the mechanisms photosynthesis, respiration, and decomposition, carried out by fungi, mediate which key ecosystem process
competition for nutrients by fungi contributes to which key ecosystem process
regulation of primary production
how do fungi affect regulation of secondary consumers
pathogenic agents- viruses and bacterial pathogens of insect, birds and reptiles
predators- nematode trapping fungi, including wood-rotting basidiomycetes; slime moulds
what mechanisms to fungi carry out to mediate the key ecosystem process of nutrient cycling
decomposition, nutrient mineralisation; mutualisms for nutrient uptake; leaching losses of N; nutrient immobilisation
decomposition of wood (ligning and cellulose) depends on
fungi and bacteria
saprophytic fungi incl. diverse range of ___ and ____________ spp
macro and microscopic
what do the enzymes and acid compounds saprophytic fungi discrete do?
they degrade large molecular complexes into simple compounds
there is usually a succession of species, ranging from those that colonise fresh material to those that do what
mop up afterwards
saprotrophic fungi form extensive ____ and networks of aligned _____ that connect and _____ nutrients over several metres (Boddy 1993)
what do some fungi use these cords as
raised webs that catch litter before it reaches the ground
in tropical rainforests, these fungal hyphae networks influence what (Guevara and Romero 2004)
local availability of nutrients
wood decay polypore fungi can also be what
aggressive pathogens that attack living plants, destroying roots/ cambial tissue and ultimately killing trees/ making them more susceptible to windthrow
what do other polypore fungi do
colonise trees but dont spread until after tree death
what have studies of Panamanian large wood-decay polypore fungi found
although the most abundant spp colonise multiple hosts, fungal diversity in this group still exceeds that of the host trees.
the majority of plant pathogens are
fungi and oomycetes
how do they disperse
where are they particularly prevalent
understorey where conditions for germination prevail such as high humidity, surface moisture and cool temperatures
what are the most familiar and what do they cause
foliar pathgoens- necrosis, chlorosis or leaf deformation
what are damping off diseases
kill seeds and seedlings
what else can pathogens do
cause cankers in stems that block plants' vascular systems, decay wood in trunks and roots and also attack flowers and developing fruits
their collective impact on plant performance and survival may be as great as, or even greater than, herbivores. why
their ubiquity and impact on a no. of life history stages and plant parts
what are the main causes of damping off disease
Phytophthora, Pythium oomycete spp
what did augspurger 1983 and augsperger and kelly 1984 find on barro colorado island
That Phytophthora and Pythium oomycete spp infected 80% of examine spp and seedling mortality of Platypodium elegans ranged from 35-81%
once considered fungi, what are oomycetes more closely related to?
photosynthetic algae such as diatoms and to the malaria parasite
pathology and persistence of Phtyophthora cinnamoni, the best known example, which is a major crop pest, is enhanced by what
what are also vulnerable to fungal diseases
seeds in soil bank
According to Hood et al 2004, what percentage annual mortality does Miconia argentea suffer
seed and seedling pathogenic agents are believed to be key players in what
the density dependent processes that contribute to the maintenance of high species diversity in the tropics.
foliar pathogenic fungi affect many larger plants but are rarely lethal and mainly do what?
reduce the photosynthetic capacity of leaves
foliar pathogenic fungi are remarkably what
widespread and abundant
what did barone 1998 find in Panama on 10 tree spp?
fungal pathogens accounted for 34% of leaf damage
How many out of 21 tree spp examined in several other localities in Panama and Brazil were affected by foliar diseases (Gilber and Sousa 2002)
While foliar pathogens appear ubiquitous across sites and seasons, there is considerable variation in the degree of infection among spp. the probability of infection appears to be related to what
leaf damage caused by herbivores does what
renders leaves more susceptible to attack by foliar pathogens
Reduction in plant growth due to fungi can be substantial, as in the case of the tree Erythrochiton gymnanthus in Costa Rica, which suffered what reduction in its growth rate due to an infection by the petiolar pathogen Phylloporia chrysita?
52% (Esquivel and Carranza 1996)
many tropical forest insects are affect by what fungi
neotropical forest spores may contain as many as _____-_______ spores g-1 of Metarhizium anisopliae which infects various insects including leafcutter ants
the large majority of ants remain uninfected despite the high exposure of leafcutter ants to pathogenic fungi, why is this
regular self grooming and secretion of antibiotics
fungal spores that germinate and penetrate the host cuticle ultimately kill the insect when the fungus what
entomopathogens often bring about weird behavioural changes in their hosts like dying animals climbing as high as possible, why do they do this?
so fungal spores spread more widely
What does the Cordyceps genera do once the mycelium has invaded the host
develop a club shaped organ containing fungal spores which is supported on the end of a stalk which may be as much as 10cm in length
What are the Laboulbeniales?
minute ascomycetous fungi, obligately associated with arthropods, mostly insects.
One genus of Laboulbeniales is Rickia, which has approx 145 spp. what is the host range?
encompasses distantly related arthropods such as mites, millipedes, mole crickets, ants and various beetles.
What do the Rickia fungi do?
attach to arthropod cuticles through which they absorb nutrients, although this appears to have little consequence for the host.
A study in North Sulawesi on Laboulbeniales collected from beetles indicates what? (Weir and Hammond 1997)
tropical diversity may be high because host species are numerous and parasites appear host specific.
Vega and Dowd 2005 found that fungi are essential to the what of many insects
What did Suh et al 2005 find when looking at digestive tracts of tropical beetles?