--- _id: '315' abstract: - lang: eng text: 'More than 100 years after Grigg’s influential analysis of species’ borders, the causes of limits to species’ ranges still represent a puzzle that has never been understood with clarity. The topic has become especially important recently as many scientists have become interested in the potential for species’ ranges to shift in response to climate change—and yet nearly all of those studies fail to recognise or incorporate evolutionary genetics in a way that relates to theoretical developments. I show that range margins can be understood based on just two measurable parameters: (i) the fitness cost of dispersal—a measure of environmental heterogeneity—and (ii) the strength of genetic drift, which reduces genetic diversity. Together, these two parameters define an ‘expansion threshold’: adaptation fails when genetic drift reduces genetic diversity below that required for adaptation to a heterogeneous environment. When the key parameters drop below this expansion threshold locally, a sharp range margin forms. When they drop below this threshold throughout the species’ range, adaptation collapses everywhere, resulting in either extinction or formation of a fragmented metapopulation. Because the effects of dispersal differ fundamentally with dimension, the second parameter—the strength of genetic drift—is qualitatively different compared to a linear habitat. In two-dimensional habitats, genetic drift becomes effectively independent of selection. It decreases with ‘neighbourhood size’—the number of individuals accessible by dispersal within one generation. Moreover, in contrast to earlier predictions, which neglected evolution of genetic variance and/or stochasticity in two dimensions, dispersal into small marginal populations aids adaptation. This is because the reduction of both genetic and demographic stochasticity has a stronger effect than the cost of dispersal through increased maladaptation. The expansion threshold thus provides a novel, theoretically justified, and testable prediction for formation of the range margin and collapse of the species’ range.' article_number: e2005372 author: - first_name: Jitka full_name: Polechova, Jitka id: 3BBFB084-F248-11E8-B48F-1D18A9856A87 last_name: Polechova orcid: 0000-0003-0951-3112 citation: ama: Polechova J. Is the sky the limit? On the expansion threshold of a species’ range. PLoS Biology. 2018;16(6). doi:10.1371/journal.pbio.2005372 apa: Polechova, J. (2018). Is the sky the limit? On the expansion threshold of a species’ range. PLoS Biology. Public Library of Science. https://doi.org/10.1371/journal.pbio.2005372 chicago: Polechova, Jitka. “Is the Sky the Limit? On the Expansion Threshold of a Species’ Range.” PLoS Biology. Public Library of Science, 2018. https://doi.org/10.1371/journal.pbio.2005372. ieee: J. Polechova, “Is the sky the limit? On the expansion threshold of a species’ range,” PLoS Biology, vol. 16, no. 6. Public Library of Science, 2018. ista: Polechova J. 2018. Is the sky the limit? On the expansion threshold of a species’ range. PLoS Biology. 16(6), e2005372. mla: Polechova, Jitka. “Is the Sky the Limit? On the Expansion Threshold of a Species’ Range.” PLoS Biology, vol. 16, no. 6, e2005372, Public Library of Science, 2018, doi:10.1371/journal.pbio.2005372. short: J. Polechova, PLoS Biology 16 (2018). date_created: 2018-12-11T11:45:46Z date_published: 2018-06-15T00:00:00Z date_updated: 2023-02-23T14:10:16Z day: '15' ddc: - '576' department: - _id: NiBa doi: 10.1371/journal.pbio.2005372 file: - access_level: open_access checksum: 908c52751bba30c55ed36789e5e4c84d content_type: application/pdf creator: dernst date_created: 2019-01-22T08:30:03Z date_updated: 2020-07-14T12:46:01Z file_id: '5870' file_name: 2017_PLOS_Polechova.pdf file_size: 6968201 relation: main_file file_date_updated: 2020-07-14T12:46:01Z has_accepted_license: '1' intvolume: ' 16' issue: '6' language: - iso: eng month: '06' oa: 1 oa_version: Published Version publication: PLoS Biology publication_identifier: issn: - '15449173' publication_status: published publisher: Public Library of Science publist_id: '7550' quality_controlled: '1' related_material: record: - id: '9839' relation: research_data status: public scopus_import: 1 status: public title: Is the sky the limit? On the expansion threshold of a species’ range tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 16 year: '2018' ...