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

摘要

Microsatellite DNA is widely used as population genetic marker, but the cost of using microsatellites is high, as they usually need to be developed and optimized for each species separately. Cross-species amplification of microsatellites is therefore commonly applied to bring down the cost, but it can also involve genotyping errors. We studied cross-species amplification of microsatellites 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 for a more distantly related Pacific species [L. subrotundata (Carpenter, 1864)] suffered from more amplification problems than markers developed for one of the species in the Atlantic group (L. saxatilis). We also compared variation in amplification success among the species and among different regions in the NE Atlantic. Approximately half of the 12 primers developed for L. subrotundata and the seven primers developed for L. saxatilis were successfully amplified in other species of the subgenus. The success was dependent on phylogenetic distance among species within the subgenus. On the other hand, the variation in performance of the loci between geographically remote populations of the same species was as high as variation among the species. In earlier studies statistical analyses indicated that several loci showed a heterozygote deficiency due to null alleles. The presence of null alleles was confirmed by a segregation analysis of the microsatellite loci in eight half-sib families of L. saxatilis.