<article>
  <front>
    <article-meta>
      <title-group>
        <article-title>Lineal admixture time: an interdisciplinary definition</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <contrib-id contrib-id-type="orcid">https://orcid.org/0000-0002-5014-4809</contrib-id>
          <name>
            <surname>Ellerman</surname>
            <given-names>E. Castedo</given-names>
          </name>
          <email>castedo@castedo.com</email>
        </contrib>
      </contrib-group>
      <permissions>
        <copyright-statement>&#169; 2023, Ellerman et al</copyright-statement>
        <license>
          <license-ref content-type="ccbylicense">https://creativecommons.org/licenses/by/4.0/</license-ref>
          <license-p>This document is distributed under a Creative Commons Attribution 4.0 International license.</license-p>
        </license>
      </permissions>
      <abstract>
        <p><b>STAGE:</b> DISCUSSION DOCUMENT</p>
        <p><b>OBJECTIVES:</b></p>
        <ul>
          <li>
            <p>Define <i>lineal admixture time</i>.</p>
          </li>
          <li>
            <p>Invite discussion and feedback, especially regarding questions at the end of
              this document.</p>
          </li>
          <li>
            <p>Facilitate the discovery of mathematical tools, using this definition, that
              are useful to downstream empirical research.</p>
          </li>
        </ul>
        <p> </p>
        <p><b>SIGNIFICANCE:</b>
This definition is interpretable within empirical research without assuming
particular mathematical models of demographic or genetic processes.</p>
        <p><b>DOWNSTREAM RESEARCH:</b>
The estimation of the timing and extent of interbreeding between previously
separated populations.</p>
      </abstract>
    </article-meta>
  </front>
  <article-body>
    <section id="background">
      <h2>Background</h2>
      <p>The genealogies of a population reflect population events of the
 past.</p>
    </section>
    <section id="definition-of-lineal-admixture-time">
      <h2>Definition of lineal admixture time</h2>
      <p>We define <i>lineal admixture time</i> per lineage. This measure in time duration
   depends on two reference time points:</p>
      <ol>
        <li>
          <p>a past time horizon when all ancestors are members of separate non-admixed
          subpopulations, and</p>
        </li>
        <li>
          <p>an observation time, such as the present.</p>
        </li>
      </ol>
      <p>Given a lineage, the <b>lineal admixture time</b> is defined as:</p>
      <p><i>the amount of time since fertilization of the first admixed individual in the
     lineage</i>.</p>
    </section>
  </article-body>
</article>
