PubMed · 5452825
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
J M Hofkosh. 1970. Organizational behavior.. https://doi.org/10.1093/ptj%2F50.8.1157
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Genetic variation in behavioral traits allows organisms to respond and adapt to environmental challenges. Genetic variation in behavior is often affected by many genes and thus has a complex genetic basis. Inversions, the reorientation of genes along the chromosome, tightly link genetic variants together because they suppress recombination. Therefore, inversions are believed to have a major impact on phenotypic variation because they combine the effects of multiple genes, which can pleiotropically alter multiple aspects of behavior. This study investigates how the inversion In(2L)t, found in Drosophila melanogaster populations around the world, impacts different aspects of behavior in an environment-sensitive manner. We test the activity, foraging, and startle-induced behavior of flies with different In(2L)t genotypes across sex and temperatures. We observe that Drosophila homozygous for In(2L)t sleep less frequently, spend more time away from a food source, and have a longer duration of startle response. Additionally, the impacts of In(2L)t on aspects of behavior can be sex-specific and are largely consistent across temperatures. Taken together, our research demonstrates that inversions can regulate aspects of behavior, and suggests hypotheses explaining the distribution of In(2L)t across space and time.
Evolution is a closed stochastic optimisation process driven by the interaction between behaviour and environment towards local maxima in fitness. It is inferred that nervous systems are selected to provide optimal control of behaviour (the 'assumption of optimality'), such that for some behaviours, the expectation of future hazards to survival are minimised. This is illustrated by goal-directed saccades in which minimising total flight-time of primary and secondary movements provides a better fit to observations than simply minimising the error of the primary movement. This optimisation is extended to intra-movement trajectories, where low-bandwidth (smooth) velocity profiles provide a more satisfactory description of observations than simple bang-bang control. Since minimum-time behaviours cannot be controlled by error feedback, it is concluded that the cerebellum must be executing a real-time unreferenced optimisation process. This requires explorative as well as exploitative behaviour. Stochastic gradient descent is discussed as a possible means by which the cerebellum may optimise behaviour.
In his classic work, Pigs for the Ancestors, Roy Rappaport proposed that the ritual cycle of the Tsembaga was a mechanism to regulate human population growth and prevent the degradation of the Tsembaga ecosystem. Rappaport provided detailed ethnographic and ecological information to support his claim, but many aspects of Rappaport's model were subsequently criticised. Several simulation models of the Tsembaga ecosystem were constructed to test Rappaport's hypothesis (Shantzis & Behrens, 1973; Foin & Davis, 1984) and evaluate possible alternatives (e.g. Foin & Davis, 1987). The basic conclusions were that it was possible to develop models supporting Rappaport's hypothesis but they were extremely sensitive to parameter choices, and other simpler population control mechanisms might be more likely (Buchbinder, 1977; Foin & Davis, 1987). In this paper, a much simpler dynamical system model for a slash-and-burn agricultural system is developed and applied to the Tsembaga system. By analysing the structure of the model for different physical and socioeconomic conditions, sources of instability and possible stabilising mechanisms are identified. The model indicates that behavioral plasticity (ability to modify behavior over a wide range of behavioral options, quickly and easily) is a fundamental source of instability which is strong enough to nullify more direct stabilising influences such as malnutrition and disease. This suggests that the only possible mechanism to counter to this fundamentally destabilising force may be cultural, i.e. the ritual cycle. Finally, a condition is outlined for which the ritual cycle will produce (local) stability.