bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative variation
Authors: Nicholas F W
Published: November 2023

The majority of traits of interest in animal breeding are continuously varying in the sense that animals cannot be readily classified into distinct classes. Milk production, fleece weight, body weight, and speed over a certain distance are just a few examples of continuously varying traits. Even a trait like egg production, which is not strictly continuous, can be considered as continuously varying because there are a large number of classes into which hens can be fitted according to the number of eggs laid in a certain period. Continuously varyin.gtraits are called quantitative traits or metric traits, and variation in them is called quantitative variation or continuous variation. Because they are measured on a continuous scale, it is not immediately obvious how variation in quantitative traits can result from the action of genes, which of course are discrete entities. The aim of this chapter is to describe the basis of quantitative variation, and to show how it can be partitioned into genetic and non genetic components.
Selection between populations
Authors: Nicholas F W
Published: November 2023

Artificial selection occurs whenever humans choose to breed from certain animals and not from others. The choice can be made between populations and/or within populations. In the former, it involves a decision as to the most appropriate source of breeding stock or commercial progeny. In the latter, it involves continual efforts to alter a population by breeding from only those animals which by some criteria are the most desirable within that population. In both cases, selection is exploiting genetic variation.
Selection and regular crossing
Authors: Nicholas F W
Published: November 2023

Traditionally, many stud breeders have regarded crossing as an insult to them and to their animals, and as a threat to their livelihoods. The aim of this chapter is to explain why these opinions are incorrect, and to illustrate that the most profitable future for both stud breeders and commercial breeders lies in breeding programmes that involve both selection and regular crossing.
The basic model: statics
Authors: Anderson Roy M , May Robert M
Published: November 2023

In this chapter, we restrict attention to the steady state of the basic model defined in Chapter 3. That is, we assume there is no time dependence in the variables X9 Y, Z of eqns (3.11)—(3.13), so that they depend only on host ages, a: X(a)9 Y(a), Z(a).
Dynamic aspects of eradication and control
Authors: Anderson Roy M , May Robert M
Published: November 2023

We have just seen that host-microparasite associations have a strong propensity to oscillate, so that even the endemic equilibrium state is often one of self-sustained cycles. The initiation of a programme of immunization, by its nature, constitutes a perturbation to such a host-microparasite system, and consequently is likely to evoke oscillations even if they are absent in the pre-immunization state. In other words, it is not to be expected that the incidence of infection will change smoothly and monotonically from its pre-immunization equilibrium value to some new and lower value (or to zero if eradication is achieved) under immunization, but instead we should often expect to see oscillations—sometimes quite pronounced—superimposed on the trends.
Indirectly transmitted microparasites
Authors: Anderson Roy M , May Robert M
Published: November 2023

Many important microparasitic infections of humans are indirectly transmitted from person to person by biting arthropods such as mosquitoes. A list of the major infections is presented in Table 14.1. An idea of their global significance is provided by the observation that the protozoan malarial infections on the continent of Africa alone are estimated to cause in excess of one million child deaths annually (Walsh and Warren 1979). The term ‘vector transmitted’ is often used to describe these infections but it should be noted that the vector is invariably a true intermediate host, in the sense that the parasite undergoes a phase of obligatory development (and often reproduction) within the arthropod.
Acquired immunity
Authors: Anderson Roy M , May Robert M
Published: November 2023

In this and the following four chapters, we turn to a series of biological complications that can have important influences on the transmission dynamics and population regulation of macroparasites. The first is that of acquired immunity. As mentioned in Chapter 15, this topic is one of much current debate. Unlike many microparasitic organisms, helminths do not induce sterile immunity to reinfection following primary exposure. Acquired host responses, however, can act to reduce rates of parasite establishment, fecundity, and survival as demonstrated by a large body of experimental work based on laboratory rodent-helminth systems (see Mitchell 1979; Dean 1983, Wakelin 1984).
Indirectly transmitted helminths
Authors: Anderson Roy M , May Robert M
Published: November 2023

For several reasons, we devote this chapter to describing models for the study of the transmission of two important indirectly transmitted infections, namely the schistosome flukes and the filarial nematodes. Their inclusion is in part due to a fascination with the complexity of their life cycles, which has resulted in much research on the biology of infection in human and snail populations, in part due to their historical significance in the development and use of mathematical models in the field of parasitology and tropical medicine, and in part for completeness.
Parasites, genetic variability, and drug resistance
Authors: Anderson Roy M , May Robert M
Published: November 2023

Much of conventional theory and practice in epidemiological and ecological research is based on the premise that an understanding of observed patterns and processes can be achieved by reference to the average phenotypic characteristics of a group or sample of individuals and to some measure of variance. This approach is widely adopted despite the certain knowledge that populations of organisms are genetically heterogeneous. It is clearly an ‘economy of thought’ which often works well in practice when the genetical structure of the population under study is relatively stable and not subject to strong directional selection. In other instances the failure to recognize the variable genetical constitution of a population can lead to erroneous conclusions concerning the factors responsible for observed trends.
Is parasitism symbiosis? A definition of terms and the evolution of concepts
Authors: Cheng Thomas C
Published: November 2023

A common language in science is essential if investigators world-wide are to communicate. Here I re-examine what we mean by ‘parasitism’ and ‘symbiosis’ in the perspective of what is known today. The term ‘symbiosis’ was coined by Antoine de Bary in 1879. It literally means ‘living together’. De Bary was interested in the association between species of algae and fungi that form lichens. In his original definition (De Bary 1879), he did not include any suggestion of exchange of mutually beneficial factors between the algae and fungi; the term was coined strictly to define intimate heterospecific associations.
Gating mechanisms of calcium channels
Authors: Kostyuk Platon G
Published: November 2023

As is clear from the preceding chapter, a distinctive feature of calcium channels in excitable membranes is their ability to activate (to open) upon a change of the transmembrane electric field. These channels are closed at high membrane potential level and pass Ca2+ ions across the membrane only during depolarization. Since the study of calcium channels started later than that of other voltage-operated channels (sodium, potassium), the understanding of the mechanism of their activation was much influenced by the data obtained earlier with respect to the latter channels. For sodium and potassium channels it is generally accepted that, together with structural components which determine the ability to select and to pass a definite ion type (the so-called ‘selectivity filter’), there are structural components able to respond to a change of intramembrane electric field by opening or closing a pathway for the movement of ions along their electrochemical gradient (‘gating’ mechanism). This idea arose from the studies of Hodgkin and Huxley (1952), who suggested a model for such a gating mechanism which is now widely accepted.
Inactivation of calcium channels
Authors: Kostyuk Platon G
Published: November 2023

Inactivation of voltage-operated ion channels is phenomenologically a wellknown process, which manifests itself in a gradual decline of the current during sustained membrane depolarization. This phenomenon has been studied in detail on sodium channels of the squid axon and frog nerve fibre membranes (reviewed by Meves 1978). Quantitatively, inactivation is taken into account by the introduction, in the corresponding equations, of the variable h (see Chapter 3). Another manifestation of inactivation is the stationary diminution of the maximal amplitude of the ionic current elicited by a test depolarization when the membrane potential was initially held at a decreased level. The dependence of this diminution on the holding potential level has an S-shaped form and is described as the steady-state inactivation function, h∞ ( V).
Modulation of calcium-channel functioning
Authors: Kostyuk Platon G
Published: November 2023

The ‘classical’ concept concerning the functioning of ion channels considers them as being operationally independent of cellular metabolism. The genetic apparatus of the cell controls the synthesis of protein macromolecules, which are transported by the mechanism of intracellular transport to the relevant sites, incorporated into the surface membrane, and then act there for a while, being replaced in time by new ones. Metabolic processes create only the necessary prerequisite for the function of the channels: they form, through the activity of the metabolically driven pumps, constant transmembrane gradients of the main inorganic ions. As long as these gradients are present, the membrane maintains its ability to respond to external stimuli by active responses in the form of ionic currents triggered by conformational changes in channels that open the pathway for ions. Cellular metabolism is not necessary for these changes; the membrane has only to maintain its labile structure, characteristic of the living cell. This concept seemed to be quite universal; however, in the past few years it has become more and more obvious that it considerably simplifies reality and that channel function can, in fact, be under the direct control of intracellular metabolic processes; this is especially true for calcium channels.
Development of calcium conductance during ontogenesis
Authors: Kostyuk Platon G
Published: November 2023

It has been established that the presence of specialized ion-conducting structures, ion channels, in the surface membrane is one of the primordial properties of living cells; they can, for example, be clearly demonstrated in the oocytes of invertebrates. Microelectrode studies of such convenient objects as oocytes of Tunicates and Echinodermata showed the presence of membrane potentials of small value (several millivolts). At such a potential a cell was not capable of generating active responses, but if the membrane was hyperpolarized by electric current, action potentials appeared upon removal of the hyperpolarizing current, which indicates the presence of electrically operated ion channels in the cell membrane (Miyazaki et al. 1974). The study of the dependence between action potentials and ionic composition of the medium, as well as the action of different toxins, showed that, just as in differentiated cells, the action potential of oocytes has ‘sodium’ and ‘calcium’ components, i.e. several types of ion channels are involved in its generation (Miyazaki et al. 1975).
Functional role of calcium ions in the nerve cell
Authors: Kostyuk Platon G
Published: November 2023

The functional role of the influx of Ca2+ ions from the extracellular medium into the cell during its activity is not always obvious. In some structures such an influx is directly connected to the triggering of a specific cellular function, and the role of these ions as messengers between the cellular membrane and the effector apparatus can be precisely analysed. This is the case for synaptic terminals which liberate a transmitter, and muscle fibres which contract in response to membrane depolarization. The important role of calcium in muscle contraction had already been defined by Ringer at the end of the nineteenth century. Subsequent numerous investigations have firmly established the fact that in all kinds of muscle fibres the intracellular level of ionized calcium is the primary regulator of the contraction-relaxation cycle, although some details of such regulation, particularly the role of Ca2+ ions entering from the extracellular space and liberated from intracellular stores, may substantially differ in different fibres.
General conclusions
Authors: Kostyuk Platon G
Published: November 2023

As can be seen from the findings summarized in this book, we now know quite a lot about the succession of events in which calcium participates during nerve-cell functioning. The basis of this participation—a highly asymmetric distribution of calcium ions between the extracellular medium and the cytoplasm—is a fundamental characteristic of the living state, and the influx of these ions into the cell, driven by their steep electrochemical trans membrane gradient, is an obligatory component of each cycle of neuronal activity.
Procedural and symbolic learning after large unilateral thalamic lesions in monkeys
Authors: Deuel Ruthmary K , Anderson Terry W
Published: November 2023

To examine the role of anterior medial thalamic nuclei in laterally distributed attention and motor behaviour, large unilateral lesions were created in five monkeys by implantation of radioactive pellets. Lesions were well-circumscribed, and destroyed Medialis Dorsalis, Ventralis Anterior and portions of Ventralis Lateralis and Ventralis Posterior Lateralis nuclei in all animals, as well as interrupting mamillo-thalamic and other anterior thalamic white matter tracts. Behavioural testing revealed no evidence for hemispatial neglect but marked impairment in a simple motor procedural task when it was carried out by the hand contralateral to the lesion. Learning and performance of three other tasks proceeded without deficit. The data are pertinent to understanding the pathophysiology of unilateral thalamic damage and localization of function in the primate cerebrum, particularly as it relates to thalamo-cor- tical interactions in higher-order motor activities.
Partial truths: a review of the use of concepts in the evolutionary sciences
Authors: Horder T J
Published: November 2023

For many reasons - among them the early disillusionment that followed the promises of Haeckelian recapitulation, and the continuing obscurities of the nature of developmental mechanisms - embryology has occupied an ill-defined and peripheral position among the disciplines contributing to evolutionary science. This paper argues, however, that embryological considerations are obligatory if we are to arrive at a rational foundation for many concepts basic to the evolutionary sciences (including homology, recapitulation, Bauplan, allometry, heterochrony, and paedomorphosis): they also expose the limitations of the modern synthesis (in its emphasis on selection and genetic reduction) and in methods of phylogenetic reconstruction and of character choice in systematics. An understanding of the complex, multifactorial nature of the actual developmental mechanisms demonstrates how such concepts are partially valid abstractions: their uses and definition depend on their interrelations with concepts and data across all biological disciplines.
Methods for rooting cladistic trees
Authors: Weston Peter H
Published: November 2023

Outgroup comparison is a special case of the more general use of parsimony in the construction of unrooted trees. The ultimate product of such analyses would be a ‘global’ unrooted tree connecting all species. A direct method for polarizing characters is needed to root such a tree. I argue that Nelson’s restated biogenetic law is one member of a class of direct methods of char acter analysis that share the same logical basis: parsimony-based analysis of hierarchically nested, homologous characters. Nested characters may be sets of ontogenetic homologues, linked by ontogenetic transformation, organogenetic transformation, or biosynthetic pathways; or sets of iterative homologues, such as serial homologues and paralogous genes. These methods can be used to decorate a tree with arrows that point towards its root. Phylogenetic loss may result in character distributions that are ambiguous or misleading, or for which the methods are inapplicable. The only assumption required beyond those inherent in parsimony-based construction of unrooted trees is that every homology represents a synapomorphy at some level. Nelson’s ‘ontogenetic criterion’ does not assume that phylogenetic change occurs exclusively or predominantly through terminal ontogenetic addition.
Estimating evolutionary rates for discrete characters
Authors: Milligan Brook G
Published: November 2023

Models play two roles in the study of evolutionary history. First, they are either explicitly or implicitly involved in the reconstruction of phylogenetic relationships. Second, they provide the means of testing alternative, biologically motivated evolutionary scenarios. Although there is widespread interest in both applications of evolutionary models, there are relatively few attempts to estimate them in a phylogenetic context. I present a general means of estimating such models specified in terms of the rate of transition between character states, and illustrate it with both molecular and morphological data. While relatively simple molecular models are easily rejected for the chloroplast gene rbcL, no compelling evidence exists for non-independent evolution of sexuality and propagule type among seed plants. These results are significant because they indicate that the models currently being used for phylogenetic reconstruction may be explicity tested and, in addition, specific evolutionary hypotheses may be investigated. This approach unifies phylogenetic inference with the comparative method.
Population dynamic principles
Authors: Lawton John H
Published: November 2023

The death of an individual, a population, or an entire species can have many causes, even if one ultimately delivers the coup de gráce. Are there, however, general rules and constraints that may help us better understand rarity and extinction? Simberloff (1986), Cracraft (1992), and Caughley (1994) all provide succinct reviews of the literature on extinctions, and seek to draw some general conclusions.
Biological models for monitoring species decline: the construction and use of data bases
Authors: Margules C R , Austin M P
Published: November 2023

A necessary prerequisite for estimating extinction rates is a database that adequately represents the biota and is comprehensive in its geographical coverage. This is a fundamental and obvious requirement. So obvious, in fact, that it is often taken for granted that such data exist. In reality, only a few small parts of the world with a long history of biological field surveys, such as the British Isles, can lay claim to adequate and comprehensive databases and even these can only be considered adequate for some components of the biota at some scales. Usually, field records are collected in a haphazard or opportunistic manner; the species recorded are the ones of interest to the collector; and the places they are recorded from are the places those species might be expected to be found, or are conveniently accessible. Accordingly, extensive and often detailed collections of field records in museums, herbaria, and various natural resource management agencies throughout the world are flawed, because they are incomplete and often biased, both in geographical coverage and in the sense that they are records of subsets of taxa.
Introduction
Authors: Cartledge Bryan
Published: November 2023

The problem is simply stated. By the end of the twenty-first century- and possibly within the lifetime of some of today’s infants and toddlers - the population of our planet is likely to have doubled, as it has done during the past fifty years. Brian Heap (below, page 48) takes the relatively optimistic view that the world’s population will reach a plateau of about 10 billion by 2100. A contributor to the last series of Linacre Lectures (John Seaman in Health and the Environment, OVP 1994), on the basis of forecasts by the UN Population Fund, predicted a figure of 11 billion by the year 2060. In this series, Geoffrey Harrison cites the illustrative estimate that if recent growth rates were to continue for a thousand years there would be 1700 people to each square yard of the Earth’s surface, land and sea: extrapolation is not predictive but it does help to concentrate the mind.
Mankind: master of this creation but servant of the Creator
Authors: Jukes John
Published: November 2023

The Rt. Revd John Jukes OFM Conv. has been the Roman Catholic Auxiliary Bishop of Southwark and titular Bishop of Strathearn since 1980. After training in Rome, he entered the Franciscan Order and was ordained in 1952. He founded the Order’s seminary in Anglesey and served as its Rector until 1959. He then served as a parish priest, in Manchester and London, for JO years until his appointment to be lecturer in canon law and Vice-Principal at the Franciscan Study Centre in Canterbury. In 1979, Bishop Jukes was elected a Minister Provincial in the English Province and Area Bishop for the Deaneries of Kent. He is Chairman of the World of Work Committee of the Bishops’ Conference of England and Wales.
Introduction
Authors: Ulijaszek Stanley J , Huss-Ashmore Rebecca
Published: November 2023

For the past 30 years, human population biology has sought to document and explain processes that have contributed to biological variability in the human species. The central concept in this field has been the idea of human adapt ability, or the ability of populations to adjust, biologically and behaviourally, to environmental conditions. While much of the early research focused on genetic variation and evolutionary change, more recent work has emphasized plasticity, or the ability to alter physiology and morphology within the individual lifetime. This volume attempts to examine the history of the study of human adaptability from its conception in 1962 to the present day, and is based on the Proceedings of the First Parkes Foundation Workshop, held in Oxford on 6-7 January 1994. The earliest human adaptability projects are examined, case-studies of human adaptability in different environments and in different parts of the world are described, and possible future directions in human adaptability research are considered. In short, this is a wide-reaching appraisal of the origins and state of human adaptability research.
Adaptability of African pastoralists
Authors: Little Michael A
Published: November 2023

A Wenner-Gren Foundation symposium, held at Burg Wartcnstcin, Austria in 1964, served to define some of the major problem areas for the Human Adaptability (HA) section of the newly formed International Biological Programme (IBP) (Baker and Weiner 1967). According to guidelines that had been established a few months earlier in Paris, one of the categories of recommended HA research was intensive multidisciplinary regional studie. (Weiner 1967). Within this category, information was to be gathered on: socio-demography of the community, the environment, population genetics of the people, medical and dental status, daily and seasonal activities, physique and growth, and working capacity. The three contributions to the conference on Africa (Hiernaux 1967; Tobias 1967; Wyndham 1967) made little mention of African pastoral populations, principally because research on pastoralists had been dominated by socio-cultural studies at that time, and virtually no work in human population biology had been done.
The evolution of human adaptability: society, funding, and the conduct of science
Authors: Schell Lawrence M
Published: November 2023

Most commentaries on trends in science are related to the commentator’s perspective and intellectual life history. The following commentary is offered from the perspective of one who uses the adaptability paradigm as described by Harrison (1966) and Lasker (1969), but has not conducted an explicit adapt ability study, that is, a more or less holistic study of a population’s adaptability to stressors from extremes in the physical environment. The work I began in 1976 on adaptation to stressors in urban environments focused on develop mental adaptation, but it focused on psychosocial stress, specifically from exposure to extreme noise, and it was conducted in a North American city. Although the project developed directly from the adaptability paradigm, in which developmental adaptation is integrated into a general model of biological adaptation (Harrison 1966; Lasker 1969), the human adaptability approach common in the 1970s did not seem suited to studying people in cities. Psychosocial stress is an anthropogenic stressor rather than part of the physical environment, and the population studied was neither remote nor exotic. Thus, for 20 years my viewpoint has been from the outside looking in toward adaptability research. Since the mid-1970s adaptability research has changed, as virtually every chapter in this volume attests, and my position has been encompassed by the adaptability paradigm in its current fonn.
Dispersal, demography, and the persistence of partnerships in Indigo Buntings
Authors: Payne Robert b. , Payne laural.
Published: November 2023

In late spring and through the summer, the song of the Indigo Bunting Passerina cyanea (see drawing above) is a familiar sound in old fields and the edges of woodlands in eastern North America. The indigo blue males are conspicuous as they sing from the tops of small trees. The brown females nest near the ground in leafy shrubs and herbs. Buntings are long-distance migrants and spend the winter in flocks in Mexico and Central America. Pairs separate after the breeding season until the birds return in the following spring, from early May, the males about 10 days earlier than the females. Males usually settle on their breeding site of the previous year; females often settle on a new territory rather than reuniting with their old mate.
Middle East Water Issues: Action and Political Will
Authors: Kamal Tolba Mostafa
Published: November 2023

For the past ten years, and in particular over the past five years, I have been persistently calling for action rather than talk. I sincerely hope that this meeting is going to set action in motion. We have plenty of recommendations from global, regional and other international conferences, meetings, seminars and the like. We have plans of action at the global, regional and national levels. We know the facts and what needs to be done. But we have yet to see real action.
Health outcomes: the socio-historical context
Authors: Armstrong Dayid
Published: November 2023

In the eighteenth century a system of medicine based on humours was, for a brief time, rivalled by a medicine grounded in astrological prediction (Wright 1979). The former won the struggle for supremacy, to be replaced in its turn a century later by the triumph of a system of medicine based on pathological anatomy. A conventional explanation for the failure of astrological medicine is that it was ineffective: if the role of medicine is to intervene to alter the outcome of illness then astrological medicine could at best only have had a placebo effect. But this explanation of success and failure is to judge astrological medicine from the perspective of the present and not in its own terms. As well as relief from illness, astrological medicine offered predictions about the future course of life, of good fortune, marriages, and achievements. However, these are not the criteria by which it is now judged: past systems of medicine are evaluated by the criteria of the most recent. Thus, the current system of medicine holds certain outcomes as important and proceeds to evaluate rival systems of medicine in terms of success in achieving these particular outcomes; but from the perspectives of these superseded systems of medicine such criteria of success and failure may be less appropriate. From the view of a medicine based on astrological prediction, modern medicine stands condemned in not even attempting life course forecasts, never mind claiming any success in this area.
Valuation as measurement: an economist’s approach to rendering health care outcomes commensurable
Authors: Fenn Paul , Mcguire Alistair
Published: November 2023

Why is it that some things are more difficult to measure than othersã Height and weight do not trouble us too much, nor do pulse rates, respiration, or temperature. These are all fairly simple, unidimensional concepts for which there are agreed standardized units and widely available means of calibration. It is with the more nebulous concepts, such as health, or well-being, that we begin to get problems. This is partly because such concepts are typically described in terms of a number of different dimensions, and partly because there may be no general agreement as to which of those dimensions are more important to our understanding of the concept. This would, of course, be a problem of semantics alone if it were not for the fact that social objectives are frequently expressed in terms of such concepts.
Sequencing methods
Authors: Cotton Richard G H
Published: November 2023

Sequencing of DNA is fundamental to the whole of molecular biology including molecular genetics. To define a mutation precisely, the sequence change must be established and this can only be determined by sequencing. (It can be achieved without sequencing by the CCM method adapted to the ABI sequencer, see below.) This being the case, sequencing is a routine technique in all molecular biology laboratories and thus it is not treated in depth here.
Diagnostic methods
Authors: Cotton Richard G H
Published: November 2023

Diagnostic methods as their name implies are usually used in the diagnostic laboratory. To a certain extent the division of these methods from scanning methods is artificial as scanning methods can be used in the diagnostic context and especially as some of the methods below can be used to investigate all nucleotide positions in a target sequence, effectively scanning the segment for any mutation. However, it is important to point out that the diagnostic methods used to detect known mutations usually identify the mutation unequivocally when one is detected, in keeping with their diagnostic use. This is in contrast to scanning methods where the same or similar signals can be generated from different mutations. For example, a C → A and a C→ t the same position could generate the same signal for the RNAse, CCM and heteroduplex methods.
Strategies for mutation detection
Authors: Cotton Richard G H
Published: November 2023

Strategies of mutation detection are of most importance in the area of mutation scanning methods. This is because their time consuming nature and their respective disadvantages make it difficult to choose between them to maximize the number of mutations detected by the approaches chosen. Of course, if we now had the ideal method which was quick and cheap this chapter would not have been written. Within-method strategies will generally not be discussed here and have been dealt with in the methods sections.
Introduction
Authors: Clayton Dale H , Moore Janice
Published: November 2023

Host-parasite evolution is a hot topic. In less than two decades, a ground swell of interest has stimulated intensive research on subjects as diverse as parasite-mediated sexual selection, host-parasite co-speciation, and the evolution of parasite virulence. This book attempts to review many of the recent developments in this field, while also providing an overview of the immense diversity of parasites reported from a single class of hosts: birds.
Gardens of the mind
Authors: Mitchell Peter
Published: November 2023

At the peak of his scientific career in the 1960s, the late Peter Mitchell spent two years not doing science, but working full time on the restoration of Glynn House, a large and beautiful Regency mansion in Cornwall. Only a year or so earlier, while director of the Clinical Biology Unit at Edinburgh University, he developed a theory which was to lead to him being awarded the Nobel prize for chemistry in 1978. His time as architect and master of works turned out to be only a temporary retirement from active research. But his departure from the formal scientific establishment was permanent. He built a personal laboratory in Glynn House, and set up the Glynn Research Foundation, a registered charity, to promote fundamental biological research for the benefit of humanity. It challenges many of our ideas about science that a distinguished scientist should abandon his research at a critical stage, and then prefer to continue outside the conventional framework, and in apparent isolation.
In agreement with nature
Authors: Bellido Antonio Garcia
Published: November 2023

Spain does not come high up on the list of countries which have made a major contribution to the development of modern biology. With the outstanding exception of the nineteenth-century anatomist, Cajal, who won a Nobel Prize for mapping neural connections in the brain, Spain has no strong tradition in biological research.
Daydreaming molecules
Authors: Black James
Published: November 2023

As recently as the 1960s, looking for new drugs was largely a matter of trawling randomly for compounds that might do something useful. Black took a much more direct approach. He set out to find compounds that would block the action of particular chemical signals. Patients with angina get a searing pain when their heart starts to beat faster. This is because the damaged coronary arteries cannot supply the heart muscle with the extra oxygen it needs. Because an increase in heart rate is a response to adrenaline, the chemical released by the nervous system in response to stress, Black reasoned that the symptoms could be relieved by blocking this reaction. This is precisely what he succeeded in doing. The beta-blocker, propranolol, works by binding to the sites in the heart, the so-called beta-receptors, which would otherwise be stimulated by adrenaline. Cimetidine, the anti-ulcer drug, works on a similar principle.
Ways of seeing
Authors: Simons Elwyn
Published: November 2023

The man to answer these questions is Elwyn Simons. Master fossil hunter, conservationist and widely regarded as the founder of primate palaeontology, he is concerned with all the stages of human ancestry, but particularly with the fossil remains of the small, monkey-like creatures which lived in the Oligocene and Eocene period between 40 and 30 million years ago, in what is now the Fayum desert of Egypt. The most famous of these is Aegyptopithecus, which is probably the first of the line which branched off and eventually led to human beings. Other Eocene primates gave rise to the lorises and lemurs which Simons studies in the forests of Madagascar and at the Primate Center at Duke University in Durham, North Carolina.
Directly to the heart
Authors: Douarin Nicole Le
Published: November 2023

Louis Pasteur’s dictum that fortune favours the prepared mind is almost a scientific cliche. It is nevertheless undeniable that the events leading up to important discoveries often seem to contain an element of chance, but equally true that chance is transformed into luck largely by the insight of the recipient. Nicole Le Douarin’s early success seems to be no exception to this rule. She was, and still is, concerned with the problems of development. How, from a single cell, the fertilized egg, billions of different cells arise and organize themselves into heads, eyes, arms and legs, and so on. How, for example, early in development, cells belonging to the neural crest in the region corresponding to the back of the head move forwards to form much of the face. Her first major contribution was to realize that there were certain differences between chick and quail cells which could be exploited to track such cell migrations. She grafted the corresponding quail cells into chick embryos, and showed that as the tissues developed, the grafted quail cells acted as visible labels, or markers, whose destiny could easily be followed. This work led to a transformation in our understanding of cell migrations, particularly those involving the head and nervous system.
Protecting plantations from damage by wildlife, pests, and pathogens
Authors: Savill Peter , Evans Julian , Auclair Daniel , Falck Jan
Published: November 2023

A plantation represents a considerable investment and so concern for its health is an important part of silviculture, as discussed in Chapter 2. In natural forests seedlings and mature trees are essential links in the ecosystems’ food chain. Many organisms are partly or fully dependent on trees for their existence. Though damage to plantations is often unpredictable, irregular, and very variable in its severity, fortunately most plantation schemes in temperate and boreal regions are successful because serious damage is rare and adequate protection is usually possible, though sometimes expensive.
Introduction
Authors: Sutherland William J
Published: November 2023

Population dynamics and animal behaviour are two subjects that have developed largely in isolation, despite the widespread acceptance that they are related and the frequent acknowledgement of a need to combine them. The major objective of this book is to demonstrate how aspects of the population ecology of vertebrates, such as population size and the response of populations to ecological change, can be related to behaviour. I will concentrate on particular questions which I consider interesting, so this should not be regarded as a comprehensive review of all aspects of these issues.
Depletion
Authors: Sutherland William J
Published: November 2023

Depletion, the removal of resources by consumers, is undoubtedly an important process in determining the distribution and intake of individuals. Depletion will always occur where consumers are feeding but in some cases it may be trivial, and in others interference may be more significant. As an extreme example, Szekely and Bamberger (1992) s.tudied the predation of chironomid larvae in lagoons by flocks of black-tailed godwits Limosa limosa, spotted redshanks Tringa erythropus and ruffs Philomachus pugnax. Exclosure experiments and observations of feeding rates showed that over thirteen days these birds removed 86.6% of the prey stock. As a result of this depletion, the intake rate from this food source declined by 32.7% for the black-tailed godwits, 14.3% for the spotted redshanks and 59. l% for the ruffs during the same period.
Prey populations
Authors: Sutherland William J
Published: November 2023

The previous chapters have considered the behaviour and distribution of the consumers. The aim of this chapter is to explore the consequences of the distribution and intake rate of consumers for the prey or resource population. In particular, how does the mortality rate vary with the prey density? In earlier chapters I outlined models that describe the distribution and intake of consumers feeding in a range of patches varying in prey density. This approach can be used to explore the manner in which the spatial variation in prey mortality will vary with the behaviour of the consumers.
Territories
Authors: Sutherland William J
Published: November 2023

In the previous chapters it has been assumed that individuals are relatively free to move between patches. However, in many species this is clearly untrue as some individuals defend territories that exclude others. In this chapter, I will consider how territory defence influences the distribution of individuals and consider the consequences for density dependence. In some species territories may be defended by groups. Territorial behaviour is usually most pronounced in the breeding season and this is the situation I consider here. However the same approach can also be applied to territoriality in the range of conditions under which it occurs. For example, the majority of Neotropical migrant passerines are probably territorial in their wintering grounds and have high site tenacity between years (Fischer 1981; Rappole and Warner 1980); the redshank is even territorial in winter (Selman and Goss-Custard 1988) but not on the breeding grounds.
Migration
Authors: Sutherland William J
Published: November 2023

Migration, the return movement of individuals, occurs in many temperate and tropical birds, fish, turtles, and some mammals, such as whales, ungulates, and bats. The scale of migration may differ between long-distance migrations undertaken by many baleen whales, turtles, and seabirds, and localized movement such as roach Rutilus rutilus undergoing annual migrations within a lake to spawn in the same tributary (V0llestad and L’Aee-Lund 1987).
Habitat loss
Authors: Sutherland William J
Published: November 2023

There is widespread concern over the damage that humans are inflicting upon the environment. One of the consequences of this is a reduction in area of various habitats. Further habitat loss may be expected due to processes such as industrial development, agricultural intensification, deforestation, and sea level rise. There is a need to be able to predict the consequences of such habitat loss for species of conservation concern. For example, in public enquiries into development proposals, it is common for conservationists to argue that a loss of habitat will result in a reduction in the total population of associated species of conservation concern while developers often argue that the displaced animals will survive by simply moving elsewhere.
Latest Ordovician extinctions: one disaster after another
Authors: Hallam A , Wignall P B
Published: November 2023

Between the end-Cambrian crisis and the next major mass extinction in the latest Ordovician, trilobites continued to flourish. However, their predominance in benthic communities was usurped by the increasingly diverse groups that belong to Sepkoski’s (1981) ‘Palaeozoic fauna’. These included articulate brachiopods, bryozoans, graptolites, condones, echinoderms, and the rugose and tabulate corals. Various mollusc orders(such as the nautiloids, bivalves, and gastropods) also diversified, although to a lesser degree than the Palaeozoic fauna. Peak Ordovician diversity coincided with the mid-Caradoc sea-level high stand which appears to have marked an all-time Phanerozoic high; both basinal black shale and platform carbonate deposition occurred over vast areas at this time (Thickpenny and Leggett 1987; Cocks and Fortney 1988; Brenchley 1989; Barnes et al. 1995). Ordovician palaeogeography was undoubtedly a contributory factor to this diversity maximum because the continents each contain their own endemic fauna (Fig. 3.1).
Palaeozoic Nemesis
Authors: Hallam A , Wignall P B
Published: November 2023

The mass extinction at the end of the Permian has long been recognized as the greatest in the history of life (see, for example, Phillips 1841); the enormity of the fauna! turn over made it an obvious choice for the Palaeozoic-Mesozoic erathem boundary. Estimates of the species-level extinction (extrapolated from generic and familial data) range from 96% (Raup 1979) to a no less impressive, conservative estimate of 75% (Hoffman 1986). More recent estimates have tended towards the higher end of this range - for example 90% (McKinney 1995). The effect was to reduce an all-time Palaeozoic high of species diversity to the lowest post-Ordovician value of the entire Phanerozoic; Permian diversity levels were not attained again until the Cretaceous (Allison and Briggs 1993; Benton 1995). Raup (1979) suggested that a quarter of a million species - a figure comparable with modern-day marine species diversity (Nicol 1979)-were reduced to less than IO 000 while family diversity was reduced from 650 to 420. With such wholesale wipe-out, survival must have been a matter of pure chance for many groups.
Extinctions within and at the close of the triassic
Authors: Hallam A , Wignall P B
Published: November 2023

One of the ‘big five’ Phanerozoic marine extinctions (Raup and Sepkoski 1982) occurred at or close to the end of the Triassic, and mass extinction on the continents has also been claimed for this time. Other notable marine and continental extinctions have been reported for earlier in the Late Triassic, in the Carnian, and so a little must be said initially about correlation between Upper Triassic marine and continental strata.
Nucleosomes: dynamic repressors of transcription
Authors: Pennings Sari , O’Neill Timothy E , Meersseman, Geert , Bradbury E Morton
Published: November 2023

The structure of the nucleosome, which was elucidated from early work on enzyme digestion patterns, neutron scatter, X-ray diffraction data, and histone— DNA crosslinking (reviewed by Van Bolde 1988), is essentially a static picture of an average structure. This is because these experimental approaches average out the heterogeneities across the largely native bulk nucleosome and chromatin samples, as well as any fluctuations in the structure over time. Most notably, the model of the nucleosome rarely includes the long N-terminal and short C-terminal ‘tails’ of the histones, which are highly dynamic and contain the sites of reversible chemical modifications associated with chromatin functions (reviewed by Bradbury 1992; also see Chapter 3). Studies of higher order structures of chromatin also hold this caveat and here the paucity of data allows for several models of the 30 nm fibril model (reviewed by Van Bolde 1988). However useful these structural models arc in understanding the packaging of chromatin, they fail to convey how chromatin structure can be flexible enough not only to accommodate the wide range of DNA sequences in the genome, but also to allow dynamic processes such as transcription and replication to take place. An insight into the dynamic nature of chromatin is essential in order to understand how chromatin can be a functional component of the active eukaryotic nucleus.
Histone modification and transcriptional competence
Authors: Wolffe Alan P
Published: November 2023

Chromosomes are highly differentiated and dynamic structures. Transcriptional activity and chromosome morphology vary throughout the cell cycle. These events can be correlated with global changes in the post-translational modification of the histone proteins that occur in all chromosomes. At a more local level individual chromosomes, chromatin domains, or genes can have their transcription modulated through developmental or signal transduction pathways. These local transitions in gene activity can also be related to changes in chromatin structure and histone modification. The focus of this chapter is to discuss the nature of histone modifications and their potential structural and functional consequences.
DNA methylation and genomic imprinting
Authors: Bartolomei Marisa S
Published: November 2023

Normally in eukaryotes each allele of a gene contributes an equal amount of gene product. However, mammals exhibit an unusual phenomenon in which the expression level of the alleles of a subset of genes depends upon the parent from which the alleles were inherited. This phenomenon is called genomic imprinting and probably affects only a small number of genes (Efstratiadis 1994). One consequence of imprinted genes is the failure of uniparental mammalian embryos to develop normally. Embryos with two maternal pronuclei would be missing genes that are expressed exclusively from the paternal genome, while embryos with two paternal pronuclei lack genes expressed exclusively from the maternal genome.