Persistent Link:
http://hdl.handle.net/10150/194797
Title:
Costs of Plasticity in Host Use in Butterflies
Author:
Snell-Rood, Emilie Catherine
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Phenotypic plasticity, the ability of a genotype to express different phenotypes in different environments, allows organisms to cope with variation in resources and invade novel environments. Biologists have long been fascinated with the costs and tradeoffs that generate and maintain variation in plasticity, such as possible increases in brain size and delays in reproduction associated with the evolution of learning. However, the costs of plasticity vary: many studies have failed to find costs of plasticity, the degree of costs often vary with the system or environments considered, and many costs of plasticity are variable even within the lifetime of an individual. This research adopts a developmental perspective to predict the degree and incidence of costs of plasticity, using host learning in butterflies as a case study. Learning, a mechanism of plasticity that develops through a trial-and-error sampling process, should result in developmental costs and allocation of energy towards development (at the expense of reproduction). Furthermore, costs of learning should be less pronounced in environments for which organisms have innate biases and for learned traits underlain by short-term memory, relative to long-term memory (which requires more developmental re-structuring). This research found support for all three predictions across three levels of costs: behavioral costs, tissue costs, and fecundity trade-offs. Butterflies exhibited genetic variation in their ability to learn to recognize different colored hosts. Genotypes with higher proxies for long-term memory emerged with relatively larger neural investment and smaller reproductive investment. In contrast to these costs of long-term learning, proxies of short-term learning were only correlated with increased exploration of a range of possible resources (types of non-hosts) early in the host-learning process. Family-level costs of plasticity emerged from the ability to learn to locate a red host, for which butterflies do not have an innate bias. Costs of learning were also induced by learning itself: following exposure to novel (red) host environments, individual butterflies, regardless of genetic background, increased exploratory behavior, increased neural investment, and re-allocated energy away from reproduction towards other functions (e.g., flight). Considering developmental mechanisms helps to predict how costs will influence the evolution of learning and plasticity.
Type:
text; Electronic Dissertation
Keywords:
butterfly; learning; brain size; phenotypic plasticity; host use; life history
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Ecology & Evolutionary Biology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Papaj, Daniel R.
Committee Chair:
Papaj, Daniel R.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleCosts of Plasticity in Host Use in Butterfliesen_US
dc.creatorSnell-Rood, Emilie Catherineen_US
dc.contributor.authorSnell-Rood, Emilie Catherineen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPhenotypic plasticity, the ability of a genotype to express different phenotypes in different environments, allows organisms to cope with variation in resources and invade novel environments. Biologists have long been fascinated with the costs and tradeoffs that generate and maintain variation in plasticity, such as possible increases in brain size and delays in reproduction associated with the evolution of learning. However, the costs of plasticity vary: many studies have failed to find costs of plasticity, the degree of costs often vary with the system or environments considered, and many costs of plasticity are variable even within the lifetime of an individual. This research adopts a developmental perspective to predict the degree and incidence of costs of plasticity, using host learning in butterflies as a case study. Learning, a mechanism of plasticity that develops through a trial-and-error sampling process, should result in developmental costs and allocation of energy towards development (at the expense of reproduction). Furthermore, costs of learning should be less pronounced in environments for which organisms have innate biases and for learned traits underlain by short-term memory, relative to long-term memory (which requires more developmental re-structuring). This research found support for all three predictions across three levels of costs: behavioral costs, tissue costs, and fecundity trade-offs. Butterflies exhibited genetic variation in their ability to learn to recognize different colored hosts. Genotypes with higher proxies for long-term memory emerged with relatively larger neural investment and smaller reproductive investment. In contrast to these costs of long-term learning, proxies of short-term learning were only correlated with increased exploration of a range of possible resources (types of non-hosts) early in the host-learning process. Family-level costs of plasticity emerged from the ability to learn to locate a red host, for which butterflies do not have an innate bias. Costs of learning were also induced by learning itself: following exposure to novel (red) host environments, individual butterflies, regardless of genetic background, increased exploratory behavior, increased neural investment, and re-allocated energy away from reproduction towards other functions (e.g., flight). Considering developmental mechanisms helps to predict how costs will influence the evolution of learning and plasticity.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectbutterflyen_US
dc.subjectlearningen_US
dc.subjectbrain sizeen_US
dc.subjectphenotypic plasticityen_US
dc.subjecthost useen_US
dc.subjectlife historyen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineEcology & Evolutionary Biologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPapaj, Daniel R.en_US
dc.contributor.chairPapaj, Daniel R.en_US
dc.contributor.committeememberDavidowitz, Goggyen_US
dc.contributor.committeememberGronenberg, Wulfilaen_US
dc.contributor.committeememberNagy, Lisa M.en_US
dc.contributor.committeememberPepper, John W.en_US
dc.identifier.proquest2369en_US
dc.identifier.oclc659748254en_US
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