Ecological Characteristics And Differentiation Mechanisms Of Fruit Color Type Of Viscum Coloratum Population In Northeast China

Viscum coloratum,a widely distributed dioecious perennial evergreen hemiparasitic shrub in East Asia,features berries with red-yellow dimorphism and relies on frugivorous birds for seed dispersal.This study focuses on the populations of Viscum coloratum in Northeast China,integrating extensive field surveys and laboratory experiments with multidisciplinary approaches including population ecology,molecular genetics,and biostatistics.It systematically investigates the host species diversity and parasitic patterns of Viscum coloratum across three latitudinal zones in Northeast China(Heilongjiang,Jilin,Liaoning,Inner Mongolia),as well as the distribution patterns and population structure,spatial variation and patterns of population quantity characteristics,geographical variation in fruit color dimorphism,and genetic diversity and structure of the populations.This provides new insights into the ecological and evolutionary significance of Viscum coloratum populations.The main findings and conclusions are as follows:1.In the secondary forests across three latitudinal zones in Northeast China,the hosts of Viscum coloratum are deciduous trees.All hosts for the 8220 individuals from23 Viscum coloratum populations encompass 2896 trees,belonging to 41 species across19 genera and 12 families.The diversity of hosts decreases with increasing latitude.Among the recorded 41 host species,including Tilia amurensis,Alnus sibirica,Carpinus cordata,Quercus acutissima,Q.rubrum,Castanea mollissima,Syringa reticulata var.amurensis,Acer tegmentosum,A.mono,Malus asiatica,M.baccata,Pyrus betulaefolia,Phellodendron amurense,and others,13 species are recorded for the first time in Northeast China.Introducing infection intensity levels into the analysis reveals Viscum coloratum’s preference for specific hosts.2.In Northeast China,the distribution coefficient of Viscum coloratum populations is greater than 8,indicating a strong clumped distribution pattern.The sex ratio(male/female)deviates significantly from the expected 1:1 in dioecious plants,suggesting age structure mostly indicative of population growth.3.Significant differences in growth and biomass production between male and female plants indicate adaptative responses to environmental changes.4.The phenotype of Viscum coloratum fruits in Northeast China can be categorized into red(spectral value 630-680 nm)and yellow(560-595 nm).Pollination experiments show that the female plant determines the fruit color,which is stable and exhibits significant linear geographical variation with latitude.This suggests a temperature adaptation hypothesis to explain the maintenance mechanism of fruit color dimorphism across different latitudinal populations.5.Viscum coloratum in Northeast China shows relatively high genetic diversity,reflecting its outcrossing reproductive characteristics.Genetic differentiation among populations is low,with an average Fst value of only 0.060.The dispersal pattern suggests initial settlement in the southern low latitude area,followed by dispersal to mid and high latitude areas,potentially related to frugivorous bird migration routes.