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Abstract Global change has profoundly altered the eco-evolutionary trajectories of plant species. Longitudinal studies often document phenotypic shifts in response to climate change, such as earlier flowering in the spring, but it remains challenging to disentangle the contributions of phenotypic plasticity and adaptive evolution to shifted phenotypic distributions. The resurrection approach has emerged as a powerful method to study genetic and plastic responses to novel selection imposed by global change by contrasting ancestral and descendant lineages from the same population under common conditions. Here, we compiled a database of 52 resurrection studies to examine key hypotheses about plant evolutionary responses to global change using a meta-analysis (40 of the studies) and quantitative review (all 52 studies). We found evidence for rapid, contemporary evolution, which often appeared adaptive, in over half of the cases, including some of the fastest cases of evolution in natural populations ever observed. Annual plants evolved earlier reproduction, and leaf economic traits associated with stress escape strategies. We also found evolution of increased plasticity for annual plants in phenology and physiology traits, and a reduction of plasticity in traits related to the leaf economic spectrum. We found less evidence for evolution in perennial species. Overall, our findings demonstrate the key role of drought escape in plant responses to a warming world. However, the lack of evolution in other traits and species indicates that constraints may dampen evolutionary responses in some scenarios. Our review also suggests promising avenues of future research for resurrection studies.
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Rapid evolution during climate change: demographic and genetic constraints on adaptation to severe drought
Populations often vary in their evolutionary responses to a shared environmental perturbation. A key hurdle in building more predictive models of rapid evolution is understanding this variation—why do some populations and traits evolve while others do not? We combined long-term demographic and environmental data, estimates of quantitative genetic variance components, a resurrection experiment and individual-based evolutionary simulations to gain mechanistic insights into contrasting evolutionary responses to a severe multi-year drought. We examined five traits in two populations of a native California plant, Clarkia xantiana , at three time points over 7 years. Earlier flowering phenology evolved in only one of the two populations, though both populations experienced similar drought severity and demographic declines and were estimated to have considerable additive genetic variance for flowering phenology. Pairing demographic and experimental data with evolutionary simulations suggested that while seed banks in both populations likely constrained evolutionary responses, a stronger seed bank in the non-evolving population resulted in evolutionary stasis. Gene flow through time via germ banks may be an important, underappreciated control on rapid evolution in response to extreme environmental perturbations.
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- PAR ID:
- 10441314
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 290
- Issue:
- 1998
- ISSN:
- 0962-8452
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Under global change, the impact of seed banks on evolutionary rescue is uncertain. They buffer plant populations from demographic and genetic stochasticity but extend generation time and can become a reservoir of maladapted alleles. We built analytical and individual-based models to predict the effect of seed banks on the persistence of small annual plant populations facing an abrupt or sustained directional change in uni- or multivariate trait optima. Demogenetic dynamics predict that under most scenarios seed banks increase the lag yet enhance persistence to 200–250 years by absorbing demographic losses. Simulations indicate that the seed bank has a minimal impact on the genetic skew, although we suggest that this result could depend on the fitness component under selection. Our multivariate model reveals that by enlarging and reshaping the G matrix, seed banks can diminish the impact of mutational correlation and even accelerate adaptation under antagonistic pleiotropy relative to populations without a bank. We illustrate how the magnitude of optimum fluctuations, type and degree of optimum change, selection strength, and vital rates are weights that tip the scales determining persistence. Finally, our work highlights that migration from the past is not maladaptative when optimum fluctuations are large enough to create stepping stones to the new optimum.more » « less
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Abstract BackgroundThe frequency and intensity of droughts are expected to increase under global change, driven by anthropogenic climate change and water diversion. Precipitation is expected to become more episodic under climate change, with longer and warmer dry spells, although some areas might become wetter. Diversion of freshwater from lakes and rivers and groundwater pumping for irrigation of agricultural fields are lowering water availability to wild plant populations, increasing the frequency and intensity of drought. Given the importance of seasonal changes and extremes in soil moisture to influence plant reproduction, and because the majority of plants are flowering plants and most of them depend on pollinators for seed production, this review focuses on the consequences of drought on different aspects of reproduction in animal-pollinated angiosperms, emphasizing interactions among drought, flowering and pollination. ScopeVisual and olfactory traits play crucial roles in attracting pollinators. Drought-induced floral changes can influence pollinator attraction and visitation, together with pollinator networks and flowering phenology, with subsequent effects on plant reproduction. Here, we review how drought influences these different aspects of plant reproduction. We identify knowledge gaps and highlight areas that would benefit from additional research. ConclusionsVisual and olfactory traits are affected by drought, but their phenotypic responses can vary with floral sex, plant sex, population and species. Ample phenotypic plasticity to drought exists for these traits, providing an ability for a rapid response to a change in drought frequency and intensity engendered by global change. The impact of these drought-induced changes in floral traits on pollinator attraction, pollen deposition and plant reproductive success does not show a clear pattern. Drought affects the structure of plant–pollinator networks and can modify plant phenology. The impact of drought on plant reproduction is not always negative, and we need to identify plant characteristics associated with these more positive responses.more » « less
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rspb.2023.0336
