Small population size

About: Small population size is a research topic. Over the lifetime, 1651 publications have been published within this topic receiving 73759 citations.

POPULATION GENETIC CONSEQUENCES OF SMALL POPULATION SIZE: Implications for Plant Conservation

Abstract: Although the potential genetic risks associated with rare or endangered plants and small populations have been discussed previously, the practical role of population genetics in plant conservation remains unclear. Using theory and the available data, we examine the effects of genetic drift, inbreeding, and gene flow on genetic diversity and fitness in rare plants and small populations. We identify those circumstances that are likely to put these plant species and populations at genetic risk. Warning signs that populations may be vulnerable include changes in factors such as population size, degree of isolation, and fitness. When possible, we suggest potential management strategies.

Conservation and the genetics of populations

Abstract: Authors of Guest Boxes. Preface. List of Symbols. PART I: INTRODUCTION. 1 Introduction. 1.1 Genetics and conservation. 1.2 What should we conserve?. 1.3 How should we conserve biodiversity?. 1.4 Applications of genetics to conservation. Guest Box 1 by L. S. Mills and M. E. Soule: The role of genetics in conservation. 2 Phenotypic Variation in Natural Populations. 2.1 Color pattern. 2.2 Morphology. 2.3 Behavior. 2.4 Differences among populations. Guest Box 2 by C. J. Foote: Looks can be deceiving: countergradient variation in secondary sexual color in sympatric morphs of sockeye salmon. 3 Genetic Variation in Natural Populations: Chromosomes and Proteins. 3.1 Chromosomes. 3.2 Protein electrophoresis. 3.3 Genetic variation within populations. 3.4 Genetic divergence among populations. 3.5 Strengths and limitations of protein electrophoresis. Guest Box 3 by A. Young and B. G. Murray: Management implications of polploidy in a cytologically complex self-incompatible herb. 4 Genetic Variation in Natural Populations: DNA. 4.1 Mitochondrial and chloroplast DNA. 4.2 Single copy nuclear loci. 4.3 Multilocus techniques. 4.4 Sex-linked markers. 4.5 DNA sequences. 4.6 Additional techniques and the future. 4.7 Genetic variation in natural populations. Guest Box 4 by N. N. FitzSimmons: Multiple markers uncover marine turtle behavior. PART II: MECHANISMS OF EVOLUTIONARY CHANGE. 5 Random Mating Populations: Hardy-Weinberg Principle. 5.1 The Hardy-Weinberg principle. 5.2 Hardy-Weinberg proportions. 5.3 Testing for Hardy-Weinberg proportions. 5.4 Estimation of allele frequencies. 5.5 Sex-linked loci. 5.6 Estimation of genetic variation. Guest Box 5 by V. Castric and L. Bernatchez: Testing alternative explanations for deficiencies of heterozygotes in populations of brook trout in small lakes. 6 Small Populations and Genetic Drift. 6.1 Genetic drift. 6.2 Changes in allele frequency. 6.3 Loss of genetic variation: the inbreeding effect of small populations. 6.4 Loss of allelic diversity. 6.5 Founder effect. 6.6 Genotypic proportions in small populations. 6.7 Fitness effects of genetic drift. Guest Box 6 by P. L. Leberg and D. L. Rogowski: The inbreeding effect of small population size reduces population growth rate in mosquitofish. 7 Effective Population Size. 7.1 Concept of effective population size. 7.2 Unequal sex ratio. 7.3 Nonrandom number of progeny. 7.4 Fluctuating population size. 7.5 Overlapping generations. 7.6 Variance effective population size. 7.7 Cytoplasmic genes. 7.8 Gene genealogies and lineage sorting. 7.9 Limitations of effective population size. 7.10 Effective population size in natural populations. Guest Box 7 by C. R. Miller and L. P. Waits: Estimation of effective population size in Yellowstone grizzly bears. 8 Natural Selection. 8.1 Fitness. 8.2 Single locus with two alleles. 8.3 Multiple alleles. 8.4 Frequency-dependent selection. 8.5 Natural selection in small populations. 8.6 Natural selection and conservation. Guest Box 8 by C. A. Stockwell and M. L. Collyer: Rapid adaptation and conservation. 9 Population Subdivision. 9.1 F-statistics. 9.2 Complete isolation. 9.3 Gene flow. 9.4 Gene flow and genetic drift. 9.5 Cytoplasmic genes and sex-linked markers. 9.6 Gene flow and natural selection. 9.7 Limitations of FST and other measures of subdivision. 9.8 Estimation of gene flow. 9.9 Population subdivision and conservation. Guest Box 9 by C. S. Baker and F. B. Pichler: Hector's dolphin population structure and conservation. 10 Multiple Loci. 10.1 Gametic disequilibrium. 10.2 Small population size. 10.3 Natural selection. 10.4 Population subdivision. 10.5 Hybridization. 10.6 Estimation of gametic disequilibrium. Guest Box 10 by S. H. Forbes: Dating hybrid populations using gametic disequilibrium. 11 Quantitative Genetics. 11.1 Heritability. 11.2 Selection on quantitative traits. 11.3 Quantitative trait loci (QTLs). 11.4 Genetic drift and bottlenecks. 11.5 Divergence among populations (QST). 11.6 Quantitative genetics and conservation. Guest Box 11 by D. W. Coltman: Response to trophy hunting in bighorn sheep. 12 Mutation. 12.1 Process of mutation. 12.2 Selectively neutral mutations. 12.3 Harmful mutations. 12.4 Advantageous mutations. 12.5. Recovery from a bottleneck. Guest Box 12 by M. W. Nachman: Color evolution via different mutations in pocket mice. PART III: GENETICS AND CONSERVATION. 13 Inbreeding Depression. 13.1 Pedigree analysis. 13.2 Gene drop analysis. 13.3 Estimation of F and relatedness with molecular markers. 13.4 Causes of inbreeding depression. 13.5 Measurement of inbreeding depression. 13.6 Genetic load and purging. Guest Box 13 by R. C. Lacy: Understanding inbreeding depression: 20 years of experiments with Peromyscus mice. 14 Demography and Extinction. 14.1 Estimation of population size. 14.2 Inbreeding depression and extinction. 14.3 Population viability analysis. 14.4 Loss of phenotypic variation. 14.5 Loss of evolutionary potential. 14.6 Mitochondrial DNA. 14.7 Mutational meltdown. 14.8 Long-term persistence. 14.9 The 50/500 rule. Guest Box 14 by A. C. Taylor: Noninvasive population size estimation in wombats. 15 Metapopulations and Fragmentation. 15.1 The metapopulation concept. 15.2 Genetic variation in metapopulations. 15.3 Effective population size. 15.4 Population divergence and fragmentation. 15.5 Genetic rescue. 15.6 Long-term population viability. Guest Box 15 by R. C. Vrijenhoek: Fitness loss and genetic rescue in stream-dwelling topminnows. 16 Units of Conservation. 16.1 What should we try to protect?. 16.2 Systematics and taxonomy. 16.3 Phylogeny reconstruction. 16.4 Description of genetic relationships within species. 16.5 Units of conservation. 16.6 Integrating genetic, phenotypic, and environmental information. Guest Box 16 by R. S. Waples: Identifying conservation units in Pacific salmon. 17 Hybridization. 17.1 Natural hybridization. 17.2 Anthropogenic hybridization. 17.3 Fitness consequences of hybridization. 17.4 Detecting and describing hybridization. 17.5 Hybridization and conservation. Guest Box 17 by L. H. Rieseberg: Hybridization and the conservation of plants. 18 Conservation Breeding and Restoration. 18.1 The role of conservation breeding. 18.2 Reproductive technologies and genome banking. 18.3 Founding populations for conservation breeding programs. 18.4 Genetic drift in captive populations. 18.5 Natural selection and adaptation to captivity. 18.6 Genetic management of conservation breeding programs. 18.7 Supportive breeding. 18.8 Reintroductions and translocations. Guest Box 18 by J. V. Briskie: Effects of population bottlenecks on introduced species of birds. 19 Invasive Species. 19.1 Why are invasive species so successful?. 19.2 Genetic analysis of introduced species. 19.3 Establishment and spread of invasive species. 19.4 Hybridization as a stimulus for invasiveness. 19.5 Eradication, management, and control. Guest Box 19 by J. L. Maron: Rapid adaptation of invasive populations of St John's Wort. 20 Forensic and Management Applications of Genetic Identification. 20.1 Species identification. 20.2 Individual identification and probability of identity. 20.3 Parentage testing. 20.4 Sex identification. 20.5 Population assignment. 20.6 Population composition analysis. Guest Box 20 by L. P. Waits: Microsatellite DNA genotyping identifies problem bear and cubs. Glossary. Appendix: Probability and Statistics. Guest Box A by J. F. Crow: Is mathematics necessary?. References. Index

Edge Effects and the Extinction of Populations Inside Protected Areas

Abstract: Theory predicts that small populations may be driven to extinction by random fluctuations in demography and loss of genetic diversity through drift. However, population size is a poor predictor of extinction in large carnivores inhabiting protected areas. Conflict with people on reserve borders is the major cause of mortality in such populations, so that border areas represent population sinks. The species most likely to disappear from small reserves are those that range widely-and are therefore most exposed to threats on reserve borders-irrespective of population size. Conservation efforts that combat only stochastic processes are therefore unlikely to avert extinction.

Relationship of genetic variation to population size in wildlife

Abstract: Genetic diversity is one of three levels of biological diversity requiring conservation. Genetic theory predicts that levels of genetic variation should increase with effective population size. Sould (19 76) compiled the first convincing evidence that levels of genetic variation in wildlife were related to population size, but this issue remains controversial. The hypothesis that genetic variation is related to population size leads to the following predictions: (1) genetic variation within species should be related to population size; (2) genetic variation within species should be related to island size; (3) genetic variation should be related to population size within taxonomic groups; (4) widespread species should have more genetic variation than restricted spe- cies; (5) genetic variation in animals should be negatively correlated with body size; (6) genetic variation should be negatively correlated with rate of chromosome evolution; (7) genetic variation across species should be related to population size; (8) vertebrates should have less genetic variation than invertebrates or plants; (9) island populations should have less genetic variation than mainland populations; and (10) en- dangered species should have less genetic variation than nonendangered species. Empirical observations sup- port all these hypotheses. There can be no doubt that genetic variation is related to population size, as Sould proposed. Small population size reduces the evolutionary potential of wildlife species.