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GENOMICS OF THE GLOBALLY DISTRIBUTED ECHINOID GENUS Tripneustes

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Title:GENOMICS OF THE GLOBALLY DISTRIBUTED ECHINOID GENUS Tripneustes
Authors:Laruson, Aki Jarl
Contributors:ZOOLOGY (ECOLOGY, EVOLUTION, & CONSERVATION BIOLOGY) (department)
Keywords:Marine Invertebrate
Phylogenomics
Transcriptomics
Population Genomics
Date Issued:May 2018
Publisher:University of Hawaiʻi at Mānoa
Abstract:Understanding genomic divergence can be a key to understanding population dynamics.
As global climate change continues it becomes especially important to understand
how and why populations form and dissipate, and how they may be better protected.
To this effect, the globally distributed sea urchin genus Tripneustes has been highlighted
as an ideal group for studying patterns of genomic divergence as the global distribution
is split into two physically separated species (T. ventricosus in the Atlantic and T. gratilla
the Pacific), and cryptic divergence in the absence of hard physical barriers has been suspected
within each ocean. Molecular signatures of population divergence can be affected
and skewed by a number of different biological realities. In the case of lower fitness of a
heterozygous individual (underdominance), the degree as well as network shape of the
connectivity between populations can determine wether rare alleles persist between populations,
muddying population divergence signals, or are driven to fixation at one end of
the population range while going extinct in the other, giving a signal of parapatric speciation.
In order to address questions regarding the more nuanced molecular differences
and broader evolutionary trajectories within the genus Tripneustes a draft transcriptome
for the species T. gratilla was generated. In addition to showing an expansion in tumor
suppressor genes when compared to the genome enabled sea urchin Strongylocentrotus
purpuratus, and sex-specific gene expression differences in Sex determining Region Yassociated
High Mobility Group box (SOX) genes, the transcriptome allowed for easy recovery
of the full mitochondrial genome. Following isolation and sequence confirmation,
the mitochondrial genome of T. gratilla was next compared to all previously published
sea urchins mitochondrial genomes. A phylogenetic comparison validates the morphologically
proposed superfamily Odontophora, with an estimated genesis of the group
during the Eocene-Oligocene epoch transition. Estimates of selection via proportional
non-synonymous to synonymous site substitution ratios suggest that purifying selection
is the primary force acting on echinoid mitochondria.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018.
URI:http://hdl.handle.net/10125/62844
Rights:All UHM dissertations and theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission from the copyright owner.
Appears in Collections: Ph.D. - Zoology (Ecology, Evolution and Conservation Biology)


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