ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Ecology Bagging the lag (2001)

Hochberg, Michael E. ; Weis, Arthur E.

[s.l.] : Nature Publishing Group

Nature 409 (2001), S. 992-993

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

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

Notes: [Auszug] Predicting changes in the size of natural populations has long been a goal of ecologists. But it is often far from simple to unravel the dynamics of populations. We rarely know all of the factors that affect them, let alone the many ways in which individual populations interact. Hence the ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/35059194

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2

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Differential abortion in the yucca (1995)

Richter, Kevin S. ; Weis, Arthur E.

[s.l.] : Nature Publishing Group

Nature 376 (1995), S. 557-558

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

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

Notes: [Auszug] SIR - Pellmyr and Huth1 showed that the yucca Yucca fillamentosa can prevent over-exploitation by the yucca moth Tegeticula yuccasella, a pollinator/seed predator, through differential abortion of infested fruits. Our work on Yucca whip-plei typica and Tegeticula maculata confirms these findings, ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/376557b0

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3

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Host gall size predicts host quality for the parasitoidEurytoma gigantea (Hymenoptera: eurytomidae), but can the parasitoid tell? (1993)

Weis, Arthur E.

Springer

Journal of insect behavior 6 (1993), S. 591-602

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ISSN: 1572-8889

Keywords: parasitoids ; foraging ; gallmakers ; oviposition ; size discrimination

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Simulation models presented here show that gall size of Eurosta solidaginisFitch (Diptera: Tephritidae) is a reliable predictor of its quality as a host to the parasitoid Eurytoma giganteaWalsh (Hymenoptera; Eurytomidae). The nutritional value of a gall to a parasitoid increases with diameter, but so does the likelihood that ovipositing parasitoids will fail to penetrate to the gall's central chamber. Despite the large differences in gall quality with size, this parasitoid seems incapable of distinguishing large, impenetrable galls from smaller, more suitable ones (Weis, A. E., et al., Ecol. Entomol. 10:341–348, 1985). This paper shows that Eurytomais capable of quick rejection of nonhost galls of similar size and shape to suitably sized host galls. Several lines of reasoning are explored to understand the seemingly maladaptive lack of sizediscrimination ability on host galls.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01048125

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4

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Variation in selection pressures on the goldenrod gall fly and the competitive interactions of its natural enemies (1989)

Abrahamson, Warren G. ; Sattler, Joan F. ; McCrea, Kenneth D. ; [et al.]

Springer

Oecologia 79 (1989), S. 15-22

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ISSN: 1432-1939

Keywords: Bird predation ; Eurosta solidaginis ; Parasitoids ; Selection pressures ; Solidago altissima

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Larvae of the tephritid fly Eurosta solidaginis induce ball-shaped galls on the stem of tall goldenrod, Solidago altissima. Survival probability depends on gall size; in small galls the larva is vulnerable to parasitoid oviposition, whereas larvae in large galls are more frequently eaten by avian predators. Fly populations from 20 natural old fields in central Pennsylvania were monitored in 1983 and 1984 to examine the distribution of the selection intensity imposed by natural enemies, the parasitoids Eurytoma gigantea and E. obtusiventris, the inquiline Mordellistena unicolor, and the predatory birds Dendrocopus pubescens and Parus atricapillus. Mordellistena and E. obtusiventris are able to attack galls of all diameters while E. gigantea and the predatory birds preferentially assaulted small and large diameter galls, respectively. Eurosta in intermediate sized galls had the highest survivorship, hence selection had a stabilizing component. However, parasitoid attack was more frequent than bird attack, and the two did not exactly balance, thus there was also a directional component. The mean directional selection intensity on gall size was 0.21 standard deviations of the mean, indicating that larger gall size was favored. Interactions among the insect members of the Eurosta natural enemy guild are complex and frequent.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00378234

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5

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Floral herbivore effect on the sex expression of an andromonoecious plant, Isomeris arborea (Capparaceae) (1998)

Krupnick, Gary A. ; Weis, Arthur E.

Springer

Plant ecology 134 (1998), S. 151-162

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ISSN: 1573-5052

Keywords: Andromonoecy ; Floral herbivory ; Floral sex expression ; Isomeris arborea ; Meligethes rufimanus ; Plant-herbivore interactions

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Flower-feeding insects may influence the reproductive behavior of their host plant. In plants with labile sex expression, the ratio of maternal to paternal investment may change in response to damage, an effect that goes beyond the direct reduction of plant gametes. We examined the effects of floral herbivory by the beetle Meligethes rufimanus (Nitidulidae) on the ratio of hermaphroditic flowers to male flowers in an andromonoecious shrub, Isomeris arborea (Capparaceae) in southern California. Plants exposed to herbivory had a greater rate of flower bud abortion than those protected from herbivory. Exposed plants produced a greater proportion of hermaphroditic flowers to male flowers, although damaged inflorescences still produced fewer fruit. An additional manipulative experiment showed that the removal of pistils on inflorescences led to an increase in the proportion of hermaphroditic flowers. This suggests that the presence of fruit may lead to pistil suppression in developing flowers. Adaptive responses to herbivory which favor andromonoecy thus include the continued production of hermaphroditic flowers when floral damage is high (and hence low fruit set), and a switch to male flower production when floral damage is low (and fruit production increases). The consequences of an altered six ratio induced by insect herbivores may lead to indirect effects on both the male and female reproductive success of this plant.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009762415520

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6

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Will plant vigor and tolerance be genetically correlated? Effects of intrinsic growth rate and self-limitation on regrowth (2000)

Weis, Arthur E. ; Simms, Ellen L. ; Hochberg, Michael E.

Springer

Evolutionary ecology 14 (2000), S. 331-352

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ISSN: 1573-8477

Keywords: growth rate ; herbivory ; plant defense ; tolerance

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Plants are known to maintain fitness despite herbivore attack by a variety of damage-induced mechanisms. These mechanisms are said to confer tolerance, which can be measured as the slope of fitness over the proportion of plant biomass removed by herbivore damage. It was recently supposed by Stowe et al. (2000) that another plant property, general vigor, has little effect on tolerance. We developed simple models of annual monocarpic plants to determine if a genetic change in components of growth vigor will also change the fitness reaction to damage. We examined the impact of intrinsic growth rate on the tolerance reaction norm slope assuming plants grow geometrically, i.e., without self-limitation. In this case an increase in intrinsic growth rate decreases tolerance (the reaction norm slope becomes more negative). A logistic growth model was used to examine the impact of self-limiting growth on the relationship between intrinsic growth rate and the tolerance reaction norm slope. With self-limitation, the relationship is sensitive to the timing of attack. When attack is early and there is time for regrowth, increasing growth rate increases tolerance (slope becomes less negative). The time limitations imposed by late attack prevent appreciable regrowth and induce a negative relationship between growth rate and tolerance. In neither of these simple cases will the correlation between vigor and tolerance constrain selection on either trait. However, a positive correlation between growth rate and self-limitation will favor fast growth/strong self-limitation in a high-damage environment, but slow growth/weak self-limitation in a low-damage environment. Thus, fundamental growth rules that determine vigor have constitutive effects on tolerance. The net costs and benefits of damage-induced tolerance mechanisms will thus be influenced by the background imposed by fundamental growth rules.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1010950932468

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7

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Can there be an escalating arms race without coevolution? Implications from a host-parasitoid simulation (1989)

Weis, Arthur E. ; McCrea, Kenneth D. ; Abrahamson, Warren G.

Springer

Evolutionary ecology 3 (1989), S. 361-370

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ISSN: 1573-8477

Keywords: arms race ; coevolution ; Eurosta ; Eurytoma ; gallmakers ; parasitoids ; phenotypic plasticity

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Summary Under a restricted set of conditions, predator-prey or parasite-host systems may exhibit an escalating arms race over several generations that is not coevolutionary. Preconditions for such a process include high correlation between prey/host quality and defensive capability, and phenotypic plasticity in predator/parasite-counter defenses that responds to quality. We present simulation models based on the parasitoid waspEurytoma gigantea, which lays its egg in the goldenrod gall induced by the flyEurosta solidaginis. For the parasitoid to successfully lay an egg, the gall walls must be thinner than the parasitoid's ovipositor is long. Wall thickness is highly correlated with gall size, so probability of successful attack declines with gall size. However, since the parasitoid eats the gall tissue, individuals developing in small galls have little food and mature with shorter ovipositors than those which develop in large galls. The simulation showed that the population mean parasitoid size is set by mean gall size. Since small galls are more frequently parasitized, there is a selection pressure on the gallmaker to induce larger galls. But, an additional simulation showed that since parasitoid ovipositor length depends on gall size, an evolutionary increase in gall size will also result in a non-evolutionary increase in parasitoid body size and ovipositor length over several generations.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF02285265

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