Ancient DNA from coral-hosted Symbiodinium reveal a static mutualism over the last 172 years

PLoS One. 2013;8(2):e55057. doi: 10.1371/journal.pone.0055057. Epub 2013 Feb 6.

Abstract

Ancient DNA (aDNA) provides powerful evidence for detecting the genetic basis for adaptation to environmental change in many taxa. Among the greatest of changes in our biosphere within the last century is rapid anthropogenic ocean warming. This phenomenon threatens corals with extinction, evidenced by the increasing observation of widespread mortality following mass bleaching events. There is some evidence and conjecture that coral-dinoflagellate symbioses change partnerships in response to changing external conditions over ecological and evolutionary timescales. Until now, we have been unable to ascertain the genetic identity of Symbiodinium hosted by corals prior to the rapid global change of the last century. Here, we show that Symbiodinium cells recovered from dry, century old specimens of 6 host species of octocorals contain sufficient DNA for amplification of the ITS2 subregion of the nuclear ribosomal DNA, commonly used for genotyping within this genus. Through comparisons with modern specimens sampled from similar locales we show that symbiotic associations among several species have been static over the last century, thereby suggesting that adaptive shifts to novel symbiont types is not common among these gorgonians, and perhaps, symbiotic corals in general.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Psychological / physiology
  • Animals
  • Anthozoa / genetics*
  • Biological Evolution
  • DNA / genetics*
  • DNA, Ribosomal / genetics
  • Dinoflagellida / genetics*
  • Ecology
  • Environment
  • Genotype
  • Oceans and Seas
  • Phylogeny
  • Symbiosis / genetics
  • Temperature

Substances

  • DNA, Ribosomal
  • DNA

Grants and funding

This work was funded by the Smithsonian’s Marine Science Network Fellowship and the Laboratories of Analytical Biology. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.