Heritability and quantitative genetic divergence of serotiny, a fire-persistence plant trait

• Published in: Annals of botany 2014-09, Vol.114 (3), p.571-577
• Main Authors: Hernández-Serrano, Ana, Verdú, Miguel, Santos-del-Blanco, Luís, Climent, José, González-Martínez, Santiago C, Pausas, Juli G
• Format: Article
• Language: English
• Subjects: adaptive radiation; allozymes; Bayesian theory; Ecological genetics; Evolutionary genetics; fire regime; Fires; genetic markers; Genetic Variation; Heritability; Life Sciences; natural selection; open pollination; Original; Phenotype; Phenotypic traits; Pine trees; Pinus - genetics; Pinus - growth & development; Pinus halepensis; Population genetics; provenance; Quantitative genetics; Quantitative traits; rain; Rainfall; Spain; summer; trees
• ISSN: 0305-7364; 1095-8290; 1095-8290
• DOI: 10.1093/aob/mcu142

Background and AimsAlthough it is well known that fire acts as a selective pressure shaping plant phenotypes, there are no quantitative estimates of the heritability of any trait related to plant persistence under recurrent fires, such as serotiny. In this study, the heritability of serotiny in Pinus halepensis is calculated, and an evaluation is made as to whether fire has left a selection signature on the level of serotiny among populations by comparing the genetic divergence of serotiny with the expected divergence of neutral molecular markers (QST–FST comparison).MethodsA common garden of P. halepensis was used, located in inland Spain and composed of 145 open-pollinated families from 29 provenances covering the entire natural range of P. halepensis in the Iberian Peninsula and Balearic Islands. Narrow-sense heritability (h2) and quantitative genetic differentiation among populations for serotiny (QST) were estimated by means of an ‘animal model’ fitted by Bayesian inference. In order to determine whether genetic differentiation for serotiny is the result of differential natural selection, QST estimates for serotiny were compared with FST estimates obtained from allozyme data. Finally, a test was made of whether levels of serotiny in the different provenances were related to different fire regimes, using summer rainfall as a proxy for fire regime in each provenance.Key ResultsSerotiny showed a significant narrow-sense heritability (h2) of 0·20 (credible interval 0·09–0·40). Quantitative genetic differentiation among provenances for serotiny (QST = 0·44) was significantly higher than expected under a neutral process (FST = 0·12), suggesting adaptive differentiation. A significant negative relationship was found between the serotiny level of trees in the common garden and summer rainfall of their provenance sites.ConclusionsSerotiny is a heritable trait in P. halepensis, and selection acts on it, giving rise to contrasting serotiny levels among populations depending on the fire regime, and supporting the role of fire in generating genetic divergence for adaptive traits.