Genetic versus environmental contributions to variation in seedling resprouting in Nothofagus obliqua

Abstract

Resprouting is an almost universal functional trait in temperate angiosperms and confers persistence at an individual level after the loss of above-ground biomass. The importance of genetic versus environmental sources of intraspecific variation in resprouting traits is largely unknown. We conducted two genetic field trials, 400 m apart in altitude, in order to sequentially assess seedling resprouting in four environmentally contrasting Argentinean populations of Nothofagus obliqua Mirb. (Oerst). We also performed one nursery test to determine whether populations differed in early root/shoot biomass partition, a key trade-off affecting resprouting. Initial resprouting vigour and final survival were higher in our warmer test site, located 300 m below the core range of the species. The main contrasts between populations were found for pre-clipping seedling size and resprouting profusion, the latter trait showing a clear trade-off with resprouting vigour. Site×population interactions were due mainly to the behaviour of the highest altitude population, suggesting its divergent adaptive trajectory and higher plastic-ity for resprouting traits. Within populations, trait heritability was low, in general. Episodic frost, which may limit resprouting vigour and final success, had a lower incidence in the altitudinal and xeric limit populations. Overall, our work revealed genetic variation between populations of N. obliqua in traits that determine the success of seedling resprouting, probably associated with divergent selection. Low trait heritability suggests limited in situ micro-evolutionary capacities for resprouting traits under ongoing climate warming; phenotypic plasticity may play an important role in population persistence at the low positions of the elevation gradients N. obliqua currently inhabits.

Searching for molecular insight on hybridization in Nothofagus spp. forests at Lagunas de Epulauquen, Argentina

“…Within a provenances trial, LE individuals showed lower height, although exhibiting high relative growth rates (Azpilicueta et al 2014). Meanwhile, in a study of the intraspecific variation of the resprouting capacity of N. obliqua species, LE was found to differ from other Argentinean populations in several key traits (Aparicio et al 2015). For example, LE had the lowest rate of investment in shoot per unit of root seedling biomass; it showed the lowest capacity for recovering height, in a trade-off with multiple resprouting and the highest degree of episodic frost tolerance during resprouting.…”

Variación altitudinal de caracteres fenológicos y crecimiento inicial en condiciones controladas entre poblaciones de Nothofagus pumilio provenientes del Centro-Oeste de Chubut, Argentina

“…de Sudamérica. Aparicio et al (2015) encontraron en un ensayo de orígenes de N. obliqua que la población de mayor altitud fue la menos afectada por una helada tardía de comienzos de verano y a la vez la de menor crecimiento en altura.…”