Insects shape genetic landscapes
26 Nov 2012 by Evoluted New Media
Plant-eating insects’ preferences play a fundamental role in maintaining and shaping the genetic variation of their host plants according to a recent study.
The study, which involved aphids and the research plant Arabidopsis thaliana, provides the first measurable evidence that genetic diversity is driven, in part, by the pressure that multiple natural enemies exert on plants. This forces them to create a variety of natural defences to avoid being eaten.
University of California, Davis plant scientist, Dan Kliebenstein said: “Our data demonstrate that there is a link between the abundance of two types of aphids and the continental distribution of Arabidopsis plants that are genetically different in terms of the biochemical they produced to defend against insect feeding.”
The researchers first mapped the distribution of six different chemical profiles within Arabidopsis thaliana plants across Europe, each chemical profile controlled by the variation in three genes. This mapping revealed a change in the function of one of the genes across geographic areas; changing from southwest to the northeast.
The team theorised that two aphid species –Brevicoryne brassicae and Lipaphis erysimi – were the cause of the geographic variation as both feed on Arabidopsis and related plants after discovering that the distributions of the two aphid species closely mirrored the geographic distribution of the different chemical types of Arabidopsis.
After observing the effects of different aphids feeding on five generations of Arabidopsis in the laboratory, they confirmed that the plants were genetically adapting to the aphids with each successive plant generation showing less damage from the feeding insect.
The team also found that faster-growing plants types fared much better in the laboratory, while slower growing Arabidopsis thaliana went extinct.
“The data make it clear that even functionally similar plant-eating pests can affect the biochemical and genetic makeup of plant populations, playing a major role in shaping and refining the plant defences in a natural community,” said Kliebenstein.