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Lichens. Why study lichens? Important part of Irelands biodiversity with ~1,165 species West of Ireland very important Photo: Maria Long.

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Presentation on theme: "Lichens. Why study lichens? Important part of Irelands biodiversity with ~1,165 species West of Ireland very important Photo: Maria Long."— Presentation transcript:

1 Lichens

2 Why study lichens? Important part of Irelands biodiversity with ~1,165 species West of Ireland very important Photo: Maria Long

3 Pollution indicators Disappearance of lichens led to black (melanistic) form of peppered moth Hawksworth & Rose scale (1970) 0-10 for acid and basic bark

4 Used for dyeing e.g. crottle Used in medicine Used in perfumes & pot pourri Lichens provide food and/or shelter for animals

5 Under-recorded Year-round activity

6 What are lichens? A lichen is an ecologically obligate, stable mutualism between an exhabitant fungal partner and an inhabitant population of extracellularly located unicellular or filamentous algal and/or cyanobacterial cells (Hawksworth et al., 1995) A lichen is a stable self-supporting association of a fungus (mycobiont) and an alga and/or cyanobacterium (photobiont) (Hawksworth et al., 1995) 1860s – Simon Schwendener – true nature of lichens..the unnatural union between captive algal damsel & tyrant fungal master Crombie, 1874

7 Symbiotic relationship i.e. mutual benefit to both Fungus – provides the alga with structure and shelter from extremes of temperature, light and moisture. - forms the majority of the lichen Autotrophic alga provides heterotrophic fungus with carbohydrates Cyanobacterial partner (if present) fixes nitrogen also Allows both to survive in niches and habitats that they would be unable to survive in alone

8 Very different to bryophytes! – Some may look like some thallose liverworts but lichens are: usually tougher & opaque a different colour on the underside

9 Fungal partner Name given to the lichen applies to fungal partner (mycobiont) Different fungus in each lichen 98% of lichens in phylum Ascomycota Remaining 2% in the Basidiomycota and Fungi Imperfecti ~13,500 lichens globally (some estimates up to 18,000)

10 Photobiont partner ~40 genera of photobiont: ~2/3 algae and ~1/3 cyanobacteria Same photobiont can occur in many lichens Most common: algae cyanobacterium Trebouxia genus Trentepohlia genus Nostoc genus

11 Growth forms Foliose - Thallus (lichen body) is leaf-like -May have rhizines

12 Growth forms Fruticose - Shrubby/ branched

13 Growth forms Leprose -Powdery -No fruiting bodies

14 Growth forms Crustose – Thallus lies flat on substratum – Most common form

15 Sexual Reproduction Fungal partner – long-lived fruiting bodies release spores After germination the spore must meet a suitable algal partner before it can develop further Ascomycota Ascocarps - Most common – spores in ascus - usually 8 spores – produced in perithecia & apothecia Basidiomycota Basidiocarps - Spores on a basidium ->

16 Ascocarp fruiting bodies Various forms of apothecia Hymenium

17 Apothecia fruiting bodies Disc-shaped Lecanorine – the margin is the same colour as the thallus (contains algal cells) Lecideine – No thalline margin

18 Lirellate (elongate) Athonioid – apothecia are poorly defined

19 Squash preparations Multiseptate spores Muriform spores Graphis scripta Graphina anguina

20 Lichen reproduction - Asexual Thallus fragmentation or More specialised structures: 1) Isidia - minute outgrowths from the thallus that contain both fungal and algal cells and are easily broken off by passing animals and invertebrates and dispersed

21 Lichen reproduction - Asexual 2) Soredia - fine powdery granules also containing both fungal and algal cells and can be spread by water, animals and wind.

22 Lichen acids Secondary metabolites – antibiotic properties to defend themselves from bacteria and fungi – allelopathic effects - assist in competing for space with higher plants and bryophytes – prevent against being eaten ~400 known 1-3 in any given lichen Help with identification

23 Chemical tests Potassium chloride (K) Sodium hypochlorite (C) & Para-phenylenediamine (Pd) Cause characteristic colour changes Drops usually placed on the cortex for example…..

24 Lichen Ecology Climate – wetting/drying cycles Light availability –shade-tolerant spp. Quality of environment – air pollution, disturbance,etc

25 Substratum type – important in identification also Lichens can be: - corticolous (growing on bark) - saxicolous (growing on rock) - lignicolous (growing on wood) - terricolous (growing on soil) - muscicolous (growing on moss) - lichenicolous (growing on other lichens) The condition of the particular substratum is also a factor, for example, acid rocks/bark may support a different range of species than basic rocks/ bark.

26 Collecting - Equipment Hand lens (x 10 & x20) Spray bottle Knife Secateurs (for cutting twigs) Hammer & chisel (for collecting lichens on rocks) Paper packets

27 Some books on lichens: Lichens – An Illustrated Guide to the British and Irish Species by Frank S. Dobson (5 th edition, 2005). The Richmond Publishing Company Ltd. Lichens by Oliver Gilbert. (2000) by Harper Collins. Lichens on Trees (British Plant Life No 3) by Alan Orange (2000) National Museum of Wales. The Lichen Flora of Britain and Ireland by O.W. Purvis, B.J Coppins, D.L. Hawksworth, P.W. James & D.M. Moore (1992) The British Lichen Society Some lichen websites: Lichens of Ireland Project: LichenIreland Project: Photographs of Irish lichens: The British Lichen Society:

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