Cited by 85Genetic diversity and population structureEvolution and Genetic DynamicsChromosomal and Genetic Variations

When gene flow really matters: gene flow in applied evolutionary biology

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Ellstrand, Norman C., Rieseberg, Loren H.·2016·Evolutionary Applications

Abstract

In the last half century, gene flow has moved from relative obscurity to a well-recognized component of evolution. Gene flow, the successful transfer of alleles from one population to another, is now known to vary considerably among species, populations, and individuals as well as over time. It frequently occurs at rates sufficient to play an important evolutionary role for populations of both animals and plants (Ellstrand 2014; Yakimowski and Rieseberg 2014; Arnold 2015). Gene flow does not automatically come to mind in the context of evolutionary applications. When the senior author shared the idea of a Special Issue on Gene Flow in Applied Evolution with a colleague, she asked, "What else is there besides crop breeding?" Considerably more, as we shall soon see. Gene flow is important in a remarkable variety of applied situations. This Special Issue presents some representative points in the galaxy of applied topics in which gene flow plays a key role. The number of possible topics precludes an exhaustive treatment. Likewise, while we acknowledge that non-sexual gene flow (horizontal transfer) has considerable applied and evolutionary significance in prokaryotes and eukaryotes (e.g. Koonin et al. 2001; Richardson and Palmer 2007; Arnold 2015), the topic is so large, we deem it worthy of separate treatment. The recognition of gene flow's magnitude and variation has led to increased attention to gene flow in applied evolutionary biology. As noted above, breeders have long been acutely aware of gene flow. Intentional anthropogenic gene flow has long been practiced by breeders to deliver desirable traits to domesticated species via wide crosses followed by repeated backcrossing (e.g. Stalker 1980). But long before humans intentionally bred plants, spontaneous gene flow played a role in plant improvement. A few thousand years ago, spontaneous interspecific hybridization gave rise to first durum wheat and then bread wheat (Feldman et al. 1995). Likewise, lager beer yeast is the result of spontaneous interspecific hybridization and of a similar age (Hebly et al. 2015). Even natural hybridization within species has had its benefits. The evolution of highland maize (Zea mays ssp. mays) landraces was the result of introgression from the wild Z. m. ssp. mexicana (Hufford et al. 2013). But gene flow involving domesticated species is not universally beneficial. Pollen contamination from conspecifics and congeners growing within cross-pollination distance can frustrate progress under artificial selection as well as jeopardize the genetic purity of seed multiplication programs (e.g. Kelly and George 1998). Spontaneous gene flow into or out of domesticated populations sometimes gives rise to new invasive and weedy lineages (Ellstrand et al. 2010). The rise of Africanized bees in the New World may be the best known example (Winston 1992). Another example is the case of the rise of herbicide-resistant weedy rice in Brazil, reviewed in this issue (Merotto et al. 2016). A new herbicide-resistant cultivar of cultivated rice had been introduced to facilitate the control of the conspecific weed. A local economic boom ensued as yields increased. But the combination of introgression of the resistance allele into the weed and strong selection by the herbicide lead to the dramatic evolutionary spread of weed populations bearing the allele for herbicide resistance, resulting in the reversal of economic fortunes. In extreme cases, the farmers were compelled to abandon their land. The foregoing scenario involving a traditionally bred crop represents one of the primary concerns associated with the release of transgenic crops (Ellstrand 2001): that is, the delivery of transgenes into free-living populations via gene flow might result in the evolution of new or more problematic weeds or invasives. It is not unusual for spontaneous gene flow from crops to their wild or weedy relatives to result in introgression (Ellstrand et al. 2013). But whether or not those alleles will persist and spread also depends on the relative fitness of free-living plants that bear those alleles versus those that do not. Relevant multigenerational field experiments involving a variety of environments remain few. One such study is presented in this Special Issue. Xia et al. (2016) measured the fitness effects of cultivated rice insect resistance transgenes that had been introgressed into various weedy rice lineages. The relative fitness effect of the transgene varied with both environment (level of insect infestation) and genotype (genetic background of the different lineages). Correspondingly, the Special Issue includes a review of field studies of the fitness effects of crop transgenes with wild or weedy ancestors (Lu et al. 2016). The review reveals that the relative fitness of lineages that are the result of gene flow between a transgenic crop and wild/weedy relative cannot easily be predicted a priori. The presence of transgenes sometimes correlates with in

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  • The fate of lineages resulting from transgenic gene flow is inherently difficult to predict.

    “the fate of lineages resulting from transgenic gene flow is inherently difficult to predict ( 110 )”

    From Environmental impacts of genetically modified crops (2024) · cites this paper as [110]

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  1. Feldman, M., F. G. H. Lupton, and T. E. Miller 1995 Wheats In: Smartt J., and Simmonds N. W., eds. Evolution of Crop Plants, 2nd edn, pp. 184– 192. Longman, Harlow.

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Authors
Ellstrand, N. C., & Rieseberg, L. H.
Affiliations
  • University of California, Riverside (US)
  • University of British Columbia (CA)
Venue
Evolutionary Applications
Publisher
Wiley
Published
2016-07-16
Volume
9
Issue
7
Pages
833-836
ISSN
  • 1752-4563 (ISSN-L)
  • 1752-4571
OpenAlex
W2462071011
Cited by
85
References
34
Citations by year
2026: 4 · 2025: 7 · 2024: 6 · 2023: 13 · 2022: 10 · 2021: 10 · 2020: 12 · 2019: 3 · 2018: 11 · 2017: 9
FWCI
6.18
Type
journal article
Language
en
Open access
Locations
  • Evolutionary Applications (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • eScholarship (California Digital Library) (submittedVersion)
Funders
Natural Sciences and Engineering Research Council of Canada
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic diversity and population structure
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Evolution and Genetic Dynamics
  • Life Sciences › Agricultural and Biological Sciences › Plant Science › Chromosomal and Genetic Variations
Keywords
gene flow, interspecific hybridization, introgression, crop breeding, domestication, hybrid zone, hybrid sterility, hybrid inviability, heterosis, hybrid zone maintenance

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