Development, regeneration, and parasitic interactions between the lichens Fulgensia bracteata and Toninia caeruleonigricans

Abstract

A possible source of Trebouia algae for lichens are the thalli of lichens that are attacked by another mycobiont that captures the algae for its own symbiotic use. Such a process is described for Fulgensia bracteata living in parasitic association with Toninia caeruleonigricans. The development of the thalli of Toninia and the parasitic attack of Fulgensia are analysed in detail. The infection of Toninia is achieved by ascosporcs and can be demonstrated by the presence of secondary lichen substances typical for Fulgensia, which occur in infected thalli of Toninia. Fulgensia also overgrows other lichens, but these thalli are not invaded. The special abilities of Toninia and various methods for distribution and regeneration compensate for the parasitism and the association remains stable. The ecology of the small developmental stages of Toninia and Fulgensia shows important differences.R6um6 : Chez les lichens, une source possible d'algue Trebouia pour la formation du lichen reside dans les thalles de lichens qui sont attaquCs par un autre mycobionte, lequel s'approprie des algues de I'h8te pour ses propres fins symbiotiques. Les auteurs decrivent ce procCdC chcz le Fulgensia bracteata vivant en parasite avec le Tonnia caeruleonigricans. 11s analysent en d6tails le d6veloppement du thalle du Toninia et l'attaque parasitaire du Fulgensia. L'infection du Toninia est rkaliste par des ascospores et peut &re dCmontrCe par la presence de mktabolites lichkniques secondaires typiques du Fulgensia, lesquels se retrouvent dans les thalles infect& du Toninia. Le Fulgensia peut Cgalement attaquer d'autres lichens mais sans en envahir les thalles. Les capacitCs speciales du Toninia ainsi que diffkrentes mtthodes de distribution et de reginbration compensent pour le parasitisme et l'association demeure stable. L'Ccologie des premiers stades de dtveloppement du Toninia et du Fulgensia montrent des diffirences importantes.

On the relationship between abiotic stress and co‐occurrence patterns: an assessment at the community level using soil lichen communities and multiple stress gradients

“…(Belnap 2002), and increased water availability in the surrounding of those species capturing dew (Kidron et al 2002) or promoting moisture retention (Verrechia et al 1995). They can also be found when the mycobiont of particular lichen species can use the photobionts of other species to form a new thallus (Ott et al 1995). On the other hand, negative interactions can arise through mechanisms such as allelopathy (Souza‐Egipsy et al 2002), genuine competitive displacement (Armstrong and Welch 2007), or physical interferences of some lichens acting as barriers to the propagules of other species (Cantón et al 2004).…”

Selectivity of photobiont choice in a defined lichen community: inferences from cultural and molecular studies

“…That mycobionts may be able to capture photobionts from host lichens seems likely as some lichen taxa exhibit a facultative or obligate lichenicolous growth at their juvenile stages. Especially in the case of saturated lichen communities with delimited space resources, the development of multiple associations with two or more mycobionts and a taking over of algae by the lichenicolous taxon seem to be an important strategy (Ott, 1987 a, b ;Ott, Meier & Jahns, 1995). A survey of the more than 750 known potential associations of this type (including about 600 ' inter-lecanoralean associations ') has been presented by Rambold & Triebel (1992).…”

Life history strategy ofLepraria borealisat an Antarctic inland site, Coal Nunatak

“…Lichens possess a range of features that equip them to cope with harsh and unpredictable environmental conditions, being able to take advantage of short periods suitable for metabolic activity, interspersed with varying periods of anabiosis during which they may experience extreme temperatures, high radiation loads, desiccation and physical abrasion (Kappen & Lange 1969;Longton 1988 A characteristic feature of lichen communities are interactions. Interactions between lichens growing in close association have been described from more temperate regions (Ott & Scheidegger 1992;Ott et al 1995). The interactions are often defined by parasitic behaviour of one of the mycobionts involved.…”