Time‐traveling seeds reveal that plant regeneration and growth traits are responding to climate change

Abstract

Studies assessing the biological impacts of climate change typically rely on longterm, historic data to measure trait responses to climate through time. Here, we overcame the problem of absent historical data by using resurrected seeds to capture historic plant-trait data for a number of plant regeneration and growth traits. We collected seed and seedling trait measurements from resurrected historic seeds and compared these with modern seed and seedling traits collected from the same species in the same geographic location. We found a total of 43 species from southeastern Australia for which modern/historic seed pairs could be located. These species were located in a range of regions that have undergone different amounts of climate change across a range of temperature, precipitation, and extreme measures of climate. There was a correlation between the amount of change in climate metrics, and the amount of change in plant traits. Using stepwise model selection, we found that for all regeneration and growth trait changes (except change in stem density), the most accurate model selected at least two measures of climate change. Changes in extreme measures of climate, such as heatwave duration and changes in climate variability, were more strongly related to changes in regeneration and growth traits than changes in mean climate metrics. Across our species, for every 5% increase in temperature variability, there was a threefold increase in the probability of seed viability and seed germination success. An increase of 1 d in the maximum duration of dry spells through time led to a 1.5-fold decrease in seed viability and seeds became 30% flatter/thinner. Regions where the maximum heatwave duration had increased by 10 d saw a 1.35-cm decrease in seedling height and a 1.04-g decrease in seedling biomass. Rapid responses in plant traits to changes in climate may be possible; however, it is not clear whether these changes will be fast enough for plants to keep pace with future climate change.

A test of local adaptation to drought in germination and seedling traits in populations of two alpine forbs across a 2000 mm/year precipitation gradient

“…For both species, seedling survival declined with decreasing water availability in line with results from other studies (Everingham et al, 2021 ; Harrison & LaForgia, 2019 ; Hovenden et al, 2008 ). Surviving seedlings of V. alpina showed a higher investment in belowground biomass at low water availability in line with our prediction (P3) and other studies (Harrison & LaForgia, 2019 ; Larson et al, 2020 ).…”

“…It could also indicate a potentially non‐linear trend along the precipitation gradient where other factors than pure precipitation amount might influence the tolerance to drought. Mean annual precipitation has been found to be less important for changes in germination and seedling traits, while climatic effects such as the duration of heatwaves and dry spells, or the range of precipitation were found to be more important (Everingham et al, 2021 ; Orsenigo et al, 2014 ). In our study system, the variation in precipitation is highest in the wettest end of the gradient (Gya, 2022 ), which could mean that the high variation in precipitation in the wettest sites could also increase the number of drought events for the wettest populations.…”

Evolution of plant drought strategies and herbivore tolerance after two decades of climate change

“…A powerful method to test for recent evolution is the resurrection approach in which ancestors raised from stored seeds (e.g. from seed banks) are compared in common garden experiments to newly sampled descendants from the same populations (Franks et al ., 2007, 2018; Franks & Weis, 2008; Orsini et al ., 2013; Merilä & Hendry, 2014; Everingham et al ., 2021; Rauschkolb et al ., 2022). On its own, the resurrection approach only reveals whether evolutionary changes occurred; it cannot answer to which degree these resulted from natural selection, genetic drift, immigration of new genotypes or mutations (Niklas, 1997; Leinonen et al ., 2008).…”

Plant Diversity Conservation Challenges and Prospects—The Perspective of Botanic Gardens and the Millennium Seed Bank

“…A further issue with seed banks is that the material is in stasis, offering a snapshot of the genetic diversity of a population at the time of collecting. While this is helpful for resurrection studies (e.g., [74]) it means that material is no longer evolving. Living collections have a similar problem; while their plants can adapt and evolve, it is to conditions often outside their native range.…”