Variation of early reproductive allocation in multi-site genetic trials of Maritime pine and Aleppo pine

Abstract

Life histories in Mediterranean pines are well known to be closely related to different fire and disturbance regimes. Variation in these factors is also reflected in reproductive strategies at the specific and intraspecific level. Specifically, the onset of reproduction is a crucial stage for any organism because it has profound implications on fitness. In this paper we focus on the intraspecific variation and plasticity in the threshold size for reproduction and reproductive allocation in two Mediterranean pines, assessed at the onset of reproduction, when trade-offs between reproduction and growth are expected to be greater. Replicated common garden provenance and progeny trials of Aleppo pine and Maritime pine were used to estimate genetic parameters for reproduction and vegetative growth, as well as variation in plasticity in reproductive strategies at the intraspecific level. In both species, high variation among populations was found for both threshold size for reproduction and for reproductive allocation. Reproductive allocation was also highly variable within populations and showed moderate to high values of heritability and high coefficients of additive genetic variation. These results indicate a high genetic control of these reproductive traits, while high additive genetic variation is maintained, allowing to face selective pressures. Moreover, reproductive strategies although plastic, showed low genotype × environment interaction, and intraspecific variation was highly consistent across trial sites both at the population and the family levels. The former data confirm the strong genetic control of reproductive traits in these species. Finally, the fact that Aleppo pine starts its reproductive phase as female while Maritime pine can start reproducing either as male or female deserves further attention.Key words: Pinus halepensis; Pinus pinaster; genetic variability; plasticity; trade-offs; early reproductive strategies; threshold size for reproduction. Resumen Variación en asignación reproductiva temprana en ensayos multi-localidad de pino carrasco y pino negralLas estrategias de historia vital en pinos mediterráneos están estrechamente ligadas a diversos regímenes de incendios y perturbaciones. A su vez, la variabilidad de esos factores también se ve reflejada en las estrategias reproductivas a niveles inter e intraespecíficos. Concretamente, el comienzo de la reproducción es una etapa crucial para cualquier organismo debido a su profunda influencia en su adaptación al medio. Este trabajo se enfoca en el estudio de la variabilidad intraespecífica y la plasticidad en el tamaño umbral de reproducción y la asignación reproductiva en dos pinos mediterráneos. El estudio se realizó durante el comienzo de la fase reproductiva, momento en que se estima que la compensación entre reproducción y crecimiento es de mayor importancia. Se utilizaron ensayos multi-sitio de procedencias y progenies de pino carrasco y pino negral para estimar los parámetros genéticos de caracteres reproductivos y de crecimiento ...

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