Genetic architecture of adaptation to biotic invasions in soapberry bugs
Date
2013-10-01
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
On the Florida peninsula, the soapberry bug (Jadera haematoloma) has been able to
colonize the golden rain tree, Koelreuteria elegans, since the introduction of this invasive tree
only a few decades ago. The populations feeding on the new host have been rapidly
differentiating from the native populations. Possibly the most dramatic differentiation is that of
the beak (mouthpart) length. Derived populations showed shorter beaks more appropriate for
feeding on the flattened pods of the new host. Previous studies have shown that the divergence of
the beak length has a genetic basis and involves non-additive genetic effects. However, to date,
the soapberry bug divergence has not been studied at the molecular level. In the current study, I
have generated a three-generation pedigree from crossing the long-beaked and short-beaked
ecomorphs to construct a de novo linkage map and to locate putative QTL controlling beak
length and body size in J. haematoloma. Using the AFLP technique and a two-way
pseudo-testcross design I produced two parental maps. The maternal map covered six linkage
groups and the paternal map covered five; the expected number of chromosomes was recovered
and the putative X chromosome was identified. For beak length, QTL analyses revealed one
significant QTL. Three QTL were found for body size. Interestingly, the most significant body
size QTL co-localized with the beak length QTL, suggesting linkage disequilibrium or
pleiotropic effects of related traits. Through single marker regression analysis, nine single
markers that could not be placed on the map were also found to be associated with either trait.
However, I found no evidence for epistasis. Overall, my findings support an oligogenic model of
genetic control on beak length and body size, and the underlying genetic architectures were
complex. This study is the first to look at the molecular basis underlying adaptive traits in the
soapberry bug, and contributes to understanding of the genetic changes involved in early stages
of ecological divergence.
Description
Keywords
quantitative genetics, rapid evolution, diversification, host-plant, hemiptera
Citation
Degree
Master of Science (M.Sc.)
Department
Biology
Program
Biology