B. Stobart et Jah. Benzie, ALLOZYME ELECTROPHORESIS DEMONSTRATES THAT THE SCLERACTINIAN CORAL MONTIPORA-DIGITATA IS 2 SPECIES, Marine Biology, 118(2), 1994, pp. 183-190
Allozyme electrophoresis at five loci was used to clarify the species
status of two morphs of the scleractinian coral Montipora digitata (Da
na, 1846), using specimens collected from three locations off the Quee
nsland coast between October 1991 and April 1993. The two morphs, occu
rring sympatrically, were distinguished by one fixed gene difference a
t Locus LT-2 and frequency differences at three other loci, indicating
reproductive isolation between them. Populations of both morphs were
generally in Hardy-Weinberg equilibrium, suggesting that sexual reprod
uction does occur. Despite sampling designed to reduce the chance of c
ollecting clone-mates, the genetic diversity ratio (G(o):G(e)) indicat
ed that asexual reproduction also occurs. This is in agreement with th
e known modes of reproduction for this species. There was significant
genetic differentiation between populations of one of the morphs of M.
digitata. This could have been influenced by greater degrees of asexu
al reproduction in this morph, selection within sites, or variation in
larval survival and recruitment patterns. Relatively low F-st (differ
entiation among populations) values found for a broadcast spawning spe
cies during this study are in accordance with the hypothesis that broo
ded planulae are adapted for rapid settlement, whereas planulae produc
ed by broadcast spawners are adapted for widespread dispersal.