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United States Department of Agriculture

Agricultural Research Service

Title: Does Herbivory Select for Resistant Genotypes of the Invasive Tree Melaleuca Quinquenervia?

Authors
item Franks, Steven
item PRATT, PAUL
item DRAY, F ALLEN
item Simms, Ellen - UC BERKELEY

Submitted to: The 7th International Conference on the Ecology and Management of Alien Plant Invasions
Publication Type: Proceedings
Publication Acceptance Date: January 20, 2003
Publication Date: November 5, 2003
Citation: Franks, S.J., Pratt, P.D., Dray Jr, F.A., Simms, E.L. 2003. Does herbivory select for resistant genotypes of the invasive tree melaleuca quinquenervia?. The 7th International Conference on the Ecology and Management of Alien Plant Invasions.

Interpretive Summary: We examined the effects of herbivory on seedlings of Melaleuca quinquenervia (melaleuca) and whether seedlings with the same maternal parent showed similar levels of resistance or tolerance to herbivory. The objectives of this study were to determine 1) which traits in Melaleuca relate to tolerance and resistance to herbivory, 2) the degree to which these defensive traits are under genetic control, and 3) whether and at what rate defensive genotypes would be expected to spread through established populations. Date of first germination differed significantly between Floridian and Australian maternal lineages and among maternal lines within source locations. We explore the effect of source continent and maternal lineage on height, biomass, and amount of damage to determine if plants from invasive populations have lost resistance or tolerance to herbivory compared to plants in the native populations. If resistance traits correlate with fitness and show high levels of heritability, we predict that these traits may increase in frequency in Florida as populations of biological control insects grow and spread.

Technical Abstract: While biological control has the potential to be an important tool in managing pest populations, a biological control program may not be successful if the target species is able to evolve resistance or tolerance to the effects of the control agent. To examine how an invasive species may evolve in response to herbivory by biological control insects, we conducted a quantitative genetics study of the invasive tree species Melaleuca quinquenervia. The objectives of this study were to determine 1) which traits in Melaleuca relate to tolerance and resistance to herbivory, 2) the degree to which these defensive traits are under genetic control, and 3) whether and at what rate defensive genotypes would be expected to spread through established populations. We collected seeds from 120 maternal trees: 60 in Florida (introduced range) and 60 in Australia (native range). Seedlings from these trees were planted in the field and were either subjected to natural levels of herbivory or were protected from herbivory using insecticides. Plants were censused for survival, growth, performance, and traits relating to defense, including leaf toughness, hairiness, and the concentrations of terpenoids, phenolics, and nitrogen. Date of first germination differed significantly between Floridian and Australian maternal lineages and among maternal lines within source locations. We explore the effect of source continent and maternal lineage on height, biomass, and amount of damage to determine if plants from invasive populations have lost resistance or tolerance to herbivory compared to plants in the native populations. If resistance traits correlate with fitness and show high levels of heritability, we predict that these traits may increase in frequency in Florida as populations of biological control insects grow and spread.

Last Modified: 9/10/2014
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