the cows, the grass, and the bugs that can interact with each other plus a host of other species in the ecosystem. They concluded their research by stating that the communities with strong mutualistic interactions tend to be less nested, and thus more stable.
“When interaction strengths are weak, it becomes crucial for the community to organise into a highly nested architecture in order to maximise its population,” said first author Suweis.
Mutually beneficial interactions are a win-win situation for all species. An increase in the overall community’s population will be observed with maximising one species’ abundance. However, the system becomes stable overall but it will take more time to return to normal.
The system’s resilience, according to the team’s findings, is ultimately determined by the population of the rarest species:
“The lower the population of the rarest species,” said Simini, “the longer the time to recovery.”