The thermal niche of temperate and tropical <i>O. japonica</i> at a series of different temperature perturbations.

<p>The area in red represents the area in which tropical <i>O. japonica</i> can be grown. The area in white represents the area in which temperate <i>O. japonica</i> can be grown. Sites represented by black dots are sites where only millet has been recovered from the assemblage. Sites with a black square represent sites where rice has been unearthed in contexts dating to 6000–5000 cal. BC. Sites with an open circle are sites where rice has been unearthed between 5000–3000 cal. BC, however come from poor or undated contexts. Sites with a black triangle represent finds of rice that date between 2600–2000 cal. BC. Sites with a diamond represents sites where rice has been found that post-dates 1800 cal. BC. Map relief from ETOPO1 [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0130430#pone.0130430.ref006" target="_blank">6</a>]; country and province outlines from Natural Earth (naturalearthdata.com).