Peter W. Price

The plant vigor hypothesis and herbivore attack

Four sources of evidence are used to support the Plant Vigor Hypothesis that many herbivore species feed preferentially on vigorous plants or plant modules, as opposed to the Plant Stress Hypothesis arguing that stressed plants ae beneficial to herbivores. Evidence includes patterns of within-plant species utilization by galing insects where females select large plant modules and larvae survive better than on smaller modules. Independent evidence concerns patterns of herbivory between plant species habitually growing in rich resource environments which are heavily utilized, compared with low-resource adapted species. A third source of evidence is the forestry literature in which many cases are known of most attacks by insect herbivores occurring on young and open-grown trees

Plant-animal interactions: evolutionary ecology in tropical and temperate regions.

Tropical and Temperate Comparisons Mutualistic Relationships Between Plants and Animals Antagonistic Relationships Between Plants and Animals Plant-Butterfly Interactions Specificity in Plant Utilization Community Patterns in Natural and Agricultural Systems.

Population dynamics : new approaches and synthesis

Introduction. N. Cappuccino, Novel Approaches to the Study of Population Dynamics. Observation and Comparative Approaches: P. Turchin, Population Regulation: Old Arguments and a New Synthesis. A.F. Hunter, Ecology, Life History and Phylogeny of Outbreak and Nonoutbreak Species. N. Cappuccino, H. Damman, and J.-F. Dubuc, Spatial Behavior and Temporal Dynamics of Outbreak and Nonoutbreak Species. M.J. Auerbach, E.F. Connor, and S. Mopper, Minor Miners and Major Miners: Population Dynamics of Leaf-Mining Insects. Mechanisms and Processes of Population Dynamics: R.F. Denno and M.A. Peterson, Density-Dependent Dispersal and its Consequences for Population Dynamics. S. Harrison and N. Cappuccino, Using Density-Manipulation Experiments to Study Population Regulation. I. Hanski and M. Kuussaari, Butterfly Metapopulation Dynamics. S.J. Walde, Internal Dynamics and Metapopulations: Experimental Tests with Predator-Prey Systems. J. Roland and P.D. Taylor, Herbivore-Natural Enemy Interactions in Fragmented and Continuous Forests. G. Dwyer, Simple Models and Complex Interactions. J.H. Myers and L. Rothman, Field Experiments to Study Regulation of Fluctuating Populations. M.C. Rossiter, Impact of Life History Evolution on Population Dynamics: Predicting the Presence of Maternal Effects. Case Studies: C. Solbreck, Long-Term Population Dynamics of a Seed-Feeding Insect in a Landscape Perspective. T. Ohgushi, Adaptive Behavior Produces Stability in Herbivorous Lady Beetle Populations. P.W. Price, T.P. Craig, and H. Roininen, Working Toward Theory on Galling Sawfly Population Dynamics. J.D. Reeve, M.P. Ayres, and P.L. Lorio, Host Suitability, Predation, and Bark Beetle Population Dynamics. G.E. Belovsky and A. Joern, The Dominance of Different Regulating Factors for Rangeland Grasshoppers. Conclusion: P.W. Price and M.D. Hunter, Novelty and Synthesis in the Development of Population Dynamics. Subject Index.

THE EVOLUTION OF INFLORESCENCE SIZE IN ASCLEPIAS (ASCLEPIADACEAE)

A major feature of floral display in many species is the aggregation of individual flowers into inflorescences. Inflorescences containing different numbers of flowers are likely to be differentially successful as pollen donors and receivers, and thus inflorescence size may influence the fitness of the plant on which an inflorescence is borne. We begin with the premise that inflorescence size is fundamentally an evolved trait and attempt to show or suggest some of the selection pressures and environmental limitations that may influence inflorescence size. In particular, this study centers on three sources of reproductive failure: failure of pod initiation, failure of fruit maturation, and failure to donate pollen. We emphasize intraspecific comparisons, in view of our interest in possible adaptive consequences. Our interest in the question of the evolution of inflorescence (umbel) size in Asclepias was sparked by the general observation that the number of fruits matured per inflorescence was commonly far smaller than the number of flowers in the inflorescence, and often much smaller than the number of young pods initiated (see also Woodson, 1941; Stevens, 1945; Moore, 1946, 1947; Sparrow and Pearson, 1948; Stebbins, 1951). We then asked what might be the adaptive value of producing so many flowers with such a low probability of producing seeds.

A New ecology : novel approaches to interactive systems

Leading experts examine four rapidly developing areas in ecology emphasizing new approaches, foundations, and opportunities for new research. Examines the relationship between resources and populations, life history strategies, ecology of social behavior, and organization of communities.

A strong relationship between oviposition preference and larval performance in a shoot-galling sawfly

To investigate the relationship between oviposition preference and offspring performance we tested three hypotheses about the oviposition behavior of Euura lasiolepis: (1) the preference hierarchy hypothesis that Euura had an oviposition preference based on shoot lengths; (2) the larval survival hypothesis that the preference hierarchy corresponded to the suitability of shoots for larval survival; and (3) the flexibility hypothesis that the preference hierarchy changed as resource availability changed. The oviposition preference hierarchy of Euura lasiolepis, a shoot—galling sawfly, for plant shoots of different lengths strongly corresponded with the rank of shoot lengths for larval survival. The oviposition preference hierarchy was related to shoot growth; the more rapidly a shoot was growing the higher the probability that an oviposition site on a shoot would be attacked. Larval survival was highest on long shoots on young ramets. The probability of shoot abscission was negatively related to shoot length, and Euura in galls on abscised shoots invariably died. Intraspecific interactions and willow clone identity, independent of shoot length and ramet age, had relatively small influences on larval survival. The oviposition hierarchy was flexible; if long shoots were not available shorter shoots were accepted for oviposition. Shoots were always attacked in order of length, so that a strong relationship between preference and performance was always maintained.

Effects of resource distribution on animal-plant interactions

M.D. Hunter and P.W. Price, Introduction: Plants as a Variable Resource Base for Animals. M.C. Rossiter, The Impact of Resource Variation on Population Quality in Herbivorous Insects: A Critical Aspect of Population Dynamics. R.S. Ostfeld, Small Mammal Herbivores in a Patchy Environment: Individual Strategies and Population Responses. A.E. Weis and D.R. Campbell, Plant Genotype: A Variable Factor in Insect-Plant Interaction. B.J. Rathcke, Nectar Distributions, Pollinator Behavior, and Plant Reproductive Success. P.W. Price, Plant Resources as the Mechanistic Basis for Insect Herbivore Population Dynamics. J.C. Schultz, Factoring Natural Enemies into Plant Tissue Availability to Herbivores. T. Ohgushi, Resource Limitation on Insect Herbivore Populations. J.R. Karr, M. Dionne, and I. Schlosser, Bottom-Up versus Top-Down Regulation of Vertebrate Populations: Lessons from Birds and Fish. M.D. Hunter, Interactions Within Herbivore Communities Mediated by the Host Plant: The Keystone Herbivore Concept. D.W. Roubik, Loose Niches in Tropical Communities: Why Are There So Few Bees and So Many Trees? T.H. Fleming, How Do Fruit-and-Nectar Feeding Birds and Mammals Track Their Food Resources? T. Inoue and M. Kato, Inter-and Intraspecific Morphological Variation in Bumblebee Species, and Competition in Flower Utilization. J.M. Scriber and R.C. Lederhouse, The Thermal Environment as a Resource Dictating Patterns of Feeding Specialization of Insect Herbivores. Each chapter includes references. Index.

The adaptive significance of insect gall distribution : survivorship of species in xeric and mesic habitats

SummaryWe studied the relationship between habitat moisture and gall-forming insect populations. Population sizes for most galling taxa were significantly larger in xeric habitats compared with mesic habitats. Our results indicate that the differential abundance of galling insects in these habitats is due primarily to differential mortality and survivorship. Mortality factors acting upon eight insect galling species (belonging to eight genera and four families) were measured on six species (five genera and five families) of host plants. Survival was significantly higher for galling populations inhabiting xeric habitats compared with mesic habitats. Parasitism was higher in mesic habitats in seven of eight habitats and fungus-induced diseases were higher in five of seven habitats. Mortality due to predation and other (unknown) factors showed no clear trends. Overall, there was a tendency towards lower mortality and consequently higher survival for populations inhabiting xeric habitats. We hypothesize that reduced mortality caused by natural enemies and endophytic fungi has contributed to the speciation and radiation of galling insects in apparently harsh environments.

Resource Regulation by a Stem‐Galling Sawfly on the Arroyo Willow

We studied the impact of the stem—galling tenthredinid sawfly, Euura lasiolepis, on the growth and branch age structure of the arroyo willow, Salix lasiolepis. Normally, as willows age they become less susceptible to galling, but heavy Euura galling maintains willows at a young, relatively susceptible juvenile stage. The Euura form more galls and long shoots. Long shoots are found on clones with young branches. Heavy galling stunts or kills growth distal to the gall, stimulating sprouting by indefinitely dormant buds located near branch bases. The resulting young branches keep the clone susceptible to further galling. In contrast, increasing branch age of lightly galled clones confers resistance to galling. We term this model of gall—induced resource maintenance the resource regulation hypothesis. Resource regulation is the maintenance or increase of high—quality resources by an herbivore species that impacts immediately subsequent generations of the same herbivore species on the same plant. See full-text...

GENERAL CONCEPTS ON THE EVOLUTIONARY BIOLOGY OF PARASITES

Parasitism is a very common way of life, and probably the prevalent means of obtaining food among organisms. Adaptive radiation among parasites has been extensive, and yet ecological and evolutionary concepts on parasitism are poorly developed. Although Elton (1927) devoted a chapter in his pioneering ecology book to parasitism his conclusion was that the resemblances between predators and parasites are more important than the differences. This attitude is now prevalent in ecology texts (e.g. Andrewartha and Birch, 1954; Odum, 1971; Krebs, 1972; Colinvaux, 1973), and although much attention is devoted to predation, parasitism is almost ignored. Therefore, by using the inductive process, this paper attempts a synthesis of ecology and parasitology, the need for which has been recognized by Kennedy (1975), and it explores the evolutionary implications of parasite ecology. This synthesis should contribute to an understanding of parasites in three ways. First, a reevaluation of the abundance of parasitic species is made. Arndt (1940) estimated that 25% of animals in Germany are parasitic on others. Rothschild and Clay (1952) stated that parasitic animals probably exceed nonparasitic species in number of species and individuals, but provided little numerical support. A careful quantitative evaluation by Askew (1971) provided an estimate that 15% of insects, and 10% of all animal species are parasitic insects. Calculations presented in this paper indicate that well over 50% of the species of organisms extant today are parasitic. Second, general concepts on the ecology and evolution of parasites are presented, being derived from a combination of population biology, evolutionary theory and parasite biology. Third, predictions derived from the general concepts act as a guide to critical characteristics of parasite biology which need to be examined and tested in natural populations.