The Research On Hoarding Behaviors And Interaction Networks Of Rodents Toward Seeds On A Global Scale

Rodentia is the largest group of mammals,containing more than 2000 species and widely distributed throughout the world.Many rodents have the behavior of hoarding plant seeds,which can be categorized as scatter-and larder-hoarding.In ecosystems,the scatter-or larder-hoarding of plant seeds by rodents will affect the dispersal process of plant seeds,and further affect the establishment of plant seedlings,forest regeneration and restoration,ecosystem structure and function,and ecosystem response to global climate change.Although most of the previous studies involved seed hoarding and interaction between rodents and plants,these studies tended to focus on the local scale or specific rodent and plant taxa,lacking large-scale,multi-species comparative analysis,especially the global patterns of hoarding behavior of rodents and their complex relationships with seed plants.In order to fill in these gaps,this study collected data on rodent hoarding behaviors and their interactions with plants(seeds)around the world.Using statistical models and network analysis,we analyzed the interactions between rodents and seed plants from the perspectives of ecology and evolution.We focused on two aspects:(1)the factors affecting scatter-and larder-hoarding behavior of rodents;(2)the topology structure and assembly mechanism of the multilayer interaction network between rodents and seed plants worldwide.(1)Through extensive literature search and data mining,the hoarding behaviors of rodents were compiled for the first time on a global scale,and a dataset of rodent hoarding behavior was constructed accordingly.On this basis,the phylogenetic signals,ancestral traits and factors of the hoarding behaviors of rodents were quantitatively evaluated using phylogenetic signal analysis,ancestral trait reconstruction and phylogenetic generalized linear mixed model.We found that the phylogenetic signals of hoarding behavior of rodents fit the Brownian model of evolution,suggesting that hoarding behavior is evolutionarily conserved.The reconstruction of ancestral traits by maximum likelihood method and maximum parsimony method indicates that larder-hoarding is probably ancestral,while scatter-hoarding may have multiple independent origins in evolution.Rodents with relatively large brain volume(EQ)and omnivorous diet tended to scatter-hoard,while those with relatively small brain volume and seed-eating diet tended to larder-hoard.Overall,the effect of body mass on hoarding behavior of rodents was not significant,but in Sciuridae,heavier individuals tended to larder-hoard,suggesting an interaction between phylogenetic relationships and body mass of rodents.In addition,it was found that rodents at higher latitudes tended to larder-hoard,while those at lower latitudes tended to scatter-hoard.(2)Based on the global dataset of seed predation and hoarding interactions between rodents and plants,an aggregated network of interactions between rodents and seed plants was constructed,and the aggregated network was divided into different interaction layers(predation layer,scatter-hoarding layer and larder-hoarding layer)according to different interaction ways.Then,we analyzed the topological structure of the aggregated network and the influence of geographical distance,phylogeny and functional traits of rodents and plants.Topological structure analysis shows that the aggregation network and three layers all have modular topology,and the scatter-hoarding had a compound topology.Different layers of aggregation network were connected by a small number of shared species,and the connection of different interaction layers also has specific patterns,that is,the degree and interaction similarity of shared species among different layers are correlated.Further analysis revealed that geographic distance,phylogeny,and functional traits between rodents and seed plants leaded to layer differentiation,modular structure,and nestedness within modules.In our research,for the first time,the factors influencing hoarding behavior and the topological structure and construction mechanism of rodent and seed plant interaction network are analyzed on a global scale,providing new insights into the ecological and evolutionary mechanisms of animal behavior and the relationship between animals and plants on a large scale.