Host use, mutualism and parasitism in the Lycaeides butterfly complex
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Authors
Scholl, Cynthia F.
Issue Date
2012
Type
Thesis
Language
Keywords
host use , hybridization , Lycaeides , mutualism , parasitism
Alternative Title
Abstract
Changes in host use in herbivorous insects can lead to diversification, speciation,
and changes in other ecological interactions. In the first chapter, larval performance was
investigated in three species of Lycaeides butterflies and placed into the context of other
already studied ecological traits that potentially contribute to reproductive isolation in
this system. For the larval performance experiment, caterpillars from seven populations
were reared on five host plants, asking if host-specific, adaptive larval traits exist. We
found large differences in performance across plants and fewer differences among
populations. These patterns of performance are complex and suggest both conserved
traits (i.e. plant effects across populations) and more recent dynamics of local adaptation,
in particular for L. melissa that has colonized an exotic host. Finally, we put larval
performance within the context of several other traits that might contribute to
ecologically-based reproductive isolation in the Lycaeides complex. This larger context,
involving multiple ecological and behavioral traits, highlights the complexity of
ecological diversification and emphasizes the need for detailed studies on the strength of
putative barriers to gene flow in order to fully understand the process of ecological
speciation. One ecological factor that could affect diversification in this group is
interactions with other trophic levels. In the second chapter, interactions with mutualistic
ants and parasitoids were investigated in the context of current adaptation to a new host,
alfalfa, within one of the species previously studied, L. melissa. Over the course of two
summers, caterpillars and mutualistic ants were collected from sites with both native
hosts and sites with an exotic host. Our understanding of the natural history of this system
was broadened by identifying tending ants to species and parasitoids to subfamily. It was
ii
found that parasitoid abundance and diversity varied considerably across space and time;
however, the presence of mutualistic ants did not reduce parasitism rates. These studies
highlight the importance of investigating ecological interactions, including interactions
with other trophic levels, when studying host dynamics and diversification in herbivorous
insects.
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In Copyright(All Rights Reserved)