High association strengths are linked to phenotypic similarity,including plumage color and patterns,of participants in mixed-species bird flocks of southwestern China

Participants in mixed-species bird flocks(MSFs)have been shown to associate with species that are similar in body size,diet,and evolutionary history,suggesting that facilitation structures these assemblages.In addition,several studies have suggested that species in MsFs resemble each other in their plumage,but this question has not been systematically investigated for any MsF system.During the nonbreeding season of 2020 and 2021,we sampled 585 MSFs on 14 transects in 2 habitats of Tongbiguang Nature Reserve in western Yunnan Province,China.We performed social network analysis and the Multiple Regression Quadratic Assignment Procedure to evaluate the effect of 4 species traits(body size,overall plumage color,distinctive plumage patterns,and diet)and evolutionary history on species association strength at the whole-MSF and within-MSF levels.All 41 significant relationships showed that species with stronger associations were more similar in their various traits.Body size had the strongest effect on association strength,followed by phylogeny,plumage patterns,and plumage color;diet had the weakest effect.Our results are consistent with the hypotheses that the benefits of associating with phenotypically similar species outweigh the potential costs of interspecific competition,and that trait matching can occur in plumage characteristics,albeit more weakly than in other traits.Several explanations exist as to why similarities in plumage may occur in MSFs,including that they could reduce predators'ability to target phenotypically"odd"individuals.Whether trait matching in plumage occurs through assortative processes in ecological time or is influenced by co-evolution requires furtherstudy.

Assembly of plant communities in coastal wetlands--the role of saltcedar Tamarix chinensis during early succession

Aims The mechanisms of plant community assembly are hypothesized to vary at different stages of succession.Here,we explore the local assemblage structure of a herbaceous plant community at its early stage of succession in a supratidal wetland.specifically,we assess the role of Chinese saltcedar(Tamarix chinensis),the lone dominant shrub species,in shaping the spatial structure and species composi-tion in the local plant community,after landscape alteration.Methods We used the multivariate trend-surface analysis for analyzing the spatial structure of the community composition.a null model was also used to detect potential biotic interactions between species.statistical significance was derived from a permutation test by randomizing the presence-absence matrix and functional traits independently.sensitivity analysis by randomly selecting 50 subplots and repeating the null model tests was also done.Finally,rank correlation analysis was used to study the relationship between effect sizes and distance to nearest T.chinensis individuals.Important Findings The herbaceous plant community was highly structured and shaped by the presence of T.chinensis.at local scale,two functional traits,plant height and leaf area,were found to be significantly convergent.Dispersal,environmental stress and interspecific competition played a trivial effect on the local community assembly.The facilitating effect of T.chinensis on the pioneering herbaceous plants,through acting as a wind shelter,was put forward as the dominant community assembly process.