An investigation of the evolution of the anguimorph lizard venom system

Koludarov, Ivan (2017). An investigation of the evolution of the anguimorph lizard venom system PhD Thesis, School of Biological Sciences, The University of Queensland. doi:10.14264/uql.2017.493

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Author Koludarov, Ivan
Thesis Title An investigation of the evolution of the anguimorph lizard venom system
School, Centre or Institute School of Biological Sciences
Institution The University of Queensland
DOI 10.14264/uql.2017.493
Publication date 2017-04-10
Thesis type PhD Thesis
Supervisor Bryan G. Fry
Total pages 113
Total colour pages 14
Total black and white pages 99
Language eng
Subjects 220206 History and Philosophy of Science (incl. Non-historical Philosophy of Science)
060303 Biological Adaptation
060109 Proteomics and Intermolecular Interactions (excl. Medical Proteomics)
Formatted abstract
Over the course of the last two decades significant advances were made in our
understanding of the evolution of venom in squamate reptiles. Several studies looked at
nuclear genes from various lizards and snakes and confirmed the hypothesis put forth in
E. Kochva’s article “Phylogeny of the oral glands in reptiles as related to the origin and
evolution of snakes” – that anguimorph lizards form part of a monophyletic clade with all
the snakes. This confirmation confounded decades of morphology based taxonomy, as did
evidence of the inclusion of the Iguania lizard lineage into that group. The new group
received the name Toxicofera, emphasizing the role of oral toxins in the evolution of the
lineage. Despite being supported by genetic, anatomical and proteomic data, the
Toxicofera hypothesis remains controversial. This strengthens the necessity for thorough
investigation of toxicoferan reptile venom evolution. The oral secretions of anguimorph
lizards demand particular attention not only because they are understudied, but also for
the reason that Anguimorpha contains species with the considerable morphological
diversity of venom glands – from incipient to advanced and almost snake-like.

Therefore the primary goal of this thesis is to address the lack of knowledge on
anguimorph lizard oral secretions, in particular that of varanoid lizards which include
various monitor species (genus Varanus) as well as Heloderma (gila monster) and
Lanthanotus (Borneo earless monitor). This has been achieved through the
implementation of several proteomic techniques (in particular, gel electrophoresis) as well
as transcriptomic analysis and bioactivity testings.

Chapter One reviews all previously published information on anguimorph venom evolution,
highlighting the data in support of the Toxicofera hypothesis. Chapter Two presents new
data on Heloderma lizard venoms and the striking similarities between the venom profiles
of specimens from different localities as well as between species. The data presented and
discussed in Chapter Three represents the core finding of this study: the surprising
complexity and diversity of varanid lizard oral secretions.

Taken together, this study present a compelling argument in favour of functional diversity
and differential complexity of the venom of anguimorph lizards and discusses the
evolutionary forces that helped generate this diversity.
Keyword Molecular Evolution
Adaptive Evolution
Varanus
Venom
Toxin
Heloderma
Beaded lizard
Gila monster
Additional Notes 65-68, 95-104

Document type: Thesis
Collections: UQ Theses (RHD) - Official
UQ Theses (RHD) - Open Access
 
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Created: Mon, 27 Mar 2017, 16:18:36 EST by Ivan Koludarov on behalf of University of Queensland Graduate School