Investigation of Population Structure and Distribution of the Invasive Bryozoan Watersipora Species along the California Coast using Nuclear and Mitochondrial DNA

This study combined microsatellite nuclear DNA analysis with cytochrome c oxidase 1 (COI) mitochondrial DNA analysis to evaluate coastal population structure, environmental factors influencing population distribution, and the potential for hybridization among coexisting Watersipora haplogroups along the California coast. Mitochondrial DNA analysis of the COI gene identified three haplogroups: W. subtorquata clade A, W. subtorquata clade B, and W. new species. Analyses resulted in seven haplotypes for haplogroup clade A, and a single haplotype in each haplogroup clade B and new species. Microsatellite data indicated the greatest source of genetic variation in the two species examined (W. subtorquata and W. new species) was within individuals of the population (53.7% and 69.3%, respectively), compared to among individuals (36.2% and 20.2%, respectively), populations (5.5% and 10.5%, respectively), and regions (4.6% and 0.0%, respectively). Congruence analysis between mitochondrial and nuclear data correctly matched nuclear genotypes with mitochondrial haplogroups. Evidence of hybridization was not detected among the two Watersipora species, notwithstanding one highly variable locus. Points of introduction could not be identified; however, locations in regions with high ship traffic displayed a greater number of total alleles