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Understanding the Adaptive Ability of Corals to Changing Environments.

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Title:Understanding the Adaptive Ability of Corals to Changing Environments.
Authors:Tisthammer, Kaho H.
Contributors:Marine Biology (department)
Keywords:Porites lobata
population genetics
local adaptation
show 1 moremorphometrics
show less
Date Issued:May 2017
Publisher:University of Hawaiʻi at Mānoa
Abstract:Reduced water quality is a major local threat to coral reefs worldwide, and has caused
severe declines in the health of coral reefs in Hawaii, especially the nearshore areas. The corals
living in Maunalua Bay, Oahu are under continual stresses from sedimentation and toxicant
laden runoff as a result of large-scale urbanization that has taken place in the last century.
Despite prolonged exposure to these environmental stressors, some corals are able to thrive,
suggesting selection (adaptation). My dissertation research investigated whether corals in the
nearshore areas have genetically adapted to their reduced water quality environment. The first
chapter analyzed the population genetic structure of P. lobata, which revealed clear genetic
differentiation between the nearshore and offshore P. lobata populations in Maunalua Bay, as
well as two reefs in West Maui. My second chapter investigated the phenotypic differences
between the nearshore and offshore P. lobata genotypes, found in the first chapter, to determine
if the observed genetic differentiation was formed by selection. The reciprocal transplant and
common garden experimental results showed clear physiological and molecular response
differences between the two genotypes, highlighting the stress resilient traits of the nearshore
genotype and inherent differences in the metabolic state between the genotypes. The results from
the first and second chapters, however, suggest this local adaptation might happen at the cost of
genetic diversity.
The Porites corals are a notoriously difficult genus to identify correctly, due to their highly
variable skeletal architecture and unresolved phylogeny. In order to assess the intraspecific
morphological and genetic variations in P. lobata, morphometrics and genomic (RAD-seq)
analyses were conducted in my third chapter. The morphometric data revealed significant
groupings of skeletal characters between the geographic locations, and population genomic
analysis also supported the strong geographical signature. There was a significant correlation
between the morphological and the genetic distances, suggesting the genetic basis for the skeletal
morphology of P. lobata.
Understanding the genetic basis of coral survival offers a critical insight into their adaptive
ability, which is indispensable for protecting the essential reef-building corals from impending
environmental and climate change.
Description:Ph.D. Thesis. University of Hawaiʻi at Mānoa 2017.
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. - Marine Biology

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