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Reciprocal Adaptation (reciprocal + adaptation)
Selected AbstractsTHE EVOLUTION OF SPECIFICITY IN EVOLVING AND COEVOLVING ANTAGONISTIC INTERACTIONS BETWEEN A BACTERIA AND ITS PHAGEEVOLUTION, Issue 1 2008Virginie Poullain The evolution of exploitative specificity can be influenced by environmental variability in space and time and the intensity of trade-offs. Coevolution, the process of reciprocal adaptation in two or more species, can produce variability in host exploitation and as such potentially drive patterns in host and parasite specificity. We employed the bacterium Pseudomonas fluorescens SBW25 and its DNA phage ,2 to investigate the role of coevolution in the evolution of phage infectivity range and its relation with phage growth rate. At the phage population level, coevolution led to the evolution of broader infectivity range, but without an associated decrease in phage growth rate relative to the ancestor, whereas phage evolution in the absence of bacterial evolution led to an increased growth rate but no increase in infectivity range. In contrast, both selection regimes led to phage adaptation (in terms of growth rates) to their respective bacterial hosts. At the level of individual phage genotypes, coevolution resulted in within-population diversification in generalist and specialist infectivity range types. This pattern was consistent with a multilocus gene-for-gene interaction, further confirmed by an observed cost of broad infectivity range for individual phage. Moreover, coevolution led to the emergence of bacterial genotype by phage genotype interactions in the reduction of bacterial growth rate by phage. Our study demonstrates that the strong reciprocal selective pressures underlying the process of coevolution lead to the emergence and coexistence of different strategies within populations and to specialization between selective environments. [source] Entreprises publiques et intérêt général à l'heure de la gouvernanceCANADIAN PUBLIC ADMINISTRATION/ADMINISTRATION PUBLIQUE DU CANADA, Issue 3 2006Louis Simard Sommaire: Le contexte de la mondialisation et la remise en question du rôle de l'État ont menéà des modèles de gouvernance fondés sur la multiplicité et l'hétérogénéité des acteurs dans toute question d'intérêt public. Cette nouvelle gouvernance met en valeur des mécanismes d'ajustement mutuel basés sur la concertation, la négociation et l'adaptation réciproque des acteurs. La nouvelle donne commande une réflexion en profondeur sur la place des entreprises publiques au sein de différents secteurs d'activité. Présentées à l'origine comme étant garantes de l'intérêt général, les entreprises publiques sont elles aussi remises en question et confrontées à des logiques d'action parfois contradictoires (intégration internationale, intégration territoriale, planification stratégique et stratégies émergentes). Les auteurs brossent un tableau du nouveau contexte de gouvernance dans le secteur de l'énergie en l'illustrant par le cas d'Hydro-Québec et de l'un de ses derniers projets, la centrale thermique du Suroît. Abstract: The context of globalization and the questioning of the government's role have led to governance models based on the multiplicity and the heterogeneity of the players involved in any issue of public interest. The new governance framework promotes mutual adjustment mechanisms based on consensus-building, negotiation, and reciprocal adaptation among players. This new environment requires a thorough reflection on the role of public corporations in the various industry sectors. Presented originally as guarantors of the public interest, public corporations have also been challenged and are having to deal with occasionally contradictory principles (international integration, territorial integration, strategic planning, and emergent strategies). The authors provide a picture of the new governance context in the energy sector, using as an example Hydro-Québec and one of its most recent projects, the Suroît thermal plant. [source] DIVERSIFYING COEVOLUTION BETWEEN CROSSBILLS AND BLACK SPRUCE ON NEWFOUNDLANDEVOLUTION, Issue 8 2002Thomas L. Parchman Abstract Coevolution is increasingly recognized as an important process structuring geographic variation in the form of selection for many populations. Here we consider the importance of a geographic mosaic of coevolution to patterns of crossbill (Loxia) diversity in the northern boreal forests of North America. We examine the relationships between geographic variation in cone morphology, bill morphology, and feeding performance to test the hypothesis that, in the absence of red squirrels (Tamiasciurus hudsonicus), black spruce (Picea mariana) has lost seed defenses directed at Tamiasciurus and that red crossbills (L. curvirostra) and black spruce have coevolved in an evolutionary arms race. Comparisons of cone morphology and several indirect lines of evidence suggest that black spruce has evolved defenses in response to Tamiasciurus on mainland North America but has lost these defenses on Newfoundland. Cone traits that deter crossbills, including thicker scales that require larger forces to separate, are elevated in black spruce on Newfoundland, and larger billed crossbills have higher feeding performances than smaller billed crossbills on black spruce cones from Newfoundland. These results imply that the large bill of the Newfoundland crossbill (L. c. percna) evolved as an adaptation to the elevated cone defenses on Newfoundland and that crossbills and black spruce coevolved in an evolutionary arms race on Newfoundland during the last 9000 years since glaciers retreated. On the mainland where black spruce is not as well defended against crossbills, the small-billed white-winged crossbill (L. leucoptera leucoptera) is more efficient and specializes on seeds in the partially closed cones. Finally, reciprocal adaptations between crossbills and conifers are replicated in black spruce and Rocky Mountain lodgepole pine (Pinus contorta ssp. latifolia), with coevolution most pronounced in isolated populations where Tamiasciurus are absent as a competitor. This study further supports the role of Tamiasciurus in determining the selection mosaic for crossbills and suggests that a geographic mosaic of coevolution has been a prominent factor underlying the diversification of North American crossbills. [source] Analysing the history of the derelomine flower weevil,Carludovica association (Coleoptera: Curculionidae; Cyclanthaceae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2004NICO M. FRANZ The evolutionary history of the interaction among species of derelomine flower weevils (Coleoptera: Curculionidae: Derelomini) and the Panama-hat palm Carludovica (Cyclanthaceae) is analysed with emphasis on the congruence of (1) topologies and (2) character state transformations in each of the Neotropical clades. For this purpose cladistic analyses are complemented with host plant records, natural history information and selected morphological studies of the associated taxa. The interaction is specialized, involving pollination, oviposition into the inflorescences and the predation of seeds (particularly within Systenotelus). As results from a range of standard coevolutionary methods of analysis indicate, however, events of colonization, extinction and independent (non-reciprocal) speciation have been abundant throughout the history of the association. At the same time it is possible to specify the homology and succession of characters among species of derelomines and Carludovica and interpret them as reciprocal adaptations to attack and protect the seeds, respectively. It is argued that , in light of the limited evolutionary stability of many insect,plant interactions , the question of coevolution is most effectively addressed by combining information from the character- and topology-based approaches. © 2004 The Linnean Society of London, Biological Journal of the Linnean Society, 2004, 81, 483,517. [source] | ||||||||||