bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarons
Authors: Mott Sir Nevill
Published: November 2023

An electron in a localized state, in either a crystalline or a non-crystalline material, will always distort its surroundings to some extent. For shallow donors in silicon and germanium, and for localized states in band tails, the radius of the localized state is normally large and the distortion consequently small; it is usually neglected, though this is not the case for deep levels. However, even for a free electron in a conduction band (or a hole in a valence band), significant distortion of the surroundings can occur under certain conditions, such as large effective mass. If distortion occurs, a ‘pseudoparticle’ is formed, which can move as a whole, the electron and the distortion it produces moving together. This pseudoparticle is called a polaron.
Non-crystalline semiconductors
Authors: Mott Sir Nevill
Published: November 2023

Whereas in impurity bands in crystalline semiconductors the environment in which the electrons move is known a priori, in amorphous semiconductors this is not so. Our understanding of their electrical behaviour depends both on the rules for the motion of electrons deduced from the theories and experiments described in previous chapters, and on investigations of their structure. We shall discuss in this chapter some of the more important non¬ crystalline semiconductors and in Chapter 9 materials with large values of the band gap, such as vitreous silicon dioxide and oxide glasses. We must distinguish between materials that can be formed by rapid cooling from the melt, such as vitreous Si02 and certain of the chalcogenide glasses, and those that cannot, such as amorphous silicon and germanium.t In the latter, the coordination number is the same as that in the crystal, namely four, but in the melt it is larger, and the liquids are metallic, with properties similar to those of liquid lead. Amorphous silicon and germanium can therefore be prepared only by deposition from some gaseous phase, for instance in a glow discharge, or by bombarding the crystals with fast ions.
Vitreous silicon dioxide
Authors: Mott Sir Nevill
Published: November 2023

Vitreous silicon dioxide has a very wide gap of the order of 9 eV and is consequently an excellent insulator. It is important for many reasons; it is the raw material of the communications technology of fibre optics, and in such devices as the MOSFET (metal oxide silicon field effect transistor) layers of vitreous silica are formed on silicon by thermal oxidation (see§ 9.3). In this chapter we give a brief account of the band structure of the material, the defects in the network, and the oxidation of silicon by which it can be formed.
Geological setting and tectonic history of Mesoamerica
Authors: Donnelly Thomas W
Published: November 2023

The goal of the geologist is primarily geological history, that is, the elucidation of the sequence of events as a result of which the non-biological world as we know it came to be. This goal requires particular attention to the physical processes acting on the earth at present (‘the present is the key to the past’). The processes we can observe are mainly those acting on the surface of the earth; thus, it is not surprising that the history of surficial processes was elucidated first. Interior processes were and remain for the most part mysterious, and only recently has there been a firm and defensible basis for believing that the interior of the earth is not static but in vigorous motion, that the surface of the earth responds strongly to these interior processes, and that we can chart the changes of the surface of the earth back in time with some accuracy and so learn not only of the earth’s total history but of the forces that formed it.
Webspinners of Panama (Embiidina)
Authors: Ross Edward S
Published: November 2023

The Embiidina Embioptera, webspinners or footspinners) comprise a small order of mostly undescribed species occurring mainly in tropical and temperate regions that lack a prolonged cold season. All stages of all species spin silk galleries by means of gland-packed foretarsi. The defining characters of the order represent adaptations for effective movement in such galleries. These provide significant protection from predators and parasitoids as the embiids feed on edible substrate (outer bark, moss, lichens, and dead leaves). The primary escape is rapid backward movement into deeper recesses of the galleries or crevices. To augment such evasive movement, adult females of all species are apterous, remaining nymphoform through neoteny. Males of most species are winged and retain other primordial characteristics. Because the natural spread of a species is limited by the short distances the females can safely walk without the protection of silk galleries, the order’s spread on to geologically young land surfaces is limited. Thus, the embiid fauna of Panama is relatively small compared to the older and more diverse regions to the north and south. The present study is based principally on material collected by me during three visits to Panama. Suitable habitats exist throughout the country but, seemingly, not all are occupied. Particularly perplexing is the apparent absence of the order from forests of the Caribbean drainage system. This appears also to be the case in comparable zones of Costa Rica. The richest representation is in Panama’s montane habitats and such a pattern prevails through other regions of Central America and Mexico.
Catalogue of the Nymphalinae of Panama (Lepidoptera: Nymphalidae)
Authors: Lamas Gerardo , Small Gordon B
Published: November 2023

In recent years, there has been increasing interest in the butterfly fauna of the Neotropics, and particularly that of Central America. A number of workers in this area have indicated to us that up-to-date information on the composition of the fauna of the Republic of Panama would be useful. Little has been published on the Panamanian butterflies since the classical work of Godman and Salvin (1879-1901) and the references to it in Seitz (1907-1924). Although Panamanian butterflies have been collected since at least the latter part of the 18th century (Brown and Heineman 1972; Lamas 1979), the only comprehensive works devoted specifically to this fauna are restricted to the area of the former Canal Zone and its vicinity, and were published in this century (Dyar 1914; Bell 1931; Huntington 1932; Emmel and Leck 1970). During the last 25 years much more information has become available as the result of field trips made by the junior author, Annette Aiello, Francisco Delgado, and others. This information, together with that obtained by examination of the collections of several major museums, has enabled us.to get a clearer idea of the composition and extent of the fauna.
Anatomical philosophy: homologies, transformations, and character phylogenies
Authors: Janvier Philippe
Published: November 2023

In 1809 Lamarck published his Zoological philosophy, and in 1818 and 1822 Etienne Geoffroy Saint-Hilaire published his Anatomical philosophy. Lamarck expressed ideas on how organisms have transformed with time; Geoffroy Saint-Hilaire speculated on how organs transformed or arose from a pattern that was once common to all animals. To Geoffroy, anatomical philosophy was a way of finding order and sense in the distribution of similarities among organisms. It included ‘analogies’ (homologies in the modern sense) and theories about transformations. This sounds like idealistic morphology, but it is just what people have done—and still do—when trying to find out how fins have transformed into limbs, for example. I therefore take the risk of resurrecting this old term for the title of this chapter.
A short history of research on early vertebrates
Authors: Janvier Philippe
Published: November 2023

The reader may be surprised to see this chapter on the history of early vertebrate research at the end of the book. I think, however, that it is more fruitful to consider the history after the present-day data, theories, and beliefs have been presented and discussed. The diversity of opinion on the structure and relationships of early vertebrates stems largely from the beginning of this century, and has been initiated on the one hand by the work of the anatomists E. S. Goodrich and E. P. Allis and on the other by that of the palaeontologists E. Stensio and A. S. Romer. Opinions on extrinsic data, such as the mode of life, stratigraphy, and biogeography, are more deeply rooted into the history of geology and can be traced back to the nineteenth century. I have divided this brief historical account into two sections: first, the history of the discovery of the structure and relationships of early vertebrates, which is closely linked with the progress of comparative biology; second, the history of exploration and field discoveries, which has more to do with the history of geology.
Phosphorus
Authors: Stanton R L
Published: November 2023

Although phosphorus is little thought of, and only infrequently referred to, as a constituent of exhalative ores, it is in fact a substantial component - as apatite — of some very important deposits of this class. It is conspicuous in some of the major Proterozoic stratiform Pb-Zn deposits, such as those of Broken Hill, Gamsberg, and Aggenys; occurs in abundance in some iron-rich exhalative ores, such as those of Kiruna; appears as a noteworthy minor component of some Palaeozoic and younger exhalative base-metal deposits; and is conspicuous in some of the exhalites associated with them.
Nickel
Authors: Stanton R L
Published: November 2023

Although nickel is a highly chalcophile element, and indeed has a stronger affinity for sulphur than has iron, and although its average abundance in sea-floor basalts is some 60 per cent greater than that of copper, it is conspicuous for its scarcity in exhalative ores. It has been suggested by Lusk (1976a,b) that some of the stratiform nickel deposits associated with mafic to ultramafic lavas of the Archaean of Australia and Canada may be exhalative, and a firm case for such an origin for the nickelcobalt-bearing copper deposits of Outokumpu, in the Lower Proterozoic Karelian terrane of Finland, has been made by Peltola (1978), Koistinen (1981), and others. Apart from this, however, nickel appears as no more than a trace in exhalative deposits. As far as the writer is aware, exhalative ores containing commercial quantities of nickel are unknown in the two great epochs of exhalative ore formation: the Lower Proterozoic, c. 1500-2000 Ma, and the Lower to Middle Palaeozoic, 350-550Ma.
Petrogenesis: 2: Exhalative ores
Authors: Stanton R L
Published: November 2023

Having considered the derivation of the various components of the Solomon Islands Younger Volcanic Suite and, in particular, having deduced that the generation of the andesitic and dacitic rocks has been influenced by exhalative loss of some of the major elements of the magmas in question, it is now appropriate to examine the possible place of the exhalative ores in the overall petrogenetic process.

The very large copper-gold orebody of Panguna is contained in sub-volcanic andesitic rocks of the Younger Volcanic Suite on Bougainville.
Using this Book
Authors: Hayward P J
Published: November 2023

This book is a manual for the identification of approximately 1500 species of the north-west European marine fauna. The process of identification depends on the use of simple dichotomous keys, by which means a species’ identity is determined after choosing correctly from a sequence of paired contrasting diagnostic characters. Despite the obvious attractions of pictorial guides, the dichotomous key remains the most efficient and precise means of identifying organisms and, although keys to large taxonomic groups may appear intimidating, in practice it may not take more than half a dozen steps to arrive at a name for the specimen to hand.
Spatially Explicit Approaches
Authors: Hanski llkka
Published: November 2023

The patch models described in the previous chapter are based on the assumption that all populations are equally connected-called the mean-field approximation-hence these models deal with space only implicitly. With patch models, we can explore the metapopulation dynamic consequences of reduced average patch density, but not, for instance, the consequences of habitat destruction in any specific part of a hypothetical or real landscape. This chapter is concerned with modelling approaches, commonly referred to as spatially explicit models, which account for the actual spatial locations of populations. I have made a distinction between spatially explicit and spatially realistic models (Hanski 1994b), the latter including information about the actual geometry of fragmented landscapes and hence allowing modelling of real metapopulations.
Spatial structure of populations
Authors: Hanski llkka
Published: November 2023

Some species have practically continuous populations over large areas of suitable habitat; one example is the common shrew (Sorex araneus) in coniferous forests in Fennoscandia. Even in these cases, the environment is not quite as continuous as it might seem at first, and population density is likely to vary from one place to another. For most species, most landscapes are patchy, because the species have evolved specific habitat requirements and because the landscapes are complex habitat mosaics. It would be interesting to have a detailed description of spatial population structure for some large assemblage of species in some large area. Denoting by h; the percentage of the landscape consisting of suitable habitat for species i, one wonders what would be the distribution of the h; values in large communities? And what would be the distribution of p;, the fraction of the suitable habitat that is actually occupied at one point in time? It is frustrating that we have such basic data for only a handful of individual species, not for communities.
Comparative levels of genetic variability in harbour seals and northern elephant seals as determined by genetic fingerprinting
Authors: Lehman Niles , Ne Robert K Way , Stewart 3and Brent S
Published: November 2023

As a consequence of recent population bottlenecks, the amount of genetic variability in the northern elephant seal (Mirounga angustirostris) is thought to be extremely low. However, the species is apparently thriving throughout its breeding range in the eastern Pacific. By using analysis of hypervariable minisatellite loci in the northern elephant seal, we find that this species is indeed lacking invariation, as roughly 90% of alleles are shared among all the individuals tested. There is not enough variation to test hypotheses concerning island and beach philopatry. In contrast, harbour seals (Phocavitulina) tested from the eastern Pacific possess much greater levels of variation at these loci and demonstrate a small degree of population-genetic structuring among the breeding sites studied.
Sex allocation
Authors: Charnov Eric L
Published: November 2023

Darwin (1871) first raised the question of sex ratio evolution, and saw it as both important and enigmatic. However, he was unable to make much headway with the problem and declared it a puzzle for the future. This particular future arrived about 60 years later, when Fisher (1930) pointed out for diploid dioecy that under autosomal inheritance half the genes passed to zygotes come from males and half come from females.
Indeterminate growth
Authors: Charnov Eric L
Published: November 2023

Although many species of animals, including a diverse array of birds, mammals, cephalopods, and terrestrial arthropods, cease growing after they reach sexual maturity, this pattern of determinate growth is the exception rather than the rule. Most other vertebrates and invertebrates show indeterminate growth where they begin reproducing before they attain maximum body size. Prior to maturation, energy is allocated to maintenance and growth, whereas after maturation it is also allocated to reproduction. Indeterminate growth is commonly described by expressions such as the Bertalanffy equation; Fig. 4.1 shows a typical life history where the rate of growth declines with age and the animal eventually approaches some asymptotic length if it survives for long enough. At the age at maturation a the individual is typically 50-80 per cent of the asymptotic length (15-50 per cent of the weight) depending upon the species.
Collections and Observations
Authors: Kohn Alan J , Perron Frank E
Published: November 2023

This chapter presents the basic data that are the sources of, and are essential to, the comparative analyses, syntheses and tests of the hypotheses in Chapters 4 and 5. They consist of descriptive accounts of the reproductive biology of each of the 62 IP species of Conus for which we have information and, in Appendix Table 1, a summary of the quantitative aspects in matrix form. This is to facilitate comparisons within and between species. As Underwood (1991) noted in another marine ecological context, publication of such large-scale surveys is important, because this provides the means to test hypotheses.
Basic notions: luminescence
Authors: Aitken M J
Published: November 2023

The prime motivation that led to the initial trial of optical dating (Huntley et al. 1985) was to achieve a better method of dating sediment than was possible with thermoluminescence; subsequently it has also been found advantageous in dating pottery and for radiation dosimetry, as well as for detecting the artificial irradiation of foodstuffs. Whereas in thermoluminescence the dating signal of emitted luminescence is obtained by heating the sample, for optical dating the signal is obtained by shining a beam of light onto it; in both cases the signal, which is luminescence emitted by constituent mineral grains, is measured by means of a highly sensitive device, usually a photomultiplier. In the context of sediment dating, the primary focus of this book, the date refers to the last deposition of the sediment at which the constituent grains were exposed to daylight (Fig. 1.1);
Basic notions: radioactivity and irradiation
Authors: Aitken M J
Published: November 2023

It is not the intention to give a comprehensive discussion of radioactivity and irradiation, the reader being referred elsewhere (e.g. Aitken 1985; Berger 1988). However, a brief outline is appropriate, particularly since some characteristics of the radiation flux have a bearing on luminescence measurement procedures. It should be noted at the outset that in luminescence dating the radioactivity providing the natural dose-rate is long-lived compared with the sample age span. This is in contrast to radiometric dating proper, such as by radiocarbon, where the half-life must be comparable with the sample age span and the basis of dating is that the radioactive content of the sample changes with time.
Nerve growth factor and cholinergic neurons of the mammalian brain
Authors: Hefti F , Hartikka J , Knusel B , Laplume, M O , Mash D C
Published: November 2023

During the past few years, it has become evident that endogenous molecules called neurotrophic factors play important roles in development, maintenance of structure and function, and plasticity of neurons in the mammalian nervous system. The number of well-characterized trophic factors is still very small and most of the general concepts are derived from the function of nerve growth factor (NGF) which serves as paradigmatic example. NGF is a protein of known structure and amino acid sequence. The gene coding for NGF has been cloned, sequenced, and its location in the human genome has been determined. The biochemistry and molecular biology of NGF have been subject of recent reviews (Thoenen and Edgar 1985; Thoenen et al. 1987; Yankner and Shooter 1982). In the peripheral nervous system, NGF affects growth and differentiation of sympathetic and sensory neurons. NGF is synthesized by target tissues of these cells and acts on specific receptors on their terminals.
Responses of primate nucleus basalis neurons to water rewards and related stimuli
Authors: Richardson R T , Delong M R
Published: November 2023

Numerous electrophysiological studies have helped to further our understanding of the basal forebrain cholinergic system (BFCS). Some of the basic physiological and pharmacological properties of basal forebrain neurons have been examined in anaesthetized rats (Aston-Jones et al. 1984; Lamour et al. 1986; Reiner et al. 1987) and in a slice preparation (Griffith 1988). Other studies have provided useful information regarding the role of the BFCS in conditioning (Rigdon and Pirch 1986) and cortical desynchronization (Detari and Vanderwolf 1987; Szymusiak and McGinty 1986). The focus of this chapter is on studies of neuronal activity in the nucleus basalis of Meynert in awake behaving monkeys. These studies have also provided insights to the possible functions of the BFCS, particularly its role in reinforcement and arousal mechanisms.
New And Overlooked Generic Names Listed Under Families
Authors: Davies R A , Lloyd K M
Published: November 2023

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ACANTHACEAE SALPINCTIUM T.J. Edwards AMARYLLIDACEAE ACALICHARISA.W. Meerow ARACEAE ANAPHYLLOPSISA. Hav UROSPATH ELLA G.S. Bunting.
Spatio-temporal patterns of activity on the motor map of cat superior colliculus
Authors: Guitton D , Munoz D P , PÉlisson D
Published: November 2023

Reticular circuits responsible for generating saccadic eye movements are thought to be commanded directly by only two supra-reticular structures acting in parallel: the superior colliculus (SC) and the frontal eye field (FEF). The prime evidence supporting this hypothesis is that simultaneous bilateral destruction of the SC and FEF severely impairs monkeys’ ability to generate saccades (Schiller et al. 1980). Each structure appears to dominate the control of saccades generated in a specific behavioural context.
Self-motion and ocular motor disorders affect motion perception
Authors: Brandt T , Dieterich M , Probst T
Published: November 2023

There is evidence that the perception of object motion is impaired by the perception of concurrent self-motion, by eye movements, or by ocular motor disorders (Dieterich and Brandt 1987; Brandt and Dieterich 1988; Sekuler et al. 1990). Under natural, environmental conditions one moves freely, with the two-fold perceptual task of controlling self-motion and perceiving object motion simultaneously. Experimental studies of motion perception, however, have a laboratory tradition in which thresholds for the detection of object motion are determined with the head stationary.
Selection within populations
Authors: Nicholas F W
Published: November 2023

Ever since animals were first domesticated, humans have been attempting to alter animal populations by means of artificial selection. The vast array of different breeds and strains of domestic animals in existence today is testimony to the effectiveness of such selection. Despite the many changes that have already occurred as a result of artificial selection, there are still many improvements needed, especially in terms of the economic efficiency of production of milk, eggs, wool, meat, and other animal products. And there is also a continual demand for faster horses, better showjumpers and more intelligent guidedogs. In most situations, the traits to be improved are quantitative traits.
Breed structure
Authors: Nicholas F W
Published: November 2023

Not all animals in a breed contribute to genetic improvement within that breed; in most cases, breeds are structured so that only a minority of animals are given that opportunity.

The aim of this chapter is to describe the structure of breeds and to discuss the ways in which the structure can be modified so as to increase the overall genetic merit of the breed.
Extinction of finite metapopulations in correlated environments
Authors: Gilpin M E
Published: November 2023

Richard Levins (1970) introduced the notion of a metapopulation, a population of populations. The populations of such a metapopulation are located on discrete patches of the environment. Local extinctions on these patches are possible so not all suitable habitat patches need to be occupied. But from the system’s other occupied patches colonization of empty patches can occur. Therefore, the metapopulation is an interactive, dynamic entity with a continual turnover of local populations. Levins, as many after him, was primarily interested in the question of group selection (see Gilpin 1975 for a discussion), which involves the behaviour of gene frequencies over a metapopulation. The typical model of group selection investigates the fate of an ‘altruistic’ gene that loses out within its local group, but which confers on its home group a lower extinction rate, thereby, under certain parameter configurations, allowing it to prevail throughout the metapopulation.
Alternative models
Authors: Hastings Harold M
Published: November 2023

We briefly describe several alternative models for dynamics and time series and compare them with fractal models: cellular automaton models (see Wolfram 1984, 1985, 1986), linear models, including stochastic linear models; low-dimensional nonlinear prediction (Sugihara and May 1990b) based on low-dimensional chaos (see Grassberger and Procaccia 1983). Cellular automaton models are used in Section 8.2 (on earthquake models) and Chapter 10 (on vegetative ecosystems). Chapter 11, on models for single-species population dynamics, compares the use of fractal models, low-dimensional nonlinear prediction, and linear models for predicting local species extinction.
Social heterogeneity and sexually transmitted diseases
Authors: Anderson Roy M , May Robert M
Published: November 2023

A central theme in this chapter is that most sexually transmitted diseases (STDs) cannot be understood without acknowledging the marked heterogeneity in degrees of sexual activity within the overall population. We first consider the endemic maintenance of STDs, with particular attention to gonorrhoea. The second (and larger) part of the chapter focuses on the epidemic dynamics of STDs, using AIDS as an example.
Endemic infections in developing countries
Authors: Anderson Roy M , May Robert M
Published: November 2023

The basic model discussed in Chapters 4, 5, and 6 contains the assumptions that the infection is not itself a cause of mortality and that the human population has zero growth, with net births exactly balancing net deaths such that the population is of constant size. Essentially all conventional mathematical models for endemic or epidemic infections of humans contain this assumption (Waltman 1974; Bailey 1975; Hoppensteadt 1975; Anderson and May 1982zz). Given that the epidemiological time-scales (such as the average age at infection) are typically much shorter than the time-scales characterizing demographic change (such as population doubling time), the assumption of an unchanging host population is often a useful approximation.
Biology of host-macroparasite associations
Authors: Anderson Roy M , May Robert M
Published: November 2023

Many important diseases of humans, particularly in tropical and subtropical regions, arise from infection by macroparasites or metazoan (multicellular) organisms. The major parasites belong to the helminth and arthropod groups, and include flukes (the trematodes), tapeworms (the cestodes), nematodes, lice, fleas, and ticks. These organisms tend to have much longer generation times than microparasites; they often possess complex life cycles involving two or more obligatory host species, and direct multiplication within the definitive or final host (i.e. humans) is either absent or occurs at a low rate. Sexual reproduction often occurs in the human host, but this process entails the production of transmission stages, such as eggs or larvae, which leave the host to complete further development and maturation. Direct asexual reproduction may occur in intermediate hosts such as in the life cycle of the digenetic flukes (e.g. the schistosome parasites).
Heterogeneity within the human community
Authors: Anderson Roy M , May Robert M
Published: November 2023

The importance of heterogeneity within the host community, with respect to the way in which individual people either are exposed to infection or respond to parasite invasion, has been alluded to in the three previous chapters. The overt manifestation of its relevance is aggregation in the frequency distribution of parasite numbers per person (see Fig. 15.17 and Table 15.5). We have already seen how a clumped distribution enhances the net impact of density-dependent constraints on parasite population growth, influences the likelihood that female worms find mates within hosts, affects the design of control programmes based on chemotherapeutic treatment to reduce morbidity and transmission, and determines the observed relationship between the two main epidemiological statistics, prevalence and average intensity of infection.
Experimental epidemiology
Authors: Anderson Roy M , May Robert M
Published: November 2023

We have seen in the previous three chapters that much uncertainty surrounds the epidemiological interpretations of changes in average worm loads with respect to human age. The importance of acquired immunity, or other density-dependent constraints on parasite establishment, survival, or fecundity, in shaping observed patterns is not at all clear at present. To a very large extent this gap in our knowledge arises from the simple fact that, for obvious ethical reasons, it is rarely possible to obtain quantitative measures of the population processes influencing the abundance of an endoparasite within a human patient. Rapid advances in research on human immune responses to infectious agents raised the hope in the 1970s that new techniques would facilitate quantitative measurement of parasite abundance and effective immunity within human communities. In the case of macroparasities this hope has not as yet been realized, although recent advances in immunology and molecular biology may yet provide the epidemiologist with the practical tools required for the rapid quantification of parasite abundance and distribution under field conditions.
Ticks and disease: susceptible hosts, reservoir hosts, and vectors
Authors: éAeschlimann Andr
Published: November 2023

Ticks (both Ixodidae —hard ticks, and Argasidae —soft ticks) play an important role as vectors of diseases. They transmit pathogenic agents to wild or domestic animals and to humans (e.g. viruses, rickettsiae, borreliae, tularemia, piroplasmida, filariae). Since Smith and Kilbourn’s historical discovery in 1893 that an arthropod can transmit a pathogen (transmission of Babesia bigemina by Boophilus annulatus), the list of micro-organisms transmitted by ticks has become so long that inexperienced people may wonder if it is not exhaustive. However, the 800 tick species described world-wide (Fig. 8.1; Hoogstraal and Aeschlimann 1982) have not revealed all their secrets in this field. Surprises are always possible.
Metabolic deficiencies in parasites and their relation to host metabolism
Authors: Wang C C
Published: November 2023

Endoparasites are organisms incapable of growing, differentiating, or even surviving in a natural environment such as soil or water. They must live in nutritionally enriched surroundings such as the intestinal lumens, the bloodstreams, or the cytoplasms of other organisms. This unusual requirement for luxurious living conditions is clearly related to deficient metabolic activities in parasites, which necessitate a reliance on supplies of a variety of exogenous nutrients from the hosts. Unfortunately, consistent failures in the past to cultivating parasites free of their hosts have created the myth of a certain mysterious dependence of the parasites on their hosts. This myth has been broken only during the last two decades, when numerous parasites began to be cultivated successfully in vitro. This in vitro growth of many parasites free of contamination has been intensive and focused biochemical investigations on these parasites possible (Wang 1984). The feasibility of cloning single protozoan parasites has enabled the isolation of a genetically homogeneous population of a parasite species. The capability among some of the parasites to grow in a defined medium has further facilitated metabolic studies. The biochemical investigations performed in the past few years have accumulated a wealth of knowledge, enough for us to elucidate some interesting metabolic deficiencies among parasites and their relations to host metabolism.
Genetic engineering: progress, promises, and precepts
Authors: Heap Brian
Published: November 2023

Professor Brian Heap, CBE, FRS, was Director of the Biotechnology and Biological Science Research Council’s (BBSRC, formerly AFRC) Institute of Animal Physiology and Genetics Research at Babraham, Cambridge and Edinburgh and AFRC Director of Science. After graduating and then taking his Ph.D. at the University of Nottingham, Professor Heap moved to the University of Cambridge, where he was awarded the degree of Doctor of Science for his research in 1980. In 1963 he had begun his association with his present Institute, near Cambridge, which was to last over 30 years. After several years at Babraham asa research fellow, Professor Heap became head of the Institute’s Physiology Department in 1976 and subsequently Director. Currently, he is senior visiting fellow in the School of Clinical Medicine, University of Cambridge, and Special Professor in the University of Nottingham. Professor Heap has published numerous papers on reproductive biology and endocrinology and has advised the WHO and the government of the People’s Republic of China in these fields. He was elected a Fellow of the Royal Society in 1989 and appointed CBE in 1994.
Women: the neglected factor sustainable development
Authors: Senanayake Pramilla
Published: November 2023

Dr Senanayake has worked for the International Planned Parenthood Federation since 1975. Having served as Medical Director for ten years, in May 1987 she took up the post of Assistant Secretary Genera/for Technical Services, and has overall responsibility for the programme development, medical, AIDS prevention and evaluation functions of the IPPF.
Human adaptability research among African agriculturalists
Authors: Huss-Ashmore Rebecca
Published: November 2023

Since the 1950s, much research has been carried out in Africa on questions relating to human adaptability, and a great deal of this work has targeted populations who depend on agriculture, wholly or in part, for their living. Despite this, there is, strictly speaking, no such thing as the human adaptability of African agriculture. While there has been significant attention paid over the last 30 years to the biology, ecology, and adaptability of African foragers and pastoralists, there is no comparable body of co-ordinated research on African agriculturalists. There is, to be sure, a substantial body of knowledge on African agriculture, most of it derived from cultural geography and anthropology (e.g. de Schlippe 1956; Thomas and Whittington 1969; Ruthenburg 1971; Hill 1972 or from agricultural development (e.g. Upton 1973; Low 1986). For the most part, this literature has little or no interest in adaptation. Conversely, little of the work on adaptation has been concerned directly with agriculture. There is in addition a substantial literature on measures of biological function in African populations, things such as growth, nutrition, morbidity, and mortality, written from an interventionist rather than an adaptationist point of view (Akhtar 1987; Hill and Hill 1988; UNICEF 1988 Feachem el al. 1992). While some of these public health studies have explicitly considered the impact of agriculture on health (Kennedy and Cogill 1987; Kennedy 1989; von Braun et al. 1991), human adaptability researchers have made little use of such data.
Human adaptability studies in Papua New Guinea: original aims, successes, and failures
Authors: Norgan N G
Published: November 2023

Papua New Guinea (PNG) is a country of rich variability and striking contrasts, so much so that for this and other reasons it has been called ‘The Small Cosmos’ (Attenborough and Alpers 1992). It lies in the ‘Tropics’ between 2 and 10°S and forms the half of the island of New Guinea, east of 141°E. In its coastal and lowland areas it has much in common with such regions in other parts of Melanesia and the Pacific, but the Highlands of PNG are unique. There are several other ecozones and further contrasts occur in subsistence patterns, degree and duration of contact with outside influences, and in rural-urban differences.
Coming of age of human adaptability studies in Samoa
Authors: Bindon Jim
Published: November 2023

Studies of populations subjected to specific environmental stressors such as hypoxia, hypothermia, or seasonal hypocaloric intake are fundamentally different from studies of populations undergoing the stress of culture change. While the field-work is no easier in the former cases than in the latter, at least there arc clear-cut models from ecology, physiology, and nutrition predicting how these stressors operate on human populations. How ever, in Samoa, where the principal stressor of interest is culture change the predictive models available are problematic in many respects. This chapter begins with a discussion of the adaptation paradigm used in many of the studies done in Samoa, then considers issues of social forces as stressors. Next a review is provided of some of the progress made in 20 years of studies of Samoan response to cultural change, and finally some assessments of this research are offered and some cautions and hopes for the future tendered.
The future of human adaptability research
Authors: Huss-Ashmore Rebecca , Thomas R Brooke
Published: November 2023

All scholarship is a product of the time and place in which it was conceived and carried out. The recognition that science is culturally and historically situated has been one of the major contributions of philosophers of science during the late twentieth century, with writers from Kuhn (1970) to Quine (1969) to Haraway (1988) challenging our epistemic biases. Despite this, articles treating the social and temporal context of research are relatively rare in science. One of the goals of this volume has been to place human adaptability research within a time and place, in order to understand why particular questions were asked and particular projects undertaken in specific ways and specific places. We contend that the future cannot be charted without an understanding of the past; we must know where we arc and how we got here in order to see where to go next.
Worlds apart
Authors: Diamond Jared
Published: November 2023

There is often little love lost between the exponents of the so-called hard sciences—physics, chemistry, molecular biology and the like—and their colleagues in what they think of as the softer disciplines, such as ecology. The experimental camp considers the field sciences to be little more than stamp collecting, while the massed ranks of botanists and bird-watchers are equally uneasy about limitations of the reductionist approach. The two philosophies rarely occupy the same building, let alone the same department. So, to find an individual who subscribes to both is remarkable.
A very tidy desk
Authors: Pilbeam David
Published: November 2023

This is the age of big science; high-tech science. Of particle physicists using vast machines to mimic the very act of Creation; of molecular biologists unravelling the secrets of DNA, from the mutations which cause inherited disease to the relentless clock of random genetic change which has been ticking away, independent of environmental pressures, since life began. Where, I wanted to ask David Pilbeam, did the study of human evolution fit into a picture like this? The popular image of palaeoanthropology is still one of charismatic, driven figures, combing the Earth’s wild places for fossils, the few mute fragments of teeth and bone which are all that remain of our remote past; of tentative and even rather romantic accounts of humanity struggling painfully to be born.
Of mice and mothers
Authors: McLaren Anne
Published: November 2023

There are remarkably few outstanding women scientists. Anne McLaren is one of a small group which forms the exception. She went up to Oxford just after the war to study zoology, and became interested in the complex interface between genetics and reproduction. In the early fifties she and her then colleague, Donald Michie, were among the first to use the technique of embryo transfer in animal experiments, and were associated with the early research leading to in vitro fertilization. More recently she has been working on sex determination in mice, and in a series of very elegant experiments, carried out in collaboration with Elizabeth Simpson, showed that the favoured view that maleness resided on a particular part of the Y chromosome was wrong. Her work for the Agricultural Research Council, and as Director of the Mammalian Development Unit of the Medical Research Council has played a major role in making Britain pre-eminent in the area of mammalian developmental biology.
Interference
Authors: Sutherland William J
Published: November 2023

Interference is the decline in resource use resulting from the behaviour of other individuals. This does not include depletion, in which the resource is removed. Entomologists have long known that parasitoids at high densities are less efficient at finding hosts (Hassell 1978) but there has been much less work studying the role of interference in vertebrates. In this chapter I will consider the process of interference and its consequences in determining the distribution of individuals.
Mating systems and reproductive success
Authors: Sutherland William J
Published: November 2023

In this chapter I will consider how ideal free theory can be used to consider mating systems and especially lekking behaviour. Leks are communal mating grounds in which males display and females visit to mate, gaining no resources from attending the lek—see Wiley (1991) for a review. The approaches used here are similar to those used in previous chapters, but I will restate some of the basic concepts described in previous chapters within a framework of mating systems. I will sketch out some of the ways in which mating systems can be studied using the ideal free distribution and describe lek mating in more detail.
Applied problems
Authors: Sutherland William J
Published: November 2023

Previous chapters have explained in general terms how the distribution of consumers in relation to the food population can be understood. Although this approach can be used for examining the general principles applying to any species, the details of the natural history will influence the outcome. Of particular importance is unravelling the factors affecting habitat preferences. The two aims of this chapter are firstly to describe how to develop models of a given species in a given area and secondly to show how these models can be used to tackle applied problems. The actual problems involve the two following predictions: the consequences of increases in the number of competitors and changes in habitat management on the species of conservation interest; and the extent of future agricultural loss resulting from species whose populations are increasing.
Predation and human disturbance
Authors: Sutherland William J
Published: November 2023

Consumers may themselves be attacked and eaten by predators. Not only may this reduce the numbers of consumers but it may also cause them to change their choice of patches which may have consequences for the size of a population that could be sustained in a site. In this chapter I will describe the evidence for a trade-off between resource abundance and predation risk and will suggest a way of considering the consequences of this for the population that can be sustained in a site.
Modelling techniques
Authors: Sutherland William J
Published: November 2023

The aim of this chapter is to outline the basic approaches behind the models described in the previous chapters. There is not the space to describe every model in detail but my hope is that this chapter will make it reasonably clear how these models were created and assist anyone wanting to produce further models. The models used in this book were all programmed in Pascal and are not complex. All the models have a similar basic structure. In each case there are patches that differ in resource density and consumers distribute themselves between these patches in response to the gains available from each. These models are based on the ideal free distribution and so the assumption is that no individual can obtain higher rewards by moving elsewhere. Thus the evolutionarily stable strategy is that, for each phenotype, the gains are equal in all the patches occupied. If the gain is higher in one patch then the theoretical expectation is that individuals will move there until either the increased negative feedback from interference and depletion balances the discrepancy or all members of that phenotype have moved.
Summary
Authors: Sutherland William J
Published: November 2023

The aim of this book has been to show how simple models based on the decisions individuals make can be used to describe phenomena such as the distribution within and between sites, population abundance, and migration. It is then possible to use these models to explore conservation issues such as the consequences of habitat loss or changes in habitat management. Population ecology has usually been based upon empirical relationships. This has the disadvantage that if the environment changes it is necessary to redetermine these relationships. Behavioural models based upon optimization and game theory can be derived from the principles of natural selection. Deriving population models from behaviour thus gives the opportunity to consider population ecology from first principles.
Sex ratio and egg size manipulation
Authors: Simmons Robert E
Published: November 2023

In this chapter we will look at the ability of harriers and other raptors to manipulate the number of sons and daughters they produce (sex ratio manipulation) and determine whether harriers can adaptively change the size of the eggs they lay. Both are relatively controversial topics because there is presently no known mechanism for females to alter the sex ratio of their eggs-but growing evidence that they can do so—and little experimental evidence that birds can adaptively change the size of the eggs they produce in relation to changing environmental conditions.
Synthesis
Authors: Simmons Robert E
Published: November 2023

The aim of this book has been twofold: to review current and new research on the evolution and ecology of the world’s harriers, and to provide a behavioural ecologist’s perspective on old questions about raptors, and harriers in particular. The behavioural ecologist is generally programmed to ask the most difficult question, which is why?— why do organisms behave as they do, why have some traits been favoured over others, and so on. To even begin to answer the ‘why’ question for any behaviour or ecological trait one cannot be content with observing and recording; it also requires perturbing an organism’s behaviour in some non-obtrusive way to test its ability to respond to unusual circumstances. The cleverly crafted experiment not only creates endless possibilities for creative thinking on the part of the researcher, it also has the potential to solve numerous puzzles that have not yielded their secrets to the patient observer, even in a lifetime’s work. While I have not been very creative in this regard—the experiments reported here are often carbon copies of ones that have been tried in temperate zones—the difference lies in the fact that they have been used on species in southern climes where experimentation is much rarer and where they can provide insights into questions (on clutch size, for example) that have only been tackled from the north, down.