In situ evaluation of artificial selection and assisted gene flow for the advancement of flowering onset in Lupinus angustifolius L. (Fabaceae)

Abstract

Artificial selection and assisted gene flow represent promising conservation strategies for enhancing species’ adaptive capacity under accelerating climate change. We tested the application of artificial selection and assisted gene flow by evaluating progeny performance under field conditions, using Lupinus angustifolius L. (Fabaceae) as a model to advance flowering onset. In previous studies we examined these processes under controlled conditions using seeds that were collected from four wild populations and two contrasting latitudes in Spain. In the artificial selection experiment, we developed two early-flowering selection lines per population over three generations using both selfing and outcrossing. For the assisted gene flow experiment, we created lines from F1 hybrids by crossing northern populations with southern pollen donors, then produced F2 and F3 generations through successive self-pollination. In parallel, control lines were established through three generations of self-crossing, using randomly selected individuals representing 25% of each population. For this study, F3 seeds from these previous experiments were sown in autumn in an in situ common garden under natural conditions, near the original population sites. Measurements of flowering onset and morphological traits revealed contrasting effects depending on the experiment. Artificial selection lines showed no significant phenotypic differentiation from controls across all measured traits, in contrast to previous controlled-environment results. Conversely, assisted gene flow lines exhibited significantly earlier flowering and reduced shoot growth relative to controls, consistent with prior findings under controlled conditions. These results show greater efficacy of assisted gene flow over artificial selection for advancing flowering onset under natural conditions. They also indicate a stable pattern of phenotypic expression for gene flow under natural and more controlled conditions not found in artificial selection.