Cooperation in species: Interplay of population regulation and extinction through global population dynamics database

AbstractAntimicrobial resistance (AR) is a major global threat to public health. Understanding the population dynamics of AR is critical to restrain and control this issue. However, no study has provided a global picture of the resistome of Acinetobacter baumannii, a very important nosocomial pathogen. Here we analyze 1450+ genomes (covering > 40 countries and > 4 decades) to infer the global population dynamics of the resistome of this species. We show that gene flow and horizontal transfer have driven the dissemination of AR genes in A. baumannii. We found considerable variation in AR gene content across lineages. Although the individual AR gene histories have been affected by recombination, the AR gene content has been shaped by the phylogeny. Furthermore, many AR genes have been transferred to other well-known pathogens, such as Pseudomonas aeruginosa or Klebsiella pneumoniae. Finally, despite using this massive data set, we were not able to sample the whole diversity of AR genes, which suggests that this species has an open resistome. Ours results highlight the high mobilization risk of AR genes between important pathogens. On a broader perspective, this study gives a framework for an emerging perspective (resistome-centric) on the genome epidemiology (and surveillance) of bacterial pathogens.

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Population dynamics in echinococcosis and cysticercosis: regulation ofTaenia hydatigenaandT. ovisin lambs through passively transferred immunity

Parasitology ◽

10.1017/s0031182000079853 ◽

1990 ◽

Vol 101 (1) ◽

pp. 145-151 ◽

Cited By ~ 8

Author(s):

M. A. Gemmell ◽

J. R. Lawson ◽

M. G. Roberts ◽

J. F. T. Griffin

Keyword(s):

Population Dynamics ◽

Natural Environment ◽

Population Regulation ◽

Acquired Immunity ◽

Taenia Hydatigena ◽

Density Dependent ◽

Active Immunity ◽

Infection Pressure ◽

High Infection

SUMMARYA comparison has been made of the interactions between passively transferred and actively acquired immunity in regulating populations ofTaenia hydatigenaandT. ovis.When ewes were grazed prior to parturition under a high infection pressure, immunity was transferred to their offspring for up to 8 weeks. A qualititative difference between the species was the destruction of larvalT. ovisprior to their establishment (‘pre-encystment immunity’) and that ofT. hydatigenaafter they had become established (‘post-encystment immunity’) in the challenged lambs. The major difference in terms of population regulation between the two parasites was that infection occurred withT. hydatigenabut not withT. ovisin those lambs reared from birth for 16 weeks under high infection pressure. Passive, like active immunity, is a density-dependent constraint. It plays an important role in the population regulation ofT. ovis, but not ofT. hydatigena. This is discussed in terms of transmission in the natural environment, an hypothesis on humoral protection and the need to elucidate pathways of protection when immunization schedules are being evaluated for controlling the taeniid zoonoses.

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Evidence for the Postconquest Demographic Collapse of the Americas in Historical CO2 Levels

Earth Interactions ◽

10.1175/ei157.1 ◽

2006 ◽

Vol 10 (11) ◽

pp. 1-14 ◽

Cited By ~ 16

Author(s):

Franz X. Faust ◽

Cristóbal Gnecco ◽

Hermann Mannstein ◽

Jörg Stamm

Keyword(s):

Population Dynamics ◽

Strong Evidence ◽

Ice Cores ◽

Causal Chain ◽

Atmospheric Co2 ◽

Agricultural Fields ◽

Native Populations ◽

Co2 Levels ◽

European Colonization ◽

Global Population

Abstract This article promotes the hypothesis that the massive demographic collapse of the native populations of the Americas triggered by the European colonization brought about the abandonment of large expanses of agricultural fields soon recovered by forests, which in due turn fixed atmospheric CO2 in significant quantities. This hypothesis is supported by measurements of atmospheric CO2 levels in ice cores from Law Dome, Antarctica. Changing the focus from paleoclimate to global population dynamics and using the same causal chain, the measured drop in historic atmospheric CO2 levels can also be looked upon as further, strong evidence for the postconquest demographic collapse of the Americas.

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Establishment, survival and site selection of the cestode Eubothrium crassum in brown trout, Salmo trutta

Parasitology ◽

10.1017/s0031182000065872 ◽

1996 ◽

Vol 112 (3) ◽

pp. 347-355 ◽

Cited By ~ 5

Author(s):

C. R. Kennedy

Keyword(s):

Population Dynamics ◽

Site Selection ◽

Salmo Trutta ◽

Population Regulation ◽

Host System ◽

Mean Intensity ◽

Density Dependent ◽

Brown Trout Salmo Trutta ◽

Selection Of ◽

Heavy Mortality

SUMMARYPopulation dynamics, site selection, growth and maturation of the cestode Eubothrium crassum in a natural population of Salmo trutta in a small lake were studied over a period of 1 year, the life-span of a cohort in fish. Infection of fish commenced in spring but peaked in July. Small, plerocerciform parasites initially located in the intestine, but then some moved into the pyloric caecae whilst others, the majority in heavy infections, were lost from the fish causing a fall in abundance from 460 to 10 over 2 months. This mortality was density dependent. Initially, parasites were distributed more evenly throughout the caecae but as time increased larger parasites were found preferentially in the anterior caecae before moving back into the intestine when gravid, preparatory to being lost in the following summer. Only a small proportion of the infrapopulation became gravid. Although the proportion of caecae occupied was initially density dependent, by the time of maturation several preferred anterior caecae remained unoccupied and mean intensity always exceeded unity. Neither growth nor maturation was affected by intraspecific competition. It was concluded that caecal availability did not set a limit or threshold of infrapopulation density, and in this respect E. crassum–S. trutta differed from some acanthocephalan-fish systems but was similar to others. Heavy infection followed by heavy mortality appeared to be typical of this parasite-host system in other localities, and of several other cestode-fish systems. The implications of this for population regulation are discussed.

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Are patterns of density dependence in the Global Population Dynamics Database driven by uncertainty about population abundance?

Ecology Letters ◽

10.1111/j.1461-0248.2011.01702.x ◽

2011 ◽

Vol 15 (1) ◽

pp. 17-23 ◽

Cited By ~ 93

Author(s):

Jonas Knape ◽

Perry de Valpine

Keyword(s):

Population Dynamics ◽

Density Dependence ◽

Population Abundance ◽

Global Population

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Heterogeneity and the dynamics of host—parasitoid interactions

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1990.0193 ◽

1990 ◽

Vol 330 (1257) ◽

pp. 203-220 ◽

Cited By ~ 58

Keyword(s):

Population Dynamics ◽

Continuous Time ◽

Population Regulation ◽

Host Density ◽

General Rule ◽

Field Studies ◽

Simple Description ◽

Density Dependent ◽

Total Heterogeneity ◽

Local Host

This paper is concerned with the dynamical effects of spatial heterogeneity in host-parasitoid interactions with discrete generations. We show that the dynamical effects of any pattern of distribution of searching parasitoids in such systems can be assessed within a common, simple framework. In particular, we describe an approximate general rule that the populations of hosts and parasitoids will be regulated if the coefficient of variation squared (CV 2 ) of the distribution of searching parasitoids is greater than one. This criterion is shown to apply both generally and in several specific cases. We further show that CV 2 may be partitioned into a density-dependent component (direct or inverse) caused by the response of parasitoids to host density per patch, and a density independent component. Population regulation can be enhanced as much by density independent as by density-dependent heterogeneity. Thus the dynamical effects of any pattern of distribution of searching parasitoids can be assessed within the same common framework. The paradoxical impact of density-independent heterogeneity on dynamics is especially interesting: the greater the density independence, and thus the more scattered the data of percent parasitism against local host density, the more stable the populations are likely to be. Although a detailed analysis of host-parasitoid interactions in continuous time has yet to be done, evidence does not support the suggestion of Murdoch & Oaten (1989) that non-random parasitism may have quite different effects on the dynamics of continuous-time interactions. There appears to be no fundamental difference in the role of heterogeneity in comparable discrete- or continuous-time interactions. A total of 65 data sets from field studies have been analysed, in which percentage parasitism in relation to local host density have been recorded. In each case, estimated values of have been obtained by using a maximum likelihood procedure. The method also allows us to partition the CV 2 into the density dependent and density-independent components mentioned above. In 18 out of the 65 cases, total heterogeneity was at levels sufficient (if typical of the interactions) to stabilize the interacting populations (i.e. CV 2 > 1). Interestingly, in 14 of these it is the host-density-independent heterogeneity that contributes most to the total heterogeneity. Although heterogeneity has often been regarded as a complicating factor in population dynamics that rapidly leads to analytical intractability, this clearly need not necessarily be so. The CV 2 > 1 rule explains the consequences of heterogeneity for population dynamics in terms of a simple description of the heterogeneity itself, and provides a rough rule for predicting the effects of different kinds of heterogeneity on population regulation.

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