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Search Results: 1 - 10 of 96 matches for " coevolution "
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The bearing of biological fitness in humans and crops upon the emergence and spread of agriculture  [PDF]
Aaron Rottenberg
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.54A001
Abstract:

Past studies discussing the origins of agriculture have mainly emphasized changes in environmental and human-behavior factors as possible explanations for the shift from foraging to farming. This paper focuses on how increase in the biological fitness of both farmers and crops enabled the rapid evolution and success of farmers and agriculture. It is shown that the first plants under domestication achieved their superior fitness mainly as a consequence of some of their genetic and life-history traits. It led these species to be extensively integrated into human subsistence and eventually dominate the farmers’ fields. Concurrently, the first farmers gained their enhanced fitness by producing food surplus and by acquiring extra social prestige and power, while materializing the tendency to higher reproduction rate, and eventually to the expansion of farming populations. The unbreakable dependence between high fitness crops and high fitness man, namely their coevolution is a key issue and a promising research area in the understanding of the human story and the origins of agriculture.

Allometric and Isometric variations in the Italian Apodemus sylvaticus and Apodemus flavicollis with respect to the conditions of allopatry and sympatry / Variazioni allometriche e isometriche in Apodemus sylvaticus e Apodemus flavicollis italiani, rispetto alle condizioni di allopatria e simpatria
Giovanni Amori,Longino Contoli
Hystrix : the Italian Journal of Mammalogy , 1986, DOI: 10.4404/hystrix-1.2-3877
Abstract: In Italy there are two species of Apodemus (Sylvaemus): Apodemus sylvaticus on the mainland and the main island, and Apodemus flavicollis only on the mainland. The trend of some morphometric characters of the skull (incisive foramen length - FI; interorbital breadth = IO; length of palatal bridge = PP; upper alveolar length = $M^1M^3$ ) was analized and some theoretical models verified for A. sylvaticus. If one considers the sympatric population of A. sylvaticus and A. flavicollis simultaneously the characters PP, IO and $M^1M^3$ appear significantly isometric being directly correlated ($P leq O.O1$), while FI character results allometric with respect to the previous ones, as expected. If one considers the sympatric populations of each of the species separately, the scenario is different. For A. sylvaticus only PP and $M^1M^3$ are isometric ($P leq 0.05$). For A. flavicollis only $M^1M^3$ and FI appear to be correlated, although not as significantly as for A. sylvaticus ($P le 0.05$; one tail). The insular populations of A. sylvaticus do not show significant correlations, except for FI and $M^1M^3$ ($P le 0.05$). On the contrary, considering all populations, sympatric and allopatric, of A. sylvaticus at the same time are significant correlations ($P le 0.05$) in all combinations of characters, except for those involving the IO. We suggest that the isometric relations in sympatric assemblages are confined within a morphological range available to the genus Apodemus. In such a space, the two species are split in two different and innerly homogeneous distributions. We found no evidence to confirm the niche variation hypothesis. On the contrary, the variability expressed as SO or CV's appears higher in the sympatric populations than in the allopatric ones, for three of the four characters, confirming previous results. For the character displacement hypothesis, we found that A. sylvaticus when not found together with A. flavicollis, shows adimensional increase of PP up to an intermediate value between the mean values of A. sylvaticus and A. flavicollis sympatric assemblages. Also $M^1M^3$, FI and FI + PP increase in allopatry, but to a value greater than that of A. flavicollis; on the other hand, IO growth in allopatry is not significant, as expected, because such character is allometric in the species under study. Lastly, the model was completely inadequate for FI, a character that in sympatry is higher in A. sylvaticus, but increases to a greater extent in the allopatric populations of A. sylvaticus. As far as the convergence on a given phenotype is concern
Coevolving solutions of the 3-satisfiability problem
A. Gorbenko,V. Popov
Applied Mathematical Sciences , 2013,
Abstract: Coevolutionary genetic algorithms are genetic algorithms that evolvesimultaneously two or more populations with coupled fitness. In this paperwe consider coevolutionary genetic algorithms for the 3-satisfiabilityproblem.
Impacts of Opinion Propagation on Social Balance  [PDF]
Songlin Zhang, Lixue Chen, Dong Hu, Yuefei Guo
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.42031
Abstract:

In social networks, opinions diffusion often leads to relationships evolution. Then changes of relationships result in the change of balance degree of social system. We simulate the opinion diffusion on Barabasi & Albert (BA) network and Watts & Strogatz (WS) network to study the effects of the two types of networks, dynamical parameters and structural parameters on the balance degree of system. We employ the spectral analysis to quantify the balance degree of system before and after opinion propagation. The result reveals that it is very similar effect of BA networks and WS networks on it. However, it is opposite effects between dynamical parameters and structural parameters. The balance degree of system is proportional to the two dynamical factors (P,Q) at initial state and always inversely proportional to the two structural factors (< k >,Pne) at initial and convergence state.

Evolution of white and megatooth sharks, and evidence for early predation on seals, sirenians, and whales  [PDF]
Cajus G. Diedrich
Natural Science (NS) , 2013, DOI: 10.4236/ns.2013.511148
Abstract:

The early white shark Carcharodon Smith, 1838 with the fossil Carcharodon auriculatus (Blainville, 1818) and the extinct megatooth shark Otodus Agassiz, 1843 with species Otodus sokolovi (Jaeckel, 1895) were both present in the European proto North Sea Basin about 47.8 - 41.3 m.y. ago (Lutetian, early Middle Eocene), as well as in the Tethys realm around the Afican-Eurasian shallow marine habitats. Both top predators developed to be polyphyletic, with possible two different lamnid shark ancestors within the Early Paleocene to Early Eocene timespan with Carcharodon (white shark line-age) and Otodus (megatooth shark lineage). Their sawblade teeth developed during the early Paleogene as the result of adaptation to feeding on various marine new rising mammals, coinciding with three main waves of evolutionary emergence of seals, sirenians, and whales in parallel with the evolution of these large predatory sharks. Megatooth sharks specialized in hunting whales and sirenians only on the coastal shelves of warm oceans and disappeared globally in the Pleistocene due to climate change and ocean cooling. The cold-water adapted early white sharks have survived until the present day with body temperate change adaptation in warm to temperate oceans and are proposed to have specialized on coastal seal hunting already50 m.y. ago.

Equilibrium Allele Distribution in Trading Populations  [PDF]
Gilles Saint-Paul
Natural Science (NS) , 2015, DOI: 10.4236/ns.2015.73012
Abstract: This paper extends the results of Saint-Paul (2007) regarding the long-run survival rates of alleles in trading populations, to a more general context where the number of loci is arbitrarily large under general assumptions about sexual reproduction. The central result is that fitness-reducing alleles can survive in a trading population, provided their frequency is not too large. However, the greater the number of loci that matter for fitness, the more stringent the conditions under which these alleles can survive.
Coevolution of amino acid residues in the key photosynthetic enzyme Rubisco
Mingcong Wang, Maxim V Kapralov, Maria Anisimova
BMC Evolutionary Biology , 2011, DOI: 10.1186/1471-2148-11-266
Abstract: We found that both selection and coevolution shape Rubisco, and that positively selected and coevolving residues have their specifically favored amino acid composition and pairing preference. The mapping of these residues on the known Rubisco tertiary structures showed that the coevolving residues tend to be in closer proximity with each other compared to the background, while positively selected residues tend to be further away from each other. This study also reveals that the residues under positive selection or coevolutionary force are located within functionally important regions and that some residues are targets of both positive selection and coevolution at the same time.Our results demonstrate that coevolution of residues is common in Rubisco of land plants and that there is an overlap between coevolving and positively selected residues. Knowledge of which Rubisco residues are coevolving and positively selected could be used for further work on structural modeling and identification of substitutions that may be changed in order to improve efficiency of this important enzyme in crops.Coevolution is one of the few paramount forces acting on all levels of biological organization from bioms to nucleotides. Observations of the complementary adaptations in two or more species caused by mutual selection pressures have started from Darwin's (1862) work on orchids and their pollinators and resulted in theoretical generalizations such as 'Red Queen Hypothesis' [1,2]. More recently concepts and methodologies developed for the study of species coevolution were applied to the growing wealth of molecular data, in particular for detection of coevolution between and within proteins [3]. Identifying coevolving positions in proteins allows better understanding of their structure and function and paves the road to engineering proteins with desired properties. Several computational methods have been proposed to detect coevolving residues from multiple sequence alignments (e.g.,
New host records of Aglaomelissa duckei and a compilation of host associations of Ericrocidini bees (Hymenoptera: Apidae)
Rocha-Filho, Léo C.;Morato, élder F.;Melo, Gabriel A. R.;
Zoologia (Curitiba) , 2009, DOI: 10.1590/S1984-46702009000200012
Abstract: for the first time, confirmed host records are reported for the monotypic ericrocidini genus aglaomelissa snelling & brooks, 1985. aglaomelissa duckei (friese, 1906) emerged from trap-nests of centris (heterocentris) analis (fabricius, 1804) and c. (heterocentris) terminata smith, 1874 from two sites in the brazilian amazonian region. the parasitism ratio caused by a. duckei was high, varying from 80 to 100% of the brood cells in a single trap-nest. also, a compilation of the known host records for the species of ericrocidini is presented and host-parasite associations are discussed. host associations are known for seven of the 11 genera and about 17 of the 42 species of the tribe, involving a total of 34 confirmed or putative host species of centridini bees. all species of the tribe are known to attack only nests of centris fabricius, 1804, except mesoplia rufipes (perty, 1833) that also parasitizes nests of epicharis klug, 1807. although the phylogenetic relationships within ericrocidini and among the subgenera of centris are not well resolved, the current knowledge of the host-parasite associations points to a relatively high degree of specificity and possible coevolution between them.
Emergingdirectionsinthestudyoftheecologyandevolutionofplant-animalmutualisticnetworks:areview
Hao GU,Eben GOODALE,Jin CHEN
动物学研究 , 2015,
Abstract: Thestudyofmutualisticplantandanimalnetworksisanemergingfieldofecologicalresearch.Wereviewedprogressinthisfieldoverthepast30years.Whileearlierstudiesmostlyfocusedonnetworkstructure,stability,andbiodiversitymaintenance,recentstudieshaveinvestigatedtheconservationimplicationsofmutualisticnetworks,specificallytheinfluenceofinvasivespeciesandhownetworksrespondtohabitatloss.Currentresearchhasalsofocusedonevolutionaryquestionsincludingphylogeneticsignalinnetworks,impactofnetworksonthecoevolutionofinteractingpartners,andnetworkinfluencesontheevolutionofinteractingspecies.Weoutlinesomedirectionsforfutureresearch,particularlytheevolutionofspecializationinmutualisticnetworks,andprovideconcreterecommendationsforenvironmentalmanagers.
A Competitive Markov Approach to the Optimal Combat Strategies of On-Line Action Role-Playing Game Using Evolutionary Algorithms  [PDF]
Haoyang Chen, Yasukuni Mori, Ikuo Matsuba
Journal of Intelligent Learning Systems and Applications (JILSA) , 2012, DOI: 10.4236/jilsa.2012.43018
Abstract: In the case of on-line action role-playing game, the combat strategies can be divided into three distinct classes, Strategy of Motion(SM), Strategy of Attacking Occasion (SAO) and Strategy of Using Skill (SUS). In this paper, we analyze such strategies of a basic game model in which the combat is modeled by the discrete competitive Markov decision process. By introducing the chase model and the combat assistant technology, we identify the optimal SM and the optimal SAO, successfully. Also, we propose an evolutionary framework, including integration with competitive coevolution and cooperative coevolution, to search the optimal SUS pair which is regarded as the Nash equilibrium point of the strategy space. Moreover, some experiments are made to demonstrate that the proposed framework has the ability to find the optimal SUS pair. Furthermore, from the results, it is shown that using cooperative coevolutionary algorithm is much more efficient than using simple evolutionary algorithm.
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