Assortative mating behavioural responses.

<p>In assay arenas containing a mixture of females from two species and males from one species, (A) <i>C. nigoni</i> females are more likely than <i>C. briggsae</i> hermaphrodites to mate with <i>C. briggsae</i> males (t = 2.828, df = 24, <i>p</i> = 0.009) and <i>C. nigoni</i> males (t = 8.988, df = 24, <i>p</i>≤0.001). (B) A similar female mating bias was also observed when <i>C. elegans</i> hermaphrodites and <i>C. nigoni</i> females were presented to <i>C. elegans</i> males (t = 2.939, df = 19, <i>p</i> = 0.008) and to <i>C. nigoni</i> males (t = 28.996, df = 19, <i>p</i>≤0.001). (C) Mixtures of <i>C. remanei</i> and <i>C. nigoni</i> females show a mating bias toward <i>C. nigoni</i> females over <i>C. remanei</i> females when they are presented with <i>C. nigoni</i> males (t = 2.683, df = 24, <i>p</i> = 0.013), but not when presented with <i>C. remanei</i> males (t = 1.365, df = 24, <i>p</i> = 0.185). Positive values indicate that <i>C. nigoni</i> females mated more readily than the other female (or hermaphrodite) species that they were paired with; negative values indicate the reciprocal, while zero indicate no mating bias. Error bars represent ±1 standard error (SE); sample sizes are shown in parentheses.