Climate shapes the seed germination niche of temperate flowering plants: a meta-analysis of European seed conservation data

Abstract

Background and Aims Interactions between ecological factors and seed physiological responses during the establishment phase shape the distribution of plants. Yet, our understanding of the functions and evolution of early-life traits has been limited by the scarcity of large scale datasets. Here, we tested the hypothesis that the germination niche of temperate plants is shaped by their climatic requirements and phylogenetic relatedness, using germination data sourced from a comprehensive seed conservation database of the European flora (ENSCOBASE). Methods We performed a phylogenetically informed Bayesian meta-analysis of primary data, considering 18,762 germination tests of 2,418 species from laboratory experiments conducted across all European geographic regions. We tested for the interaction between species’ climatic requirements and germination responses to experimental conditions including temperature, alternating temperature, light and dormancy breaking treatments, while accounting for between-study variation related to seed sources and seed lot physiological status. Key Results Climate was a strong predictor of germination responses. In warm and seasonally dry climates the seed germination niche includes a cold-cued germination response and an inhibition determined by alternating temperature regimes and cold stratification, while in climates with high temperature seasonality opposite responses can be observed. Germination responses to scarification and light were related to seed mass, not climate. We also found a significant phylogenetic signal in the response of seeds to experimental conditions, providing evidence that the germination niche is phylogenetically constrained. Nevertheless, phylogenetically distant lineages exhibited common germination responses under similar climates. Conclusion This is the first quantitative meta-analysis of the germination niche at a continental scale. Our findings showed that the germination niche of European plants exhibit evolutionary convergence mediated by strong pressures at the macroclimatic level. In addition, our methodological approach highlighted how large datasets generated by conservation seed banking are valuable sources to address questions in plant macroecology and evolution.

Correlated evolution of seed mass and genome size varies among life forms in flowering plants

“…The findings of this work can help to predict the functional responses of plant traits and their prevalence in response to current and future climate change (Baskin and Baskin, 2022; Carta et al, 2022). Moreover, understanding how life-history and functional seed traits interplay may support the potential domestication process of yet to be explored wild plants, unlocking their potential economic, nutritional, medicinal and cultural value (Mattana et al, 2022).…”

Alpine plant communities differ in their seed germination requirements along a snowmelt gradient in the Caucasus

“…Alpine seed germination has been suggested to follow a common strategy aimed at increasing seedling establishment chances under harsh environmental conditions (Fernández-Pascual et al 2021;Carta et al 2022). The general tendency to a warm-cued germination detected for the study species suggests that North Caucasian alpine plants employ the same strategy to postpone seed germination to warmer summer months characterised by a comparatively low probability of severe frost events negatively affecting seedling of alpine plants (Rosbakh and Poschlod 2015); Rosbakh et al 2020b).…”

“…The physiological process of seed germination is therefore an essential life stage that must be timed to occur when the environment is favourable for subsequent seedling survival and growth (Poschlod et al 2013). This has led to a widespread alpine seed germination strategy characterized primarily by physiological seed dormancy, a strong need for cold stratification to break dormancy and warm-cued germination (Fernández-Pascual et al 2021;Carta et al 2022). However, this common strategy most likely hides important variability among species.…”

Low availability of functional seed trait data from the tropics could negatively affect global macroecological studies, predictive models and plant conservation

“…SeedArc: http://unioviedo.es/seedarc/ ). In addition, the availability of seed trait data generated by conservation seed banks could help overcome this geographical bias, as shown for example by the germination data downloaded from the Millennium Seed Bank Partnership Data Warehouse ( http://brahmsonline.kew.org/msbp ) in Sentinella et al (2020) (see also the methodological approach in Carta et al , 2022 ). Because reasons for geographical bias include availability of funding and geographical distribution of researchers ( Culumber et al , 2019 ), our suggested strategies could be enabled and supported through additional funding opportunities for tropical plant research, as well as international collaborations.…”