Microsatellite cross-species amplification in the genus Littorina and detection of null alleles in Littorina saxatilis

Microsatellite DNA is widely used as population genetic marker,but the cost of using microsatellites is high, as they usuallyneed to be developed and optimized for each species separately.Cross-species amplification of microsatellites is thereforecommonly applied to bring down the cost, but it can also involvegenotyping errors. We studied cross-species amplification ofmicrosatellites in four species of the Atlantic group of Littorina(Neritrema): L. saxatilis (Olivi, 1792), L. obtusata (Linnaeus,1758), L. fabalis (Turton, 1825) and L. arcana Hannaford Ellis,1978 to investigate whether markers originally developed fora more distantly related Pacific species [L. subrotundata (Carpenter,1864)] suffered from more amplification problems than markersdeveloped for one of the species in the Atlantic group (L. saxatilis).We also compared variation in amplification success among thespecies and among different regions in the NE Atlantic. Approximatelyhalf of the 12 primers developed for L. subrotundata and theseven primers developed for L. saxatilis were successfully amplifiedin other species of the subgenus. The success was dependenton phylogenetic distance among species within the subgenus.On the other hand, the variation in performance of the locibetween geographically remote populations of the same specieswas as high as variation among the species. In earlier studiesstatistical analyses indicated that several loci showed a heterozygotedeficiency due to null alleles. The presence of null alleleswas confirmed by a segregation analysis of the microsatelliteloci in eight half-sib families of L. saxatilis. (Received 2 April 2007; accepted 19 November 2007)