Adaptive genetic diversity of dominant species contributes to species co-existence and community assembly

The synthesis of evolutionary biology and community ecology aims to understand how genetic variation within one species can shape community properties and how the ecological properties of a community can drive the evolution of a species.A rarely explored aspect is whether the interaction of genetic variation and community properties depends on the species'ecological role.Here we investigated the interactions among environmental factors,species diversity,and the within-species genetic diversity of species with different ecological roles.Using high-throughput DNA sequencing,we genotyped a canopydominant tree species,Parashorea chinensis,and an understory-abundant species,Pittosporopsis kerrii,from fifteen plots in Xishuangbanna tropical seasonal rainforest and estimated their adaptive,neutral and total genetic diversity;we also surveyed species diversity and assayed key soil nutrients.Structural equation modelling revealed that soil nitrogen availability created an opposing effect in species diversity and adaptive genetic diversity of the canopy-dominant Pa.chinensis.The increased adaptive genetic diversity of Pa.chinensis led to greater species diversity by promoting co-existence.Increased species diversity reduced the adaptive genetic diversity of the dominant understory species,Pi.kerrii,which was promoted by the adaptive genetic diversity of the canopy-dominant Pa.chinensis.However,such relationships were absent when neutral genetic diversity or total genetic diversity were used in the model.Our results demonstrated the important ecological interaction between adaptive genetic diversity and species diversity,but the pattern of the interaction depends on the identity of the species.Our results highlight the significant ecological role of dominant species in competitive interactions and regulation of community structure.

Genetic diversity and differentiation follow secondary succession in a multi-species study on woody plants from subtropical China

Aims Species diversity and genetic diversity may be affected in parallel by similar environmental drivers.However,genetic diversity may also be affected independently by habitat characteristics.We aim at disentangling relationships between genetic diversity,species diversity and habitat characteristics of woody species in subtropical forest.Methods We studied 11 dominant tree and shrub species in 27 plots in Gutianshan,China,and assessed their genetic diversity(A_(r))and population differentiation(F′_(ST))with microsatellite markers.We tested if Ar and population specific F′_(ST) were correlated to local species diversity and plot characteristics.Multi-model inference and model averaging were used to determine the relative importance of each predictor.Additionally,we tested for isolation-by-distance(IBD)and isolation-by-elevation by regressing pairwise F′_(ST) against pairwise spatial and elevational distances.Important Findings Genetic diversity was not related to species diversity for any of the study species.Thus,our results do not support joint effects of habitat characteristics on these two levels of biodiversity.Instead,genetic diversity in two understory shrubs,Rhododendron simsii and Vaccinium carlesii,was affected by plot age with decreasing genetic diversity in successionally older plots.Population differentiation increased with plot age in R.simsii and Lithocarpus glaber.This shows that succession can reduce genetic diversity within,and increase genetic diversity between populations.Furthermore,we found four cases of IBD and two cases of isolation-by-elevation.The former indicates inefficient pollen and seed dispersal by animals whereas the latter might be due to phenological asynchronies.These patterns indicate that succession can affect genetic diversity without parallel effects on species diversity and that gene flow in a continuous subtropical forest can be restricted even at a local scale.