Relative influence of host plant genetics on a macrofungal log decay
community
by Michelle Storer
[Honours Project,
The project involved a study of the influence of genetic variation in Eucalyptus globulus on macrofungal wood decay communities. The project was based on the concept of the extended phenotype (Dawkins 1982), which predicts that genetically-based traits in foundation species will influence community and ecosystem processes. For example, it has been shown that variation in leaf chemical traits in Poplars can influence nutrient cycling in their associated ecosystem by altering soil chemistry (Whitham et al. 2006). It was hypothesised that genetic variation in E. globulus may have a similar influence through alteration of the fungal communities associated with wood decay.
The project utilised a log decay trial which was established in native Eucalyptus E. globulus woodland in 2002. The trial was composed of two replicates of 80 logs which represented eight genetic races of E. globulus, known to differ significantly in traits such as wood density and bark thickness. Logs were arranged in a grid pattern with cut ends facing north and south. Fungal assessments were carried out in autumn and winter of 2007. The richness, abundance and composition of fungal communities on whole logs, and on microhabitats within logs (i.e. north cut end, south cut end, east side, top of log etc.) were assessed using fruit body counts.
A
significant effect of genetic race
on macrofungal community richness was detected; this effect was consistent
within the fungal community at both the whole-log and microhabitat levels. The influence of log genetics was small,
however, relative to the influence of environmental factors such as log
microhabitat. As such, it was concluded
that genetic variation in E. globulus is unlikely to influence ecosystem
processes via the macrofungal decay community.
Nevertheless, the presence of a significant influence of host tree genetics
on the macrofungal log decay community represents a previously unconsidered influence
on wood decay fungal communities.
References
Dawkins R (1982) 'The Extended Phenotype: The Gene as the Unit of Selection.' (Oxford University Press: Oxford)
Whitham TG, Bailey JK,
et al. (2006) A framework for community and ecosystem genetics: From genes
to ecosystems. Nature Reviews Genetics 7,
510-523.