Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Dec;100(12):e02857.
doi: 10.1002/ecy.2857. Epub 2019 Jul 31.

Trade-offs constrain the evolution of an inducible defense within but not between plant species

Anurag A Agrawal  1   2 , Amy P Hastings  1
Affiliations

Trade-offs constrain the evolution of an inducible defense within but not between plant species

Anurag A Agrawal et al. Ecology. 2019 Dec.

Abstract

Inducible defense is a common form of phenotypic plasticity, and inducibility (change in defense after herbivore attack) has long been predicted to trade off with constitutive (or baseline) defense to manage resource allocation. Although such trade-offs likely constrain evolution within species, the extent to which they influence divergence among species is unresolved. We studied cardenolide toxins among genetic families in eight North American Asclepias species, spanning the full range of defense in the genus. Using common environment experiments and chemical assays, we report a consistent trade-off (negative genetic correlation) between concentrations of constitutive cardenolides and their inducibility within each species. However, no trade-off was found in a phylogenetic analysis across species. To investigate factors driving differences in defense allocation among species we used latitude as a proxy for growing season and herbivore pressure and found that divergence into lower latitudes resulted in evolution of higher cardenolides overall. Next we used an enzymatic assay of the cellular target of cardenolides (sodium-potassium ATPase) and confirm that higher cardenolides resulted in stronger toxicity to a sensitive species, but not to specialized monarch butterflies. Thus, plant speciation into biogeographic regions with alternative resources or pest pressure resulted in the macroevolution of cardenolide defense, especially against unspecialized herbivores. Nonetheless, trade-offs persist in the extent to which this defense is allocated constitutively or is inducible among genotypes within each species.

Keywords: cardenolide cardiac glycoside; chemical ecology; milkweed Asclepias; monarch butterfly Danaus plexippus; phenotypic plasticity; plant defense theory; trade-offs.

PubMed Disclaimer

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

Literature Cited

    1. Adler, F. R., and R. Karban. 1994. Defended fortresses or moving targets? Another model of inducible defenses inspired by military metaphors. American Naturalist 144:813-832.
    1. Agrawal, A. A. 2005. Natural selection on common milkweed (Asclepias syriaca) by a community of specialized insect herbivores. Evolutionary Ecology Research 7:651-667.
    1. Agrawal, A. A. 2007. Macroevolution of plant defense strategies. Trends in Ecology and Evolution 22:103-109.
    1. Agrawal, A. A. 2011. Current trends in the evolutionary ecology of plant defence. Functional Ecology 25:420-432.
    1. Agrawal, A. A., and M. Fishbein. 2006. Plant defense syndromes. Ecology 87:S132-S149.

Publication types