Integrating plant species contribution to mycorrhizal and seed dispersal mutualistic networks

Abstract

Mutualistic interactions like those established between plants and mycorrhizal fungi or seed dispersers are key drivers of plant population dynamics and ecosystem functioning; however, these interactions have rarely been explored together. We assembled a tripartite fungi-plant -disperser network in the Gorongosa National Park-Mozambique, to test (1) if diversity and importance of plant mutualists above-and belowground are correlated, and (2) whether biotically and abiotically dispersed plants are associated with distinct arbuscular mycorrhizal fungi (AMF). We quantified seed dispersal by animals for 1 year and characterized the AMF of 26 common plant species. Sixteen plant species were dispersed by 15 animals and colonized by 48 AMF virtual taxa (VT), while the remaining 10 plant species were not dispersed by animals and associated with 34 AMF VT. We found no evidence for a correlation between the number of plant partners above-and belowground or on plant specialization on both types of partners. We also found no evidence for differentiation of AMF communities between biotically and abiotically dispersed plants. Our results suggest that the establishment of plant interactions with seed dispersers and mycorrhizal fungi is largely independent and that both biotically and abiotically dispersed plants seem to associate with similar communities of AMF.

Codependency between plant and arbuscular mycorrhizal fungal communities: what is the evidence?

“…Notwithstanding the above, there are reasons why codependency may be counterintuitive: AM fungi are globally distributed (Davison et al ., 2015; but see Bruns & Taylor, 2016) and most AM fungi do not appear to suffer dispersal limitations (Correia et al ., 2019; Kivlin, 2020). If every fungus has the opportunity to occur in every habitat, regardless of plant community identity, specific associations may be less common. The Glomeromycota have significantly fewer taxa than their hosts (<1000 AMF species vs 391 000 plant species) making it improbable that plants develop strict specificity with fungal partners. AM fungi are obligate biotrophs.…”

Tripartite networks show that keystone species can multitask

“…However, there are still relatively few studies simultaneously quantifying multiple interaction types at the same site (17,20). Therefore, it is now increasingly clear that only by jointly considering the multiple dimensions that characterize species interaction networks can we get closer to understanding the intrinsic complexity of real ecosystems (6,7,28).…”

“…Nevertheless, the study of ecological networks with specieslevel resolution is still dominated by bipartite networks, where species of two groups are linked by a single type of interaction, such as pollination (14), seed dispersal (15), or parasitism (16). Only more recently, some studies have started to explore the relationship between two types of species interactions within a network framework (17)(18)(19)(20). For instance, recent research suggests a positive correlation between the importance of mammals as seed dispersers and seed predators (17) and also between birds acting as seed dispersers and pollinators (18), but no association in the importance of frugivorous and nectarivorous bats (19) or between plant mycorrhizal fungi and frugivores (20).…”

“…Only more recently, some studies have started to explore the relationship between two types of species interactions within a network framework (17)(18)(19)(20). For instance, recent research suggests a positive correlation between the importance of mammals as seed dispersers and seed predators (17) and also between birds acting as seed dispersers and pollinators (18), but no association in the importance of frugivorous and nectarivorous bats (19) or between plant mycorrhizal fungi and frugivores (20). However, none of these pairwise comparisons accounted for the effect of species abundance as a key driver of species importance.…”

Ecological plasticity governs ecosystem services in multilayer networks

“…Typically, such services of weed seed regulation and pest predation are studied autecologically, in isolation. A network analysis of a joined-up weed seed regulation and pest predation system could have been done using tri-partite 18 , 19 or coupled network 20 approaches. The multilayer network approach, as we use it, allows us to consider weed seed regulation and pest predation as two otherwise simple trophic networks, the layers, whose interaction can also be analysed by the consideration of the carabid nodes that are shared.…”