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"Spatial and temporal heterogeneity explain disease dynamics in a spatially explicit network model" Christopher P. Brooks, Janis Antonovics, and Timothy H. Keitt


Infected Fire Pink (Silene virginica: photographs by J. Antonovics)

Using spatially explicit, network-based models to predict the spread of a common fungal pathogen in a native wildflower population, the authors were able to predict the number of new infections two seasons in advance with almost 75% accuracy. Understanding the consequences of host variation in disease spread may provide insights for improving the control of infectious disease outbreaks.

In the News

Featured in New York Times
"Tongue orchids' sexual guile: Utterly convincing" July 15, 2008
Orchid Sexual Deceit Provokes Ejaculation
A. C. Gaskett, C. G. Winnick, M. E. Herberstein
"The discovery that orchids can induce such an extreme response is more than just bizarre natural history, because biologists have always assumed that the sexual misrepresentations of orchids were harmless to the duped males, no more than a comical exercise in frustration.Yet the study, published last month in The American Naturalist, suggests a potentially huge cost to the wasps."

Featured in Reuters
"Sexy orchids do more than embarrass wasps?" May 8, 2008
Orchid Sexual Deceit Provokes Ejaculation
A. C. Gaskett, C. G. Winnick, and M. E. Herberstein
"Insects pollinating Australian tongue orchids (Cryptostylis species) frequently ejaculate and waste copious sperm," they wrote in a report in The American Naturalist.

Featured in Nature
"Those clever flowers" May 8, 2008
Orchid Sexual Deceit Provokes Ejaculation
A. C. Gaskett, C. G. Winnick, and M. E. Herberstein
Secondly, researchers have found just how effective orchids can be at mimicking female wasps, as a way to lure male wasps in to collect their pollen . Not only do they attract the boys (which was already known), but they also seem to excite them enough to cause an ejaculation (releasing “copious sperm” according to the report). Obviously this is a waste of time and energy for the wasps, but apparently it helps the orchids, somehow – I guess by increasing stickiness? “Orchid species provoking such extreme pollinator behavior have the highest pollination success," they report in The American Naturalist.

Featured in New York Times
"Even by Parasite Standards, These Worms Stand Out" April 8, 2008
Parasite-Induced Fruit Mimicry in a Tropical Canopy Ant
S. P. Yanoviak, M. Kaspari, R. Dudley, and G. Poinar Jr
Dissecting the ants, the researchers found that the gasters were full of hundreds of tiny eggs containing developing worms. Dr. Yanoviak and his colleagues were then able to determine the stages in the parasite-host cycle, which they describe in a paper in The American Naturalist.

May 2007

Volume 169, Number 5
Am Nat 2007. Vol. 169, pp. 673–683
0003-0147/2007/16905-41584$15.00
DOI: 10.1086/513484

A Perfect Storm: The Combined Effects on Population Fluctuations of Autocorrelated Environmental Noise, Age Structure, and Density Dependence

Christopher C. Wilmers,1,*

Eric Post,2, and

Alan Hastings3,

1. Environmental Studies Department, University of California, Santa Cruz, California 95064;

2. Department of Biology, Eberly College of Science, and Penn State Institutes of the Environment, Penn State University, University Park, Pennsylvania 16802;

3. Department of Environmental Science and Policy, University of California, Davis, California 95616

Abstract:

While it is widely appreciated that climate can affect the population dynamics of various species, a mechanistic understanding of how climate interacts with life-history traits to influence population fluctuations requires development. Here we build a general density-dependent age-structured model that accounts for differential responses in life-history traits to increasing population density. We show that as the temporal frequency of favorable environmental conditions increases, population fluctuations also increase provided that unfavorable environmental conditions still occur. As good years accumulate and the number of individuals in a population increases, successive life-history traits become vulnerable to density dependence once a return to unfavorable conditions prevails. The stronger this ratcheting of density dependence in life-history traits by autocorrelated climatic conditions, the larger the population fluctuations become. Highly fecund species, and those in which density dependence occurs in juvenile and adult vital rates at similar densities, are most sensitive to increases in the frequency of favorable conditions. Understanding the influence of global warming on temporal correlation in regional environmental conditions will be important in identifying those species liable to exhibit increased population fluctuations that could lead to their extinction.

Submitted January 23, 2006; Accepted November 22, 2006; Electronically published March 7, 2007

Keywords:

climate change, autocorrelation, population dynamics, North Atlantic Oscillation (NAO), Isle Royale.

Associate Editor: William F. Morris

Editor: Donald L. DeAngelis

Cited by

Thomas Hovestadt, Piotr Nowicki. (2008) Process and measurement errors of population size: their mutual effects on precision and bias of estimates for demographic parameters. Biodiversity and Conservation
Online publication date: 16-Aug-2008.
CrossRef
Guiming Wang, N. Thompson Hobbs, Saran Twombly, Randall B. Boone, Andrew W. Illius, Iain J. Gordon, John E. Gross. (2008) Density dependence in northern ungulates: interactions with predation and resources. Population Ecology
Online publication date: 27-Jul-2008.
CrossRef
Masami Fujiwara. (2008) Effects of an autocorrelated stochastic environment and fisheries on the age at maturity of Chinook salmon. Theoretical Ecology 1:2, 89-101
Online publication date: 1-Jul-2008.
CrossRef
CHRISTOPHER C. WILMERS, ERIC POST, ALAN HASTINGS. (2007) The anatomy of predator–prey dynamics in a changing climate. Journal of Animal Ecology 76:6, 1037-1044
Online publication date: 1-Dec-2007.
CrossRef
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