Patterns of genetic differentiation in resting egg banks of a rotifer species complex in Spain
Ortells, Raquel; Snell, Terry W.; Gómez, Africa; Serra, Manuel
Archiv für Hydrobiologie Volume 149 Number 4 (2000), p. 529 - 551
published: Nov 24, 2000
ArtNo. ESP141014904000, Price: 29.00 €
Here we present the first population study on the genetic diversity of a rotifer species complex (Brachionus plicatilis) in a geographic area (Eastern Spain), which includes inland and coastal habitats. A novel approach was used by hatching resting eggs from sediment samples rather than sampling rotifers from the water column. Hatchlings from resting eggs sampled at 22 sites resulted in 434 clones which were screened using four polymorphic allozyme loci. A high level of genetic diversity was found consisting of 43 multilocus genotypes which were clustered into six well differentiated groups, often found in sympatry, with few or no hybrids between them. Mating experiments revealed preferences that supported the observed pattern of genetic differentiation. Some groups had restricted geographical distributions, and showed a preference for habitat type. Our results confinn patterns found in other zooplanktonic organisms and suggest that classical taxonomy has underestimated biological diversity in rotifers. The presence of additional cryptic sibling species in this complex seems very probable. Our study demonstrates the feasibility of using sediment sampling to explore genetic differentiation between species and populations, and shows the role of the resting egg bank in maintaining genetic diversity.