---
_id: '12264'
abstract:
- lang: eng
  text: Reproductive isolation (RI) is a core concept in evolutionary biology. It
    has been the central focus of speciation research since the modern synthesis and
    is the basis by which biological species are defined. Despite this, the term is
    used in seemingly different ways, and attempts to quantify RI have used very different
    approaches. After showing that the field lacks a clear definition of the term,
    we attempt to clarify key issues, including what RI is, how it can be quantified
    in principle, and how it can be measured in practice. Following other definitions
    with a genetic focus, we propose that RI is a quantitative measure of the effect
    that genetic differences between populations have on gene flow. Specifically,
    RI compares the flow of neutral alleles in the presence of these genetic differences
    to the flow without any such differences. RI is thus greater than zero when genetic
    differences between populations reduce the flow of neutral alleles between populations.
    We show how RI can be quantified in a range of scenarios. A key conclusion is
    that RI depends strongly on circumstances—including the spatial, temporal and
    genomic context—making it difficult to compare across systems. After reviewing
    methods for estimating RI from data, we conclude that it is difficult to measure
    in practice. We discuss our findings in light of the goals of speciation research
    and encourage the use of methods for estimating RI that integrate organismal and
    genetic approaches.
acknowledgement: 'We are grateful to the participants of the ESEB satellite symposium
  ‘Understanding reproductive isolation: bridging conceptual barriers in  speciation  research’  in  2021  for  the  interesting  discussions  that  helped  us  clarify  the  thoughts  presented  in  this  article.  We  thank  Roger
  Butlin, Michael Turelli and two anonymous reviewers for their thoughtful comments
  on this manuscript. We are also very grateful to Roger Butlin and the Barton Group
  for the continued conversa-tions about RI. In addition, we thank all participants
  of the speciation survey. Part of this work was funded by the Austrian Science Fund
  FWF (grant P 32166)'
article_processing_charge: Yes (via OA deal)
article_type: review
author:
- first_name: Anja M
  full_name: Westram, Anja M
  id: 3C147470-F248-11E8-B48F-1D18A9856A87
  last_name: Westram
  orcid: 0000-0003-1050-4969
- first_name: Sean
  full_name: Stankowski, Sean
  id: 43161670-5719-11EA-8025-FABC3DDC885E
  last_name: Stankowski
- first_name: Parvathy
  full_name: Surendranadh, Parvathy
  id: 455235B8-F248-11E8-B48F-1D18A9856A87
  last_name: Surendranadh
  orcid: 0000-0001-6395-386X
- first_name: Nicholas H
  full_name: Barton, Nicholas H
  id: 4880FE40-F248-11E8-B48F-1D18A9856A87
  last_name: Barton
  orcid: 0000-0002-8548-5240
citation:
  ama: Westram AM, Stankowski S, Surendranadh P, Barton NH. What is reproductive isolation?
    <i>Journal of Evolutionary Biology</i>. 2022;35(9):1143-1164. doi:<a href="https://doi.org/10.1111/jeb.14005">10.1111/jeb.14005</a>
  apa: Westram, A. M., Stankowski, S., Surendranadh, P., &#38; Barton, N. H. (2022).
    What is reproductive isolation? <i>Journal of Evolutionary Biology</i>. Wiley.
    <a href="https://doi.org/10.1111/jeb.14005">https://doi.org/10.1111/jeb.14005</a>
  chicago: Westram, Anja M, Sean Stankowski, Parvathy Surendranadh, and Nicholas H
    Barton. “What Is Reproductive Isolation?” <i>Journal of Evolutionary Biology</i>.
    Wiley, 2022. <a href="https://doi.org/10.1111/jeb.14005">https://doi.org/10.1111/jeb.14005</a>.
  ieee: A. M. Westram, S. Stankowski, P. Surendranadh, and N. H. Barton, “What is
    reproductive isolation?,” <i>Journal of Evolutionary Biology</i>, vol. 35, no.
    9. Wiley, pp. 1143–1164, 2022.
  ista: Westram AM, Stankowski S, Surendranadh P, Barton NH. 2022. What is reproductive
    isolation? Journal of Evolutionary Biology. 35(9), 1143–1164.
  mla: Westram, Anja M., et al. “What Is Reproductive Isolation?” <i>Journal of Evolutionary
    Biology</i>, vol. 35, no. 9, Wiley, 2022, pp. 1143–64, doi:<a href="https://doi.org/10.1111/jeb.14005">10.1111/jeb.14005</a>.
  short: A.M. Westram, S. Stankowski, P. Surendranadh, N.H. Barton, Journal of Evolutionary
    Biology 35 (2022) 1143–1164.
corr_author: '1'
date_created: 2023-01-16T09:59:24Z
date_published: 2022-09-01T00:00:00Z
date_updated: 2025-04-15T08:20:40Z
day: '01'
ddc:
- '570'
department:
- _id: NiBa
doi: 10.1111/jeb.14005
external_id:
  isi:
  - '000849851100002'
  pmid:
  - '36063156'
file:
- access_level: open_access
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  content_type: application/pdf
  creator: dernst
  date_created: 2023-01-30T10:05:31Z
  date_updated: 2023-01-30T10:05:31Z
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file_date_updated: 2023-01-30T10:05:31Z
has_accepted_license: '1'
intvolume: '        35'
isi: 1
issue: '9'
keyword:
- Ecology
- Evolution
- Behavior and Systematics
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
page: 1143-1164
pmid: 1
project:
- _id: 05959E1C-7A3F-11EA-A408-12923DDC885E
  grant_number: P32166
  name: Snapdragon Speciation
publication: Journal of Evolutionary Biology
publication_identifier:
  eissn:
  - 1420-9101
  issn:
  - 1010-061X
publication_status: published
publisher: Wiley
quality_controlled: '1'
related_material:
  record:
  - id: '12265'
    relation: other
    status: public
scopus_import: '1'
status: public
title: What is reproductive isolation?
tmp:
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  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: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 35
year: '2022'
...