Allopatric (red) and sympatric (blue) <i>Drosophila</i> species pairs plotted against level of pre-zygotic isolation and genetic distance (evolutionary age). Gradients indicate the the predictions of reinforcement for allopatric and sympatric populations. Based on Coyne and Orr (1997).<sup id="cite_ref-1" class="reference"><a href="#cite_note-1">[1]</a></sup>
<a href="//commons.wikimedia.org/wiki/User:Azcolvin429" title="User:Azcolvin429">Andrew Z. Colvin</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>