Fire coral of the genus Millepora are prevalent in tropical western Atlantic reefs. Two distinct morphologies of Millepora, currently classified as separate species, exist off the coast of the Bahamas. M. complanata is characterized as having broad, smooth blades and preferring shallow waters while M. alcicornis is known for its finer, knobby branches and preference to deeper waters. Upon discovery of an intermediate morphology, the question arose as to whether these different morphologies represent different species or whether the differences result from phenotypic plasticity. The phenotypic plasticity hypothesis is supported by the different preferences of water depth displayed by the two morphologies. In order to understand the taxonomic relationships between the three morphological forms, DNA was collected from all three morphs and the internal transcribed spacer (ITS) regions of rDNA were examined. Since the ITS regions are not part of the rRNA coding regions used to make ribosomes, changes in this region of DNA are more common than in coding sections. Consequently, DNA sequence comparison of ITS regions from different colonies should help determine the taxonomic relationship of the three morphs. Complete DNA sequence was obtained from 19 coral colonies. Our results suggest the existence of two genetically isolated clades represented by five single nucleotide polymorphisms (SNPs) that are present in M. alcicornis, M. complanata, and the intermediate. This finding suggests the existence of two reproductively isolated species that cannot be identified from each other by geographic location of the reef or coral morphology.
Haley Elledge, ’07 Marion, IA
Majors: Chemistry, Biochemistry and Molecular Biology
Craig Tepper, Ph.D.
Robert Black, Ph.D.
Sponsor: Craig Tepper