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Exploring the emergence of cooperation in the populations of self-interested individuals is of huge challenge. Evolutionary game theory has been utilized to investigate the evolution of cooperation. In recent years, many researchers have paid massive attention on the evolution of cooperative behavior from the perspective of multiple games, especially the transition of games. Nevertheless, not only are the current interactive actions crucial, but also the historical interactive experience is fateful. Motivated by this, the persistence-based game transition mechanism is proposed and introduced to investigate the evolution of cooperation, where both the current pairwise strategies and the persistence of the pairwise strategies determine the game played in the next time step. Through analyzing the evolutionary results of strategies and games, we find that the cooperation can be facilitated by the enhanced network reciprocity as the persistence-based game transition makes mutual cooperators play games with weak dilemma more persistently. • A persistence-based game transition is proposed in multi-games. • In our model, both pairwise interactive strategies and the persistence of pairwise strategies determine the game transition. • The persistence-based game transition can facilitate cooperation through enhancing network reciprocity. [ABSTRACT FROM AUTHOR]

Herbivores strongly affect the ecological structure and functioning in seagrass bed ecosystems, but may exhibit density-dependent effects on primary producers and carbon sequestration. This study examined the effects of herbivorous snail (Cerithidea rhizophorarum) density on snail intraspecific competition and diet, dominant seagrass (Thalassia hemprichii) and epiphyte growth metrics, and sediment organic carbon (SOC). The growth rates of the herbivorous snail under low density (421 ind m−2) and mid density (842 ind m−2) were almost two times of those at extremely high density (1684 ind m−2), indicating strong intraspecific competition at high density. Herbivorous snails markedly reduced the epiphyte biomass on seagrass leaves. Additionally, the seagrass contribution to herbivorous snail as food source under high density was about 1.5 times of that under low density, while the epiphyte contribution under low density was 3 times of that under high density. A moderate density of herbivorous snails enhanced leaf length, carbon, nitrogen, total phenol and flavonoid contents of seagrasses, as well as surface SOC content and activities of polyphenol oxidase and β-glucosidase. However, high density of herbivorous snails decreased leaf glucose, fructose, detritus carbon, and total phenols contents of seagrasses, as well as surface SOC content and activities of polyphenol oxidase and β-glucosidase. Therefore, the effects of herbivorous snail on seagrass, epiphyte and SOC were density-dependent, and moderate density of herbivorous snail could be beneficial for seagrasses to increase productivity. This provided theoretical guidance for enhancing carbon sink in seagrass bed and its better conservation. [Display omitted] • Intraspecific competition inhibited herbivorous snail growth. • The presence of herbivorous snail markedly reduced the epiphyte biomass. • Moderate snail density facilitated seagrass by removing epiphyte and enhanced SOC. • High snail density adversely affected seagrass and sediment carbon sequestration. • Cultivate herbivore in moderate density benefits seagrass conservation. [ABSTRACT FROM AUTHOR]

In repeated games, historical interactions lead to varying environment. Among existing studies, the variation of environment or game is basically considered from the perspective of nodes, while in pairwise game, it is more reasonable to consider the interactive environment from the perspective of edges. In addition, since historical interactive experience of pairwise players has an impact on the current interactive environment, the duration of pairwise strategies produces differentiated results. Therefore, we consider the persistence-dependent dynamic interactive environment where the persistence of pairwise strategy affects the weight between two interacting players, and the game resource of interactive environment is influenced by varying weight. The results suggest that the introduction of persistence-dependent dynamic interactive environment can effectively enhance cooperation, and a larger weight increment of CD link generates a higher cooperation level as it indicates that the reward for cooperative behavior is significant, although a single cooperator for the pairwise interacting players. • We introduce the persistence-dependent dynamic interactive environment in prisoner's dilemma game. • An intermediate variable, weight, is introduced and influenced by the strategy persistence of pairwise players. • The fluctuation scale of weight is dependent on distinct kinds of edge links, and a parameter η for CD link is introduced. • The variation of weight determines the changing resources for the interactive environment. • Our new model can boost cooperation significantly, especially for the larger η. [ABSTRACT FROM AUTHOR]

In previous studies about heterogeneous investment, many researchers only focus on the monodirectional effect of reputation, but ignore the reversed influence about the heterogeneity of reputation fluctuation driven by investment. Given this, considering the interplay between reputation and heterogeneous investment, we explore the evolution of cooperation in public goods game. In detail, each player's reputation situations in different groups determine its differentiated investment amounts, and in turn, the heterogeneity of reputation fluctuation is dependent on how much it invests into each group. Furthermore, we introduce two parameters, α and β , to characterize the effect degree of investment on heterogeneous reputation fluctuation and the one of reputation on heterogeneous investment, respectively. The simulation results suggest that cooperation can be boosted to some extent, especially for the larger α and β , as they magnify the interplay of reputation and heterogeneous investment. • We introduce the interplay between reputation and heterogeneous investment in the public goods game. • Reputation effects unequal investment and heterogeneous reputation fluctuation is effected by investment in turn. • We introduce parameter α to characterize the effect degree of investment on heterogeneous reputation fluctuation. • Parameter β is presented to denote the effect degree of reputation on heterogeneous investment. • Our new model can boost cooperation significantly, especially for the larger α and β. [ABSTRACT FROM AUTHOR]

• A new framework of multiple public goods games considering the persistence and transition of games is proposed. • The heterogeneous public resource of public goods game evolves with the persistence and transition of games. • Our new model can promote cooperation effectively, especially under the condition with scarce resource. Many various projects may exist in an enterprise in parallel, which leads to distinct group interactions. Team members cooperate in their respective projects, and sometimes it is possible to engage in several concurrent projects. Owing to practice makes perfect, the longer the duration of members participating in an identical project is, the higher benefits will be under same contribution. However, in a fiercely competitive environment, a huge conflict of interest between groups and individuals which results in social dilemma makes projects difficult to proceed smoothly. The experience of direct reciprocity shows that repeated interactions can alleviate this problem, but most multi-person dilemma studies consider a single game scenario, and public resources remain constant. Here we introduce a general framework of multiple public goods games. Taking the public goods game with threshold into consideration, public resource evolves with the persistence and transition of games. Our results suggest although collaborators are at a disadvantage in different game scenarios, our model can still effectively promote the overall cooperation in multiple public goods games. Especially, it performs better when public resource is relative scarce. [ABSTRACT FROM AUTHOR]

Zn, Pb, Cr, Cu, Ni, Cd concentration and ecological risk were studied in three bays to evaluate the heavy metal (HM) contamination of seagrasses. Seasonal HM accumulation varied according to locations, seagrass species and tissues. Halophila beccarii had much higher HM concentrations except for Cr in Zhelin Bay, however, bioconcentration factors (BCF) of Cu, Ni, Pb, Zn were higher in Liusha than Zhelin Bay. Cr was much enriched in Thalassia hemperichii and Enhalus acoroides than Halophila beccarii and Halophila ovalis. Cr, Cu, Ni, Pb were easy to accumulate in belowground tissues in Halophila ovalis. In contrast, almost all HM were more enriched in aboveground tissues in other species. Generally, BCF exceeding 1 and high metal pollution index suggested HM had potential ecological risk on seagrasses. The results provide the reference for managing and protecting seagrass ecosystem in South China, and are significant to expand the global seagrass detection network. • Seasonal variations of heavy metal concentrations in seagrasses were significant. • Cd, Cr, Cu, Ni concentrations in H. beccarri were at the high levels in Zhelin Bay. • Cr was much more concentrated by T. hemperichii and E. acoroide in Xincun Bay. • Cr, Cu, Ni, Pb were easier to concentrate in belowground tissues in H. ovalis. • High BCFs and MPIs indicated the potential ecological risk on seagrasses. [ABSTRACT FROM AUTHOR]

Seagrass beds act as blue carbon sinks globally; however, little attention has been given to carbon dynamics in the seagrass rhizosphere. Hence, in this study, the quantity and characteristics of dissolved organic carbon (DOC) from root exudation of the three dominant tropical seagrasses (Thalassia hemprichii , Enhalus acoroides , and Cymodocea rotundata) and sediment pore water beneath them were compared, to examine their interspecific differences, and to establish a connection between seagrass root exudation and sediment carbon. The rate of root-exuded DOC from T. hemprichii (2.15 ± 1.06 mg g DW root-1 h-1) was significantly higher (p < 0.05) than that from E. acoroides (0.72 ± 0.39 mg g DW root-1 h-1) and C. rotundata (0.46 ± 0.25 mg g DW root-1 h-1). Root exudation rates were more affected by root hair density and root hair length than by root carbon, nitrogen, and soluble sugar content. Simultaneously, DOC concentrations of the sediment pore water beneath T. hemprichii , E. acoroides and C. rotundata were 22.05 ± 11.61 mg l-1, 15.55 ± 2. 66 mg l-1, and 14.32 ± 1.82 mg l-1, respectively. The corresponding absorption coefficients at 254 nm (a 254) were 30.53 ± 18.00, 17.31 ± 2.24, and 14.07 ± 2.03, respectively, while the relevant specific ultraviolet absorbances at 254 nm (SUVA 254) were 1.38 ± 0.29, 1.19 ± 0.26 and 1.03 ± 0.28, respectively. Therefore, the roots of T. hemprichii exuded DOC at a higher rate, leading to a higher pore-water DOC pool in the sediment. This suggests that T. hemprichii played a greater role in the sediment carbon pool through root exudation. Thus, it can be considered as the priority species for transplantation to promote the carbon sink function of seagrass beds. [Display omitted] • Interspecific differences in root exudation existed among three tropical seagrasses. • Higher rate of root-exuded DOC from Thalassia hemprichii was observed. • T. hemprichii played a greater role in sediment carbon pool through root exudation. • T. hemprichii can be the priority species for transplantation to promote carbon sink. [ABSTRACT FROM AUTHOR]

• A reputation-based strategy persistence mechanism in evolutionary game is proposed. • Our mechanism illuminates that the scale of reputation fluctuation totally depends on the persistence of last strategy. • A parameter, α , illustrating the impact of strategy persistence on reputation variation, is introduced. • Cooperation can be promoted effectively by our new mechanism. Understanding the emergence and maintenance of cooperation in social dilemma has received a lot of attention. In previous research, many scholars found that the reputation mechanism can promote cooperation, and the variation of reputation is consistent. However, in reality, according to both one's current action and past experiences, every individual's impression from others is modified to varying extent everyday. In other words, the length of duration of the same performance influences the diverse scale of their own reputation fluctuation. Therefore, a reputation-based strategy persistence mechanism, in which the increment of current reputation is determined by the persistence of last strategy, is proposed. Moreover, we introduce a parameter α to illustrate the impact of strategy persistence on reputation variation. The results of simulation show that the new mechanism paves the way for cooperation in evolutionary game, and the smaller α is, the better the mechanism performs. [ABSTRACT FROM AUTHOR]

In previous studies of evolutionary games, players change reference objects at each time step. However, in real life, many people tend to consistently imitate outstanding role models instead of changing reference objects frequently. From this, a persistent imitation rule is proposed. In detail, a persistent imitator will persist in imitating his or her reference object until the wealth exceeds that of the reference object or the duration of continuous imitation exceeds a specific value. Furthermore, to reflect inter-individual differences, we divide the players into two categories, persistent imitators and random imitators. The simulation suggests that the presence of a high proportion of persistent imitators has a significant effect on the development of cooperation, and the level of cooperation increases as the maximum duration of imitation increases. However, when the proportion of persistent imitators or the maximum duration of imitation is small, the promotion effect on cooperation is not obvious. • The persistent imitation of reference objects is proposed. • Persistent imitators refresh the role model if their payoff exceeds the last one's. • After the maximum duration, the persistent imitator chooses a new reference object. • The presence of persistent imitators can effectively facilitate cooperation. [ABSTRACT FROM AUTHOR]

Previous experience suggests that prior agreement (a mechanism to test how strongly peers are committed to a common goal) and posterior compensation (a way to compensate cooperators by punishing defectors who violate their commitments) together contribute to the flourishing of cooperation. Far less is known, however, how the determination of the optimal threshold for prior agreement in force and the posterior compensation affect collaboration, and the relevance of different strategies. Here, in the context of public goods games and using an evolutionary game theory model, we investigate the evolution of cooperation and the relevance of different strategies by introducing prior agreements and posterior compensation in structured populations. Analytical results show that posterior compensation does not always promote cooperation and that there are sudden increases and decreases in the first-order phase transition. Interestingly, prior agreements without posterior compensation can also effectively restrain defectors, with cooperation abundance remaining at a high level. Furthermore, the threshold of effective agreement has nonlinear effects on cooperation, with cooperation abundance peaking at intermediate thresholds under specific parameters. • The prior agreements and posterior compensation are introduced in network reciprocity. • The model aims to determine the optimal threshold of agreements and the correlation between different strategies. • The effects of posterior compensation and the threshold of agreements in force on the proportion of cooperation are not linear. [ABSTRACT FROM AUTHOR]

Identifying the most influential individuals in structured populations is an important research topic throughout network science. Previous studies, whether identifying the initial cooperators in a network that can lead to the spread of cooperation or assessing the chances that an intrusive defector may lead to the collapse of cooperation, have assumed that all individual attributes are homogeneous. However, heterogeneity among humans is widespread and can sometimes affect cooperation and welfare. For example, the layout of non-cooperative individuals in cooperative individuals inhibits the evolution of cooperation. Therefore, specifying the heterogeneity of individuals and studying the effect of their initial position on cooperation is the focus of our attention. Here we hypothesize that individuals in the network are divided into cooperative and non-cooperative individuals according to the heterogeneity of social value orientations, and we investigate the effects of the initial position of non-cooperative individuals on cooperation by adding them through different ranking rules to the network composed of cooperative individuals. We investigate separately the effects of the proportion of non-cooperative individuals, the proportion of initial cooperators of different types of individuals and different game scenarios on cooperation under different ranking rules. The results show that the addition of non-cooperative individuals to cooperative populations can effectively hinder the spread of cooperation. We also find that the proportion of initial cooperators for different types of individuals and the effects of different game types on population evolution also differ significantly under different ranking rules. • Identifying how the most influential individuals have an impact on the evolution of cooperation under different ranking rules. • Our model classifies individuals into non-cooperative and cooperative individuals through the heterogeneity of their social value orientations, and thus investigates the impact of strategically positioned non-cooperative individuals who tend to defect. • Non-cooperative individuals block cooperation between cooperative individuals; the initial proportion of different types of individuals as well as different game scenarios also have a significant effect on the evolution of cooperation. [ABSTRACT FROM AUTHOR]

Seagrass-herbivore interactions play a principal role in regulating the structure and function of coastal food webs, which were affected by nutrient enrichment. Seawater nutrient enrichment might change seagrass palatability by altering seagrass physical and chemical traits, consequently modulating herbivory patterns, but this remains elusive. In this study, the dominant tropical seagrass Thalassia hemprichii was cultured in different ammonium concentrations to examine the response of seagrass nutritional quality, deterrent secondary metabolites, and leaf toughness, as well as the subsequent effect of the changed physical (e.g., leaf toughness) and chemical traits (e.g., nitrogen content; total phenol) on the grazing activity of the herbivorous snail Cerithidea rhizophorarum. Ammonium enrichment enhanced seagrass nutritional quality and decreased physical defence. Low ammonium enrichment increased total phenol content, while high ammonium enrichment reduced it. Both low and high ammonium enrichment enhanced the grazing intensity of C. rhizophorarum on seagrass. Interestingly, nutritional quality mostly determined the herbivory preference of C. rhizophorarum on the intact seagrass having physical structure, with a chemical deterrent (total phenol) playing a secondary role. In contrast, chemical deterrent mainly determined the grazing intensity on agar seagrass food which was made artificially to exclude physical structure. This indicated that seagrass leaf physical structure might hinder phenol compounds from deterring herbivores. Overall, the results presented here demonstrate that ammonium enrichment remarkably increased seagrass palatability and subsequently induced higher susceptibility to herbivory, which might induce seagrass loss. Schematic pictures of the effects of ammonium enrichment on seagrass palatability and subsequent effects on herbivory. Symbols of Thalassia hemprichii are courtesy of the Integration and Application Network, University of Maryland Center for Environmental Science (http://ian.umces.edu/symbols/). The different sizes of symbols represent the relative sizes of seagrass leaf traits. [Display omitted] • Ammonium enrichment significantly increased seagrass palatability. • Nutritional quality mostly determined the feeding preference on intact seagrass. • Seagrass physical structure had an effect on reducing efficiency of chemical deterrents. [ABSTRACT FROM AUTHOR]

• The evolution of cooperation hypothesized that individual selection is inevitable is investigated. • Distinct from the traditional models, our model studied the effects of wealth-based rule when individual selection is inevitable, where only the top V individuals with relatively high cumulative payoffs in each group can be selected for costly PGG. • The effects of participation costs on the proportion of cooperation, the proportion of different individuals, and the gap between rich and poor individuals are distinctly different under different V. Individual selection, as an effective mechanism, is often used in spatial evolutionary games to promote cooperation. Previous research assumes that, individual selection usually occurs with people who fail to meet a certain criterion. However, individual selection is usually inevitable, regardless of whether players in population cooperate or defect. This paper studies the effects of wealth-based rule in costly public goods games when individual selection is inevitable. Specifically, we assume that only the top V individuals with relatively high cumulative payoffs in each group can be selected for costly PGG. The results show that when V is large, the increase of participation cost has slight inhibitory effects on the evolution of cooperation, but it alleviates the polarization of individuals. However, when V is small, the increase of participation cost within a certain range promotes cooperation prosperity, but it also causes an increase in the proportion of polarized individuals and a widening of the wealth gap between rich and poor individuals. [ABSTRACT FROM AUTHOR]

• The evolution of cooperation hypothesized that emotion can influence one's own willingness to change strategies is investigated. • Distinct from the traditional evolutionary model, our model hypothesized that individuals are divided into two categories, namely, non-competitive individuals and competitive individuals, and their emotion is considered quantifiable and cumulative. • The existence of non-competitive individuals has a significant positive effect on the survival of cooperators, but the presence of competitive individuals also makes non-competitive individuals much less effective in promoting cooperation. • The emotional cumulative length plays a key role in promoting overall cooperation, but surprisingly, the cooperation rate of competitive individuals peaks at an intermediate value of emotional cumulative length. Emotion emerges along with individuals' interactions, and numerous experimental studies have shown that emotion plays an important role in individual decision making. However, how emotion affects the evolution of cooperation in structured population is largely unknown. Here we introduce emotion into network reciprocity, where emotion is considered quantifiable and cumulative, and then divide individuals into two types, namely non-competitive individuals whose social value orientation is mutually beneficial and competitive individuals whose social value orientation is maximizing outcomes for the self. Here, we explore the effects of the proportion of non-competitive individuals and emotional cumulative length on the evolution of cooperation. Simulation results show that the existence of non-competitive individuals promotes cooperation in the system. Furthermore, we also find that emotional cumulative length plays a key role in promoting overall cooperation, but surprisingly, the cooperation rate of competitive individuals peaks at an intermediate value of emotional cumulative length. [ABSTRACT FROM AUTHOR]