High genetic diversity in gametophyte clones of Undaria pinnatifida from Vladivostok, Dalian and Qingdao revealed using microsatellite analysis

Breeding practice for Undaria pinnatifida （Harvey） Suringar requires the screening of a large number of offspring from gametophyte crossings to obtain an elite variety for large-scale cultivation. To better understand the genetic relationships of different gametophyte cultures isolated from different sources, 20 microsatellite loci were screened and 53 gametophyte clone cultures analyzed for U. pinnatijqda isolated from wild sporophytes in Vladivostok, Russia and from cultivated sporophytes from Dalian and Qingdao, China. One locus was abandoned because of poor amplification. At the sex-linked locus of Up-AC-2AS, 3 alleles were detected in 25 female gametophyte clones, with sizes ranging from 307 to 316 bp. At other loci, 3 to 7 alleles were detected with an average of 4.5 alleles per locus. The average number of alleles at each locus was 1.3 and 3.7 for Russian and Chinese gametophyte clones, respectively. The average gene diversity for Russian, Chinese, and for the combined total of gametophyte clones was 0.1, 0.4, and 0.5, respectively. Russian gametophyte clones had unique alleles at 7 out of the 19 loci. In cluster analysis, Russian and Chinese gametophyte clones were separated into two different groups according to genetic distance. Overall, high genetic diversity was detected in gametophyte clones isolated from the two countries. These gametophyte cultures were believed to be appropriate parental materials for conducting breeding programs in the future.

Restricted dispersal determines fine-scale spatial genetic structure of Mongolian gerbils

Restricted gene flow may cause positive spatial genetic autocorrelation of animal populations at fine spatial scales. The Mongolian gerbil Meriones unguiculatus is a territorial, social rodent. Territoriality may create social fences to restrict dispersal or gene flow of Mongolian gerbils to a short distance. Restricted dispersal may differentiate fine-scale spatial genetic structure of populations with increasing distances （i.e., isolation by distance [IBD]）. Competition for mates and inbreeding avoidance may result in equal dispersal propensity and subsequently similar spatial genetic autocorrelation between males and females of monogamous gerbils. We genotyped 327 gerbils, live captured from 26 burrow systems on a 9-ha plot in northcentral Inner Mongolia, China, using seven microsateliite loci. Spatial genetic autocorrelation was positive within 80 m and became negative from 80 m to 200 m, suggesting restricted gene flow. Inter-group genetic and geographic distances were related positively, supporting the IBD model. Live trapping data demonstrated equal dispersal propensities of male and female gerbils. Restricted dispersal and social organization may determine fine-scale spatial population genetic structure of social rodents.