Mating System And Dispersal Patterns Of The Natural Populations Of Metasequoia Glyptostroboides

Biodiversity plays an essential role in the maintenance of ecosystem functioning,and it also provides a huge biological resource that is of great potential for human exploitation.However,human activities and other factors are now seriously threatening biodiversity,leading to habitat fragmentation that decreases population size and segregates the remnant populations,consequently resulting in the loss of genetic diversity and inbreeding depression of endangered species and eventually increasing the risk of extinction.It is therefore necessary to understand the patterns of genetic diversity,mating system,pollen and seed dispersal of endangered plants for theoretical guidance in genetic breeding,which is the core of genetics conservation.Metasequoia glyptostroboides is a highly endangered species unique to China.In the present study,we focused on natural populations of M.glyptostroboides and studied its selfing and outcrossing offspring rates,spatial genetic structure and the effective gene dispersal distance using 6 polymorphic microsatellite loci.The result of parentage analysis revealed that selfing and outcrossing offspring proportions were 33.08%and 66.92%in natural populations of M.glyptostroboides respectively,suggesting high extent of selfing.Using the mixed mating model(MLTR),the multilocus outcrossing rate was estimated as 0.639 ± 0.066,which was consistent with the result of parentage analysis.The effective number of paternity was 2.5-3.6 per offspring,indicating lack of effective pollen donor in the studied populations.In addition,we failed to detect significant spatial genetic structure in the three natural populations of M.glyptostroboides probably because of the stronger dispersal of pollen and seeds than genetic drift.According to the result of the parentage analysis,we analyzed the gene dispersal patterns where the dispersal distances of the majority of both pollen(74.73%)and seeds(94.52%)were within the range of 500 m.Considering the discontinuous distribution of natural populations induced by anthropological activities,the preserve areas of wild M.glyptostroboides should not only be within the population but also extend to the perimeter zone,in order to facilitate the gene dispersal among populations and population regeneration.