Cyanobacterial lichen symbiosis: the fungal partner as an optimal harvester
(2002) In Oikos 98(3). p.498-504- Abstract
- Lichen symbiosis has been traditionally treated as a model case of mutualism in which both partners, the fungus and the photobiont. gain benefits reciprocally. Some recent evidence, however, supports an alternative view that lichen symbiosis may represent an association largely controlled by the commensal or even parasitic fungal partner. The latter gains photosynthates from the photobiont (algae and/or cyanobacteria) which may not always substantially benefit from the symbiosis. We analyze from this perspective how a lichen fungus may maximize photosynthetic gains in bipartite and tripartite associations. We treat the frequency of nitrogen-fixing cells called heterocysts in cyanobacteria and the relative proportion of green algal cells... (More)
- Lichen symbiosis has been traditionally treated as a model case of mutualism in which both partners, the fungus and the photobiont. gain benefits reciprocally. Some recent evidence, however, supports an alternative view that lichen symbiosis may represent an association largely controlled by the commensal or even parasitic fungal partner. The latter gains photosynthates from the photobiont (algae and/or cyanobacteria) which may not always substantially benefit from the symbiosis. We analyze from this perspective how a lichen fungus may maximize photosynthetic gains in bipartite and tripartite associations. We treat the frequency of nitrogen-fixing cells called heterocysts in cyanobacteria and the relative proportion of green algal cells vs. that of cyanobacteria per unit fungus as the variables to be manipulated for maximal carbon gain. The model predicts that even with a negligible cost of cephalodia (compartments containing cyanobacteria) it is in the interest of the tripartite lichen, first, to increase the heterocyst frequency, and second, keep the relative number of cyanobacteria considerably lower than that of green algae. Hence, the lichen fungus achieves higher fitness by making the cyanobacterial partner to specialize on N fixation. The available empirical data support these predictions as the reported heterocyst frequencies in bipartite lichens range from 2 to 8%, and in tripartite lichens between 10 and 55%. It is concluded that interaction asymmetry (i.e. commensalism or parasitism rather than mutualism) provides a sound basis to understand the high phenotypic plasticity expressed by fungi-forming bipartite and tripartite associations with cyanobacteria and green algae. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/147627
- author
- Hyvärinen, M ; Härdling, Roger LU and Tuomi, J
- organization
- publishing date
- 2002
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Oikos
- volume
- 98
- issue
- 3
- pages
- 498 - 504
- publisher
- Wiley-Blackwell
- external identifiers
-
- wos:000178440000014
- scopus:0036745295
- ISSN
- 1600-0706
- DOI
- 10.1034/j.1600-0706.2002.980314.x
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Theoretical ecology (Closed 2011) (011006011), Department of Ecology (Closed 2011) (011006010)
- id
- 1279c382-5f17-487f-b94a-ff4c1b0c5b31 (old id 147627)
- date added to LUP
- 2016-04-01 12:20:41
- date last changed
- 2022-01-27 02:18:54
@article{1279c382-5f17-487f-b94a-ff4c1b0c5b31,
abstract = {{Lichen symbiosis has been traditionally treated as a model case of mutualism in which both partners, the fungus and the photobiont. gain benefits reciprocally. Some recent evidence, however, supports an alternative view that lichen symbiosis may represent an association largely controlled by the commensal or even parasitic fungal partner. The latter gains photosynthates from the photobiont (algae and/or cyanobacteria) which may not always substantially benefit from the symbiosis. We analyze from this perspective how a lichen fungus may maximize photosynthetic gains in bipartite and tripartite associations. We treat the frequency of nitrogen-fixing cells called heterocysts in cyanobacteria and the relative proportion of green algal cells vs. that of cyanobacteria per unit fungus as the variables to be manipulated for maximal carbon gain. The model predicts that even with a negligible cost of cephalodia (compartments containing cyanobacteria) it is in the interest of the tripartite lichen, first, to increase the heterocyst frequency, and second, keep the relative number of cyanobacteria considerably lower than that of green algae. Hence, the lichen fungus achieves higher fitness by making the cyanobacterial partner to specialize on N fixation. The available empirical data support these predictions as the reported heterocyst frequencies in bipartite lichens range from 2 to 8%, and in tripartite lichens between 10 and 55%. It is concluded that interaction asymmetry (i.e. commensalism or parasitism rather than mutualism) provides a sound basis to understand the high phenotypic plasticity expressed by fungi-forming bipartite and tripartite associations with cyanobacteria and green algae.}},
author = {{Hyvärinen, M and Härdling, Roger and Tuomi, J}},
issn = {{1600-0706}},
language = {{eng}},
number = {{3}},
pages = {{498--504}},
publisher = {{Wiley-Blackwell}},
series = {{Oikos}},
title = {{Cyanobacterial lichen symbiosis: the fungal partner as an optimal harvester}},
url = {{http://dx.doi.org/10.1034/j.1600-0706.2002.980314.x}},
doi = {{10.1034/j.1600-0706.2002.980314.x}},
volume = {{98}},
year = {{2002}},
}