Population origin determines the adaptive potential for the advancement of flowering onset in Lupinus angustifolius L. (Fabaceae)

Abstract

In the present framework of global warming, it is unclear whether evolutionary adaptation can happen quick enough to preserve the persistence of many species. Specifically, we lack knowledge about the adaptive potential of the different populations in relation to the various constraints that may hamper particular adaptations. There is evidence indicating that early flowering often provides an adaptive advantage to plants in temperate zones in response to global warming. Thus, the objective of this study was to assess the adaptive potential for advancing flowering onset in Lupinus angustifolius L. (Fabaceae). Seeds from four populations from two contrasting latitudes in Spain were collected and sown in a common garden environment. Selecting the 25% of the individuals that flowered earlier in the first generation, over three generations, three different early flowering selection lines were established, involving both self‐crosses and outcrosses. All artificial selection lines advanced their flowering significantly with respect to the control line in the northernmost populations, but not in the southern ones. Selection lines obtained from outcrossing had a greater advancement in flowering than those from self‐crossing. No differences were found in the number or weight of the seeds produced between control and artificial selection lines, probably because plants in the common garden were drip irrigated. These results suggest that northern populations may have a greater adaptive potential and that southern populations may be more vulnerable in the context of climate warming. However, earlier flowering was also associated with changes in other traits (height, biomass, shoot growth, specific leaflet area, and leaflet dry matter content), and the effects of these changes varied greatly depending on the latitude of the population and selection line. Assessments of the ability of populations to cope with climate change through this and other approaches are essential to manage species and populations in a more efficient way.

Effects of assisted gene flow on the flowering onset of the annual legumeLupinus angustifoliusL.: from phenotype to genotype

“…Sacristán-Bajo et al (2022) observed that southern populations flower earlier than northern populations when grown together in a common garden. Therefore, it is reasonable to expect that hybrids from artificial crosses of northern mother plants with pollen from southern populations (GFL) will flower earlier than their respective northern population controls.…”

“…Gene flow may not only affect the trait of interest to be shifted (in this case, flowering onset), but this modification may lead to changes in other traits, including traits related to reproductive success (Aitken & Whitlock, 2013; Morente-López et al, 2021; Prieto-Benítez et al, 2021). Considering that the southern populations are known to produce fewer but heavier seeds than the northern populations (Matesanz et al, 2020; Sacristán-Bajo et al, 2022), the GFL produced heavier seeds than the CFL individuals, making the hybrids more similar to the individuals of the southern populations. In our study, the GFL showed lower shoot growth and also a tendency to lower SLA than the CFL.…”

“…Inside the greenhouse, the temperature varied between 1 to 25 degrees Celsius, and plants only received natural light. In November 2016, three seeds from each maternal genotype were scarified to ensure germination and sown in a 6 L pot, following the same protocol described in Sacristán-Bajo et al 2022. In spring 2017, the pots were transferred outside of the greenhouse to the CULTIVE experimental field and were distributed in a randomized block design where the plants from the different populations were evenly represented in each block.…”

“…All possible crosses between these two pairs of populations (considered as replicates) were performed considering the need of having overlapped flowering periods between their individuals. The procedure to carry out manual crosses was the same as that described in Sacristán-Bajo et al (2022), based on the emasculation of individuals of the northern region and their subsequent pollination with pollen from individuals from the southern region. Seeds produced were separately collected for each mother plant.…”

“…Moreover, it is also a polygenic trait in which a large number of genes are involved and has a complex regulation (Blümel et al, 2015). However, the timing of flowering onset is often correlated with other traits of great importance for plant survival and adaptation, which may constrain its evolution (Etterson & Shaw, 2001; Sacristán-Bajo et al, 2022; Walsh & Blows, 2009). Therefore, a better understanding of the genomic basis of flowering onset and the possible genetic constraints due to correlations between traits may help to design more accurately potential future assisted gene flow actions.…”