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	Predicting Invasions of Nonindigenous Plants and Plant Pests
		In its simplest form, the demographic effects of environmental perturbations are assumed to be equally distributed across all individuals in a particular age or stage class in a population.
		Interactions between an Allee effect and environmental variability in larger colonies were more deleterious than the sum of their independent influences; a few years with bad conditions reduced population density to a level where negative population growth eventually led to extinction (Grevstad, 1999a,b).
		Because of the local effect of selection by host resistance on the diversity and complexity of the pathogen population, immigrations by new genotypes are often detected on the basis of abrupt changes in pathogenicity or mating type.
	books.nap.edu /openbook.php?record_id=10259&page=41 (9547 words)

	Allee effect - Wikipedia, the free encyclopedia
		The Allee effect is a phenomenon in biology named after W.
		The effect may be due to any number of causes.
		In some species, reproduction—finding a mate in particular—may be increasingly difficult as the population density decreases.
	en.wikipedia.org /wiki/Allee_effect (138 words)

	APC, INC. - Functional Proteins for Animal Health and Nutrition
		Effect of spray dried animal plasma and colistin on performance, structure of small intestine and ileal and caecal microbiology of weanling pigs experimentally infected with Escherichia coli K99.
		Effect of spray-dried plasma and lipopolysaccharide exposure on weaned pigs: I. Effects on the immune axis of weaned pigs.
		Effect of spray-dried plasma and Eschericia coli on intestinal morphology and the hypothalamic-pituitary-adrenal (HPA) axis of the weaned pig.
	www.americanprotein.com /functional_prots/research_review/reference_list.html (3170 words)

	Ayres Abstracts (Site not responding. Last check: )
		Effects of pine oleoresin on colonization and population dynamics of Dendroctonus frontalis.
		The effects of tree oleoresin and beetle colonization rates on host-tree colonization and population dynamics of an eruptive pine bark beetle, Dendroctonus frontalis were evaluated.
		The demographic effects from tree defenses and specialist natural enemies probably interact because the addition of an Allee effect to predator-prey cycles increases the amplitude and period of the endogenous cycles.
	www.dartmouth.edu /~mpayres/pubs/abs60.htm (311 words)

	Références Bibliographiques (Site not responding. Last check: )
		Revised estimates of the effects of turbulence on fertilization in the purple sea urchin, Strongylocentrotus purpuratus.
		Allee effect and population dynamics in the Glanville fritillary butterfly.
		Effect of sperm concentration and sperm ageing on fertilisation success in the Antarctic soft-shelled clam Laternula elliptica and the Antarctic limpet Nacella concinna.
	www.theses.ulaval.ca /2004/21737/apa.html (1261 words)

	Nat' Academies Press, Predicting Invasions of Nonindigenous Plants and Plant Pests (2002)
		An Allee effect occurs when low-density populations sustain a zero or even negative rate of increase because of reduced reproduction or survival when con-specifics are insufficiently abundant.
		The dynamics of Allee effects, therefore, can exert a substantial influence on whether a colony of a newly arrived organism is able to persist and become established.
		The strength of an Allee effect on the persistence of a population depends on the processes influenced by inverse density dependence.
	www.nap.edu /openbook.php?record_id=10259&page=47 (701 words)

	Laws of Population Ecology
		Allee's Law says that there is a positive relationship between individual fitness and either the numbers or density of conspecifics (conspecifics are other individuals of the same species).
		Synonyms: The Maternal Effect (Ginzburg and Colyvan 2004).
		Stephens PA, Sutherland WJ (1999) Consequences of the Allee effect for behaviour, ecology and conservation.
	www.ecology.info /laws-population-ecology.htm (3371 words)

	- A I M S
		We show that the strong Allee effect can be important factor that change ecosystems dynamics dramatically, in comparison, for example, with the system with logistic growth of prey alone, and can enhance chaotic behavior.
		We also examine a completely new dynamics of the system with the Allee effect, which is the spread of species via propagation of patches without smooth fronts (even when diffusion coefficients are equal).
		The chaotic patchy invasion becomes a result of fully deterministic predator-prey interactions influenced by the Allee effect and not by environmental stochasticity.
	aimsciences.org /AIMS-Conference/jsp/display-conference-abstract.jsp?id=2252 (215 words)

	Allee Effect
		Another example of how density dependence can operate in small populations is provided by the Allee effect (Allee 1931), i.e., the per capita birth rate declines at low densities (Fig.
		This is known as €Allee-type behavior€ (of the per capita birth rate), and its effect on the per capita population growth rate, €R(t)€, is called an Allee effect.
		In theory, a low density equilibrium would be sustained in a deterministic equilibrium, where the birth rate equals the death rate.
	welcome.warnercnr.colostate.edu /~gwhite/pva/fslide45.htm (111 words)

	[No title] (Site not responding. Last check: )
		Allee effects occur for a wide variety of reasons including the presence of conspecifics reducing predation risk or increasing the likelihood of mating success.
		Allee effects often lead to a critical population density below which extinction is unavoidable.
		Population with fluctuating dynamics and an Allee effect are especially vulnerable to extinction as the fluctuations may dip below the critical density.
	www.pims.math.ca /science/2001/mathbio/schreiber.html (261 words)

	DIALOG Dissertation Abstracts (Site not responding. Last check: )
		Allee (1931) first reported that reproductive success in free-spawning marine invertebrates was dependent on population density.
		However, little attention was paid to the 'Allee' effect until Pennington's (1985) pivotal paper describing the consequeces of sperm dilution in echinoid fertilization.
		Commercial shellfish are particularly prone to the deleterious 'Allee' effect.
	aslo.org /phd/dialog/200105-10.html (238 words)

	Romuald N. Lipcius - Fisheries Science (Site not responding. Last check: )
		Periodic dynamics in a two-stage Allee effect model are driven by tension between stage equilibria.
		Simulated effects of seagrass loss and restoration on settlement and recruitment of blue crab postlarvae and juveniles in the York River, Chesapeake Bay.
		Effect of seagrass habitat fragmentation on juvenile blue crab survival and abundance.
	www.vims.edu /fish/faculty/lipcius_rn.html (850 words)

	ARS \| Publication request: An Allee Effect Limits the Invasive Potential of Tilletia Indica (Site not responding. Last check: )
		We developed a simple population model of T. indica that incorporates an Allee effect by calculating the probability of infection for different numbers of spores in the infection court.
		An Allee effect is predicted to be important at the frontier of an invasion, for establishment of new disease foci by a small population of resting spores, and when the environment is nonconducive for the production of new infective spores.
		We developed a simple population model of T. indica that incorporates an Allee effect by calculating the probability of infection for different numbers of secondary sporidia in the infection court.
	www.ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=136460&pf=1 (519 words)

	[No title]
		Population means of individual annual fecundity ranged from 0 to 182 in 1997 and from 0 to 156 in 1998 and were predicted by population means of SP and the rate of seed set, but not by floret production.
		Empirically, we investigated effects of local flowering plant density on pollination and of population size on mate availability in a common, self-incompatible purple coneflower, Echinacea angustifolia, growing in fragmented prairie habitat.
		But SI species experienced an additional, genetic contribution to the Allee effect (S -Allee effect) caused by allele loss at the S locus, which reduces mate availability, thereby decreasing reproduction.
	echinacea.umn.edu /bib/echinacea_citations.bib (761 words)

	[No title] (Site not responding. Last check: )
		In contrast to enrichment, the system is stabilised by an influx of prey in the form of a rescue effect, and destabilised by an outflux of prey in the form of an Allee effect.
		Limit cycles are not sustained by the Allee effect; instead both populations collapse to zero over a large region of the predator-prey phase plane.
		The catastrophic extinction of prey requires the presence of both an Allee effect on prey and a predator with a type II functional response, though neither needs to contribute a large impact to prey dynamics.
	www.soton.ac.uk /~cpd/kds.html (318 words)

	A Threefold Genetic Allee Effect: Population Size Affects Cross-Compatibility, Inbreeding Depression and Drift Load in ...
		A Threefold Genetic Allee Effect: Population Size Affects Cross-Compatibility, Inbreeding Depression and Drift Load in the Self-Incompatible Ranunculus reptans -- Willi et al.
		The effect of allelic diversity indicates that populations that
		Effects of population size and mating history on inbreeding depression.
	www.genetics.org /cgi/content/full/169/4/2255 (4712 words)

	Phytopathology - November 2002 Abstracts (Site not responding. Last check: )
		Our objective was to characterize how the Allee effect might reduce the invasive potential of this economically important pathogen.
		An Allee effect is predicted to be important at the frontier of an invasion, for establishment of new foci by a small population of teliospores, and when the environment is nonconducive for the production of secondary sporidia.
		The frequency of sexual reproduction has a profound effect on the population structure and the adaptive potential of a facultatively sexual parasite.
	www.apsnet.org /phyto/abstract/2002/pno02ab.htm (3769 words)

	Abstract (Site not responding. Last check: )
		The negative frequency-dependent effect of reproductive success in animals on population growth refers to a category of phenomena termed the Allee effect.
		Lack of breeding and reduced reproductive success of females at low population densities are commonly described in situations where females have little or no opportunity to choose a mate, consistent with this suggestion.
		We developed a demographic model that incorporated the effects of lack of female choice on rates of reproduction.
	www.oikos.ekol.lu.se /oikos.92.1.abstracts/10765moller.htm (156 words)

	[No title]
		Cultivation effect — this is when the activities of one stage in the life history increases the fitness of another stage — e.g.
		Better minds than me spend time arguing about the niceties of definitions of these terms, but to all intents and purposes, Allee effects and depensation are the same — a decline in fitness and per capita population growth rate at low density.
		Allee effects in fisheries In fisheries models we are concerned about mortality — since what fishing does (mainly) is increase mortality.
	www.sos.bangor.ac.uk /~oss405/OXB2014-Allee.doc (1642 words)

	ASLO Summer Meeting 2005, Santiago de Compostela, Spain (Site not responding. Last check: )
		The requirement for sexual reproduction suggests the viability of small populations of H. shoshone could be limited by an Allee effect resulting from inability to find mates.
		We initiated a whole-lake reintroduction experiment in seven Sierra Nevada lakes to test for an Allee effect.
		Preliminary results are consistent with an Allee effect, with recovery in only two lakes stocked at high density.
	aslo.org /meetings/santiago2005/abstracts/366.htm (233 words)

	PLoS Biology - Rarity Value and Species Extinction: The Anthropogenic Allee Effect
		This human-generated feedback loop is very similar to the Allee effect [3,4], an important process in basic ecology and applied conservation biology.
		Although studies on Allee effects are continuing, it has been generally accepted that the Allee effect is intrinsic to the species concerned, which express it naturally at low density.
		Stephens PA, Sutherland WJ (1999) Consequences of the Allee effect for behavior, ecology and conservation.
	biology.plosjournals.org /perlserv?request=get-document&doi=10.1371/journal.pbio.0040415&ct=1 (4527 words)

	ESA 2002 - Interactive Index
		Allee effects and random catastrophes in the population dynamics of a social spider.
		Effects of soil fertilization on the chemical defense and performance of a specialist insect herbivore.
		Effects of aspen budbreak phenology and leaf chemistry on levels of defoliation during a forest tent caterpillar outbreak.
	abstracts.co.allenpress.com /pweb/esa2002/termindex/subject-A.html (5451 words)

	Register of Ecological Models: PREY_FLUX
		In contrast to enrichment, the system is stabilised by an influx of prey in the form of a rescue effect, and destabilised by an outflux of prey in the form of an Allee effect.
		Limit cycles are not sustained by the Allee effect; instead both populations collapse to zero over a large region of the predator-prey phase plane.
		The catastrophic extinction of prey requires the presence of both an Allee effect on prey and a predator with a type II functional response, though neither needs to contribute a large impact to prey dynamics.
	eco.wiz.uni-kassel.de /model_db/mdb/prey_flux.html (438 words)

	Field Crops: pollinators
		The models will also incorporate the potential effects of decreased pollinator abundance on plant reproduction and population dynamics, which has direct implications for both native plants and agricultural crops.
		The effect of reduced pollinator visitation in small population fragments will be represented as an Allee effect.
		Effects of environmental and demographic stochasticity will also be included.
	www.clemson.edu /scg/field/johnson.ar.htm (1067 words)

	Ecological Archives E086-169-A1
		Lastly, it is unclear whether immigrants from outside of the study area have a significant effect on the regional dyanamics of C.
		These analyses indicated that the best fit and most parsimonious model was of the following form: (1) with a power decay function of dispersal, (2) without an Allee effect, (3) with a power decay function for the extinction-patch size relationship, (4) without a rescue effect, (5) without post-natal dispersal, and (6) without remote migration.
		When the Allee effect was removed from the model this greatly improved the model fit (ΔAIC = 59.90).
	esapubs.org /archive/ecol/E086/169/appendix-A.htm (594 words)

	Statistical Programs: Seminar -
		An Allee effect, or positive density dependence, could seriously increase a population's risk of extinction.
		Theoretical studies of Allee effects have been predominantly deterministic and have featured population models that typically display a lower unstable equilibrium (critical population size) below which extinction is certain.
		Formulating the problem in a stochastic framework is a possible key to testing for an Allee effect in species translocation or colonization data.
	www.uidaho.edu /ag/statprog/seminars/dennis_01.html (192 words)

	Edge density key to controlling gypsy moth spread
		Without an Allee effect, these colonies would establish, but because gypsy moths exhibit an Allee effect, the low populations are insufficient for establishment of permanent populations.
		However, when the it is a factor, not only does pulsed expansion occur, but it mimics the historic pulses of the gypsy moth population from 1960 to 2002 found in the quarantine records.
		If researchers can determine that the Allee effect is in place, than this same plan of containment might aid in controlling a variety of pests.
	www.eurekalert.org /pub_releases/2006-11/ps-edk111406.php (548 words)

	Interceptions of nonindigenous plant pests at U.S. ports of entry and border crossings over a 17 year period
		Further we discuss the role of Allee effects during the establishment and early growth of invading populations and how knowledge of these population processes can be used to optimize the detection and eradication of such populations.
		The magnitude of Allee effects vary tremendously among species due to variation in life history traits, however virtually every sexually reproducing species can be expected to exhibit an Allee effect at low densities.
		(2003) used an Allee effect model to illustrate the numerical relationships between initial numbers of individuals, the strength of an eradication treatment (% killed), and the probability of population persistence to document the existent of a positive relationship between the initial size of the founder population and the probability of establishment.
	www.iufro.org /uploads/media/t2-liebhold-et-al.doc (3504 words)

	Keetsa Mattress Store - Keetsa! Blog - Eco-Friendly and Green News » Blog Archive » Understanding the Allee ...
		While we are all aware that there are some areas where we would usually have population control problems, the essence of it all is that existence and survival is entirely dependent as well on how the proper reproduction and survival of individuals can be done.
		The Allee Effect is not entirely familiar with most of us.
		The Allee effect is a phenomenon in biology named after Warder Clyde Allee, who first wrote extensively on it.
	keetsa.com /blog/organic/understanding-the-allee-effect (371 words)

	Allee Effect
		The ecologist W. Allee (1931) was one of the first to write extensively on the ecological significance of animal aggregations and, because of this, the positive relationship between population density and the reproduction and survival of individuals is often known as the "Allee effect".
		An Allee or underpopulation effect arises when the per-capita birth rate (B) increases with population density to some maximum value, the reproductive potential of the species, and the death rate (D) remains constant (see figure).
		The point U where the two rates intersect is an unstable equilibrium because:
	classes.entom.wsu.edu /529/Allee.htm (183 words)

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