Directionality theory: an empirical study of an entropic principle in life‐history evolution

Understanding the relationship between ecological constraints and life-history properties constitutes a central problem in evolutionary ecology. Directionality theory, a model of the evolutionary process based on demographic entropy, a measure of the uncertainty in the age of the mother of a randomly chosen newborn, provides an analytical framework for addressing this problem. The theory predicts that in populations that spend the greater part of their evolutionary history in the stationary growth phase (equilibrium species), entropy will increase. Equilibrium species will be characterized by high iteroparity and strong demographic stability. In populations that spend the greater part of their evolutionary history in the exponential growth phase (opportunistic species), entropy will decrease when population size is large, and will undergo random variation when population size is small. Opportunistic species will be characterized by weak iteroparity and weak demographic stability when population size is large, and random variations in these attributes when population size is small. This paper assesses the validity of these predictions by employing a demographic dataset of 66 species of perennial plants. This empirical analysis is consistent with directionality theory and provides support for its significance as an explanatory and predictive model of life-history evolution

Grundlagen und Beispiele

Hardcover, 17x24Der Einfluss des Menschen auf Waldbaumpopulationen weltweit, insbesondere in Mitteleuropa, hat sich bereits heute auf deren genetische Variation ausgewirkt. Genetische Information geht verloren, weil immer mehr Bäume von immer weniger Eltern abstammen. Einige Baumarten sind selten geworden oder in reproduktiv isolierte Populationen zerstückelt. Populationen anderer Arten wurden mit Vermehrungsgut gepflanzt, welches über ökologische Gradienten hinweg verschoben oder durch Introgression aus benachbarten Populationen ursprünglich allopatrischer Arten verändert wurde. Das Ausmaß genetischer Variation in Populationen und deren Differenzierung wird durch Parameter charakterisiert, die für die Planung von Maßnahmen der Erhaltung angemessen großer Genressourcen in situ oder ex situ unentbehrlich sind. Genetische Auswirkungen weithin angewandter forstlicher Maßnahmen einschließlich der Züchtung auf erwünschte Merkmale werden analysiert. Zum Schluss werden genetische Implikationen von Gesetzen betrachtet. In der Öffentlichkeit erfährt die Erhaltung genetischer Ressourcen derzeit leider noch wenig Aufmerksamkeit, obgleich sie das Fundament nachhaltigen Artenschutzes liefert.Man’s impact on forest tree populations worldwide and in Central Europe in particular has affected their genetic variation in the past and will continue to do so. The parental pool of tree populations is becoming smaller, causing loss of genetic information. Some tree species have become rare or fragmented into reproductively isolated populations. Populations of other species were planted from reproductive material that was shifted over ecological gradients or introgressed from neighboring populations of formerly allopatric species. The amount of genetic variation within populations and the differentiation between them is characterised by genetic parameters that are indispensable in designing measures for the conservation of gene resources of sufficient size in situ or ex situ. The genetic consequences of widely used forest operations, including the breeding of trees for desired traits, is analysed. Finally, the genetic implications of legislation are considered. Regrettably, the conservation of genetic resources currently receives little public attention, even though it provides the basis of sustainable species management

Intensive study sites

Intensive study site

Human cytomegalovirus seropositivity is associated with reduced patient survival during sepsis

$\bf Background$ Sepsis is one of the leading causes of death. Treatment attempts targeting the immune response regularly fail in clinical trials. As HCMV latency can modulate the immune response and changes the immune cell composition, we hypothesized that HCMV serostatus affects mortality in sepsis patients. $\bf Methods$ We determined the HCMV serostatus (i.e., latency) of 410 prospectively enrolled patients of the multicenter SepsisDataNet.NRW study. Patients were recruited according to the SEPSIS-3 criteria and clinical data were recorded in an observational approach. We quantified 13 cytokines at Days 1, 4, and 8 after enrollment. Proteomics data were analyzed from the plasma samples of 171 patients. $\bf Results$ The 30-day mortality was higher in HCMV-seropositive patients than in seronegative sepsis patients (38% vs. 25%, respectively; $\it p$ = 0.008; HR, 1.656; 95% CI 1.135–2.417). This effect was observed independent of age ($\it p$ = 0.010; HR, 1.673; 95% CI 1.131–2.477). The predictive value on the outcome of the increased concentrations of IL-6 was present only in the seropositive cohort (30-day mortality, 63% vs. 24%; HR 3.250; 95% CI 2.075–5.090; $\it p$ < 0.001) with no significant differences in serum concentrations of IL-6 between the two groups. Procalcitonin and IL-10 exhibited the same behavior and were predictive of the outcome only in HCMV-seropositive patients. $\bf Conclusion$ We suggest that the predictive value of inflammation-associated biomarkers should be re-evaluated with regard to the HCMV serostatus. Targeting HCMV latency might open a new approach to selecting suitable patients for individualized treatment in sepsis