Study On Relationship Between Species-Genetic Diversity Of Two Dominant Submerged Plants In Honghu,Lake.

Species diversity and genetic diversity are the two important parts of the biodiversity.The research of species-genetic diversity correlation(SGDC)will deepen the understanding about the nature of biodiversity.However,most recent studies only focused on the terrestrial plant communities,and the aquatic plant communities have been neglected.Submerged macrophytes play a structuring role in the shallow lake ecosystems.Here,a community survey and genetic analyses(based on AFLP markers)were carried out for two dominant submerged aquatic plants Potamogeton wrightii and Myriophyllum spicatum in Honghu Lake,a typical large,shallow,subtropical lake in the middle reaches of the Yangtze River.We estimated the species diversity(SD)and genetic diversity(GD)for the two species,and compared the level of genetic diversity and SGDCs between the conserved and disturbed areas in the lake.The results showed:For the two species,P.wrightii and M spicatum,there were no significant differences for Simpson index,species richness and genetic diversity both in conserved and disturbed area.The dominant values(DV)of P.wrightii changed in a large range(16.1-77.5%)in the disturbed area,while remained relatively stable in the conserved area(11.6-18.6%).In contrast,a relatively flat in both areas was found in M.spicatum,with 10.0-13.1%in conserved area and 7-11.2%in conserved area.Mantel test revealed non-correlation between genetic differentiation and geographical distances for both P.wrightii(r=0.139,P=0.808)and M.spicatum(r= 0.0046,P=0.804).For the two species,no correlation was found between SD and GD in the conserved area,disturbed area and whole Honghu Lake,which may be explained by nonparallel changes in SD and GD.SD was influenced by species recovery in the ecological niches,while GD was influenced by species life forms,habitat features,historical connectivity and founder effects.This study provides a new insight and basic information to relationship between species diversity and genetic diversity of submerged plant communities in shallow lakes.Based on the results,conservation strategies should be set on both levels of diversity(SD and GD)in order to restore and protect the diversity of submerged macrophytes in Honghu Lake.