Skyrail Nature Diary - Symbiosis in the Rainforest
A lichen is not a single organism, but the result of a partnership (mutualistic in the tropical and temperate rain forests are Basidiomycetes, the "mushrooms". A mutualistic relationships is more likely to happen with organisms that have widely ranging This is a picture of the Capuchin monkey and a flowering tree in the rain forest. It is a picture of algae and fungi, the two parts that make up lichen. Symbiosis in lichens is the mutually helpful symbiotic relationship of green algae and/or . when dampened or wet. Many of these characterize the Lobarion communities of higher rainfall areas in western Britain, e.g., in the Celtic Rainforest.
For fungi this is a simple matter of growing towards the source of the attractant and making the connection. Algae often have mobile spores that can move towards their partner as long as they have water to move in.
Mycorrhizae are perhaps the single most important association in the tropical rainforest. All trees seem to have a close relationship between their roots and a fungus. Fungi are generally much better at collecting minerals than tree roots.
The main reason for this is their unique body shape as a simple mass of very long threads. However, rainforest floors generally have very little organic material available.
This is where the trees come in. Trees are amazing producers of organic material via the use of photosynthesis, the process of using sunlight as an energy source to turn simple carbon dioxide into food. In some rare cases the mineral collectors are a special kind of fungal like bacteria known as actinomycetes.
Fungi Symbiosis ( Read ) | Biology | CK Foundation
European Alders have actinomycets on their roots. The fungal partners are of three basic types. The ectomycorrhizae attach to the tree roots as an external sheath. Most conifers have this kind of mycorrhiza. There are two types of fungi that penetrate the insides of the tree roots. One simply drills into the roots while maintaining its thread shape. The Vesicular-Arbuscular Mycorrhizae form into bladder and bush like structures that interact very closely with the roots.
This latter type of mycorrhiza is by far the most common in nature.
Symbiosis in the Rainforest
Nitrogen fixation is an important process in nutrient poor soils. By far the most common source of nitrogen is in the atmosphere in the form of gaseous nitrogen. This molecule is very difficult to break down and only bacteria have been shown to be able to do it successfully. 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.
Symbiosis in lichens
One fungus, for example, can form lichens with a variety of different algae. 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. Another cyanolichen group, the jelly lichens e.