In fig gardens, trees and wasps have been locked in a delicate, 90-million-year-old eco-evolutionary dance1. Fig wasps use the fruit of the fig tree as a sweet incubator for their eggs, while fig trees rely on wasps to pollinate their flowers. Neither can live without the other. This is an example of an obligate mutualism — a bi-directional interdependency that is essential for each partner’s survival. Given how intertwined the two partners are, it’s easy to assume that obligate mutualisms are limiting; that is, one partner can live only where the other thrives, thus constraining the range of environments that support the growth of the pair. Writing in Nature Ecology & Evolution, Oña, et al.2 use synthetic microbial communities to demonstrate that quite the opposite can occur: obligate mutualists facilitate the growth of their partners and expand their range of habitable environments, including environments in which neither could survive alone. Such examples of ‘niche expansion’, as the authors define it, may provide clues as to how vast swaths of species diversity are maintained in nature.
Source: Ecology - nature.com
