Speciation in the serranid fish Hypoplectrus

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Marine Biology and Fisheries

First Committee Member

C. Richard Robins - Committee Chair


Research was conducted to determine the species status of individual color morphs of fish in the genus Hypoplectrus (family Serranidae). Crossing two different morphs of Hypoplectrus in the laboratory produced an F1 generation with an intermediate phenotype to that of the parental types. This intermediate morph cannot be assigned to any known morph and is thus termed a hybrid. Individuals of several Hypoplectrus morphs were found to select only individuals of the same morph as a mate when provided a choice. Individual fish can sometimes be forced to mate with an individual of a different morph by not providing a choice of mates. The occurrence of hybrids was found to be low in the field, corresponding to the low occurrence of mixed matings in the field. Some differences in distribution were found between the different hamlet morphs. The new data provided by this study indicates that the different color morphs warrant full species rank. It is hypothesized that speciation in Hypoplectrus was driven by the rise and fall of sea level during the last ice age.


Biology, Ecology; Biology, Genetics; Biology, Oceanography

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