Title:
A test of optimal defense theory vs. the growth-differentiation balance hypothesis as predictors of seaweed palatability and defenses

dc.contributor.advisor Hay, Mark E.
dc.contributor.advisor Kubanek, Julia
dc.contributor.author Heckman, Melanie L. en_US
dc.contributor.committeeMember Duffy, Meghan A.
dc.contributor.committeeMember Jiang, Lin
dc.contributor.department Biology en_US
dc.date.accessioned 2012-02-17T19:14:52Z
dc.date.available 2012-02-17T19:14:52Z
dc.date.issued 2011-08-31 en_US
dc.description.abstract Because organisms have limited resources to allocate to multiple life history traits, the Optimal Defense Theory (ODT) and the Growth-Differentiation Balance Hypothesis (GDBH) were developed by terrestrial plant ecologists to predict intraindividual defense allocation based on the cost of defense and these life history trade-offs. However, these theories have garnered equivocal experimental support over the years and are rarely experimentally extended from predictions of plant physiology to the palatability of the tissues an herbivore experiences. We therefore examined tissue palatability, nutritional value, and defense mechanisms in multiple Dictyotalean seaweeds in two Caribbean locations, using two herbivores. Relative palatability of tissues varied greatly with algal species, grazer species, and location. Because older bases were not consistently defended, GDBH did not predict relative palatability. We could not reject ODT without intensive measures of tissue fitness value and herbivore risk, and this theory was therefore not useful in making broad predictions of tissue palatability. In testing the physiological predictions of these theories, we found the young, growing apices of these seaweeds to be generally more nutritionally valuable than the old, anchoring bases and found organic-rich apices to be more chemically deterrent, thus supporting ODT. However, the combined chemical, nutritional, and structural traits of these algae all influenced herbivore choice. As a result, these patterns of apical value and chemical defense reflected palatability of live tissues for only one of five algal species, which rendered ODT and GDBH poor predictors of relative palatability for most algae. en_US
dc.description.degree MS en_US
dc.identifier.uri http://hdl.handle.net/1853/42720
dc.publisher Georgia Institute of Technology en_US
dc.subject Defense theory en_US
dc.subject Seaweeds en_US
dc.subject Herbivory en_US
dc.subject Chemical defense en_US
dc.subject Defense allocation en_US
dc.subject Macroalgae en_US
dc.subject.lcsh Marine algae
dc.subject.lcsh Plant defenses
dc.subject.lcsh Plant chemical defenses
dc.title A test of optimal defense theory vs. the growth-differentiation balance hypothesis as predictors of seaweed palatability and defenses en_US
dc.type Text
dc.type.genre Thesis
dspace.entity.type Publication
local.contributor.advisor Kubanek, Julia
local.contributor.advisor Hay, Mark E.
local.contributor.corporatename College of Sciences
local.contributor.corporatename School of Biological Sciences
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relation.isOrgUnitOfPublication 85042be6-2d68-4e07-b384-e1f908fae48a
relation.isOrgUnitOfPublication c8b3bd08-9989-40d3-afe3-e0ad8d5c72b5
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