Section 7
Chapter 6,259

Rapid host range evolution in a population of the phytophagous mite tetranychus urticae

Gould, F.

Evolution 33(3): 791-802


ISSN/ISBN: 0014-3820
Accession: 006258740

This study was made to gain detailed information on microevolutionary processes involved in host range evolution which could influence macroevolutionary patterns of host range found in natural systems. A population of the two-spotted spider mite, Tetranychus urticae, was divided in 2. One-half was reared on a monoculture of lima bean (a favorable host). The other half was placed in a simple plant community of lima beans and a toxic host, mite-resistant cucumber. The 2 lines of mites were allowed to adapt to their respective plant communities and their fitness on the 2 host-plants was monitored over a 21-mo. period. The line maintained in the cucumber-bean community had higher fitness on cucumber and lower fitness on bean than the line maintained in the bean monoculture. The line maintained in the cucumber-bean community had higher survivorship on 2 of 3 other marginal hosts tested (tobacco and potato but not plantain). Results indicate that host range evolution can be a rapid process and suggest that cross-adaptation to sets of plants as well as the ecological proximity of a set of plant species to an herbivore population may be an important factor in evolution of host range patterns.

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