The role of intraspecific diversity in coral-algal symbiosis ecology and evolution

Open Access
Author:
Parkinson, John Everett
Graduate Program:
Biology
Degree:
Doctor of Philosophy
Document Type:
Dissertation
Date of Defense:
June 06, 2014
Committee Members:
  • Iliana Brigitta Baums, Dissertation Advisor
  • Todd C La Jeunesse, Committee Chair
  • Mary Alice Coffroth, Special Member
  • Istvan Albert, Committee Member
  • James Harold Marden, Committee Member
  • Andrew Fraser Read, Committee Member
Keywords:
  • Acropora palmata
  • climate change
  • coral reef
  • molecular biology
  • stress response
  • Symbiodinium
  • symbiosis ecology
  • taxonomy
Abstract:
Coral-algal mutualisms, the foundation of reef ecosystems, can break down during periods of thermal stress. The extent to which such partnerships may acclimate or evolve to survive a changing climate is poorly understood. Though evolutionary responses are driven by the natural selection of functional variation among individuals within species, such variation has been difficult to quantify in coral systems. Here, I use high-resolution molecular techniques to differentiate individuals, populations, and species within coral symbioses and subsequently quantify the ecological and evolutionary relevance of intraspecific variation. In the first chapter, I review the technological advances that have made such work possible, and describe preliminary data from several researchers indicating that intraspecific variation may be extensive among coral hosts and symbionts. In the second chapter, I test the value of manipulating coral-algal partnerships during host larval development for restoration purposes, finding little influence of symbiont identity on growth rates during early ontogeny. In the third chapter, I formally describe several new species of Symbiodinium, the morphologically cryptic dinoflagellate endosymbionts that associate with cnidarians, and draw attention to the ecological diversity that can be found even among closely-related groups. In the fourth chapter, I characterize molecular variation among individuals of the coral Acropora palmata that affects the photochemistry of a clonal symbiont responding to thermal stress, emphasizing that fine scale partner interactions can yield functional variation among coral holobionts with potential evolutionary consequences. In the fifth chapter, I compare gene content and steady-state expression among several closely related Symbiodinium within the Clade B lineage, identifying phylogenetic and ecological transcriptional signatures among species. This work represents a few first steps into the complex and exciting territory of fine scale variation among marine mutualisms.