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Open Access item Sex and life-history stage alter herbivore responses to a chemically defended red alga
Paul, Nicholas A.
Steinberg, Peter D.
|Keywords:||Life history, Plant-herbivore interaction, Algae, Aplysia parvula, Asparagopsis armata, Chemical defense, Dioecy, Herbivory, Heteromorphic life cycle|
|Publisher:||Ecological Society of America|
|Citation:||Ecology 89(5) : 1334–1343 (2008)|
|Abstract:||Intraspeciﬁc variation in resistance to herbivory among genders and life-history
phases of primary producers can signiﬁcantly alter the ecological and evolutionary
consequences of plant–herbivore interactions. Seaweeds (macroalgae) with complex life
histories have multiple distinct phases with associated variation in traits that can potentially
lead to differences in resistance to consumers and provide a unique system in which to
simultaneously test the effects of sex and life-history stage on herbivory. We tested the
susceptibility to grazing of the three life-history stages and separate sexes of the chemically
defended red alga Asparagopsis armata against the sea hare Aplysia parvula, and we related
this to the plant quality traits of different stages and genders. Differences in nutrient content
and halogenated secondary metabolites between life-history phases were highly sex dependent.
Male gametophytes had a low concentration of secondary metabolites and the highest nutrient
content. The highest secondary metabolite content was found within the female gametophyte,
in the wall of the reproductive structures (cystocarps) that contain the microscopic
carposporophyte phase. Feeding choices by A. parvula were consistent with differences in
algal quality and defense and resulted in the haploid male gametophytes being the most
preferred food type. The diploid carposporophyte found inside the chemically rich cystocarps
was the least consumed life-history stage. Selective herbivory of male gametophytes by A.
parvula is consistent with an observed shift in gametophyte sex ratio in the ﬁeld from unity at
the beginning of the reproductive season to female bias at the end. The variation in
susceptibility to herbivory found between sex and life-history stages of A. armata represents
the ﬁrst example of sex-biased consumption in seaweeds and may contribute to the
maintenance of complex life histories such as those found in red algae.|
|Description:||10 páginas, 1 tabla, 5 figuras.|
|Publisher version (URL):||http://www.esajournals.org/doi/pdf/10.1890/07-0248.1|
|Appears in Collections:||(CEAB) Artículos|
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