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The Evolutionary Ecology of Ultraviolet Floral Pigmentation

Koski, Matthew (2015) The Evolutionary Ecology of Ultraviolet Floral Pigmentation. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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The color of flowers varies widely in nature, and this variation has served as an important model for understanding evolutionary processes such as genetic drift, natural selection, speciation and macroevolutionary transitions in phenotypic traits. The flowers of many taxa reflect ultraviolet (UV) wavelengths that are visible to most pollinators. Many taxa also display UV reflectance at petal tips and absorbance at petal bases, which manifests as a ‘bullseye’ color patterns to pollinators. Most previous research on UV floral traits has been largely descriptive in that it has identified species with UV pattern and speculated about its function with respect to pollination. This dissertation addresses the ecological and evolutionary relevance of UV floral pattern at micro- and macroevolutionary scales. First I use a widespread plant (Argentina anserina) to describe the degree to which UV floral pattern varies, and determine the genetic contribution to variation. With the same system, I then use experimental manipulation to test whether and how the UV bullseye pattern mediates plant-pollinator interactions in the field. I then evaluate whether spatial variation in biotic (pollinator) and abiotic selective agents contribute to geographic variation in UV floral traits at regional (Colorado Rocky Mountains elevation gradient) and global (four latitudinal gradients) scales. Finally, I create a molecular phylogeny of the species-rich cinquefoil (Potentilla) group to address whether variation in UV pattern among taxa is constrained by evolutionary history, and whether biogeography and bioclimatic factors contribute to interspecific variation. Findings from this dissertation that pollinators contribute to variation in UV pattern, broaden the understanding of the traits that contribute to pollinator-mediated reproductive success of flowering plants. UV irradiance can also impose selection on UV pattern and drive latitudinal trends in floral pigmentation, extending an ecological rule formulated for animals—Gloger’s rule—to plants. Finally, I detected low phylogenetic signal for UV pigmentation in Potentilla, but strong biogeographic associations, which together suggest that selection could play a role in shaping UV floral variation among taxa. Overall, this dissertation enhances the understanding of how spatially varying selection regimes contribute to geographic variation and macroevolutionary patterns in a cryptic pigmentation trait in flowers.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Koski, Matthewmhk20@pitt.eduMHK20
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairAshman, Tia-Lynntia1@pitt.eduTIA1
Committee MemberKalisz, Susankalisz@pitt.eduKALISZ
Committee MemberTonsor, Stephentonsor@pitt.eduTONSOR
Committee MemberRebeiz, Markrebeiz@pitt.eduREBEIZ
Committee MemberMorehouse, Nathannim@pitt.eduNIM
Committee MemberSmith,
Date: 26 September 2015
Date Type: Publication
Defense Date: 4 May 2015
Approval Date: 26 September 2015
Submission Date: 14 June 2015
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 172
Institution: University of Pittsburgh
Schools and Programs: Dietrich School of Arts and Sciences > Biological Sciences
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Argentina anserina, flower color, flower color pattern, Gloger's rule, natural selection, pollination, Potentilla
Date Deposited: 27 Sep 2015 01:20
Last Modified: 26 Sep 2017 05:15


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