ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Condition and fecundity of the damselfly, Enallagma ebrium (Hagen): the importance of ectoparasites (1991)

Forbes, Mark R. L. ; Baker, Robert L.

Springer

Oecologia 86 (1991), S. 335-341

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ISSN: 1432-1939

Keywords: Arrenurus ; Enallagma ; Mite ; Damselfly ; Host-parasite interactions

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary The extent, magnitude, and cause of natural covariation between degree of parasitism and other variables known or suspected of influencing host fitness (such as host age or body size) has been understudied. We demonstrate that degree of parasitism by larval water mites (Arrenurus spp.) was associated with reduced condition of males and with lowered fecundity of young females of the damselfly, Enallagma ebrium (Hagen) (Odonata: Coenagrionidae). We also demonstrate that degree of parasitism can covary with both age and size of host damselflies. We explain the putative causes of such natural covariation, and we suggest that degree of parasitism, host age, and host size can all interact to determine damselfly fitness. We expect that natural covariation between the host's phenotype and degree of parasitism will be frequently observed. Studies of such natural covariation will help researchers to assess better the importance of several variables on host reproductive success and to understand better the dynamics of host-parasite interactions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00317598

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2

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Fluctuating asymmetry in relation to indices of quality and fitness in the damselfly, Enallagmaebrium (Hagen) (1997)

Leung, Brian ; Forbes, Mark R.

Springer

Oecologia 110 (1997), S. 472-477

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ISSN: 1432-1939

Keywords: Key wordsDamselflies ; Ectoparasitic mites ; Fluctuating asymmetry ; Longevity ; Measurement error

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Fluctuating asymmetry (FA) refers to random deviations from symmetry of otherwise bilaterally symmetric traits. Researchers have hypothesized that FA should be inversely related to individual quality or fitness. In this study, we tested for FA-quality and FA-fitness relations in the damselfly, Enallagmaebrium (Hagen). We used wet mass of an individual as a measure of its quality and longevity as a measure of its fitness. Contrary to predictions, we found no relation between FA and quality or fitness, even after we controlled for possible confounding factors, such as measurement error and inadequate sample size.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s004420050182

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3

Electronic Resource

The evolution of virulence: A stochastic simulation model examining parasitism at individual and population levels (1998)

Leung, BRIAN ; Forbes, MARK R.

Springer

Evolutionary ecology 12 (1998), S. 165-177

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ISSN: 1573-8477

Keywords: co-infection ; competition ; infectiousness ; myxomatosis ; parasite fitness ; positive frequency dependence ; transmission ; virulence

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We modelled the evolution of virulence when co-infections were permitted and compared patterns generated by our modelling approach with those of other models. In support of current models, we found that strains with virulences above the maximum basic reproductive rate (Ro) were competitively superior, and that both high host density (as indexed by host encounter rate) and high parasite infectiousness favoured evolution of strains with high virulence. However, we found that co-existence typically did not continue indefinitely and that parasites with high virulences, and Ro values approaching unity, often did not persist. We examined the extent to which processes such as stochasticity and positive frequency dependence influenced patterns generated by our model. Also, we examined commonly used indices of parasite fitness [i.e. Ro and rate of spread (ROS)], and found that only ROS was positively related to competitive ability when co-infections were permitted. However, there was considerable variation in competitive ability that was not explained by variation in ROS. We conclude that our modelling approach can significantly influence patterns generated and that conclusions from single models or conclusions based on current indices of parasite fitness should be viewed with caution. We suggest empirical tests that distinguish our model from other models and further examine the impact of mechanisms such as positive frequency dependence on the evolution of virulence.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006579512133

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4

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Sex ratios, mating behavior and sexual size dimorphism of the northern water snake, Nerodia sipedon (1995)

Weatherhead, Patrick J. ; Barry, Frances E. ; Brown, Gregory P. ; [et al.]

Springer

Behavioral ecology and sociobiology 36 (1995), S. 301-311

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ISSN: 1432-0762

Keywords: Nerodia sipedon ; Sexual size dimorphism ; Sex ratios ; Mating behavior

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Competition among males to mate is generally associated with male-biased size dimorphism. In this study we examine mating behavior in the northern water snake (Nerodia sipedon), a species in which males are much smaller than females despite substantial competition among males to mate. Competition among males was a consequence of a male-biased operational sex ratio due to slightly higher female mortality from a birth sex ratio of 1 : 1, and, in 1 year, more synchronous and longer mating activity by males. Approximately one-third of both males and females appeared not to mate in a given year. Larger males were generally more likely to attempt mating, but size did not explain the variance in the number of aggregations in which individual males participated. Within aggregations, males that were successful at achieving intromission were larger than unsuccessful males in 1 of 2 years. Variation in condition (mass relative to length) and relative tail length were not generally useful predictors of either mating effort or success in males. Because large size was often advantageous to males, sexual size dimorphism appeared not to be a consequence of sexual selection favoring smaller males. Because sexual dimorphism was evident at birth, and both males and females matured sexually at about 4 years, sexual dimorphism was not simply a consequence of one sex growing at the maximum rate for longer. Female fecundity increased with size, and sex differences in size-fecundity relations may underly the pattern of sexual size dimorphism. However, because multiple mating by females is common, sperm competition is likely to be important in determining male reproductive success. Therefore, allocation of energy to sperm rather than growth may also prove to be an important influence on male growth rates and sexual size dimorphism.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00167791

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5

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Risk-taking by female ducks: intra- and interspecific tests of nest defense theory (1994)

Forbes, Mark R. L. ; Clark, Robert G. ; Weatherhead, Patrik J. ; [et al.]

Springer

Behavioral ecology and sociobiology 34 (1994), S. 79-85

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ISSN: 1432-0762

Keywords: Life history theory ; Parental investment ; Predation risk ; Waterfowl ; Observer effect

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract We tested several predictions of nest defense theory by observing variation in flushing distance and probability of nest abandonment within and between six species of waterfowl. In these species, only the females incubate eggs and attend offspring. First, we examined whether flushing distance by females varied in relation to clutch size, stage of incubation, and time of season, after controlling for the number of visits made to nests by observers. Revisits by observers appeared to affect flushing distance by females for reasons unrelated to the relative value of the current clutch. We found that as incubation progressed, females allowed observers to approach more closely before flushing from the nest. In some species, females with larger clutches allowed closer approaches to nests before flushing which was also consistent with nest defense theory. In contrast, time of season (Julian date) did not relate to flushing distance for any species. When species were compared, we found that species with moderate to high yearly mortality and high reproductive output per breeding attempt (e.g., northern shoveler and blue-winged teal) were less likely to abandon nesting attempts and exhibited “riskier” behavior (remained at nests when approached closely by observers) than species that had lower yearly mortality (e.g., mallard). Our results show that flushing distance and patterns of nest abandonment by female ducks conform to several predictions of nest defense theory.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00164178

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Avian cholera, a threat to the viability of an Arctic seabird colony? (2012)

Descamps, Sebastien ; Jenouvrier, Stephanie ; Gilchrist, H. Grant ; [et al.]

Public Library of Science

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Publication Date: 2022-05-26

Description: © The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 7 (2012): e29659, doi:10.1371/journal.pone.0029659.

Description: Evidence that infectious diseases cause wildlife population extirpation or extinction remains anecdotal and it is unclear whether the impacts of a pathogen at the individual level can scale up to population level so drastically. Here, we quantify the response of a Common eider colony to emerging epidemics of avian cholera, one of the most important infectious diseases affecting wild waterfowl. We show that avian cholera has the potential to drive colony extinction, even over a very short period. Extinction depends on disease severity (the impact of the disease on adult female survival) and disease frequency (the number of annual epidemics per decade). In case of epidemics of high severity (i.e., causing 〉30% mortality of breeding females), more than one outbreak per decade will be unsustainable for the colony and will likely lead to extinction within the next century; more than four outbreaks per decade will drive extinction to within 20 years. Such severity and frequency of avian cholera are already observed, and avian cholera might thus represent a significant threat to viability of breeding populations. However, this will depend on the mechanisms underlying avian cholera transmission, maintenance, and spread, which are currently only poorly known.

Description: The study was supported by the Canadian Wildlife Service-Environment Canada (http://www.ec.gc.ca/), Nunavut Wildlife Management Board (http:// www.nwmb.com/), Greenland Institute of Natural Resources (http://www.natur.gl/), Polar Continental Shelf Project (http://polar.nrcan.gc.ca/), Fonds Que´be´cois de la Recherche sur la Nature et les Technologies (http://www.fqrnt.gouv.qc.ca/), Canadian Network of Centres of Excellence ArcticNet (http://www.arcticnet.ulaval. ca/), Natural Sciences and Engineering Research Council of Canada (http://www.nserc-crsng.gc.ca/), and the Department of Indian Affairs and Northern Canada (http://www.ainc-inac.gc.ca/).

Repository Name: Woods Hole Open Access Server

Type: Article

Format: application/pdf

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Multicentury perspective assessing the sustainability of the historical harvest of seaducks (2019)

Hargan, Kathryn E. ; Gilchrist, H. Grant ; Clyde, Nikolas M. T. ; [et al.]

National Academy of Sciences

In: PNAS - Proceedings of the National Academy of Sciences of the United States of America. 2019; 116(17): 8425-8430. Published 2019 Apr 01. doi: 10.1073/pnas.1814057116.

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Publication Date: 2019-04-01

Description: Where available, census data on seabirds often do not extend beyond a few years or decades, challenging our ability to identify drivers of population change and to develop conservation policies. Here, we reconstruct long-term population dynamics of northern common eiders (Somateria mollissima borealis). We analyzed sterols together with stable nitrogen isotopes in dated pond sediment cores to show that eiders underwent broadscale population declines over the 20th century at Canadian subarctic breeding sites. Likely, a rapidly growing Greenland population, combined with relocation of Inuit to larger Arctic communities and associated increases in the availability of firearms and motors during the early to mid-20th century, generated more efficient hunting practices, which in turn reduced the number of adult eiders breeding at Canadian nesting islands. Our paleolimnological approach highlights that current and local monitoring windows for many sensitive seabird species may be inadequate for making key conservation decisions.

Print ISSN: 0027-8424

Electronic ISSN: 1091-6490

Topics: Biology , Medicine , Natural Sciences in General

Published by National Academy of Sciences

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Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback (2016)

John C. Forbes; Mark R. Krumholz; Nathan J. Goldbaum; Avishai Dekel

Springer Nature

In: Nature

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Publication Date: 2016-07-28

Description: Suppression of star formation in dwarf galaxies by photoelectric grain heating feedback Nature 535, 7613 (2016). doi:10.1038/nature18292 Authors: John C. Forbes, Mark R. Krumholz, Nathan J. Goldbaum & Avishai Dekel Photoelectric heating—heating of dust grains by far-ultraviolet photons—has long been recognized as the primary source of heating for the neutral interstellar medium. Simulations of spiral galaxies have shown some indication that photoelectric heating could suppress star formation; however, simulations that include photoelectric heating have typically shown that it has little effect on the rate of star formation in either spiral galaxies or dwarf galaxies, which suggests that supernovae are responsible for setting the gas depletion time in galaxies. This result is in contrast with recent work indicating that a star formation law that depends on galaxy metallicity—as is expected with photoelectric heating, but not with supernovae—reproduces the present-day galaxy population better than does a metallicity-independent one. Here we report a series of simulations of dwarf galaxies, the class of galaxy in which the effects of both photoelectric heating and supernovae are expected to be strongest. We simultaneously include space- and time-dependent photoelectric heating in our simulations, and we resolve the energy-conserving phase of every supernova blast wave, which allows us to directly measure the relative importance of feedback by supernovae and photoelectric heating in suppressing star formation. We find that supernovae are unable to account for the observed large gas depletion times in dwarf galaxies. Instead, photoelectric heating is the dominant means by which dwarf galaxies regulate their star formation rate at any given time, suppressing the rate by more than an order of magnitude relative to simulations with only supernovae.

Print ISSN: 0028-0836

Electronic ISSN: 1476-4687

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics