Protected polymorphisms and evolutionary stability of patch-selection strategies in stochastic environments

We consider a population living in a patchy environment that varies stochastically in space and time. The population is composed of two morphs (that is, individuals of the same species with different genotypes). In terms of survival and reproductive success, the associated phenotypes differ only in their habitat selection strategies. We compute invasion rates corresponding to the rates at which the abundance of an initially rare morph increases in the presence of the other morph established at equilibrium. If both morphs have positive invasion rates when rare, then there is an equilibrium distribution such that the two morphs coexist; that is, there is a protected polymorphism for habitat selection. Alternatively, if one morph has a negative invasion rate when rare, then it is asymptotically displaced by the other morph under all initial conditions where both morphs are present. We refine the characterization of an evolutionary stable strategy for habitat selection from [Schreiber, 2012] in a mathematically rigorous manner. We provide a necessary and sufficient condition for the existence of an ESS that uses all patches and determine when using a single patch is an ESS. We also provide an explicit formula for the ESS when there are two habitat types. We show that adding environmental stochasticity results in an ESS that, when compared to the ESS for the corresponding model without stochasticity, spends less time in patches with larger carrying capacities and possibly makes use of sink patches, thereby practicing a spatial form of bet hedging.Comment: Revised in light of referees' comments, Published on-line Journal of Mathematical Biology 2014 http://link.springer.com/article/10.1007/s00285-014-0824-

The rhetoric of rape: a critical mapping of the discursive landscape in France = La rhétorique du viol: une recension critique du paysage discursif français

The Rhetoric of Rape: A Critical Mapping of the Discursive Landscape in France comprises three theoretically distinct, but thematically contiguous essays, each of which touches upon the highly contentious topic of 'la tournante'. From the expression 'faire tourner', meaning something like 'to hand, or to pass (something) around; to share', the word has taken on an additional, specialized, and more sinister sense: that of gang-rape. In place of the politically polarized lens through which 'la tournante' has been seen, The Rhetoric of Rape offers an alternative set of theoretical, respectively phenomenological (Maurice Merleau-Ponty), linguistic (John Langshaw Austin), and psychoanalytical (Sigmund Freud) perspectives from which the practice and its discursive conditions of possibility — its underlying archaeology — can be mapped. This triangulation of views reveals how certain political (pouvoir), epistemic (savoir), and erotic (plaisir) strategies mobilize rape and its rhetoric

Mean-field interacting multi-type birth-death processes with a view to applications in phylodynamics

Multi-type birth-death processes underlie approaches for inferring evolutionary dynamics from phylogenetic trees across biological scales, ranging from deep-time species macroevolution to rapid viral evolution and somatic cellular proliferation. A limitation of current phylogenetic birth-death models is that they require restrictive linearity assumptions that yield tractable likelihoods, but that also preclude interactions between individuals. Many fundamental evolutionary processes -- such as environmental carrying capacity or frequency-dependent selection -- entail interactions, and may strongly influence the dynamics in some systems. Here, we introduce a multi-type birth-death process in mean-field interaction with an ensemble of replicas of the focal process. We prove that, under quite general conditions, the ensemble's stochastically evolving interaction field converges to a deterministic trajectory in the limit of an infinite ensemble. In this limit, the replicas effectively decouple, and self-consistent interactions appear as nonlinearities in the infinitesimal generator of the focal process. We investigate a special case that is amenable to calculations in the context of a phylogenetic birth-death model, and is rich enough to model both carrying capacity and frequency-dependent selection.Comment: 30 pages, 1 figur

Nye mål for naturfagsundervisning i USA – vil vi samme vej i Danmark?

Analysen ser nærmere på den nye ramme for naturfagsundervisning i USA som udkom i 2011, og som i år bliver udmøntet i nye målbeskrivelser. Den nye ramme er opbygget ud fra tre dimensioner: praksisser inden for naturvidenskab og ingeniørarbejde, tværgående begreber og faglige kerneidéer. Rammen fremhæver at naturfagsundervisning bør bygge på en progression gennem uddannelsesforløbet, at undervisningen skal fokusere på nogle få faglige kerneidéer i naturvidenskab og teknologi for at undgå stoftrængsel, og at arbejde med at lære naturvidenskabelig viden skal integreres med det at arbejde undersøgelsesbaseret (inquiry based), herunder også med designmetoder, bl.a. for at øge fokus på det kreative og ingeniørarbejde. Analysen afsluttes med at opsummere hvad i det amerikanske arbejde der kan være inspiration for udviklingen af dansk naturfagsundervisning

The rhetoric of rape: a critical mapping of the discursive landscape in France = La rhétorique du viol: une recension critique du paysage discursif français

The Rhetoric of Rape: A Critical Mapping of the Discursive Landscape in France comprises three theoretically distinct, but thematically contiguous essays, each of which touches upon the highly contentious topic of 'la tournante'. From the expression 'faire tourner', meaning something like 'to hand, or to pass (something) around; to share', the word has taken on an additional, specialized, and more sinister sense: that of gang-rape. In place of the politically polarized lens through which 'la tournante' has been seen, The Rhetoric of Rape offers an alternative set of theoretical, respectively phenomenological (Maurice Merleau-Ponty), linguistic (John Langshaw Austin), and psychoanalytical (Sigmund Freud) perspectives from which the practice and its discursive conditions of possibility — its underlying archaeology — can be mapped. This triangulation of views reveals how certain political (pouvoir), epistemic (savoir), and erotic (plaisir) strategies mobilize rape and its rhetoric

The Spatial Extent of (U)LIRGs in the Mid-Infrared. II. Feature Emission

We present results from the second part of our analysis of the extended mid-infrared (MIR) emission of the Great Observatories All-Sky LIRG Survey (GOALS) sample based on 5-14 micron low-resolution spectra obtained with the IRS on Spitzer. We calculate the fraction of extended emission as a function of wavelength for all galaxies in the sample, FEE_lambda, and spatially separate the MIR spectrum of galaxies into their nuclear and extended components. We find that the [NeII] emission line is as compact as the hot dust MIR continuum, while the polycyclic aromatic hydrocarbon (PAH) emission is more extended. The 6.2 and 7.7 micron PAH emission is more compact than that of the 11.3 micron PAH, which is consistent with the formers being enhanced in a more ionized medium. The presence of an AGN or a powerful nuclear starburst increases the compactness of the hot dust MIR continuum, but has a negligible effect on the spatial extent of the PAH emission on kpc-scales. Globally, the spectra of the extended emission component are homogeneous for all galaxies in GOALS. This suggests that the physical properties of star formation taking place at distances farther than 1.5 kpc from the nuclei of (U)LIRGs are very similar, resembling local star-forming galaxies with L_IR < 10^11 Lsun, as well as star formation-dominated ULIRGs at z~2. In contrast, the MIR spectra of the nuclear component of local (U)LIRGs are very diverse. This implies that the observed variety of their integrated MIR properties arise, on average, only from the processes that are taking place in their cores.Comment: 16 pages, 7 figures, accepted for publication in Ap

Distance-dependent duplex DNA destabilization proximal to G-quadruplex/i-motif sequences

G-quadruplexes and i-motifs are complementary examples of non-canonical nucleic acid substructure conformations. G-quadruplex thermodynamic stability has been extensively studied for a variety of base sequences, but the degree of duplex destabilization that adjacent quadruplex structure formation can cause has yet to be fully addressed. Stable in vivo formation of these alternative nucleic acid structures is likely to be highly dependent on whether sufficient spacing exists between neighbouring duplex- and quadruplex-/i-motif-forming regions to accommodate quadruplexes or i-motifs without disrupting duplex stability. Prediction of putative G-quadruplex-forming regions is likely to be assisted by further understanding of what distance (number of base pairs) is required for duplexes to remain stable as quadruplexes or i-motifs form. Using oligonucleotide constructs derived from precedented G-quadruplexes and i-motif-forming bcl-2 P1 promoter region, initial biophysical stability studies indicate that the formation of G-quadruplex and i-motif conformations do destabilize proximal duplex regions. The undermining effect that quadruplex formation can have on duplex stability is mitigated with increased distance from the duplex region: a spacing of five base pairs or more is sufficient to maintain duplex stability proximal to predicted quadruplex/i-motif-forming region