Human-induced environmental changes have ushered in the rapid decline of coral reef ecosystems, particularly by disrupting the symbioses between reef-building corals and their photosymbionts. However, escalating stressful conditions enable some symbionts to thrive as opportunists. We present evidence that a stress-tolerant “zooxanthella” from the Indo-Pacific Ocean, Symbiodinium trenchii, has rapidly spread to coral communities across the Greater Caribbean. In marked contrast to populations from the Indo-Pacific, Atlantic populations of S. trenchii contained exceptionally low genetic diversity, including several widespread and genetically similar clones. Colonies with this symbiont tolerate temperatures 1–2 °C higher than other host–symbiont combinations; however, calcification by hosts harboring S. trenchii is reduced by nearly half, compared with those harboring natives, and suggests that these new symbioses are maladapted. Unforeseen opportunism and geographical expansion by invasive mutualistic microbes could profoundly influence the response of reef coral symbioses to major environmental perturbations but may ultimately compromise ecosystem stability and function.
R-script for the analysis Symbiodinium trenchii in the Caribbean
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of S. trenchii in the Greater Caribbean, West Atlantic Ocean.
PWD analysis S.trenchii Caribbean.R
R-script for the analysis Symbiodinium trenchii in the Andaman Sea (Thailand)
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of S. trenchii in the Andaman Sea (Thailand), Eastern Indian Ocean.
PWD analysis S.trenchii Thailand.R
R-script for the analysis Symbiodinium trenchii in the Western Pacific (Palau
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of S. trenchii in the West Pacific Ocean (Palau).
PWD analysis S.trenchii Palau.R
R-script for the analysis Symbiodinium type A3 in the Eastern Caribbean
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of Symbiodinium A3 (S. ‘fitti’ nomen nudum) in the Eastern Caribbean, West Atlantic Ocean.
PWD analysis Sym. A3 East Carib.R
R-script for the analysis Symbiodinium type B7 in the Caribbean
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of Symbiodinium B7 from corals in the genus Madracis in the Caribbean, West Atlantic Ocean.
PWD analysis Sym. B7 Caribbeanwide.R
R-script for the analysis Symbiodinium type C7 in the western Caribbean
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of Symbiodinium C7 in the Western Caribbean (Belize), West Atlantic Ocean.
PWD analysis Sym. C7 Belize.R
R-script for the analysis Symbiodinium type D1 ‘S. glynni’ in the Eastern Pacific
Source code for the analysis of observed pairwise genetic difference (PWD), expected PWD under panmixia, and permutation test for departure from expected pairwise genetic difference for microsatellite MLGs datasets from a population of Symbiodinium ‘glynni’ (nomen nudum, = type D1) in the Gulf of California (La Paz), Eastern Pacific Ocean.
PWD analysis Sym. D1 Gulf of California.R
Symbiodinium trenchii Caribbean
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium trenchii in the Caribbean
Symbiodinium trenchii Thailand
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium trenchii in the Andaman Sea (Thailand)
Symbiodinium trenchii Palau
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium trenchii in the Western Pacific (Palau)
Symbiodinium type A3_East Carib
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium type A3 in the Eastern Caribbean
Symbiodinium type B7 Caribbean
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium type B7 in the Caribbean.
Symbiodinium type C7 Belize
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium type C7 in the western Caribbean.
Symbiodinium type D1 Gulf of California
Excel data files of multilocus genotypes (MLGs) based on microsatellites for Symbiodinium type D1 ‘S. glynni’ in the Eastern Pacific.
Symbiodinium type D1 gulf of california.csv