scholarly journals Reducing the Extinction Risk of Populations Threatened by Infectious Diseases

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 63
Author(s):  
Gael L. Glassock ◽  
Catherine E. Grueber ◽  
Katherine Belov ◽  
Carolyn J. Hogg
Keyword(s):  
Gene Flow ◽  
Infectious Diseases ◽  
Extinction Risk ◽  
Population Decline ◽  
Outbreeding Depression ◽  
Tasmanian Devil ◽  
Adaptive Potential ◽  
Genetic Management ◽  
Animal Populations ◽  
Devil Facial Tumour Disease

Extinction risk is increasing for a range of species due to a variety of threats, including disease. Emerging infectious diseases can cause severe declines in wild animal populations, increasing population fragmentation and reducing gene flow. Small, isolated, host populations may lose adaptive potential and become more susceptible to extinction due to other threats. Management of the genetic consequences of disease-induced population decline is often necessary. Whilst disease threats need to be addressed, they can be difficult to mitigate. Actions implemented to conserve the Tasmanian devil (Sarcophilus harrisii), which has suffered decline to the deadly devil facial tumour disease (DFTD), exemplify how genetic management can be used to reduce extinction risk in populations threatened by disease. Supplementation is an emerging conservation technique that may benefit populations threatened by disease by enabling gene flow and conserving their adaptive potential through genetic restoration. Other candidate species may benefit from genetic management via supplementation but concerns regarding outbreeding depression may prevent widespread incorporation of this technique into wildlife disease management. However, existing knowledge can be used to identify populations that would benefit from supplementation where risk of outbreeding depression is low. For populations threatened by disease and, in situations where disease eradication is not an option, wildlife managers should consider genetic management to buffer the host species against inbreeding and loss of genetic diversity.

Genetic Management of Fragmented Animal and Plant Populations

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Biological Diversity ◽  
Extinction Risk ◽  
Outbreeding Depression ◽  
Genetic Rescue ◽  
Isolated Populations ◽  
Genetic Management ◽  
Plant Populations ◽  
Loss Of Genetic Diversity

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.

scholarly journals Transmissible cancer in Tasmanian devils: localized lineage replacement and host population response

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151468 ◽  
Author(s):  
Rodrigo K. Hamede ◽  
Anne-Maree Pearse ◽  
Kate Swift ◽  
Leon A. Barmuta ◽  
Elizabeth P. Murchison ◽  
...  
Keyword(s):  
Population Decline ◽  
Emerging Infectious Diseases ◽  
Infectious Agent ◽  
Host Population ◽  
Future Research ◽  
Tasmanian Devil ◽  
Genetic Management ◽  
Genetic Lineages ◽  
Devil Facial Tumour Disease ◽  
Transmissible Cancer

Tasmanian devil facial tumour disease (DFTD) is a clonally transmissible cancer threatening the Tasmanian devil ( Sarcophilus harrisii ) with extinction. Live cancer cells are the infectious agent, transmitted to new hosts when individuals bite each other. Over the 18 years since DFTD was first observed, distinct genetic and karyotypic sublineages have evolved. In this longitudinal study, we investigate the associations between tumour karyotype, epidemic patterns and host demographic response to the disease. Reduced host population effects and low DFTD infection rates were associated with high prevalence of tetraploid tumours. Subsequent replacement by a diploid variant of DFTD coincided with a rapid increase in disease prevalence, population decline and reduced mean age of the population. Our results suggest a role for tumour genetics in DFTD transmission dynamics and epidemic outcome. Future research, for this and other highly pathogenic emerging infectious diseases, should focus on understanding the evolution of host and pathogen genotypes, their effects on susceptibility and tolerance to infection, and their implications for designing novel genetic management strategies. This study provides evidence for a rapid localized lineage replacement occurring within a transmissible cancer epidemic and highlights the possibility that distinct DFTD genetic lineages may harbour traits that influence pathogen fitness.

Managing gene flow among isolated population fragments. I. Limited information

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Population Genetics ◽  
Gene Flow ◽  
Management Strategies ◽  
Genetic Data ◽  
Outbreeding Depression ◽  
Isolated Population ◽  
Limited Information ◽  
Detailed Data ◽  
Genetic Management ◽  
Better Than

When the decision is made to augment gene flow into an isolated population, managers must decide how to augment gene flow, when to start, from where to take the individuals or gametes to be added, how many, which individuals, how often and when to cease. Even without detailed genetic data, sound genetic management strategies for augmenting gene flow can be instituted by considering population genetics theory, and/or computer simulations. When detailed data are lacking, moving (translocating) some individuals into isolated inbred population fragments is better than moving none, as long as the risk of outbreeding depression is low.

scholarly journals Fitness consequences of targeted gene flow to counter impacts of drying climates on terrestrial-breeding frogs

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Tabitha S. Rudin-Bitterli ◽  
Jonathan P. Evans ◽  
Nicola J. Mitchell
Keyword(s):  
Gene Flow ◽  
Outbreeding Depression ◽  
Hybrid Vigour ◽  
Adaptive Potential ◽  
Isolated Populations ◽  
Northern Population ◽  
Management Actions ◽  
Fitness Consequences ◽  
Frog Species ◽  
East West

AbstractTargeted gene flow (TGF) could bolster the adaptive potential of isolated populations threatened by climate change, but could also lead to outbreeding depression. Here, we explore these possibilities by creating mixed- and within-population crosses in a terrestrial-breeding frog species threatened by a drying climate. We reared embryos of the crawling frog (Pseudophryne guentheri) on wet and dry soils and quantified fitness-related traits upon hatching. TGF produced mixed outcomes in hybrids, which depended on crossing direction (origin of gametes from each sex). North-south crosses led to low embryonic survival if eggs were of a southern origin, and high malformation rates when eggs were from a northern population. Conversely, east-west crosses led to one instance of hybrid vigour, evident by increased fitness and desiccation tolerance of hybrid offspring relative to offspring produced from within-population crosses. These contrasting results highlight the need to experimentally evaluate the outcomes of TGF for focal species across generations prior to implementing management actions.

scholarly journals Disruption of Metapopulation Structure Reduces Tasmanian Devil Facial Tumour Disease Spread at the Expense of Abundance and Genetic Diversity

Pathogens ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1592
Author(s):  
Rowan Durrant ◽  
Rodrigo Hamede ◽  
Konstans Wells ◽  
Miguel Lurgi
Keyword(s):  
Genetic Diversity ◽  
Disease Transmission ◽  
Transmission Rate ◽  
Extinction Risk ◽  
Disease Prevalence ◽  
Disease Spread ◽  
Tasmanian Devil ◽  
Local Populations ◽  
Metapopulation Structure ◽  
Devil Facial Tumour Disease

Metapopulation structure plays a fundamental role in the persistence of wildlife populations. It can also drive the spread of infectious diseases and transmissible cancers such as the Tasmanian devil facial tumour disease (DFTD). While disrupting this structure can reduce disease spread, it can also impair host resilience by disrupting gene flow and colonisation dynamics. Using an individual-based metapopulation model we investigated the synergistic effects of host dispersal, disease transmission rate and inter-individual contact distance for transmission, on the spread and persistence of DFTD from local to regional scales. Disease spread, and the ensuing population declines, are synergistically determined by individuals’ dispersal, disease transmission rate and within-population mixing. Transmission rates can be magnified by high dispersal and inter-individual transmission distance. The isolation of local populations effectively reduced metapopulation-level disease prevalence but caused severe declines in metapopulation size and genetic diversity. The relative position of managed (i.e., isolated) local populations had a significant effect on disease prevalence, highlighting the importance of considering metapopulation structure when implementing metapopulation-scale disease control measures. Our findings suggest that population isolation is not an ideal management method for preventing disease spread in species inhabiting already fragmented landscapes, where genetic diversity and extinction risk are already a concern.

scholarly journals Quantitative genetics in conservation biology

1999 ◽  
Vol 74 (3) ◽  
pp. 237-244 ◽  
Author(s):  
RICHARD FRANKHAM
Keyword(s):  
Genetic Diversity ◽  
Endangered Species ◽  
Quantitative Genetics ◽  
Conservation Biology ◽  
Extinction Risk ◽  
Outbreeding Depression ◽  
Genetic Adaptation ◽  
Genetic Management ◽  
Captive Populations ◽  
Adaptation To Captivity

Most of the major genetic concerns in conservation biology, including inbreeding depression, loss of evolutionary potential, genetic adaptation to captivity and outbreeding depression, involve quantitative genetics. Small population size leads to inbreeding and loss of genetic diversity and so increases extinction risk. Captive populations of endangered species are managed to maximize the retention of genetic diversity by minimizing kinship, with subsidiary efforts to minimize inbreeding. There is growing evidence that genetic adaptation to captivity is a major issue in the genetic management of captive populations of endangered species as it reduces reproductive fitness when captive populations are reintroduced into the wild. This problem is not currently addressed, but it can be alleviated by deliberately fragmenting captive populations, with occasional exchange of immigrants to avoid excessive inbreeding. The extent and importance of outbreeding depression is a matter of controversy. Currently, an extremely cautious approach is taken to mixing populations. However, this cannot continue if fragmented populations are to be adequately managed to minimize extinctions. Most genetic management recommendations for endangered species arise directly, or indirectly, from quantitative genetic considerations.

scholarly journals The genetics of assisted gene flow: immediate costs and long-term benefits

2021 ◽  
Author(s):  
Jared A. Grummer ◽  
Tom R. Booker ◽  
Remi Matthey-Doret ◽  
Pirmin Nietlisbach ◽  
Andréa T. Thomaz ◽  
...  
Keyword(s):  
Climate Change ◽  
Genetic Variation ◽  
Gene Flow ◽  
Genetic Material ◽  
Population Level ◽  
Physiological Adaptation ◽  
Outbreeding Depression ◽  
Climate Change Scenarios ◽  
Animal Populations

ABSTRACTPlant and animal populations are facing several novel risks such as human-mediated habitat fragmentation and climate change that threaten their long-term productivity and persistence. With the genetic health of many populations deteriorating due to climate change outpacing physiological adaptation, human interventions in the form of assisted gene flow (AGF) may provide genetic variation to adapt populations to predicted climate change scenarios and result in more robust and productive populations. We ran genetic simulations to mimic a variety of AGF scenarios and measured their outcomes on population-level fitness to answer the question: in which circumstances is it worthwhile to perform AGF? Based on the parameters we explored, AGF may be harmful in certain situations over the short term (e.g., the first ∼10-20 generations), due to outbreeding depression and introducing deleterious genetic variation. Moreover, under many parameter sets, the benefits of AGF were relatively weak or took many generations to accrue. In general, when the adaptive trait is controlled by many loci of small effect, the benefits of assisted gene flow take much longer to realize–potentially too long for most climate-related management decisions. We also show that when translocation effort is divided across several generations and outbreeding depression is strong, the recipient population experiences a smaller decrease in fitness as compared to moving all individuals in a single effort. Importantly, in most cases, we show that the genomic integrity of the recipient population remains relatively intact following AGF; the amount of genetic material from the donor population typically ends up constituting no more of the recipient population’s genome than the fraction introduced. Our results will be useful for conservation practitioners and silviculturists, for instance, aiming to intervene and adaptively manage so that populations maintain a robust genetic health and maintain productivity into the future given anthropogenic climate change.

scholarly journals Extensive population decline in the Tasmanian devil predates European settlement and devil facial tumour disease

2014 ◽  
Vol 10 (11) ◽  
pp. 20140619 ◽  
Author(s):  
Anna Brüniche-Olsen ◽  
Menna E. Jones ◽  
Jeremy J. Austin ◽  
Christopher P. Burridge ◽  
Barbara R. Holland
Keyword(s):  
Genetic Diversity ◽  
Environmental Changes ◽  
Southern Oscillation ◽  
Demographic History ◽  
Population Decline ◽  
Tasmanian Devil ◽  
Term Survival ◽  
Temporal Sampling ◽  
Low Genetic Diversity ◽  
Devil Facial Tumour Disease

The Tasmanian devil ( Sarcophilus harrisii ) was widespread in Australia during the Late Pleistocene but is now endemic to the island of Tasmania. Low genetic diversity combined with the spread of devil facial tumour disease have raised concerns for the species’ long-term survival. Here, we investigate the origin of low genetic diversity by inferring the species' demographic history using temporal sampling with summary statistics, full-likelihood and approximate Bayesian computation methods. Our results show extensive population declines across Tasmania correlating with environmental changes around the last glacial maximum and following unstable climate related to increased ‘El Niño–Southern Oscillation’ activity.

Introduction

2019 ◽  
pp. 1-12
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Climate Change ◽  
Genetic Diversity ◽  
Gene Flow ◽  
Global Climate Change ◽  
Global Climate ◽  
Extinction Risk ◽  
Genetic Erosion ◽  
Isolated Populations ◽  
Genetic Management ◽  
Loss Of Genetic Diversity

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.

Introduction

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Climate Change ◽  
Gene Flow ◽  
Global Climate Change ◽  
Mating Systems ◽  
Global Climate ◽  
Extinction Risk ◽  
Genetic Erosion ◽  
Isolated Populations ◽  
Genetic Management ◽  
Loss Of Genetic Diversity

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.

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