Pathogen accumulation on an invasive plant species can occur over time, through co-invasion, or adaptation of native pathogen species. While accumulated pathogens can reduce the success and spread of an invasive species, they can also spill-over into native plant communities or valuable non-native populations. Transmission of pathogens may be density-dependent, with dense invasive populations creating better opportunities for pathogen spread than scattered individuals.
There are very few, if any, ecosystems that are not profoundly influenced by the activity of microbial communities. Microorganisms, encompassing domains Bacteria and Archaea as well as microscopic members of the Eukarya such as protozoa, yeasts and many other fungi, are tremendously abundant and contribute significantly to the major biogeochemical processes.
Plant–invertebrate mutualisms involve the production of food and/or shelter by plants to co-opt invertebrate groups in order to either prevent herbivore or pathogen damage or facilitate seed dispersal. Plant structures and the provision of food are relatively expensive, and a reactive plant response to attack may reduce those costs provided the fitness benefit of the mutualism is maintained.
We outline the scope of this special issue of New Zealand Journal of Ecology, which reviews progress in New Zealand ecology to 2009, based on a symposium in 2007. Both the issue and symposium update a 1986 conference and 1989 special issue of NZ J Ecol called “Moas, Mammals and Climate” which has been influential and widely cited.