Evidence for genetic-based climate adaptation in Eucalyptus pauciflora

Understanding the genetic basis of adaptation to contemporary environments is key to predicting the evolutionary response of tree species to future climates. Such knowledge is also important to guide forest restoration and translocation activities. We have been studying the adaptive potential of the widespread Eucalyptus pauciflora, a tree species of increasing interest for restoration purposes due to its capacity to withstand harsh environments. Using pedigreed glasshouse and field trials, we assessed quantitative genetic variation of seedling from 281 open-pollinated families from 37 native populations from the island of Tasmania. We analysed 26 morphological traits in the glasshouse, while in the field trials, early growth and survival, insect damage and frost damage were assessed on a periodic basis. Most traits exhibited significant genetic variation both within and between populations. Multivariate analyses provided strong evidence that population differentiation was associated with climate adaptation, with mean maximum temperature of the warmest month at the site of seed origin appearing to be the main driver of the genetic differentiation