- Email: [email protected]
Short-term dynamics of a neotropical forest: why ecological research matters to tropical conservation and management
144
Selected Abstracts
of species disappearances of birds and rodents is predictable based on population density in undisturbed habitat. Distance effects on species diversity are weak to nonexistent, and habitat area effects are strong. Edge effects and cumulative habitat loss following isolation of the remnants are correlated with loss of species diversity. Recolonization in these taxa occurs rarely. Rodents appear to be extremely susceptible to extinction. Small, old patches retain a predictable subset of bird and rodent species, reinforcing the principle that larger reserves are generally superior. -Authors 92Z/00008 Short-term dynamics of a neotropical forest: why ecological research matters to tropical conservation and management S. P. Hubbell & R. B. Foster, Oikos, 63(1), 1992, pp 48-61. Sustainable management of natural tropical forests is not possible without a better holistic understanding of how such forests actually work ecologically and interact with humans. Because time is short, we must learn, 'on-the-job' by conducting research as we implement management plans. The authors base their argument on experience with a large-scale study of the tropical forest on Barro Colorado Island, Panama. In the space of 5 yr, it was possible to collect essential silvics data on stocking levels, growth, yield, survival rates, and microhabitat requirements of a large fraction of the tree community of >300 native species. A program of comparable studies of representative natural and managed tropical forests at key sites throughout the tropics would rapidly improve the global fund of knowledge on which to base better decisions for the conservation and management of trepical forests. -from Authors 92Z/00009 Gene flow by pollen: implications for plant conservation genetics N.C. El]strand, Oikos, 63(1), 1992, pp 77-86. The absence of gene flow is frequently emphasized in conservation genetics, but the presence of gene flow can play an equally important role in determining the genetic fate of populations. Gene flow by pollen is often substantial among plant populations. The author reviews the expectations for gene flow patterms in the small populations typical of endangered species, then considers what role gene flow can play in plant conservation genetics. Geographically dlsjunct populations might not always be as reproductively isolated as previously thought, and thereby less vulnerable to detrimental drift-based processes. On the other hand, conspecific or heterospecific hybridization may lead to extinction by outhreeding depression or genetic assimilation. Also, the field release of transgenic plants may lead to the escape of engineered genes by crop-wild plant hybridization. Such 'genetic pollution' could have profound effects on the fitness of wild species with the potential for disrupting natural communities. -from Author 92Z/00010 Human impacts on genetic diversity in forest ecosystems F.T. Ledig, Oikos, 63(1), 1992,pp 87-108. Many human activities have impacted genetic diversity in forests (species diversity and genetic diversity within species) by their influence on the evohtionary processes of extinction, selection, drift, gene flow, and mutation, sometimes increasing diversity, as in the case of domestication, but often reducing it. Even in the absence of changes in diversity, mating systems were altered, changing the genetic structure of populations. Demographic changes (conversion of old-growth to younger, even-aged stands) influenced selection by increasing the incidence of disease. Introduction of exotic diseases, insects, mammalian herbivores, and competing vegetation has had the best-documented effects on genetic diversity, reducing both species diversity and intraspecific diversity. Deforestation has operated on a vast scale to reduce diversity by direct elimination of locally-adapted populations. Atmospheric poLlution and global warming will be a major threat in the near future, particularly because forests are fragmented and migration is impeded. Genetic inventories of indicator species can p.rovide the baselines against which to measure Changes in diversity. -from Author
92Z/00011 Human impact on plant gene pools and sampling for their conservation A. H. D. Brown, Oikos, 63(1), 1992, pp 109-118. Many human activities affect genetic structure either by markedly altering (usually decreasing) the level of genetic diversity, or by causing large changes in specific allele frequencies. The former changes are due to such stochastic evolutionary forces as reduced population size, increased migration and recombination, a n d t h e latter changes are due to systematic selection pressure. The leading examples of each are habitat destruction and environmental degradation. Interaction between stochastic and detemfinistic evolution is well displayed by introduced colonizing weeds. To combat unwanted evolutionary changes in plant population genetic structure, conservation measures should employ sampling strategies that meet both stochastic and systematic needs. -from Author 92Z/00012 Genetic conservation of world crop plants ed J. G. Hawkes, Biological Journal - Linnean Society, 43(1), 1991, pp 1-80. This volume, based on a symposium held in March 1990, jointly organised by the Linnean Society of London and the Association of Applied Biologists, sets out the more important aspects o f germplasm conservation of c.rop plants and their wild relatives, as well as the value of th~ to plant breeders and the financial and admlnistl~tive contributions needed for its effective utilization throughout the world. The eight papers explore the themes of: the importance of genetic resources m plant breeding; methods and problems of exploration and field collecting; genetic conservation in seed banks; in-vitro conservation; the use of genetic resources in breeding and breeding research; regional gene banks - cooperative ]~rogrammes; global support and coordination for conservmg germplasm of world crop species and their relatives; molecular biology and genetic conservation programmes (in which the impact of genetic engineering and molecular techniques is discussed in relation to the more conventional use of genetic resources in seed banks and in-vitro storage). -after Editor 92Z/00013 The conservation of biological diversity: using birds to set priorities J. Fj'eldsa, in: Environmental concerns, ed J.A. Hansen, (Elsevier Applied Science), 1991, pp 157-175. Only birds have been studied and charted with sufficient uniformity for a global survey of patterns of endemism. A roject compiling and analyzing current data on endemic irds, supplemented with surveys of unexplored portions of potential priority areas and consensus of judgement from other life-form experts, may become a central tool for global planning. -from Author
~
92Z/00014 Conservation genetics: techniques and fundamentals P . W . Hedrick & P. S. Miller, Ecological Applications, 2(1), 1992, pp 30-46. Conservation genetics utilizes the tools and concepts of genetics and applies them to problems in conservation biology. For example, molecular genetic techniques, such as protein electrophoresis, and analysis of mitochondrial DNA and highly variable nuclear genes (including DNA fingerprinting), have been important in documenting the extent and pattern of genettc variation in endangered species. For captive animal populations, pedigree analysis has become the basic approach to evaluate breeding priority of particular individuals. Peeling and gene dropping give the most information. The rationale for much conservation genetic interpretation is based in evolutionary genetics. The authors discuss the avoidance of inbreeding depression and the maintenance of genetic variation. Mention is made of three evolutionary topics (the relationship of heterozygosity and fitness, population bottlenecks, and outbreeding depression) that have implications for conservation genetics. -from Authors 922:/00015 Endangered species and the safe minimum standard R. C. Ready & R. C. Bishop, American Journal of Agricultural Economics, 73(2), 1991, pp 309-312.
Selected Abstracts
of species disappearances of birds and rodents is predictable based on population density in undisturbed habitat. Distance effects on species diversity are weak to nonexistent, and habitat area effects are strong. Edge effects and cumulative habitat loss following isolation of the remnants are correlated with loss of species diversity. Recolonization in these taxa occurs rarely. Rodents appear to be extremely susceptible to extinction. Small, old patches retain a predictable subset of bird and rodent species, reinforcing the principle that larger reserves are generally superior. -Authors 92Z/00008 Short-term dynamics of a neotropical forest: why ecological research matters to tropical conservation and management S. P. Hubbell & R. B. Foster, Oikos, 63(1), 1992, pp 48-61. Sustainable management of natural tropical forests is not possible without a better holistic understanding of how such forests actually work ecologically and interact with humans. Because time is short, we must learn, 'on-the-job' by conducting research as we implement management plans. The authors base their argument on experience with a large-scale study of the tropical forest on Barro Colorado Island, Panama. In the space of 5 yr, it was possible to collect essential silvics data on stocking levels, growth, yield, survival rates, and microhabitat requirements of a large fraction of the tree community of >300 native species. A program of comparable studies of representative natural and managed tropical forests at key sites throughout the tropics would rapidly improve the global fund of knowledge on which to base better decisions for the conservation and management of trepical forests. -from Authors 92Z/00009 Gene flow by pollen: implications for plant conservation genetics N.C. El]strand, Oikos, 63(1), 1992, pp 77-86. The absence of gene flow is frequently emphasized in conservation genetics, but the presence of gene flow can play an equally important role in determining the genetic fate of populations. Gene flow by pollen is often substantial among plant populations. The author reviews the expectations for gene flow patterms in the small populations typical of endangered species, then considers what role gene flow can play in plant conservation genetics. Geographically dlsjunct populations might not always be as reproductively isolated as previously thought, and thereby less vulnerable to detrimental drift-based processes. On the other hand, conspecific or heterospecific hybridization may lead to extinction by outhreeding depression or genetic assimilation. Also, the field release of transgenic plants may lead to the escape of engineered genes by crop-wild plant hybridization. Such 'genetic pollution' could have profound effects on the fitness of wild species with the potential for disrupting natural communities. -from Author 92Z/00010 Human impacts on genetic diversity in forest ecosystems F.T. Ledig, Oikos, 63(1), 1992,pp 87-108. Many human activities have impacted genetic diversity in forests (species diversity and genetic diversity within species) by their influence on the evohtionary processes of extinction, selection, drift, gene flow, and mutation, sometimes increasing diversity, as in the case of domestication, but often reducing it. Even in the absence of changes in diversity, mating systems were altered, changing the genetic structure of populations. Demographic changes (conversion of old-growth to younger, even-aged stands) influenced selection by increasing the incidence of disease. Introduction of exotic diseases, insects, mammalian herbivores, and competing vegetation has had the best-documented effects on genetic diversity, reducing both species diversity and intraspecific diversity. Deforestation has operated on a vast scale to reduce diversity by direct elimination of locally-adapted populations. Atmospheric poLlution and global warming will be a major threat in the near future, particularly because forests are fragmented and migration is impeded. Genetic inventories of indicator species can p.rovide the baselines against which to measure Changes in diversity. -from Author
92Z/00011 Human impact on plant gene pools and sampling for their conservation A. H. D. Brown, Oikos, 63(1), 1992, pp 109-118. Many human activities affect genetic structure either by markedly altering (usually decreasing) the level of genetic diversity, or by causing large changes in specific allele frequencies. The former changes are due to such stochastic evolutionary forces as reduced population size, increased migration and recombination, a n d t h e latter changes are due to systematic selection pressure. The leading examples of each are habitat destruction and environmental degradation. Interaction between stochastic and detemfinistic evolution is well displayed by introduced colonizing weeds. To combat unwanted evolutionary changes in plant population genetic structure, conservation measures should employ sampling strategies that meet both stochastic and systematic needs. -from Author 92Z/00012 Genetic conservation of world crop plants ed J. G. Hawkes, Biological Journal - Linnean Society, 43(1), 1991, pp 1-80. This volume, based on a symposium held in March 1990, jointly organised by the Linnean Society of London and the Association of Applied Biologists, sets out the more important aspects o f germplasm conservation of c.rop plants and their wild relatives, as well as the value of th~ to plant breeders and the financial and admlnistl~tive contributions needed for its effective utilization throughout the world. The eight papers explore the themes of: the importance of genetic resources m plant breeding; methods and problems of exploration and field collecting; genetic conservation in seed banks; in-vitro conservation; the use of genetic resources in breeding and breeding research; regional gene banks - cooperative ]~rogrammes; global support and coordination for conservmg germplasm of world crop species and their relatives; molecular biology and genetic conservation programmes (in which the impact of genetic engineering and molecular techniques is discussed in relation to the more conventional use of genetic resources in seed banks and in-vitro storage). -after Editor 92Z/00013 The conservation of biological diversity: using birds to set priorities J. Fj'eldsa, in: Environmental concerns, ed J.A. Hansen, (Elsevier Applied Science), 1991, pp 157-175. Only birds have been studied and charted with sufficient uniformity for a global survey of patterns of endemism. A roject compiling and analyzing current data on endemic irds, supplemented with surveys of unexplored portions of potential priority areas and consensus of judgement from other life-form experts, may become a central tool for global planning. -from Author
~
92Z/00014 Conservation genetics: techniques and fundamentals P . W . Hedrick & P. S. Miller, Ecological Applications, 2(1), 1992, pp 30-46. Conservation genetics utilizes the tools and concepts of genetics and applies them to problems in conservation biology. For example, molecular genetic techniques, such as protein electrophoresis, and analysis of mitochondrial DNA and highly variable nuclear genes (including DNA fingerprinting), have been important in documenting the extent and pattern of genettc variation in endangered species. For captive animal populations, pedigree analysis has become the basic approach to evaluate breeding priority of particular individuals. Peeling and gene dropping give the most information. The rationale for much conservation genetic interpretation is based in evolutionary genetics. The authors discuss the avoidance of inbreeding depression and the maintenance of genetic variation. Mention is made of three evolutionary topics (the relationship of heterozygosity and fitness, population bottlenecks, and outbreeding depression) that have implications for conservation genetics. -from Authors 922:/00015 Endangered species and the safe minimum standard R. C. Ready & R. C. Bishop, American Journal of Agricultural Economics, 73(2), 1991, pp 309-312.