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Latitudinal patterns in plant defense: evolution of cardenolides, their toxicity and induction following herbivory
Author(s) -
Rasmann Sergio,
Agrawal Anurag A.
Publication year - 2011
Publication title -
ecology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.852
H-Index - 265
eISSN - 1461-0248
pISSN - 1461-023X
DOI - 10.1111/j.1461-0248.2011.01609.x
Subject(s) - cardenolide , biology , chemical defense , herbivore , botany , ecology , shoot , plant defense against herbivory , latitude , glycoside , biochemistry , gene , geodesy , geography
Ecology Letters (2011) 14: 476–483 Abstract Attempts over the past 50 years to explain variation in the abundance, distribution and diversity of plant secondary compounds gave rise to theories of plant defense. Remarkably, few phylogenetically robust tests of these long‐standing theories have been conducted. Using >50 species of milkweed ( Asclepias spp.), we show that variation among plant species in the induction of toxic cardenolides is explained by latitude, with higher inducibility evolving more frequently at lower latitudes. We also found that: (1) the production of cardenolides showed positive‐correlated evolution with the diversity of cardenolides, (2) greater cardenolide investment by a species is accompanied by an increase in an estimate of toxicity (measured as chemical polarity) and (3) instead of trading off, constitutive and induced cardenolides were positively correlated. Analyses of root and shoot cardenolides showed concordant patterns. Thus, milkweed species from lower latitudes are better defended with higher inducibility, greater diversity and added toxicity of cardenolides.