Should Lichen Classification Methods Be Changed?

NickAdams
12 Jan 2016
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NickAdams
12 Jan 2016
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The current methods of classifiying lichen species should be changed.

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Tentatively Established
The current methods of classifiying lichen species should be changed.
Lichens are products of a symbiotic relationship between fungi and another organism, but only the fungi is named in today's classification
Two lichens with the same fungal component and different photobiont components may have different properties but same classification
The current classification system has been accepted for over a century
Long-term acceptance of a system does not make it valid.
Transition could be difficult, akin to changing from British to metric units
"What is a lichen?" Australian National Botanical Gardens.
Phylogeny should not classify lichens, as they do not have a natural line of descent
Lichens are products of symbiotic relationships and may have markedly different characteristics than either symbiont
Holt, Jack. "The Lichens." Susquehanna University.
Lichens may be "ecologically meaningful but not phylogenetically meaningful"
"Multiple Origins of Lichen Symbioses in Fungi Suggested by SSU rONA Phylogeny." Science, Vol. 268. Page 1494.

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The current classification system has been accepted for over a century




http://www.cpbr.gov.au/lichen/what-is-lichen.html  "A lichen is not a single organism. Rather, it is a symbiosis between different organisms - a fungus and an alga or cyanobacterium. Cyanobacteria are sometimes still referred to as 'blue-green algae', though they are quite distinct from the algae. The non-fungal partner contains chlorophyll and is called the photobiont. The fungal partner may be referred to as the mycobiont. While most lichen partnerships consist of one mycobiont and one photobiont, that's not universal for there are lichens with more than one photobiont partner. "


A lichen does not necessarily reproduce itself. Instead, at least two separate organisms, a fungus and at least one photobiont combine in a usually symbiotic relationship. This relationship produces the lichen, which has very different characteristics from either fungi or the photobionts.

http://comenius.susqu.edu/biol/202/fungi/lichens/default.htm  "By convention, the lichens are classified as members of the Kingdom Fungi. However, because the fungus (the mycobiont) and the alga (the phycobiont) can live separately in a free-living state, both components should have separate taxonomic designations. The difficulty is compounded by the lichen itself. The symbiotic chimeroid structure called the lichen truly is a different organism from either of its fungal or algal components thus it should have its own "taxonomic" designation, one based on form rather than phylogeny."


Phylogeny is the branch of biology dealing with how organisms have evolved and diversified over time. Similar to taxonomy. https://en.wikipedia.org/wiki/Taxonomic_rank#/media/File:Taxonomic_Rank_Graph.svg gives a good example of the way a fox is classified through taxonomy. Different information can be gained from this definition. In the Wikipedia picture, a fox is in the Canidae family, the same as dogs, which implies that they had a common ancestor, a starting point in common. Lichens, on the other hand, don't all share a common ancestor. They appear to have come about at least five different times, which means that lichens may be an adaptation that developed in parallel between different species of fungi, instead of developing linearly.

http://www.symbiology.com/pdf/Gargas1492.pdf 


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