The DLX Gene Family and Vertebrate Evolution: Insights from Lampreys
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Authors
Neidert, Adam H.
Issue Date
2000
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
The development of the embryonic head structure of vertebrates is an evolutionary hallmark that sets the clade apart from all other organisms. Agnathans Gawless
vertebrates) and gnathostomes Gawed vertebrates) make up the taxon vertebrata.
Agnathans are considered the more primitive vertebrates and retain more primitive
characteristics. The agnathan taxa separated from the gnathostome evolutionary line
fairly early on in the evolutionary time line and their morphology is considered to be most
similar to the proto vertebrate common ancestor. Because of their phylogenetic position
as agnathans, lampreys can serve as a modem day proxy for the common ancestor of all vertebrates and thus provide insight into the evolution of such gnathostome
characteristics as the jawbone, larger tri-partite brain, and paired appendages. The Dlx
gene family is an important marker for these gnathostome morphological innovations. By comparing the Dlx gene family in lampreys with the Dlx homologs in gnathostomes and cephalochordates, we can gain insight into the role of gene duplication in early vertebrate evolution and its subsequent affect on morphology. To this extent, we cloned two distinct lamprey Dlx orthologs. Expression of these lamprey Dlx orthologs is found in
the developing forebrain, pharyngeal arches, neural crest cells, otic and olfactory placodes.
Phylogenetic analysis indicates that these are outgroups to the two major clades of
gnathostoine Dlx genes and are most likely more closely related to the Dlx genes in the
protovertebrate common ancestor.
With honors.
With honors.
Description
v, 36 p.
Citation
Publisher
Kalamazoo College
License
U.S. copyright laws protect this material. Commercial use or distribution of this material is not permitted without prior written permission of the copyright holder.