() found similar genetic structures for the lichen symbiosis between Sexual reproduction in green algal photobionts (apart from those in the .. from a test randomising the association matrix for fungi and algae for the six. About 90% of all known lichens have a green alga as a symbiont. has single cells that are globose, which is common in lichens. The tiny lichen is a critical part of the food chain, but how do algae and fungi work together to form these What are these strange, plant-like green things?.
Lichenized and nonlichenized fungi can even be found in the same genus or species. TrebouxiophyceaePhaeophyceaeChlorophyceae have been found to associate with the lichen-forming fungi. One fungus, for example, can form lichens with a variety of different algae.Lichens - Millie Davenport
The thalli produced by a given fungal symbiont with its differing partners will be similar, and the secondary metabolites identical, indicating that the fungus has the dominant role in determining the morphology of the lichen.
Further, the same algal species can occur in association with different fungal partners. Lichens are known in which there is one fungus associated with two or even three algal species. Rarely, the reverse can occur, and two or more fungal species can interact to form the same lichen. Chlorococcales is now a relatively small order and may no longer include any lichen photobionts. Algae that resemble members of the Trebouxia are presumed to be in the class Trebouxiophyceae and go by the same descriptive name Trebouxioid.
Cyanolichens[ edit ] Although the photobionts are almost always green algae chlorophytasometimes the lichen contains a blue-green alga instead cyanobacterianot really an algaand sometimes both types of photobionts are found in the same lichen. A cyanolichen is a lichen with a cyanobacterium as its main photosynthetic component photobiont.
What is a Lichen? | The British Lichen Society
Another cyanolichen group, the jelly lichens e. For each dataset, we used the DNA sequences from the ITS regions of both the fungal and algal genomes from lichen specimens to produce genetic distance matrices. Phylogenetic congruence was highly significant for all datasets and a large proportion of variance in both algal and fungal genetic distances was explained by partner genetic variation.
Spatial variables, primarily at large and intermediate scales, were also important for explaining genetic diversity patterns in all datasets. Interestingly, spatial structuring was stronger for fungal than algal genetic variation. Different lichen taxa showed some variation in their phylogenetic congruence and spatial genetic patterns and where greater sample replication was used, the amount of variation explained by partner genetic variation increased.
Fungi Symbiosis ( Read ) | Biology | CK Foundation
Our results suggest that the phylogenetic congruence pattern, at least at small spatial scales, is likely due to reciprocal co-adaptation or co-dispersal.
However, the detection of these patterns varies among different lichen taxa, across spatial scales and with different levels of sample replication. This work provides insight into the complexities faced in determining how evolutionary and ecological processes may interact to generate diversity in symbiotic association patterns at the population and community levels.
Further, it highlights the critical importance of considering sample replication, taxonomic diversity and spatial scale in designing studies of co-diversification.
Symbiosis in lichens
Over the last few decades, there has been an increase in interest in the role of positive interactions, with many empirical studies showing that it is the balance between positive and negative interactions that is important in structuring communities e.
Because mutualistic symbioses involve very close positive interactions between two distinct organismal lineages, they provide an excellent opportunity to specifically explore how positive interactions influence community structure and to evaluate the relative importance of evolutionary and ecological processes in the way that positive interactions affect community structure. What is not as clear is whether most obligate species-level symbiotic relationships, such as seen in lichens and corals, also have measureable levels of codivergence.
Typically, these diffuse symbiotic and mutualistic interactions are complicated by variation in partner identity or where more than one symbiotic partner is involved, such as vascular plants and their root-inhabiting mutualists Hollants et al.
Further, it is much less clear that the causal processes involved in these coevolving symbiotic relationships will produce a pattern of codivergence given the increased opportunity for host switching. Lichens are a classic example of a mutualistic symbiosis. Lichen thalli are the result of an association between a fungus the mycobiont and a photobiont, which is usually a green alga, but may also be a cyanobacterium Nash, In all lichens, the photobiont provides photosynthate to the mycobiont, which in turn provides habitat, water and nutrients to the photobiont Honegger, ; Nash, The symbionts of lichens are relatively poorly known because they are very often difficult to culture and identify, particularly many of the photobiont partners Ahmadjian, ; del Campo et al.
What is a Lichen?
However, in the last two decades a great deal of molecular work has been done to address this, showing variable patterns in partner identity and other patterns of association DePriest, This variable, and seemingly diffuse, mutualism provides a complex model system for addressing questions regarding the role of evolutionary processes in forming and driving ecological patterns in species interactions and how this affects community structure.
The first step in understanding how a mutualistic symbiosis might affect community structure is to determine whether or not there is specificity in the symbiosis. For example, Widmer et al. Thus, it appears that there is variability in association patterns among different lichen taxa Fahselt,