C. G. Johnson

Bio: C. G. Johnson is an academic researcher. The author has contributed to research in topics: Insect migration & Biological dispersal. The author has an hindex of 1, co-authored 1 publications receiving 1234 citations.

Habitat, the template for ecological strategies?

Abstract: The very etymology of Ecology, from the greek 'Qikos', 'the household', implies that ecologists should devote some attention to the 'house' or habitat of the population or community they are studying. However, as Charles Elton (1966) has so forcibly pointed out, 'definition of habitats, or rather lack of it, is one of the chief blind spots in Zoology'. Elton himself has provided us with a qualitative classification of habitats, while another past President, Alex Watt (1947) highlighted the dynamic nature of habitats by his phrase, 'pattern and process'. Elton referred to the need to quantify habitat characteristics. In this Address I will attempt some quantification;however, you will all be aware that in doing this I will not be able to emulate those former Presidents who have been able to provide a definitative synthesis of a field or of their own studies, my offering can be but a small beginning, an indication of the type of characteristics we should quantify. In considering ecosystem patterns and environment R. M. May (1974) writes 'it is to be emphasized that although patterns may underlie the rich and varied tapestry of the natural world, there is no single simple pattern. Theories must be pluralistic'. Indeed, the complexity of the subject is daunting and in any attempt to formulate some type of general framework, one is continually beset with exceptions. In stressing the need for a framework I am echoing a plea of my predecessor Amyan Macfadyen (1975) who cited K. E. F. Watt's (1971) vivid image 'if we do not develop a strong theoretical core that will bring all parts of ecology back together we shall all be washed out to sea in an immense tide of unrelated information'. In some ways I think we may see ourselves at a similar point to the inorganic chemist before the development of the periodic table; then he could not predict, for example, how soluble a particular sulphate would be, or what was the likelihood of a particular reaction occurring. Each fact had to be discovered for itself and each must be remembered in isolation. It is noteworthy that from Dobereiner's early efforts in 1816 it took more than fifty years before Mendeleeff ormulated his Periodic Law (1869) and even after this there were various attempts at rearrangement. Another parallel may be drawn with astronomy before the development of the Hertzsprung-Russell diagram that relates the evolution and the properties of stars. Again in our own subject biology, the situation is somewhat analagous to that before the formulation of the Linnean system of classification; but now from this system of classification, we are able to organize our knowledge of, for example, the functional morphology of organisms and we can even make assumptions, with a high probability

The Physiology of Life History Trade-Offs in Animals

Abstract: ▪ Abstract The functional causes of life history trade-offs have been a topic of interest to evolutionary biologists for over six decades. Our review of life history trade-offs discusses conceptual issues associated with physiological aspects of trade-offs, and it describes recent advances on this topic. We focus on studies of four model systems: wing polymorphic insects, Drosophila, lizards, and birds. The most significant recent advances have been: (a) incorporation of genetics in physiological studies of trade-offs, (b) integration of investigations of nutrient input with nutrient allocation, (c) development of more sophisticated models of resource acquisition and allocation, (d) a shift to more integrated, multidisciplinary studies of intraspecific trade-offs, and (e) the first detailed investigations of the endocrine regulation of life history trade-offs.

Temperature requirements of some aphids and their parasites

Abstract: The rate of insect development depends upon the temperature to which the insects are exposed. For each species, the temperature below which no measurable development occurs is its threshold of development. The amount of heat required over time for an insect to complete some aspect of development is considered to be a thermal constant (Andrewartha & Birch 1954; Bursell 1964). Messenger (1959, 1970) has shown that the threshold and the thermal constant may be useful indicators of an insect's potential distribution and abundance. This paper is concerned with differences between the developmental thresholds and temperature requirements of A cyrtihosiphon pisum (Harris), Aphis craccivora Koch, Brevicoryne brassicae (L.), Macrosiphum avenae (F.), and Masonaphis maxima (Mason) (Homoptera: Aphididae); their parasites Aphidius smithi Sharma & Subba Rao, A. ervi ervi Haliday, A. e. pulcher Baker, A. rubifolii Mackauer, Diaeretiella rapae (M'Intosh), and Praon pequodorum Viereck (Hymenoptera: Aphidiidae); and hyperparasites Dendrocerus (= Lygocerus) niger (Howard) (Hymenoptera: Ceraphronidae) and Asaphes lucens (Provancher) (Hymenoptera: Pteromalidae). No attempt is made to review the extensive literature on temperature effects on insect development in general. Andrewartha & Birch (1954), Bodenheimer & Swirski (1957), Howe (1967), Messenger (1959) and Schwerdtfeger (1963) have critically reviewed methods for determining temperature coefficients.

Altruism and Related Phenomena, Mainly in Social Insects

Abstract: In what sense can the self-sacrificing sterile ant be considered to "struggle for existence" or to endeavor to maximize the numbers of its descendants? Since the founding of the theory of evolution by natural selection, most biologists have evaded this question by focusing attention exclusively on the colony as the reproducing unit. There is a powerful precedent for this. Darwin himself took this course. He saw only a "minor" difficulty in the evolution of sterility, and he passed over it in a few lines as he proceeded to discuss the "great" difficulty of how the special aptitudes of the workers could be passed on in latent form by their fertile sisters (26). A difficulty over sterility exists, nevertheless, and it is the more surprising that Darwin should have passed over it in that he discussed-but left unsolved-a parallel one raised by the social virtues (courage and self-sacrifice) in man (25). He saw that such qualities would be promoted in intergroup selection but counter-selected within each group. Perhaps the possible avenues of indiscipline in social insects had been so little reported in Darwin's time that the problems they raised were easily overlooked. Darwin's inadequate understanding of heredity may, likewise, have helped to keep the problem out of focus. With better knowledge of heredity and with more facts regarding the social insects to draw upon, Weismann (154) recognized the possible conflict between intergroup and intragroup selection in the evolution of worker attributes. He made the perceptive comment that, "Obviously the workers must be more rapidly improved when all in a hive are progeny of one queen-i.e. they are all alike or almost alike." But this comment was made in the course of discussion of another topic, and he did not pursue the matter. Soon Mendelian genetics resolved Darwin's difficulty of latency, apart from details of mechanism. But the disappearance of this problem does not seem to have given greater prominence to the other, and the question of how worker sterility comes to be selected continued to receive only occasional comment for a long time. Sturtevant (142) in 1938 again outlined it with admirable clarity and with special reference to multiqueened (polygynic) organization, which was by then well known. Rau (118) in 1940 also briefly touched on this crux when he noted how small might be the step separating workerlike behavior in auxiliary Polistes queens 193

Biology of Coccinellidae

Abstract: Preface. 1. Morphology and Anatomy I. Kovar. 2. Phylogeny I. Kovar. 3. Variability and Genetic Studies A. Honek. 4. Life History and Development A. Honek. 5. Distribution in Habitats A. Honek, I. Hodek. 6. Food Relationships I. Hodek. 7. Dormancy I. Hodek. 8. Enemies of Coccinellidae P. Ceryngier, I. Hodek. 9. Effectiveness and Utilization I. Hodek, A. Honek. References. Author Index. Taxonomic Index. Subject Index.