Phenotypic plasticity contributes more to the variations in nutrient resorption than genetic differentiation in a grassland dominant

1. Phenotypic plasticity and genetic differentiation are the two important
processes determining the leaf nutrient resorption among and within plant
species, which is critical for understanding the adaptability of plants.
However, relative contributions of these two processes have never been
quantified at a large geographical scale. 2. Here, we investigated
intraspecific variations in nutrient resorption among 14 Stipa breviflora
populations along a latitude gradient in 2018 and 2019. Furthermore, we
sow seeds from these populations in two common gardens at different
latitudes, and examined the variations in nutrient resorption. 3. Our
results showed that nitrogen and phosphorus resorption efficiency (NRE and
PRE) among S. breviflora populations in nature were positively related to
latitude, while this trend disappeared in the common gardens. The
heritability of NRE and PRE was 11.45 % and 16.78 %, respectively. These
results suggested that phenotypic plasticity contributed much more than
genetic variation to nutrient resorption of S. breviflora. Moreover, the
structural equation modeling (SEM) suggested that latitude indirectly
affected nutrient resorption mainly by altering soil nutrients. With the
increasing of latitude, soil nutrients decreased while nutrient resorption
increased. This suggested the main process regulating nutrient resorption
is negative feedback to soil nutrient availability. 4. Our study provides
new insights into the role of nutrient resorption in plant adaptations to
geographic variations.