Group selection, kin selection, altruism and cooperation: When inclusive fitness is right and when it can be wrong

Group selection theory has a history of controversy. After a period of being in disrepute, models of group selection have regained some ground, but not without a renewed debate over their importance as a theoretical tool. In this paper I offer a simple framework for models of the evolution of altruism and cooperation that allows us to see how and to what extent both a classification with and one without group selection terminology are insightful ways of looking at the same models. Apart from this dualistic view, this paper contains a result that states that inclusive fitness correctly predicts the direction of selection for one class of models, represented by linear public goods games. Equally important is that this result has a flip side: there is a more general, but still very realistic class of models, including models with synergies, for which it is not possible to summarize their predictions on the basis of an evaluation of inclusive fitness.     

Nepotistic nosiness: inclusive fitness and vigilance of kin members' romantic relationships

The logic of inclusive fitness suggests that people should be attentive to the mating relationships of their kin—especially their genetically closest kin. This logic further suggests that people will be especially attentive to close kin members' relationships when a greater indirect fitness benefit is at stake. Three studies tested implications of this analysis. The primary results were that (a) people maintain greater vigilance over (and attempt greater influence on) the romantic relationships of genetically closer kin; (b) this effect is largely mediated by feelings of emotional closeness and perceptions of physical similarity; (c) women are more vigilant than men over their kin members' relationships; (d) people are more vigilant over the relationships of female kin, as compared to male kin, but only under conditions with especially clear implications for indirect fitness; and (e) people are more vigilant over kin members' long-term committed relationships, as compared to their casual relationships. These results indicate that a subtle form of nepotism is manifest in people's concern with their kin members' romantic relationships.     

The volunteer's dilemma and the optimal size of a social group

If one or few individuals are enough to perform an action that produces a collective good and if this action has a cost, living in group can be beneficial because the cost can be shared with other individuals. Without coordination, however, the production of a collective good by the contribution of one or few individuals is inefficient and can be modelled as a volunteer's dilemma. In the volunteer's dilemma the individuals that pay the cost for the production of the collective good benefit from their action if nobody else volunteers, but the cost is wasted if too many individuals volunteer. Increasing group size reduces the need of volunteering for each member of the group; the overall benefit for the group, however, decreases too because the larger the group is, the less likely it is that the collective good is produced. This problem persists even with a high degree of relatedness between group members; an optimal, intermediate group size exists that maximizes the probability to produce the collective good.     

Further evidence for the phylogenetic coherence of actinomycetes with Group B-peptidoglycan and evidence for the phylogenetic intermixing of the genera Microbacterium and Aureobacterium as determined by 16S rDNA analysis

Abstract A 16S rDNA study was performed on at least two species, including the type strain of the type species, of each genus described to possess peptidoglycan of Group B. Analyses confirm that these actinomycetes form a phylogenetically coherent cluster within the arthrobacteria subline of descent. While members of the genera Agromyces, Clavibacter, Curtobacterium and Rathayibacter appear to be phylogenetically coherent, members of Microbacterium and Aureobacterium do not cluster according to their taxonomic affiliation but form one large cluster in which species of both genera are intermixed. Species with no taxonomic standing, i.e. Corynebacterium aquaticum , and Brevibacterium helvolum form three separate sublines of descent and can be considered nuclei of future novel genera.     

A simple and rapid method for evaluation of Mark–Houwink–Sakurada constants of linear random coil polysaccharides using molecular weight and intrinsic viscosity determined by high performance size exclusion chromatography: application to guar galactomannan

A rapid method for establishing the constants in the Mark–Houwink–Sakurada equation, relating intrinsic viscosity and molecular weight (MW), of guar galactomannan is described. Following partial acid hydrolysis, the galactomannan was analyzed using high performance size exclusion chromatography employing viscosimetry and right angle light scattering detectors. In this way, a large number of samples of polysaccharides with a wide range of MW distributions were prepared, without need for isolation, and intrinsic viscosity and MW rapidly determined. The a and K values found for guar galactomannan were 0.72 and 5.13×10⁻⁴ ([η] in dl/g) respectively, in good agreement with previously published values.