Evolution: networks of coevolution (Evolution)

by David Turell @, Wednesday, October 18, 2017, 20:00 (33 days ago) @ David Turell

The interaction of species fighting off or cooperating with other species create networks of relationships that affect each species evolution. This is a study of those networks:


"Coevolution, which occurs when species interact and adapt to each other, is often studied in the context of pair-wise interactions between mutually beneficial symbiotic partners. But many species have mutualistic interactions with multiple partners, leading to complex networks of interacting species.


"a group of ecologists and evolutionary biologists from five universities has attempted to understand how species coevolve within large webs of mutualistic species. The study yielded surprising findings about the relative importance of direct and indirect effects within such networks.


"Natural selection favors predators that are better at capturing prey, prey that have better defenses, and individuals that compete better against other species. Among mutualistic species, natural selection favors, for example, plants that are better at attracting pollinating insects and flower-visiting insects that are better at extracting pollen and nectar from flowers.

"Each web had, at one extreme, species that interact with only one other species and, at the other extreme, species that interact with many other species. When drawn as a network, each species is a node and each interaction between species is a line between two nodes. Each line is therefore a direct interaction between two species.

"Their analyses suggested two counterintuitive results. First, the stronger the importance of coevolutionary selection between partners, the greater the importance of indirect effects on overall evolution throughout the network. Second, in mutualisms involving multiple partners, the most specialized species—those species with the fewest direct partners—are more influenced by indirect effects than by their direct partners.

"These two results, together with other results reported in the paper, have many implications for the understanding of evolution and coevolution within webs of interacting species. Among the most important are two conclusions that link evolution, coevolution, and the rate of environmental change.

"With slow environmental change, the indirect effects of species on the evolution of other species may help mutualistic interactions persist over long periods of time. In contrast, rapid environmental change may slow the overall rate of evolution driven by direct interactions within large networks, making each species more vulnerable to extinction. With rapid environmental change, then, environments may change faster than species can adapt within large mutualistic networks.

"'The indirect effects serve to buffer the system under slow environmental change, keeping it stable. With the kinds of rapid environmental changes we're seeing now, however, this buffering effect can actually prevent species from adapting fast enough," Thompson said."

Comment: This research will help us understand more exactly how econiches work in balance of nature. It has been shown how top predators are essential. But so is cooperation. These complex networks must have existed since life began 3.6-3.8 billion years ago.

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