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Herbivores and Their Host Plants in a Warmer World
Reference
Andrew, N.R. and Hughes, L. 2007. Potential host colonization by insect herbivores in a warmer climate: a transplant experiment. Global Change Biology 13: 1539-1549.

Background
With respect to past and possible future global warming, the authors write that "individualistic responses of species to current and future changes, especially differential migration rates, will result in the progressive decoupling of present day ecological interactions, together with the formation of new relationships potentially leading to profound changes in the structure and composition of present day communities," which changes, we would add, are almost universally claimed by climate alarmists to be detrimental to the species involved and, ultimately, bad for the entire biosphere.

What was done
Andrew and Hughes "investigated how the relationship of herbivorous insects and their host plants may change under a warmer climate" by "transplanting a host plant species to locations subject to mean annual temperatures 1.2C higher than at the species' current warmest boundary and 5.5C higher than at its coolest edge," after which they "compared the structure and composition of the herbivorous insect community that colonized the transplants (i) to that of the host plant species within its natural range and (ii) to a congeneric plant species that grew naturally at the transplant latitude." In addition, they "investigated whether the herbivore community and rates of herbivory were affected by the latitudinal origin of the transplants."

What was learned
The two Australian researchers report that "rates of herbivory did not significantly differ between the transplants and plants at sites within the natural range," and that "there were no significant differences in herbivore species richness or overall rates of herbivory on the transplants originating from different latitudes."

What it means
The general conclusion of Andrew and Hughes, as stated in their abstract, is that "if this result holds for other plant-herbivore systems, we might expect that under a warmer climate, broad patterns in insect community structure and rates of herbivory may remain similar to that at present, even though species composition may change substantially." Or as stated in their concluding paragraph, "if these results can be generalized to other plant hosts, we might predict that as climate zones shift poleward and mobile organisms like flying insects respond by migrating to stay within their current climatic envelope, plants will be colonized by new herbivore species within similar guilds to those currently supported," and that "changes in the composition, but not necessarily the structure, of these new communities may, therefore, result."

Consequently, in a warmer world of the future, the biosphere may well be significantly different in terms of who does what to whom, but all of its major functions are likely to be preserved and little altered.

Reviewed 9 January 2008