Franck Courchamp, Luděk Berec, and Joanna Gascoigne
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780198570301
- eISBN:
- 9780191717642
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198570301.003.0004
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter focuses on Allee effects in relation to genetics and evolution. These topics intersect in four different ways. First, genetics creates its own set of Allee effect mechanisms (e.g., via ...
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This chapter focuses on Allee effects in relation to genetics and evolution. These topics intersect in four different ways. First, genetics creates its own set of Allee effect mechanisms (e.g., via inbreeding depression). Second, there may be genetic differences among members of a population in their susceptibility to ecological Allee effects. Third, Allee effects are considered in the light of evolution — have populations evolved mechanisms to avoid Allee effects, and if so, how is it possible to find anything other than the ‘ghosts of Allee effects past’ in modern populations? Finally, Allee effects themselves may act as a selection pressure, and members of populations subject to Allee effects may thus evolve different characteristics as compared with those bounded only by negative density dependence. The chapter considers all these four issues in turn.Less
This chapter focuses on Allee effects in relation to genetics and evolution. These topics intersect in four different ways. First, genetics creates its own set of Allee effect mechanisms (e.g., via inbreeding depression). Second, there may be genetic differences among members of a population in their susceptibility to ecological Allee effects. Third, Allee effects are considered in the light of evolution — have populations evolved mechanisms to avoid Allee effects, and if so, how is it possible to find anything other than the ‘ghosts of Allee effects past’ in modern populations? Finally, Allee effects themselves may act as a selection pressure, and members of populations subject to Allee effects may thus evolve different characteristics as compared with those bounded only by negative density dependence. The chapter considers all these four issues in turn.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780198783398
- eISBN:
- 9780191826313
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783398.003.0003
- Subject:
- Biology, Biodiversity / Conservation Biology
The harmful impacts of inbreeding are generally greater in species that naturally outbreed compared to those in inbreeding species, greater in stressful than benign environments, greater for fitness ...
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The harmful impacts of inbreeding are generally greater in species that naturally outbreed compared to those in inbreeding species, greater in stressful than benign environments, greater for fitness than peripheral traits, and greater for total fitness compared to its individual components. Inbreeding reduces survival and reproduction (i.e., it causes inbreeding depression), and thereby increases the risk of extinction. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Natural selection may remove (purge) the alleles that cause inbreeding depression, especially following inbreeding or population bottlenecks, but it has limited effects in small populations and usually does not completely eliminate inbreeding depression. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies.Less
The harmful impacts of inbreeding are generally greater in species that naturally outbreed compared to those in inbreeding species, greater in stressful than benign environments, greater for fitness than peripheral traits, and greater for total fitness compared to its individual components. Inbreeding reduces survival and reproduction (i.e., it causes inbreeding depression), and thereby increases the risk of extinction. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Natural selection may remove (purge) the alleles that cause inbreeding depression, especially following inbreeding or population bottlenecks, but it has limited effects in small populations and usually does not completely eliminate inbreeding depression. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies.
John C. Avise
- Published in print:
- 2008
- Published Online:
- January 2009
- ISBN:
- 9780195369670
- eISBN:
- 9780199871063
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195369670.003.0006
- Subject:
- Biology, Evolutionary Biology / Genetics
Habitual self-fertilization by hermaphroditic individuals is a sexual route by which genetically identical individuals can arise. The phenomenon occurs in various plants and invertebrates but is ...
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Habitual self-fertilization by hermaphroditic individuals is a sexual route by which genetically identical individuals can arise. The phenomenon occurs in various plants and invertebrates but is known in only one vertebrate species: the mangrove killifish. Selfing is an extreme form of inbreeding (even less severe cases of which often result in inbreeding depression), and for this and other reasons constitutive self-fertilization is rare in the biological world. Instead, most selfing species also outcross occasionally, and thus have a mixed mating system. Habitual selfers nevertheless have some special adaptive advantages not shared by their sexual counterparts. This chapter compares population-genetic and ecological features of mangrove killifish with those of analogous plants and invertebrate animals that likewise have mixed-mating systems. Such species probably gain the best of two worlds by capitalizing jointly on the short-term advantages of selfing (fertilization assurance, and the propagation of fit “clonal” genoypes) and also the long-term as well as short-term advantages of outcrossing (genetic health and adaptability).Less
Habitual self-fertilization by hermaphroditic individuals is a sexual route by which genetically identical individuals can arise. The phenomenon occurs in various plants and invertebrates but is known in only one vertebrate species: the mangrove killifish. Selfing is an extreme form of inbreeding (even less severe cases of which often result in inbreeding depression), and for this and other reasons constitutive self-fertilization is rare in the biological world. Instead, most selfing species also outcross occasionally, and thus have a mixed mating system. Habitual selfers nevertheless have some special adaptive advantages not shared by their sexual counterparts. This chapter compares population-genetic and ecological features of mangrove killifish with those of analogous plants and invertebrate animals that likewise have mixed-mating systems. Such species probably gain the best of two worlds by capitalizing jointly on the short-term advantages of selfing (fertilization assurance, and the propagation of fit “clonal” genoypes) and also the long-term as well as short-term advantages of outcrossing (genetic health and adaptability).
Bruce Walsh and Michael Lynch
- Published in print:
- 2018
- Published Online:
- September 2018
- ISBN:
- 9780198830870
- eISBN:
- 9780191868986
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198830870.003.0023
- Subject:
- Biology, Evolutionary Biology / Genetics, Biochemistry / Molecular Biology
When dominance is presence, the selection response equations under inbreeding can become rather complex, they require additional variance components beyond the additive-genetic variance. Further, ...
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When dominance is presence, the selection response equations under inbreeding can become rather complex, they require additional variance components beyond the additive-genetic variance. Further, both transient and permanent components of response can arise. This chapter examines the theory of both the covariance of relatives under general inbreeding, as well as the expected selection response under inbreeding. Due to the decrease in the effective recombination rate under selfing, the Bulmer effect can be rather dramatic, as any linkage disequilibrium generated by selection is only weakly removed by recombination. Finally, this chapter also examines the evolutionary forces that interact to determine the selfing rate for a given population.Less
When dominance is presence, the selection response equations under inbreeding can become rather complex, they require additional variance components beyond the additive-genetic variance. Further, both transient and permanent components of response can arise. This chapter examines the theory of both the covariance of relatives under general inbreeding, as well as the expected selection response under inbreeding. Due to the decrease in the effective recombination rate under selfing, the Bulmer effect can be rather dramatic, as any linkage disequilibrium generated by selection is only weakly removed by recombination. Finally, this chapter also examines the evolutionary forces that interact to determine the selfing rate for a given population.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2019
- Published Online:
- November 2019
- ISBN:
- 9780198783411
- eISBN:
- 9780191826337
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783411.003.0003
- Subject:
- Biology, Biodiversity / Conservation Biology, Evolutionary Biology / Genetics
Inbreeding reduces survival and reproduction (i.e. it causes inbreeding depression), and thereby increases extinction risk. Inbreeding depression is due to increased homozygosity for harmful alleles ...
More
Inbreeding reduces survival and reproduction (i.e. it causes inbreeding depression), and thereby increases extinction risk. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies. Impacts of inbreeding are generally greater in species that naturally outbreed than those that inbreed, in stressful than benign environments, and for fitness than peripheral traits. Harmful effects accumulate across the life cycle, resulting in devastating effects on total fitness in outbreeding species.Species face ubiquitous environmental change and must adapt or they will go extinct. Genetic diversity is the raw material required for evolutionary adaptation. However, loss of genetic diversity is unavoidable in small isolated populations, diminishing their capacity to evolve in response to environmental changes, and thereby increasing extinction risk.Less
Inbreeding reduces survival and reproduction (i.e. it causes inbreeding depression), and thereby increases extinction risk. Inbreeding depression is due to increased homozygosity for harmful alleles and at loci exhibiting heterozygote advantage. Inbreeding depression is nearly universal in sexually reproducing organisms that are diploid or have higher ploidies. Impacts of inbreeding are generally greater in species that naturally outbreed than those that inbreed, in stressful than benign environments, and for fitness than peripheral traits. Harmful effects accumulate across the life cycle, resulting in devastating effects on total fitness in outbreeding species.Species face ubiquitous environmental change and must adapt or they will go extinct. Genetic diversity is the raw material required for evolutionary adaptation. However, loss of genetic diversity is unavoidable in small isolated populations, diminishing their capacity to evolve in response to environmental changes, and thereby increasing extinction risk.
Matthew E. Wolak and Lukas F. Keller
- Published in print:
- 2014
- Published Online:
- August 2014
- ISBN:
- 9780199674237
- eISBN:
- 9780191779275
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199674237.003.0007
- Subject:
- Biology, Evolutionary Biology / Genetics, Ecology
It is assumed that dominance genetic variance contributes little to the prediction of evolutionary change in polygenic traits. This is based on the assumption that populations are large, panmictic, ...
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It is assumed that dominance genetic variance contributes little to the prediction of evolutionary change in polygenic traits. This is based on the assumption that populations are large, panmictic, and randomly mating. However, the ecological contexts of most wild populations studied to date violate one, if not several, of these assumptions, and the widespread occurrence of inbreeding and inbreeding depression of phenotypic traits and fitness suggests dominance genetic effects are ubiquitous. This chapter reviews what genetic dominance represents at the level of a single locus and how this contributes to phenotypic variation and discusses how to estimate dominance variance with emphasis on the complications arising in wild populations and with inbreeding. Next, empirical estimates of dominance variance are reviewed. Since no estimates exist of dominance variance in the wild (except for humans), laboratory and agricultural populations are examined, and it is shown that dominance variance is a major contributor to phenotypic variation and in some cases contributes as much as additive genetic variance. This chapter also discusses how inbreeding and dominance affect predictions of evolutionary change, and ends with a review of some of the empirical questions for which genetic dominance is an important quantity in its own right. In this chapter, it is argued that dominance variance has been ignored for too long, may hamper the ability to predict evolutionary change, can be a major contributor to phenotypic variance, is interesting to study in its own right, and provides many avenues of research to be addressed by empirical study.Less
It is assumed that dominance genetic variance contributes little to the prediction of evolutionary change in polygenic traits. This is based on the assumption that populations are large, panmictic, and randomly mating. However, the ecological contexts of most wild populations studied to date violate one, if not several, of these assumptions, and the widespread occurrence of inbreeding and inbreeding depression of phenotypic traits and fitness suggests dominance genetic effects are ubiquitous. This chapter reviews what genetic dominance represents at the level of a single locus and how this contributes to phenotypic variation and discusses how to estimate dominance variance with emphasis on the complications arising in wild populations and with inbreeding. Next, empirical estimates of dominance variance are reviewed. Since no estimates exist of dominance variance in the wild (except for humans), laboratory and agricultural populations are examined, and it is shown that dominance variance is a major contributor to phenotypic variation and in some cases contributes as much as additive genetic variance. This chapter also discusses how inbreeding and dominance affect predictions of evolutionary change, and ends with a review of some of the empirical questions for which genetic dominance is an important quantity in its own right. In this chapter, it is argued that dominance variance has been ignored for too long, may hamper the ability to predict evolutionary change, can be a major contributor to phenotypic variance, is interesting to study in its own right, and provides many avenues of research to be addressed by empirical study.
Corey J. A. Bradshaw and Barry W. Brook
- Published in print:
- 2010
- Published Online:
- February 2010
- ISBN:
- 9780199554232
- eISBN:
- 9780191720666
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199554232.003.0017
- Subject:
- Biology, Ecology, Biodiversity / Conservation Biology
In this chapter, Corey J. A. Bradshaw and Barry W. Brook, discuss measures of biodiversity patterns followed by an overview of experimental design and associated statistical paradigms. Conservation ...
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In this chapter, Corey J. A. Bradshaw and Barry W. Brook, discuss measures of biodiversity patterns followed by an overview of experimental design and associated statistical paradigms. Conservation biology is a highly multidisciplinary science employing methods from ecology, Earth systems science, genetics, physiology, veterinary science, medicine, mathematics, climatology, anthropology, psychology, sociology, environmental policy, geography, political science, and resource management. Here we focus primarily on ecological methods and experimental design. It is impossible to census all species in an ecosystem, so many different measures exist to compare biodiversity: these include indices such as species richness, Simpson's diversity, Shannon's index and Brouillin's index. Many variants of these indices exist. The scale of biodiversity patterns is important to consider for biodiversity comparisons: α (local), β (between‐site), and γ (regional or continental) diversity. Often surrogate species ‐ the number, distribution or pattern of species in a particular taxon in a particular area thought to indicate a much wider array of taxa ‐ are required to simplify biodiversity assessments. Many similarity, dissimilarity, clustering, and multivariate techniques are available to compare biodiversity indices among sites. Conservation biology rarely uses completely manipulative experimental designs (although there are exceptions), with mensurative (based on existing environmental gradients) and observational studies dominating. Two main statistical paradigms exist for comparing biodiversity: null hypothesis testing and multiple working hypotheses – the latter paradigm is more consistent with the constraints typical of conservation data and so should be invoked when possible. Bayesian inferential methods generally provide more certainty when prior data exist. Large sample sizes, appropriate replication and randomization are cornerstone concepts in all conservation experiments. Simple relative abundance time series (sequential counts of individuals) can be used to infer more complex ecological mechanisms that permit the estimation of extinction risk, population trends, and intrinsic feedbacks. The risk of a species going extinct or becoming invasive can be predicted using cross‐taxonomic comparisons of life history traits. Population viability analyses are essential tools to estimate extinction risk over defined periods and under particular management interventions. Many methods exist to implement these, including count‐based, demographic, metapopulation, and genetic. Many tools exist to examine how genetics affects extinction risk, of which perhaps the measurement of inbreeding depression, gene flow among populations, and the loss of genetic diversity with habitat degradation are the most important.Less
In this chapter, Corey J. A. Bradshaw and Barry W. Brook, discuss measures of biodiversity patterns followed by an overview of experimental design and associated statistical paradigms. Conservation biology is a highly multidisciplinary science employing methods from ecology, Earth systems science, genetics, physiology, veterinary science, medicine, mathematics, climatology, anthropology, psychology, sociology, environmental policy, geography, political science, and resource management. Here we focus primarily on ecological methods and experimental design. It is impossible to census all species in an ecosystem, so many different measures exist to compare biodiversity: these include indices such as species richness, Simpson's diversity, Shannon's index and Brouillin's index. Many variants of these indices exist. The scale of biodiversity patterns is important to consider for biodiversity comparisons: α (local), β (between‐site), and γ (regional or continental) diversity. Often surrogate species ‐ the number, distribution or pattern of species in a particular taxon in a particular area thought to indicate a much wider array of taxa ‐ are required to simplify biodiversity assessments. Many similarity, dissimilarity, clustering, and multivariate techniques are available to compare biodiversity indices among sites. Conservation biology rarely uses completely manipulative experimental designs (although there are exceptions), with mensurative (based on existing environmental gradients) and observational studies dominating. Two main statistical paradigms exist for comparing biodiversity: null hypothesis testing and multiple working hypotheses – the latter paradigm is more consistent with the constraints typical of conservation data and so should be invoked when possible. Bayesian inferential methods generally provide more certainty when prior data exist. Large sample sizes, appropriate replication and randomization are cornerstone concepts in all conservation experiments. Simple relative abundance time series (sequential counts of individuals) can be used to infer more complex ecological mechanisms that permit the estimation of extinction risk, population trends, and intrinsic feedbacks. The risk of a species going extinct or becoming invasive can be predicted using cross‐taxonomic comparisons of life history traits. Population viability analyses are essential tools to estimate extinction risk over defined periods and under particular management interventions. Many methods exist to implement these, including count‐based, demographic, metapopulation, and genetic. Many tools exist to examine how genetics affects extinction risk, of which perhaps the measurement of inbreeding depression, gene flow among populations, and the loss of genetic diversity with habitat degradation are the most important.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780198783398
- eISBN:
- 9780191826313
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783398.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation ...
More
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation increases, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding and reduced fitness inevitable consequences for many species. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow into them from another population within the species, but this is very rarely done. This novel and authoritative book addresses the issues involved in genetic management of fragmented animal and plant populations, including inbreeding depression, loss of genetic diversity and elevated extinction risk in small isolated populations, augmentation of gene flow, genetic rescue, causes of outbreeding depression and predicting its occurrence, desirability and implementation of genetic translocations to cope with climate change, and defining and diagnosing species for conservation purposes.Less
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of animal and plant populations decrease and fragmentation increases, loss of genetic diversity reduces their ability to adapt to changes in the environment, with inbreeding and reduced fitness inevitable consequences for many species. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow into them from another population within the species, but this is very rarely done. This novel and authoritative book addresses the issues involved in genetic management of fragmented animal and plant populations, including inbreeding depression, loss of genetic diversity and elevated extinction risk in small isolated populations, augmentation of gene flow, genetic rescue, causes of outbreeding depression and predicting its occurrence, desirability and implementation of genetic translocations to cope with climate change, and defining and diagnosing species for conservation purposes.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2019
- Published Online:
- November 2019
- ISBN:
- 9780198783411
- eISBN:
- 9780191826337
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783411.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology, Evolutionary Biology / Genetics
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of wild animal and plant populations decreases and ...
More
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of wild animal and plant populations decreases and fragmentation increases, inbreeding reduces fitness and loss of genetic diversity reduces their ability to adapt to changes in the environment. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow from another population within the species, but this is very rarely done. This book provides a practical guide to the genetic management of fragmented animal and plant populations.Less
The biological diversity of the planet is being rapidly depleted due to the direct and indirect consequences of human activity. As the size of wild animal and plant populations decreases and fragmentation increases, inbreeding reduces fitness and loss of genetic diversity reduces their ability to adapt to changes in the environment. Many small isolated populations are going extinct unnecessarily. In many cases, such populations can be genetically rescued by gene flow from another population within the species, but this is very rarely done. This book provides a practical guide to the genetic management of fragmented animal and plant populations.
Sandra H. Anderson, Dave Kelly, Alastair W. Robertson, and Jenny J. Ladley
- Published in print:
- 2016
- Published Online:
- September 2019
- ISBN:
- 9780226382463
- eISBN:
- 9780226382777
- Item type:
- chapter
- Publisher:
- University of Chicago Press
- DOI:
- 10.7208/chicago/9780226382777.003.0004
- Subject:
- Biology, Biodiversity / Conservation Biology
Avian pollination is thought to be less prevalent and less at risk than avian seed-dispersal. The extent of recently revealed bird pollination that does not conform to the classic ...
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Avian pollination is thought to be less prevalent and less at risk than avian seed-dispersal. The extent of recently revealed bird pollination that does not conform to the classic ornithophily-nectarivore template suggests this mutualism may be cryptic and more prevalent than considered to date. Widespread anthropogenic disturbance has disproportionately impacted the connections between birds and flowers, so that bird pollination may be systematically under-reported. Evidence suggests that where plants are visited by more than one pollinator guild, the relative effectiveness of birds is high compared to invertebrates. In the absence of replacement, the loss of bird pollinators has resulted in pollination failure, increased inbreeding depression, and decreased plant density. Confirmation of seed limitation in pollen-limited plants serviced by birds provides a precautionary sign of the possible long term effects of bird pollinator loss. The quality of pollination service provided by birds has important consequences for gene flow and offspring survival. Pollen limitation experiments suggest that bird-pollinated plants in New Zealand, the Americas, Southeast Asia, and Africa suffer similar levels of pollen limitation, and are typically more strongly pollen-limited than insect-pollinated plants. Thus, bird-pollination appears to be under-reported, hard to replace and at greater risk of failure than currently assumed.Less
Avian pollination is thought to be less prevalent and less at risk than avian seed-dispersal. The extent of recently revealed bird pollination that does not conform to the classic ornithophily-nectarivore template suggests this mutualism may be cryptic and more prevalent than considered to date. Widespread anthropogenic disturbance has disproportionately impacted the connections between birds and flowers, so that bird pollination may be systematically under-reported. Evidence suggests that where plants are visited by more than one pollinator guild, the relative effectiveness of birds is high compared to invertebrates. In the absence of replacement, the loss of bird pollinators has resulted in pollination failure, increased inbreeding depression, and decreased plant density. Confirmation of seed limitation in pollen-limited plants serviced by birds provides a precautionary sign of the possible long term effects of bird pollinator loss. The quality of pollination service provided by birds has important consequences for gene flow and offspring survival. Pollen limitation experiments suggest that bird-pollinated plants in New Zealand, the Americas, Southeast Asia, and Africa suffer similar levels of pollen limitation, and are typically more strongly pollen-limited than insect-pollinated plants. Thus, bird-pollination appears to be under-reported, hard to replace and at greater risk of failure than currently assumed.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2017
- Published Online:
- September 2017
- ISBN:
- 9780198783398
- eISBN:
- 9780191826313
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783398.003.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small ...
More
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small isolated populations that are potentially suffering from inbreeding and loss of genetic diversity (genetic erosion), leading to elevated extinction risk. Fortunately, genetic deterioration can usually be remedied by augmenting gene flow (crossing between populations within species), yet this is rarely done, in part because of fears that crossing may be harmful (but it is possible to predict when this will occur). Benefits and risks of genetic problems are sometimes altered in species with diverse mating systems and modes of inheritance. Adequate genetic management depends on appropriate delineation of species. We address management of gene flow between previously isolated populations and genetic management under global climate change.Less
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small isolated populations that are potentially suffering from inbreeding and loss of genetic diversity (genetic erosion), leading to elevated extinction risk. Fortunately, genetic deterioration can usually be remedied by augmenting gene flow (crossing between populations within species), yet this is rarely done, in part because of fears that crossing may be harmful (but it is possible to predict when this will occur). Benefits and risks of genetic problems are sometimes altered in species with diverse mating systems and modes of inheritance. Adequate genetic management depends on appropriate delineation of species. We address management of gene flow between previously isolated populations and genetic management under global climate change.
Richard Frankham, Jonathan D. Ballou, Katherine Ralls, Mark D. B. Eldridge, Michele R. Dudash, Charles B. Fenster, Robert C. Lacy, and Paul Sunnucks
- Published in print:
- 2019
- Published Online:
- November 2019
- ISBN:
- 9780198783411
- eISBN:
- 9780191826337
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198783411.003.0001
- Subject:
- Biology, Biodiversity / Conservation Biology, Evolutionary Biology / Genetics
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small ...
More
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small isolated populations that are potentially suffering from inbreeding and loss of genetic diversity (genetic erosion), leading to elevated extinction risk. Fortunately, genetic deterioration can usually be remedied by gene flow from another population (crossing between populations within species), yet this is rarely done, in part because of fears that crossing may be harmful (but we can predict when this will occur). We address management of gene flow between previously isolated populations and genetic management under global climate change.Less
Genetic management of fragmented populations is one of the major, largely unaddressed issues in biodiversity conservation. Many species across the planet have fragmented distributions with small isolated populations that are potentially suffering from inbreeding and loss of genetic diversity (genetic erosion), leading to elevated extinction risk. Fortunately, genetic deterioration can usually be remedied by gene flow from another population (crossing between populations within species), yet this is rarely done, in part because of fears that crossing may be harmful (but we can predict when this will occur). We address management of gene flow between previously isolated populations and genetic management under global climate change.
Liz Pásztor, Zoltán Botta-Dukát, Gabriella Magyar, Tamás Czárán, and Géza Meszéna
- Published in print:
- 2016
- Published Online:
- August 2016
- ISBN:
- 9780199577859
- eISBN:
- 9780191823787
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199577859.003.0011
- Subject:
- Biology, Ecology
The inherent stochastic nature of individual life histories implies that finite populations always carry a risk of going extinct, even if their long-term growth potential is positive. The ...
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The inherent stochastic nature of individual life histories implies that finite populations always carry a risk of going extinct, even if their long-term growth potential is positive. The consequences of demographic stochasticity are explored in this chapter, using individual-based computer simulations and simple discrete- and continuous-state stochastic models (branching processes and diffusion models). Simple examples of population viability analysis (PVA) are presented. Demographic stochasticity on the allele level is genetic drift—which leads to reduced viability and evolutionary potential of small populations via inbreeding depression. The ecological pendant of genetic drift is in the focus of the ‘ecological neutral theory’ of Hubbell. Some conceptual and methodological problems of the neutral theory in the context of species abundance distributions are discussed at the end of the chapter.Less
The inherent stochastic nature of individual life histories implies that finite populations always carry a risk of going extinct, even if their long-term growth potential is positive. The consequences of demographic stochasticity are explored in this chapter, using individual-based computer simulations and simple discrete- and continuous-state stochastic models (branching processes and diffusion models). Simple examples of population viability analysis (PVA) are presented. Demographic stochasticity on the allele level is genetic drift—which leads to reduced viability and evolutionary potential of small populations via inbreeding depression. The ecological pendant of genetic drift is in the focus of the ‘ecological neutral theory’ of Hubbell. Some conceptual and methodological problems of the neutral theory in the context of species abundance distributions are discussed at the end of the chapter.
Dietland Müller-Schwarze
- Published in print:
- 2011
- Published Online:
- August 2016
- ISBN:
- 9780801450105
- eISBN:
- 9780801460869
- Item type:
- chapter
- Publisher:
- Cornell University Press
- DOI:
- 10.7591/cornell/9780801450105.003.0012
- Subject:
- Biology, Animal Behavior / Behavioral Ecology
This chapter provides an overview of beaver dispersal. There are a number of reasons why beavers have to disperse from their native family. As a relatively long-lived species, beavers produce 3–4 ...
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This chapter provides an overview of beaver dispersal. There are a number of reasons why beavers have to disperse from their native family. As a relatively long-lived species, beavers produce 3–4 newborns every year. If the young stay with their parents and siblings, the colony would grow huge in a few years and soon outstrip its food resources. More importantly, grown-up offpring must find mates to start reproducing themselves. Mating with close relatives would often result in disastrous genetic defects, a phenomenon called inbreeding depression. This chapter discusses the risks that come with dispersal and explains how natural dispersal differs from translocation and homing. It also considers the age at which beavers usually leave their family, along with the timing, direction, distance, and duration of dispersal.Less
This chapter provides an overview of beaver dispersal. There are a number of reasons why beavers have to disperse from their native family. As a relatively long-lived species, beavers produce 3–4 newborns every year. If the young stay with their parents and siblings, the colony would grow huge in a few years and soon outstrip its food resources. More importantly, grown-up offpring must find mates to start reproducing themselves. Mating with close relatives would often result in disastrous genetic defects, a phenomenon called inbreeding depression. This chapter discusses the risks that come with dispersal and explains how natural dispersal differs from translocation and homing. It also considers the age at which beavers usually leave their family, along with the timing, direction, distance, and duration of dispersal.
