Search Results (6)

Harrison’s Rule (HR) postulates a positive allometry between host and parasite body sizes. We tested HR for Syringophilid quill mites parasitizing birds. Using host body mass and parasite body length as size indices, this pattern was absent in the Syringophilidae family and the Syringophilinae subfamily as a whole. However, when considering the parasite genera as units of study, as proposed originally by Harrison, we found that host body mass positively correlates with both male and female parasite body length in seven genera (Aulobia, Aulonastus, Neoaulonastus, Picobia, Neopicobia, Syringophilopsis, and Torotrogla). Most of these relationships were non-significant. On the contrary, male and female Syringophiloidus mites exhibited negative relationships with host mass (both non-significant). This apparent contradiction disappeared when we applied wing length as an index of host body size. Since species of this genus are specific to the host flight feathers (secondaries and also primaries), wing length is a more meaningful index of host body size than body mass. Overall, most cases corresponded to the positive direction predicted by Harrison when examined on the genus level. This finding also implies a surprising reliability of the genus concept, at least in this group of ectoparasites. Full article

Maternally inherited obligate endosymbionts codiverge with their invertebrate hosts and reflect their host’s evolutionary history. Whiteflies (Hemiptera: Aleyrodidae) harbor one obligate endosymbiont, Candidatus Portiera aleyrodidarum (hereafter Portiera). Portiera was anciently acquired by whitefly and has been coevolving with its host ever since. Uncovering the divergence of endosymbionts provides a fundamental basis for inspecting the coevolutionary processes between the bacteria and their hosts. To illustrate the divergence of Portiera lineages across different whitefly species, we sequenced the Portiera genome from Aleyrodes shizuokensis and conducted a comparative analysis on the basic features and gene evolution with bacterial genomes from five whitefly genera, namely Aleurodicus, Aleyrodes, Bemisia, Pealius, and Trialeurodes. The results indicated that Portiera from Bemisia possessed significantly larger genomes, fewer coding sequences (CDSs), and a lower coding density. Their gene arrangement differed notably from those of other genera. The phylogeny of the nine Portiera lineages resembled that of their hosts. Moreover, the lineages were classified into three distinct genetic groups based on the genetic distance, one from Aleurodicus (Aleurodicinae), one from Bemisia (Aleyrodinae), and another from Aleyrodes, Pealius, and Trialeurrodes (Aleyrodinae). Synonymous and nonsynonymous rate analyses, parity rule 2 plot analyses, neutrality plot analyses, and effective number of codons analyses supported the distinction of the three genetic groups. Our results indicated that Portiera from distant hosts exhibit distinct genomic contents, implying codivergence between hosts and their endosymbionts. This work will enhance our understanding of coevolution between hosts and their endosymbionts. Full article

We investigate the effects of external and autonomous global interaction fields on an adaptive network of social agents with an opinion formation dynamics based on a simple imitation rule. We study the competition between global fields and adaptive rewiring on the space of parameters of the system. The model represents an adaptive society subject to global mass media such as a directed opinion influence or feedback of endogenous cultural trends. We show that, in both situations, global mass media contribute to consensus and to prevent the fragmentation of the social network induced by the coevolutionary dynamics. We present a discussion of these results in the context of dynamical systems and opinion formation dynamics. Full article

In this paper, a multipopulation dynamic adaptive coevolutionary strategy is proposed for large-scale optimization problems, which can dynamically and adaptively adjust the connection between population particles according to the optimization problem characteristics. Based on analysis of the network evolution characteristics of collaborative search between particles, a dynamic adaptive evolutionary network (DAEN) model with multiple interconnection couplings is established in this algorithm. In the model, the swarm type is divided according to the judgment threshold of particle types, and the dynamic evolution of collaborative topology in the evolutionary process is adaptively completed according to the coupling connection strength between different particle types, which enhances the algorithm’s global and local searching capability and optimization accuracy. Based on that, the evolution rules of the particle swarm dynamic cooperative search network were established, the search algorithm was designed, and the adaptive coevolution between particles in different optimization environments was achieved. Simulation results revealed that the proposed algorithm exhibited a high optimization accuracy and converging rate for high-dimensional and large-scale complex optimization problems. Full article

Transferring a quantity of credible knowledge is a key sustainable competitive advantage for multi-agent cooperation in an interorganizational network (ION). This study presents simulation research to identify the impacts of reputation mechanisms in interorganizational knowledge transfer through systematic evolutionary game theory, addressing the sustainability of knowledge transfer behaviors in innovation, R&D, and low green carbon. The simulation results showed that an agent’s reputation provides information about having valuable knowledge, which can reduce some of the opportunistic behaviors of knowledge transfer faced by knowledge agents. Regardless of its form, we found that reputation distribution significantly promotes interorganizational knowledge transfer behaviors. In addition, higher reputation thresholds and more significant differences in the impact of high and low reputations prominently contribute to knowledge transfer efficiency and effectiveness. The relationship between reputation mechanisms and the efficiency and effectiveness of knowledge transfer is examined. This study sheds light on the sustainable management of interorganizational projects from reputation mechanisms. Full article

Homologous sequence alignments contain important information about the constraints that shape protein family evolution. Correlated changes between different residues, for instance, can be highly predictive of physical contacts within three-dimensional structures. Detecting such co-evolutionary signals via direct coupling analysis is particularly challenging given the shared phylogenetic history and uneven sampling of different lineages from which protein sequences are derived. Current best practices for mitigating such effects include sequence-identity-based weighting of input sequences and post-hoc re-scaling of evolutionary coupling scores. However, numerous weighting schemes have been previously developed for other applications, and it is unknown whether any of these schemes may better account for phylogenetic artifacts in evolutionary coupling analyses. Here, we show across a dataset of 150 diverse protein families that the current best practices out-perform several alternative sequence- and tree-based weighting methods. Nevertheless, we find that sequence weighting in general provides only a minor benefit relative to post-hoc transformations that re-scale the derived evolutionary couplings. While our findings do not rule out the possibility that an as-yet-untested weighting method may show improved results, the similar predictive accuracies that we observe across conceptually distinct weighting methods suggests that there may be little room for further improvement on top of existing strategies. Full article