Search Results

Does natural selection act primarily on individual organisms, on groups, on genes, or on whole species? This book provides a comprehensive analysis of the long-standing controversy in evolutionary biology over the levels of selection, focusing on conceptual, philosophical, and foundational questions. In the first half of the book, a systematic framework is developed for thinking about natural selection acting at multiple levels of the biological hierarchy; the framework is then used to help resolve outstanding issues. Considerable attention is paid to the concept of causality as it relates to the levels of selection, particularly the idea that natural selection at one hierarchical level can have effects that ‘filter’ up or down to other levels. Full account is taken of the recent biological literature on ‘major evolutionary transitions’ and the recent resurgence of interest in multi-level selection theory among biologists. Other biological topics discussed include Price's equation, kin and group selection, the gene's eye view, evolutionary game theory, selfish genetic elements, species and clade selection, and the evolution of individuality. Philosophical topics discussed include reductionism and holism, causation and correlation, the nature of hierarchical organization, and realism and pluralism about the levels of selection.

Bees play a vital role as pollinators for many agricultural crops. This book discusses the interplay between bees, agriculture, and the environment. Although honey bees are well recognized as pollinators, managed bumble bees and solitary bees are also critical for the successful pollination of certain crops, while wild bees provide a free service. As bees liberally pass pollen from one plant to the next, they also impact the broader ecosystem, and not always to the benefit of humankind. Bees can enhance the unintentional spread of genes from genetically engineered plants, and may increase the spread of invasive weeds. Conversely, genetically engineered plants can impact pollinators, and invasive weeds can supply new sources of food for these insects. Bees' flower-visiting activities also can be exploited to spread biological control agents that help to control crop pests. Bee pollination is important for production of native plants used for restoration of wild lands. Managing bees for pollination is complex and must consider bee natural history, physiology, pathology, and behavior. Furthermore, transporting bees from native ranges to new areas for pollination services can be controversial, and should be done only after assuring that a non-native bee introduction will not disrupt the ecosystem. Even though bees are small, unobtrusive creatures, they play large roles in the ecosystem. The connection between bees and humankind is symbolic of a broader interconnection between humans and the natural world.

From years prior to the release of the first commercial transgenic crop in 1995 to the present, many concerned activists, regulators, and scientists have questioned how genetic engineering might impact the environment. No measurable negative environmental impacts have been observed for commercial genetically modified crops to date, even though several risks have been identified in experimental releases. Even so, none have approached doomsday scenarios posed by activists. The risks that have been extensively studied are gene flow from crops to weeds or crop landraces; side-effects of insecticidal transgenic proteins, such as accidental killing of monarch butterflies or beneficial insects; viral recombination; and transgene combinations. Close examination has uncovered no negative effects, but plenty of positive environmental impacts from growing crops engineered for insect resistance and herbicide resistance. Insect resistant cotton and corn kill only the insects that attempt to eat the crops and have saved several million gallons of chemical insecticide applications. Herbicide resistant soybean and corn have helped in soil conservation efforts since farmers do not have to use as much tillage to control weeds. In addition to these benefits, scientists are conducting research to produce genetically engineered plants to clean up toxins, produce plastics and biofuels, and perform other ecological services. The responsible use of genetic engineering is part of sustainable agriculture now and in the future.

This book contains the texts of 17 lectures, delivered to the British Academy in 2001. Topics include Chinese Mountain Painting, prosperity and power in the age of Bede and Beowulf, Glyn Dwr, Shakespeare's sense of an exit, learning, liberty, poetry, social ethics, the House of Savoy during the Risorgimento, the disease of language and the language of disease, Gertrude Stein's differential syntax, Keith Douglas, Common Law's approach to property, Welfare-to-Work and genes.

This book surveys the momentous morphological change in plant evolution that created the terrestrial biosphere as we know it today. It takes as its premise that the study of plant evolution at its grandest is the study of how mutations in genes have changed the way the planet functions. The evolution of the leaf, for instance, change terrestrial carbon cycling and primary productivity, so changing the earth's atmosphere and the distribution of carbon. The book charts the rise to complexity of the three many organs systems of complex land plants, the axis or stem, the leaf, and the root. These organs system are surveyed morphologically in the light of empirical morphology, in which organ concepts are considered as hypotheses to be tested in a developmental, molecular, and phylogenetic framework. It also tackles the evolution of the seed (via heterospory and covering of the megasporangium) and the flower (by complex patterning of sporophylls and sterile phyllomes). All this is placed where possible in its molecular context, with the aim of demonstrating how evolving gene networks have given rise to increasing morphological complexity.

This book discusses novel advances in informatics and statistics in molecular cancer research. Through eight chapters it discusses specific topics in cancer research, talks about how the topics give rise to development of new informatics and statistics tools, and explains how the tools can be applied. The focus of the book is to provide an understanding of key concepts and tools, rather than focusing on technical issues. A main theme is the extensive use of array technologies in modern cancer research — gene expression and exon arrays, SNP and copy number arrays and methylation arrays — to derive quantitative and qualitative statements about cancer, its progression and aetiology, and to understand how these technologies at one hand allow us learn about cancer tissue as a complex system and at the other hand allow us to pinpoint key genes and events as crucial for the development of the disease. Cancer is characterized by genetic and genomic alterations that influence all levels of the cell's machinery and function.

In the past decade, there have been tremendous developments in the understanding of the structure, biosynthesis, and function of glycoconjugates present in the nervous system. These developments were initiated by advances in the molecular cloning of glycosyltransferases that direct the synthesis of these complex carbohydrates. In particular, the molecular cloning of polysialyltransferases, HNK-1 sulfotransferase, ganglioside sialyltransferases, and proteoglycan sulfotransferases provided a great opportunity to determine the roles of these glycans in the nervous system. Moreover, the availability of gene inactivation by homologous recombination in mouse, the ‘knockout mouse’, has led to an explosion of knowledge in understanding the physiological functions of glycoconjugates during embryonic development and organogenesis. In certain studies, the physiological function of glycoconjugates in adult mice can be evaluated in depth by examining the phenotype of adult knockout mice. This book focuses on topics in and expands descriptions of neuroglycobiology, based on recent advances in this field. The book includes eight chapters from various authors representing the field of neuroglycobiology. In the first two chapters, the biosynthesis and roles of glycoprotein glycosylation are described. Chapter 3 describes HNK-1 glycans. Chapter 4 describes the biosynthesis and roles of the brain glycolipids. The biosynthetic pathway and the roles of gangliosides based on gene knockout mice are described in Chapter 5. The final two chapters are devoted to summarizing recent findings on diseases caused by abnormal metabolism in glycoproteins and glycolipids.

The human genome of three billion letters has been sequenced. So have the genomes of thousands of other organisms. With unprecedented resolution, modern technologies are allowing us to peek into the world of genes, biomolecules, and cells, and flooding us with data of immense complexity that we are just barely beginning to understand. A huge gap separates our knowledge of the components of a cell and what is known from our observations of its physiology. This book explores what has been done to close this gap of understanding between the realms of molecules and biological processes. It contains illustrative mechanisms and models of gene regulatory networks, DNA replication, the cell cycle, cell death, differentiation, cell senescence, and the abnormal state of cancer cells. The mechanisms are biomolecular in detail, and the models are mathematical in nature.

Homology—a similar trait shared by different species and derived from common ancestry, such as a seal's fin and a bird's wing—is one of the most fundamental yet challenging concepts in evolutionary biology. This book provides the first mechanistically based theory of what homology is and how it arises in evolution. The book argues that homology, or character identity, can be explained through the historical continuity of character identity networks—that is, the gene regulatory networks that enable differential gene expression. It shows how character identity is independent of the form and function of the character itself because the same network can activate different effector genes and thus control the development of different shapes, sizes, and qualities of the character. Demonstrating how this theoretical model can provide a foundation for understanding the evolutionary origin of novel characters, the book applies it to the origin and evolution of specific systems, such as cell types; skin, hair, and feathers; limbs and digits; and flowers. The first major synthesis of homology to be published in decades, this book reveals how a mechanistically based theory can serve as a unifying concept for any branch of science concerned with the structure and development of organisms, and how it can help explain major transitions in evolution and broad patterns of biological diversity.

The theory of evolution may be successful in explaining natural history, but it is of limited value when applied to the human world. Because of our reflectiveness and rationality, as embodied in language, we give ourselves ideals that cannot be justified in terms of survival‐promotion or reproductive advantage. Evolutionary theory is unable to give satisfactory accounts of such distinctive features of human life as the quest for knowledge, our moral sense, and the appreciation of beauty. At most, it can account for their prefiguration at some earlier stage of development than the human. In all these areas we transcend our biological origins, and such mechanisms as genetic survival, kin selection, reciprocal altruism, and sexual selection. But because of our rationality we can also transcend our cultural inheritance explanation of which in terms of memes is both hollow and misleading. We are rooted both in our biology and in our cultural inheritance; but, sociobiology and sociology notwithstanding, we are prisoners neither of our genes nor of the ideas we encounter as we each make our personal journey through life.