Analysis Of Mitochondrial DNA Sequence Variation And Ecological Distribution Of Six Color Morphologies Of The Serranid Fish Hypoplectrus

William P. Christenson*
University of Charleston, 205 Ft Johnson, Charleston, SC 29412; Phone: (843) 762-5406; Fax: (843) 406-4001; email: wpchrist@hotmail.com

Members of the genus Hypoplectrus are small, brightly colored coral reef fish commonly referred to as hamlets. The twelve color morphologies of this genus are structurally invariant rendering them indistinguishable save for color. These various color morphs have historically been regarded as either many different or one polychromatic species evidenced by morphology, protein polymorphism and/or behavioral characteristics. However, strong genetic evidence has previously been lacking. In this study, the genetic structure of six color morphs of Hypoplectrus in the British Virgin islands and Cayman islands has been investigated using nucleotide sequences of regions of the mitochondrial DNA molecule via the polymerase chain reaction. No variation was found among sequences of the 16s rRNA region from individuals of 'yellowbelly', 'yellowtail', 'shy', 'barred', or 'black' hamlets. Sequences from the 'butter' hamlet differed by only one base with sequences from the previous five color morphs. Data were also gathered on the ecological distribution of each color morph. Habitat separation may be a prezygotic reproductive isolating mechanism within the genus. The phylogenetic and systematic implications of these and other data will be discussed.