Genetic Analysis of Fire Coral

April 17th, 2004

Coral are important components of underwater ecosystems and contribute to reef biodiversity. The Millepora genus (fire coral) is a hydrozoan represented predominately by two species prevalent on tropical western Atlantic reefs. Each species has distinct morphological features: M. complanata is broad, smooth, and blade-like while M. alcicornis is thin with knobby branches (Kaplan, 1982). However, some fire coral exhibit characteristics of both species (intermediate morphological characteristics) making taxonomic identification ambiguous. We have collected M. complanata, M. alcicornis and intermediates exhibiting morphological characterisitics of both species. Due to the wide range of intermediate morphologies present and mass spawning events there is controversy about whether M. alcicornis and M. complanata represent independent lineages, interspecific hybrids, or whether this is one species group. Vollmer and Palumbi (2002) have shown that occasionally sperm from one species fertilize eggs from another species creating interspecific hybrids.

We are currently surveying offshore reefs of San Salvador , Bahamas to ascertain relative abundance of both species and intermediates. We are also conducting a genetic analysis using Amplified Fragment Length Polymorphisms (AFLP). AFLP analysis is a polymerase chain reaction (PCR) based technique that allows us to compare individual genomes. Pst 1 digested genomic DNA is ligated to DNA adapters and amplified (via PCR) with primers matching the DNA adapters (Vos et al. 1995). Comparison of these amplified DNA fragments on agarose gels allows us to visualize genetic similarities and differences between individuals.

We have successfully developed the AFLP-Pst 1 protocol and can reliably reproduce individual DNA fragment patterns. Multiple DNA isolations from the same coral colony yield identical DNA fragment patterns. Preliminary results indicate that we may have identified a species specific monomorphic DNA fragment for one primer that may allow us to distinguish between M. alcicornis and M. complanata . Future research needs to be conducted to determine if the monomorphic DNA fragment is present in larger sample sizes and if it is present in any intermediates. We also need to amplify individual DNA samples with other primers.

Megan Waldrop, ’04 Temecula , CA
Majors: Biochemistry & Molecular Biology

Sponsor: Craig Tepper

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