MEPS 188:73-79 (1999)  -  doi:10.3354/meps188073

ABSTRACT: The occurrence of inbreeding was investigated in Celleporella hyalina, which has been reported as being capable of selfing. In total, 4 tetranucleotide microsatellite markers were scored in populations from sites within the Menai Strait (Wales) and the Yealm Estuary (Plymouth, England). All loci in all populations were in Hardy-Weinberg equilibrium, with insignificant F_is values, which indicates that C. hyalina in these populations generally outbreed. No significant differences were found between populations up to 8 km apart, indicating sufficient gene flow on this scale to form a single breeding population despite geographic separation. The Plymouth population was significantly (p < 0.00001) deviant from the others, indicating possible isolation by distance at the scale of 900 km. C. hyalina cultured in the laboratory were observed to spawn sperm into the surrounding seawater. Sib larvae were found to settle randomly with respect to each other. In isolation C. hyalina failed to produce offspring, though a small proportion brooded abortive embryos. Pairings between individuals of differing genotypes resulted in the production of offspring, all of which, when genotyped with respect to the parent colonies, were found to be the result of outcrossing.

KEY WORDS: Inbreeding · Fertilisation · Outcrossing · Sibs · Genetics · Bryozoan · Celleporella