Millepora complanata and Millepora alcicornis are two related species of fire coral found in the tropical western Atlantic Ocean (San Salvador, Bahamas). Each species has distinct morphological features: M complanata is broad, smooth, and blade-like and M alcicornis is thin with knobby branches (Tepper, 2000). However, some fire coral exhibit characteristics of both species (intermediate morphological characteristics) making taxonomic identification difficult. Previous research in our lab has indicated that these unclassified morphological intermediates may be interspecific hybrids (Tepper and Cauley, 2001). Coral release their gametes on the same few nights once a year and Vollmer and Palumbi (2002) have shown that occasionally sperm from one species fertilizes eggs from another species creating interspecific hybrids.
Our results are based on a DNA fingerprinting technique called RAPD (Random Amplified Polymorphic DNA), but we have decided to discard this technique due to the presence of artifacts and inconsistent results. We have begun using AFLP (Amplified Fragment Length Polymorphism) analysis, a polymerase chain reaction (PCR) based technique, that allows us to compare inter/intra species DNA fingerprints without the production of artifacts. In this technique, restriction enzyme digested genomic DNA is ligated to DNA adapters and amplified (via PCR) with primers matching the DNA adapters (Vos et al. 1995). Analysis of these DNA fingerprint fragments on agarose gels allows us to visualize genetic similarities and differences between our samples.
Preliminary results indicate that we may have identified species specific diagnostic markers that allow us to distinguish M complanata from M alcicornis. Further research needs to be conducted to confirm the presence of these species specific diagnostic markers and their suitability in allowing us to identify intermediate forms that may be interspecific.
Megan Waldrop, ’04 Temecula, CA
Majors: Biochemistry and Molecular Biology, French
Sponsor: Craig Tepper