Gene flow between three eucalypt species at Snug Plains

<p>The extent of hybridisation and gene flow between the three <i>Monocalyptus species</i>, <i>Eucalyptus pulchella</i>, <i>E. coccifera</i> (series <i>Piperitae</i>) and <i>E. delegatensis</i> (series <i>Obliquae</i>) at Snug Plains (600 m) in southeastern Tasmania was examined. The flowering time of <i>E. pulchella</i> was two months later than usual for this normally low-altitude species. It consequently overlapped the flowering period of both sub-alpine species <i>E. coccifera</i> and <i>E. delegatensis</i> and had its peak f10wering period intermediate between the two. The movements of pollinators across the species boundaries indicated the potential for hybridisation between <i>E. pulchella</i> and the other two species.</p> <p>Adult morphology suggested that the Snug Plains <i>E. pulchella</i> tended towards <i>E. coccifera</i> compared to typical, low-altitude <i>E. pulchella</i> and progeny tests reinforced this view. In addition, two out of twelve <i>E. pulchella</i> adults sampled appeared intermediate between this species and <i>E. coccifera</i> and produced progeny overlapping those from <i>E. coccifera</i>. These results suggest that introgression of <i>E. coccifera</i> genes may be occurring into <i>E. pulchella</i> at Snug Plains although adaptive convergence cannot be excluded. Quite a different picture is seen for the results of hybridisation between <i>E. pulchella</i> and <i>E. delegatensis</i>. Six putative F_l hybrids between <i>E. pulchella</i> and <i>E. delegatensis</i> occurred in progeny from two <i>E. pulchella</i> mothers. However, this appears to have had little genetic impact on the species, since no evidence of introgression or convergence was apparent in adult populations of these species.</p>