Columbia Science Review
  • Home
  • About
    • Executive Board
    • Editorial Board
  • Blog
  • Events
    • 2022-2023
    • 2021-2022
    • 2020-2021
    • 2019-2020
    • 2018-2019
    • 2017-2018
    • 2016-2017
  • Publications
  • COVID-19 Public Hub
    • Interviews >
      • Biology of COVID-19
      • Public Health
      • Technology & Data
    • Frontline Stories >
      • Healthcare Workers
      • Global Health
      • Volunteer Efforts
    • Resources & Links >
      • FAQ's
      • Resource Hubs
      • Student Opportunities
      • Podcasts & Graphics
      • Mental Health Resources
      • Twitter Feeds
      • BLM Resources
    • Columbia Events >
      • Campus Events
      • CUMC COVID-19 Symposium
      • CSR Events
    • Our Team
  • Contact

Escaping the Vortex: Genetic Rescue as Means of Conservation

11/23/2014

0 Comments

 
Picture
By Alexandra DeCandia

Humans have a talent for disrupting natural processes. Through the overharvest of species and inundation of landscapes with highways and suburbs, we’ve continuously rendered wild populations small and fragmented. Compared to larger, outbred populations, these communities exhibit higher rates of inbreeding. If their circumstances do not improve, inbreeding depression, or reduced reproductive fitness, may lock these populations in “extinction vortices,” whereby genetic and demographic declines work synergistically towards ultimate extinction.

Luckily, it is possible to escape this vortex. “Genetic rescue,” a more positive example of human disruption, has been proposed as means of mitigating inbreeding depression. It occurs when immigrants into a small population drastically improve overall fitness beyond theoretical predictions. These immigrants inject genetic diversity into ailing populations and thereby reduce their genetic load by disrupting homozygous deleterious alleles. This then enables rapid population expansion and overall improved fitness.

As a management strategy, genetic rescue can be achieved in two ways: (1) facilitating natural gene flow through improved connectivity between fragmented populations, and (2) artificially translocating immigrants into an inbred population. The management of Mexican wolves presents an example of the first strategy. Mexican wolves (Canis lupus baileyi) are the most genetically distinct descendants of the North American gray wolf. Due to habitat loss and human hunting throughout the 19th and 20th centuries, these once abundant carnivores were reduced to seven captive individuals by the mid-20th century. Unsurprisingly, signs of inbreeding depression appeared in reintroduced populations as a result of founder effects and geographic isolation. To prevent further declines, conservation geneticists combined population viability analysis with topographic data to propose a series of corridors between the introduced populations. Increased connectivity, when combined with Mexican wolves’ dispersal capabilities, now facilitates natural gene flow between populations.

Alternatively, the second management strategy, translocation, artificially transports foreign gametes or individuals into inbred populations. Source populations for these organisms include other wild populations (e.g. California bighorn sheep), captive populations (e.g. Houbara bustard), and wild populations of different subspecies (e.g. Florida panther). Genetically distinct, translocated individuals deposit variation from their source populations into those suffering from inbreeding depression. Occasionally, translocations even possess specific genotypic aims. In the case of the American chestnut (Castanea dentata), for example, conservation geneticists sought to imbue the once widespread species with genetic resistance to blight fungus. Through hybridization with the Chinese chestnut (C. mollissima) and repeated backcrossing with resistant American chestnuts, the species was able to maintain unique morphologies alongside appropriated fungal-resistance.

While successful in the aforementioned cases, genetic rescue should not be considered a panacea for all species suffering from heavy genetic loads. As genetic management of wild populations remains relatively novel, few studies document its long-term effects. In some cases, the intentional hybridization of divergent populations can render hybrids and their offspring maladapted to a particular environment, a phenomenon termed outbreeding depression. These fitness reductions may even increase pathogen susceptibility, as was documented in an experimental crossing of two genetically distinct populations of largemouth bass (Micropterus salmoides). As a result, the decision to implement genetic rescue through connectivity or translocation becomes a cost-benefit analysis of the relative risks associated with inbreeding and outbreeding depression. What’s more, if the ultimate causes of a population’s decline are not removed, no number of translocations will be able to sustain the species in perpetuity.
​
Despite these limitations, however, genetic rescue has proven a viable management strategy for highly inbred populations. Without it, the world would no longer have greater prairie chickens, Swedish adders, black-footed ferrets, freshwater mussels, South Island robins, golden lion tamarins, and a plethora of other species. Through improving connectivity and managing translocations of captive and wild individuals, humans are attempting to undo some of the damage we have inflicted upon the natural world. We are doing our part to aid in the escape from extinction vortices.
0 Comments



Leave a Reply.

    Categories

    All
    Artificial Intelligence
    Halloween 2022

    Archives

    November 2022
    October 2022
    June 2022
    January 2022
    May 2021
    April 2021
    March 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    May 2020
    April 2020
    March 2020
    February 2020
    January 2020
    November 2019
    October 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    April 2018
    March 2018
    February 2018
    November 2017
    October 2017
    May 2017
    April 2017
    April 2016
    March 2016
    February 2016
    December 2015
    November 2015
    October 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    May 2014
    April 2014
    March 2014
    February 2014
    December 2013
    November 2013
    October 2013
    April 2013
    March 2013
    February 2013
    January 2013
    December 2012
    November 2012
    October 2012
    April 2011
    March 2011
    February 2011
    September 2010
    August 2010
    July 2010
    June 2010
    May 2010
    April 2010
    March 2010
    February 2010
    January 2010
    December 2009
    November 2009
    July 2009
    May 2009

Columbia Science Review
© COPYRIGHT 2022. ALL RIGHTS RESERVED.
Photos used under Creative Commons from driver Photographer, BrevisPhotography, digitalbob8, Rennett Stowe, Kristine Paulus
  • Home
  • About
    • Executive Board
    • Editorial Board
  • Blog
  • Events
    • 2022-2023
    • 2021-2022
    • 2020-2021
    • 2019-2020
    • 2018-2019
    • 2017-2018
    • 2016-2017
  • Publications
  • COVID-19 Public Hub
    • Interviews >
      • Biology of COVID-19
      • Public Health
      • Technology & Data
    • Frontline Stories >
      • Healthcare Workers
      • Global Health
      • Volunteer Efforts
    • Resources & Links >
      • FAQ's
      • Resource Hubs
      • Student Opportunities
      • Podcasts & Graphics
      • Mental Health Resources
      • Twitter Feeds
      • BLM Resources
    • Columbia Events >
      • Campus Events
      • CUMC COVID-19 Symposium
      • CSR Events
    • Our Team
  • Contact