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P. Bishop Museum, Honolulu, Hawaii 96819 PERSPECTIVES AND OVERVIEWWhy some species of animals would lose such obviously adaptive characters as eyes and pigmentation to live only in the seemingly inhospitable environ ment of caves has long intrigued both laymen and biologists. Evidence that early man recognized cave invertebrates dates back to an engraving of a cave cricket, Troglophilus sp., on a bison bone, discovered in a cave in the French Pyrenees (161), and believed to be 18,000 years old (86). However, serious studies on cave faunas began only about 150 years ago (5, 6).Vandel's monograph (161) provides the most recent overview of the whole science of biospeleology from a worldwide perspective, with an em phasis on Europe where most work has been done. Barr provided a thor ough review of ecological and evolutionary studies, drawing primarily on work in North America (6). Poulson's review (131) of the ecology and physiology of cave fauna emphasized aquatic species; Poulson & White (139) pointed out the potential for further ecological studies; Ueno (159) reviewed lava tube faunas in Japan; and Reddell (144), the Central Ameri can cave faunas. In general, the science of bios pel eo logy in the United States has lagged far behind studies in Europe, and it was not until the 1950s that the modern period of cave biology began in North America (5). The early studies were primarily taxonomic, since detailed ecological and physi ological studies require an accurate base of properly identified species. Advances in cave biology have followed the development of cave explora tion techniques, and the improvements in the last few decades have allowed biologists to visit and study longer and more complex cave systems in relative safety (e.g. 36, 105). In addition, the increasing ease of world travel has made possible the exploration of the more inaccessible, rugged tropical caves (e.g. see 16, 73, 128). Further ANNUAL REVIEWS 366 HOWARTHCavernicoles can be divided into three ecological categories: (a) troglo bites, obligate cave species that are unable to survive outside of the hypo gean environment; (b) troglophiles, facultative species that live and reproduce in caves but that are also found in similar dark, humid mi crohabitats on the surface; and (c) trogloxenes, species that regularly in habit caves for refuge but normally return to the surface environment to feed. A fourth group, accidentals, wander into caves but cannot survive there. Because of the difficulty of assigning a species to its correct category without detailed knowledge of its ecology and distribution (24), most recent authors have relied on a troglomorphic interpretation whereby a species is considered troglobitic if it displays morphological characters that appear to restrict it to subterranean habitats (6, 24,66,139,160,161). Of the many species of animals, predominantly arthropods, that utilize caves, the most interesting are the troglobites because of their often bizarre adaptations.At the time of the last thorough review 15 years ago, Barr (6) cou...

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The introduction of alien, or nonindigenous, animals and plants has been identified by scientists and policy makers as a major threat to biodiversity in marine ecosystems. Although government agencies have struggled to control alien species on land and freshwater for decades with mixed success, the control of alien marine species is in its infancy. Prevention of introduction and establishment must be the first priority, but many populations of alien marine species are already well established worldwide. National and international policies leave loopholes for additional invasions to occur and provide only general guidance on how to control alien species once they are established. To address this issue, a multinational group of 25 scientists and attorneys convened in 1998 to examine options for controlling established populations of alien marine species. The discussions resulted in a framework for control of alien marine species to provide decision-making guidance to policymakers, managers, scientists, and other stakeholders. The framework consists of seven basic steps: (1) establish the nature and magnitude of the problem, (2) set objectives, (3) consider the full range of alternatives, (4) determine risk, (5) reduce risk, (6) assess benefits versus risks, and (7) monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation. El Control de Invasiones Biológicas en los Océanos del Mundo Resumen: La introducción de animales y plantas invasoras, o no indígenas ha sido identificado por los científicos y legisladores como una de las mayores amenazas a la biodiversidad de los ecosistemas marinos. A pesar de las agencias gubernamentales han luchado por décadas por controlar a las especies invasoras en tierra y en agua dulce con resultados mezclados, el control de las especies invasoras marinas se encuentra aún en su infancia. La prevención de la introducción y el establecimiento debe ser prioritaria; sin embargo, muchas poblaciones de especies invasoras marinas ya se han establecido muy bien a nivel mundial. Las políticas nacionales e internacionales dejan espacios para que ocurran invasiones adicionales y proveen una guía solo anivel general sobre como controlar especies invasoras una vez que ya se hayan establecido. Para enfrentar este tema, un grupo multinacional de 25 científicos y abogados se reunieron en 1998 para examinar opciones para controlar poblaciones de especies marinas invasoras establecidas. Las discusiones dieron como resultado un marco de trabajo para el control de especies marinas invasoras que provee guías para la toma de decisiones para los legisladores, manejadores, científicos y otros interesados. Este marco de trabajo con- Bax et al. Controlling Alien Marine Species 1235 siste en siete pasos básicos: (1) el establecimiento de la naturaleza y la magnitud del problema, (2) la delimitación de los objetivos, (3) consideración de todas las alternativas posibles, (4) determ...

The introduction of alien, or nonindigenous, animals and plants has been identified by scientists and policy makers as a major threat to biodiversity in marine ecosystems. Although government agencies have struggled to control alien species on land and freshwater for decades with mixed success, the control of alien marine species is in its infancy. Prevention of introduction and establishment must be the first priority, but many populations of alien marine species are already well established worldwide. National and international policies leave loopholes for additional invasions to occur and provide only general guidance on how to control alien species once they are established. To address this issue, a multinational group of 25 scientists and attorneys convened in 1998 to examine options for controlling established populations of alien marine species. The discussions resulted in a framework for control of alien marine species to provide decision-making guidance to policymakers, managers, scientists, and other stakeholders. The framework consists of seven basic steps: (1) establish the nature and magnitude of the problem, (2) set objectives, (3) consider the full range of alternatives, (4) determine risk, (5) reduce risk, (6) assess benefits versus risks, and (7) monitor the situation. This framework can provide guidance for control efforts under the existing patchwork of national laws and can help provide a foundation for international cooperation. El Control de Invasiones Biológicas en los Océanos del MundoResumen: La introducción de animales y plantas invasoras, o no indígenas ha sido identificado por los científicos y legisladores como una de las mayores amenazas a la biodiversidad de los ecosistemas marinos. A pesar de las agencias gubernamentales han luchado por décadas por controlar a las especies invasoras en tierra y en agua dulce con resultados mezclados, el control de las especies invasoras marinas se encuentra aún en su infancia. La prevención de la introducción y el establecimiento debe ser prioritaria; sin embargo, muchas poblaciones de especies invasoras marinas ya se han establecido muy bien a nivel mundial. Las políticas nacionales e internacionales dejan espacios para que ocurran invasiones adicionales y proveen una guía solo a nivel general sobre como controlar especies invasoras una vez que ya se hayan establecido. Para enfrentar este tema, un grupo multinacional de 25 científicos y abogados se reunieron en 1998 para examinar opciones para controlar poblaciones de especies marinas invasoras establecidas. Las discusiones dieron como resultado un marco de trabajo para el control de especies marinas invasoras que provee guías para la toma de decisiones para los legisladores, manejadores, científicos y otros interesados. Este marco de trabajo con- Bax et al. Controlling Alien Marine Species 1235 siste en siete pasos básicos: (1) el establecimiento de la naturaleza y la magnitud del problema, (2) la delimitación de los objetivos, (3) consideración de todas las alternativas posibles, (4) determ...

Recent discoveries of obligate cave species in the tropics and in medium-sized subterranean voids provide opportunities to test hypotheses developed during pioneering work in temperate limestone caves. Most obligate cave species share similar morphological, physiological, and behavioral features, which indicates the presence of similar strong selection forces in their highly stressful subterranean environment. Major stresses include perpetual darkness and humidity, lack of important environmental cues, complex mazelike living space, stressful or even lethal gas mixtures, patchy food resources, barren rocky substrates, wet and slippery vertical surfaces, and occasional flooding. In cavernous regions the boundaries of surface species are vertical as well as linear, with abundant food resources sinking across the vertical boundary into the high-stress subterranean biome. Parsons's stress-determined species boundary model on the role of stresses in increasing phenotypic and genotypic variability at boundaries is expanded to explain how an adaptive shift could occur at such food-rich boundaries, which would allow a new population to diverge from its parent population and exploit resources in a novel environment.