Over 70% of plant species that produce flowers depend on birds to disperse their seeds. Birds feed on fruit from a wide range of different plants, and bird-plant interactions form a myriad of complex networks.
A study conducted at the Institute of Biosciences of the University of Sao Paulo (IB-USP) in Brazil shows that the evolutionary stability of each bird species depends on the position it occupies in these networks, increasing with the number and centrality of its interactions with potential partner plant species and the number of network connections it maintains.
The study was funded by the São Paulo Research Foundation — FAPESP and is featured in the journal Science.
“Bird species that occupy more central positions in a network, which have more connections, tend to be more stable in macro-evolutionary terms,” ??Gustavo Burin, first author of the article, told Agência FAPESP.
According to Burin, establishing this correlation between interactions between species and their evolutionary dynamics was a huge challenge because it required an analysis of two processes – seed dispersal and evolution – occurring on completely different time scales. Seed dispersal occurs every year, while evolution takes place over millions of years.
“We have been working on this for four years, integrating data on 468 bird species belonging to 29 seed dispersal networks,” he said. “We have shown that the more bonds a bird species establishes with plant species, the greater its evolutionary possibilities.
‘More precisely, the greater the evolutionary stability of a bird species, the greater the chances we have of observing its relative importance in a seed dispersal network, as measured by the number and pattern of interactions established by the bird species.
“Species that occupy central positions in a network have two important traits: they either live longer or belong to groups that accumulate many species in a relatively short time, so that if one species disappears, it is replaced by many similar ones.”
Among birds native to Brazil, examples of long-lived species include the red-bellied thrush (Turdus rufiventris) and the Sayaca tanager (Thraupis sayaca).
“Here we are emphasizing the importance of interaction with plants for the evolutionary success of bird species, but the reverse may also be true, in the sense that plants that can rely on more bird species to disperse their seeds have greater probability of propagating and surviving. When there is a dispersing vertebrate, the seeds can be transported tens of miles away from the plant, “Burin said.
This mechanism is more intense and effective in warm and humid regions less subject to seasonal variations. It is no coincidence that the world’s leading animal and plant biodiversity hotspots are found in the Amazon region of Colombia and Southeast Asia.
The study combined ecological data, mathematical and computational models and analytical tools derived from complex network analyzes. The other co-authors are Paulo Guimarães Jr. and Tiago Quental.
Central bird species in seed dispersal networks have stable evolutionary lineages
Gustavo Burin et al, Macroevolutionary stability predicts species interaction patterns in seed dispersal networks, Science (2021). DOI: 10.1126 / science.abf0556
Quote: Birds That Disperse More Seed Types Have Better Evolutionary Chances (2021, Aug 11) Retrieved Aug 11, 2021 from https://phys.org/news/2021-08-birds-disperse-seed-evolutionary-chances. html
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