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Abstract

The evolution of plant defensive traits in
response to selection pressures imposed by herbivores is
central to co-evolutionary theory. To demonstrate the
role of herbivores as selective agents on plant resistance
there must be variability in plant resistance to herbivores
within a plant population. This variability must be
under genetic control, and the variability in plant
resistant traits and consequently herbivore damage to
plants must reflect variability in plant fitness. We used a
common eucalypt species, Eucalyptus globulus, and two
major mammalian herbivores, the common brushtail
possum (Trichosurus vulpecula) and the red-bellied
pademelon (Thylogale billardierii), as a system to
investigate intraspecific variation in plant resistance to
mammalian herbivores and to investigate if this variation
has a genetic basis. We measured mammalian browsing
damage on 2,302 individual trees of E. globulus, from
563 families derived from range-wide native stand seed
collections of known pedigree and grown in a common
environment field trial. Using a selection of trees from
the field trial we then conducted a feeding trial with
captive herbivores to assess if the genetic variation in
plant resistance in the field was reflected in feeding
preferences of captive animals, as measured by relative
intake. Results from the field trial showed significant
genetic variation in plant resistance amongst races,
localities and amongst different families. These results
were consolidated in the captive trial with similar trends
in genetic variation among E. globulus localities. Dry
matter intake of foliage by Trichosurus vulpecula was
consistently greater than that by Thylogale billardierii;
however, the intraspecific preferences of the two herbivores
were significantly correlated.

Item Type:	Article
Authors/Creators:	O'Reilly-Wapstra, J and McArthur, C and Potts, BM
Keywords:	Plant · Mammal interactions · Co-evolution · Selection · Herbivory
Journal or Publication Title:	Oecologia
ISSN:	0029-8549
DOI / ID Number:	https://doi.org/10.1007/s004420100797
Additional Information:	BM Potts. The original publication is available at www.springerlink.com
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