Enhancing genetic fitness while maintaining genetic variability in araucaria angustifolia

Abstract

Araucaria angustifolia provides timber, edible seeds and pharmaceuticals and has a unique ecology (once shared with that of the dinosaurs), yet is now threatened with extinction. Here, we assess and reconcile the counteracting goals of enhancing genetic fitness and maintaining genetic variability during ex-situ conservation of A. angustifolia in a provenance-and-progeny test to improve growth vigor. After 33 years, survival, height, diameter at breast height, and volume of trees were determined. Sixteen selection scenarios were tested using two strategies: Selection among and within progenies, and selection only within progenies, each one for eight values of selection intensity of total survival in the trial (7.6, 11.5, 15.3, 19.1, 22.9, 26.8, 30.6, and 34.4%). The variance components and genetic parameter estimates were determined using REML/BLUP. There was significant genetic variation among provenances and progenies for all traits. For all growth-phenotype traits, the heritability at mean (0.419-0.542) and within progeny level (0.186-0.207) indicate the potential for tree improvement by selection among and within progenies. The selection strategy enhanced growth phenotype whilst maintaining an effective population size of 19.1% selected individuals within progenies (three females and two males). This preserved sufficient genetic variability among and within provenances, and resulted in genetic gain, providing higher-value seed production.