10.5061/DRYAD.B537CS5
Chagnon, Pierre-Luc
Département des Sciences Biologiques, Institut de Recherche en Biologie
Végétale Université de Montréal Montréal Québec Canada
Magain, Nicolas
Duke University
Miadlikowska, Jolanta
Duke University
Lutzoni, Francois
Duke University
Data from: Species diversification and phylogenetically constrained
symbiont switching generated high modularity in the lichen genus Peltigera
Dryad
dataset
2019
symbiotic history reconstruction
ecological networks
Modularity
cyanolichens
specificity
community phylogenetics
2019-05-31T11:36:49Z
2019-05-31T11:36:49Z
en
https://doi.org/10.1111/1365-2745.13207
39022 bytes
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CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
1. Ecological interactions range from purely specialized to extremely
generalized in nature. Recent research has showed very high levels of
specialization in the cyanolichens involving Peltigera (mycobionts) and
their Nostoc photosynthetic partners (cyanobionts). Yet, little is known
about the mechanisms contributing to the establishment and maintenance of
such high specialization levels. 2. Here, we characterized interactions
between Peltigera and Nostoc partners at a global scale, using more than
one thousand thalli. We used tools from network theory, community
phylogenetics and biogeographical history reconstruction to evaluate how
these symbiotic interactions may have evolved. 3. After splitting the
interaction matrix into modules of preferentially interacting partners, we
evaluated how module membership might have evolved along the mycobionts’
phylogeny. We also teased apart the contributions of geographical overlap
vs phylogeny in driving interaction establishment between Peltigera and
Nostoc taxa. 4. Module affiliation rarely evolves through the splitting of
large ancestral modules. Instead, new modules appear to emerge
independently, which is often associated with a fungal speciation event.
We also found strong phylogenetic signal in these interactions, which
suggests that partner switching is constrained by conserved traits.
Therefore, it seems that a high rate of fungal diversification following a
switch to a new cyanobiont can lead to the formation of large modules,
with cyanobionts associating with multiple closely retated Peltigera
species. 5. Finally, when restricting our analyses to Peltigera sister
species, the latter differed more through partner acquisition/loss than
replacement (i.e., switching). This pattern vanishes as we look at sister
species that have diverged longer ago. This suggests that fungal
speciation may be accompanied by a stepwise process of (1) novel partner
acquisition and (2) loss of the ancestral partner. This could explain the
maintenance of high specialization levels in this symbiotic system where
the transmission of the cyanobiont to the next generation is assumed to be
predominantly horizontal. 6. Synthesis. Overall, our study suggests that
oscillation between generalization and ancestral partner loss may maintain
high specialization within the lichen genus Peltigera, and that partner
selection is not only driven by partners’ geographical overlap, but also
by their phylogenetically conserved traits.
Peltigera datasetDescription of sampled thalli for this studyPeltigera
dryad dataset.txt