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  • 1.
    Baltscheffsky, H.
    et al.
    Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Blomberg, C.
    Kungl. Tekniska högskolan.
    Liljenström, H.
    Kungl. Tekniska högskolan.
    Lindahl, B. I. B.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Århem, P.
    Karolinska Institutet.
    On the Origin and Evolution of Life: An Introduction1997In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 187, p. 453-459Article in journal (Other academic)
  • 2.
    Blomberg, C.
    et al.
    Kungl. Tekniska högskolan.
    Liljenström, H.
    Kungl. Tekniska högskolan.
    Lindahl, B. I. B.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Århem, P.
    Karolinska Institutet.
    Mind and Matter: Essays from Biology, Physics and Philosophy: An Introduction1994In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 171, p. 1-5Article in journal (Other academic)
  • 3.
    Ehn, Micael
    et al.
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution.
    Laland, Kevin
    Adaptive strategies for cumulative cultural learning2012In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 301, p. 103-111Article in journal (Refereed)
    Abstract [en]

    The demographic and ecological success of our species is frequently attributed to our capacity for cumulative culture. However, it is not yet known how humans combine social and asocial learning to generate effective strategies for learning in a cumulative cultural context. Here we explore how cumulative culture influences the relative merits of various pure and conditional learning strategies, including pure asocial and social learning, critical social learning, conditional social learning and individual refiner strategies. We replicate the Rogers' paradox in the cumulative setting. However, our analysis suggests that strategies that resolved Rogers' paradox in a non-cumulative setting may not necessarily evolve in a cumulative setting, thus different strategies will optimize cumulative and non-cumulative cultural learning.

  • 4.
    Ghachem, Montasser
    Stockholm University, Faculty of Social Sciences, Department of Economics. Harvard University, United States.
    The institution as a blunt instrument: Cooperation through imperfect observability2016In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 396, p. 182-190Article in journal (Refereed)
    Abstract [en]

    Observing others enables us to indirectly reciprocate their actions. In large societies, however, reliable individual observation is hard to achieve. Societies therefore rely on institutions to aid in observing cooperative behaviour and identifying those who cooperated. Institutions are integral part of modern societies. Here, we propose an evolutionary model in which an institution aims to label cooperators with a tag to verify their trustworthiness, as is the case for financial credit ratings or quality certificates. However, errors in assigning tags inevitably arise: the institution may accidentally leave some cooperators untagged or award tags to some defectors. Taking these two specific types of errors into account, we derive simple analytical conditions under which cooperation becomes stable and is favoured by selection. We find that these two institutional errors are not weighted equally in promoting cooperation: it is more detrimental to cooperation if tags are erroneously awarded to defectors than if they are mistakenly withheld from cooperators. Institutional tagging can lead to non-uniform interaction rates among cooperators and defectors, whereby cooperators benefit disproportionally by playing more games than defectors. This work sheds light on the significant role of institutions in promoting and maintaining societal cooperation.

  • 5.
    Höhna, Sebastian
    Stockholm University, Faculty of Science, Department of Mathematics. University of California, USA.
    The time-dependent reconstructed evolutionary process with a key-role for mass-extinction events2015In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 380, p. 321-331Article in journal (Refereed)
    Abstract [en]

    The homogeneous reconstructed evolutionary process is a birth-death process without observed extinct lineages. Each species evolves independently with the same diversification rate-speciation rate, lambda(t), and extinction rate, mu(t)-that may change over time. The process is commonly applied to model species diversification where the data are reconstructed phylogenies, e.g. trees estimated from present-day molecular data, and used to infer diversification rates. In the present paper I develop the general probability density of a reconstructed tree under any homogeneous, time-dependent birth-death process. I demonstrate how to adapt this probability density when conditioning on the survival of one or two initial lineages, or on the process realizing n species, and also how to transform between the probability density of a reconstructed tree and the probability density of the speciation times. I demonstrate the use of the general time-dependent probability density functions by deriving the probability density of a reconstructed tree under a birth-death-shift model with explicit mass-extinction events. I extend these functions to several special cases, including the pure-birth process, the pure-death process, the birth-death process, and the critical-branching process. Thus, I specify equations for the most commonly used birth-death models in a unified framework (e.g. same condition and same data) using a common notation.

  • 6.
    Hössjer, Ola
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Tyvand, Peder A.
    A monoecious and diploid Moran model of random mating2016In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 394, p. 182-196Article in journal (Refereed)
    Abstract [en]

    An exact Markov chain is developed for a Moran model of random mating for monoecious diploid individuals with a given probability of self-fertilization. The model captures the dynamics of genetic variation at a biallelic locus. We compare the model with the corresponding diploid Wright-Fisher (WF) model. We also develop a novel diffusion approximation of both models, where the genotype frequency distribution dynamics is described by two partial differential equations, on different time scales. The first equation captures the more slowly varying allele frequencies, and it is the same for the Moran and WF models. The other equation captures departures of the fraction of heterozygous genotypes from a large population equilibrium curve that equals Hardy-Weinberg proportions in the absence of selfing. It is the distribution of a continuous time Ornstein-Uhlenbeck process for the Moran model and a discrete time autoregressive process for the WF model. One application of our results is to capture dynamics of the degree of non-random mating of both models, in terms of the fixation index f(IS). Although f(IS) has a stable fixed point that only depends on the degree of selfing, the normally distributed oscillations around this fixed point are stochastically larger for the Moran than for the WF model.

  • 7.
    Jansson, Fredrik
    Stockholm University, Faculty of Humanities, Centre for the Study of Cultural Evolution. Mälardalen University, Sweden; Linköping University, Sweden.
    What games support the evolution of an ingroup bias?2015In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 373, p. 100-110Article in journal (Refereed)
    Abstract [en]

    There is an increasing wealth of models trying to explain the evolution of group discrimination and an ingroup bias. This paper sets out to systematically investigate the most fundamental assumption in these models: in what kind of situations do the interactions take place? What strategic structures – games – support the evolution of an ingroup bias? More specically, the aim here is to find the prerequisites for when a bias also with respect to minimal groups – arbitrarily defined groups void of group-specific qualities – is selected for, and which cannot be ascribed to kin selection.

    Through analyses and simulations of minimal models of two-person games, this paper indicates that only some games are conducive to the evolution of ingroup favouritism. In particular, this class does not contain the prisoners’ dilemma, but it does contain anti-co-ordination and co-ordination games. Contrasting to the prisoners’ dilemma, these are games where it is not a matter of whether to behave altruistically, but rather one of predicting what the other person will be doing, and where I would benefit from you knowing my intentions.

    In anti-co-ordination games, on average, not only will agents discriminate between groups, but also in such a way that their choices maximise the sum of the available payoffs towards the ingroup more often than towards the outgroup. And in co-ordination games, even if agents do manage to co-ordinate with the whole population, they are more likely to co-ordinate on the socially optimal equilibrium within their group. Simulations show that this occurs most often in games where there is a component of risk-taking, and thus trust, involved. A typical such game is the stag hunt or assurance game.

  • 8.
    Leimar, Olof
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Sasaki, Akira
    Doebeli, Michael
    Dieckmann, Ulf
    Limiting similarity, species packing, and the shape of competition kernels2013In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 339, p. 3-13Article in journal (Refereed)
    Abstract [en]

    A traditional question in community ecology is whether species' traits are distributed as more-or-less regularly spaced clusters. Interspecific competition has been suggested to play a role in such structuring of communities. The seminal theoretical work on limiting similarity and species packing, presented four decades ago by Robert MacArthur, Richard Levins and Robert May, has recently been extended. There is now a deeper understanding of how competitive interactions influence community structure, for instance, how the shape of competition kernels can determine the clustering of species' traits. Competition is typically weaker for greater phenotypic difference, and the shape of the dependence defines a competition kernel. The clustering tendencies of kernels interact with other effects, such as variation in resource availability along a niche axis, but the kernel shape can have a decisive influence on community structure. Here we review and further extend the recent developments and evaluate their importance.

  • 9.
    Lind, Johan
    Stockholm University, Faculty of Science, Department of Zoology, Ethology.
    What determines the probability of surviving predator attacks in bird migration?: The relative importance of vigilance and fuel load2004In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 231, no 2, p. 223-227Article in journal (Refereed)
    Abstract [en]

    Migrating birds must accumulate fuel during their journeys and this fuel load should incur an increased risk of predation. Migratory fuelling should increase individual mass-dependent predation risk for two reasons. First, acquisition costs are connected to the increased time a bird must spend foraging to accumulate the fuel loads and the reduced predator detection that accompanies foraging. Second, birds with large fuel loads have been shown to suffer from impaired predator evasion which makes them more vulnerable when actually attacked. Here, I investigate the relative importance of these two aspects of mass-dependent predation risk and I have used published data and a hypothetical situation for a foraging bird to investigate how much migratory fuelling in terms of escape performance and natural variation in predator detection contribute to individual risk during foraging. Results suggest that for birds foraging close to protective cover the negative impact of fuel load on flight performance is very small, whereas variation in time to predator detection is of great importance for a bird's survival. However, the importance of flight performance for predation risk increases as the distance to cover increases. Hence, variation in predator detection (and vigilance) probably influences individual survival much more than migratory fuel load and consequently, to understand risk management during migration studies that focus on vigilance and predator detection during fuelling are much needed

  • 10.
    Lindahl, B. I. B.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Consciousness and Biological Evolution1997In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 187, p. 613-629Article in journal (Refereed)
    Abstract [en]

    It has been suggested that if the preservation and development of consciousness in the biological evolution is a result of natural selection, it is plausible that consciousness not only has been influenced by neural processes, but has had a survival value itself; and it could only have had this, if it had also been efficacious. This argument for mind–brain interaction is examined, both as the argument has been developed by William James and Karl Popper and as it has been discussed by C. D. Broad. The problem of identifying mental phenomena with certain neural phenomena is also addressed. The main conclusion of the analysis is that an explanation of the evolution of consciousness in Darwinian terms of natural selection does not rule out that consciousness may have evolved as a mere causally inert effect of the evolution of the nervous system, or that mental phenomena are identical with certain neural phenomena. However, the interactionistic theory still seems, more plausible and more fruitful for other reasons brought up in the discussion.

  • 11.
    Lindahl, B. I. B.
    et al.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Århem, P.
    Karolinska Institutet.
    Mind as a Force Field: Comments on a New Interactionistic Hypothesis1994In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 171, p. 111-122Article in journal (Refereed)
    Abstract [en]

    The survival and development of consciousness in biological evolution call for an explanation. An interactionistic mind-brain theory seems to have the greatest explanatory value in this context.

    An interpretation of an interactionistic hypothesis, recently proposed by Karl Popper, is discussed both theoretically and based on recent experimental data. In the interpretation, the distinction between the conscious mind and the brain is seen as a division into what is subjective and what is objective, and not as an ontological distinction between something immaterial and something material. The interactionistic hypothesis is based on similarities between minds and physical forces. The conscious mind is understood to interact with randomly spontaneous spatio-temporal patterns of action potentials through an electromagnetic field. Consequences and suggestions for future studies are discussed.

  • 12.
    Lindahl, B. I. B.
    et al.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Århem, Peter
    Karolinska Institutet.
    The Mental Force Field Hypothesis: A Reply to Libet1996In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 178, p. 225-226Article in journal (Other academic)
  • 13.
    Lindahl, B. I. B.
    et al.
    Stockholm University, Faculty of Humanities, Department of Philosophy.
    Århem, Peter
    Karolinska Institutet.
    The Relation Between the Conscious Mind and the Brain: A Reply to Beck1996In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 181, p. 95-96Article in journal (Other academic)
1 - 13 of 13
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