Changing climates are leading to more frequent and severe heat waves, potentially threatening plant populations. Both acclimation to stress and selection for heat-escape or heat-resistance phenotypes occur during heat waves. However, plastic responses and selection do not necessarily interact cohesively-even producing trait responses in opposite directions that could cause maladaptation. We examined patterns of maternal provisioning and natural selection on seed mass and germination characteristics after two natural heat waves across 12 annual populations of Mimulus guttatus. We then recreated heat-wave events occurring early and late within a growing season using a manipulative experiment to determine the reproducibility of our results. There was selection for greater seed mass during the year of the early season heat wave, and seed mass remained high through the late-season heat wave. Maternal provisioning also impacted seed mass and germination during the late-season heat wave. Field observations of seed mass only reflect selection for increased seed mass after the early season heat wave, and plants that experienced a late season heat wave had small seeds that germinated later. This pattern during the late season heat wave reflects decreased maternal provisioning coinciding with selection for larger seeds. Our results demonstrate that the relationship between selection and maternal provisioning fluctuates between years, facilitating adaptive evolution during an early-season heat wave and causing conflict during a late-season heat wave. The consequences for evolutionary responses are uncertain and depend on the seed bank, but could result in high mortality in heat waves occurring during successive years.

Understanding the habitat requirements of imperiled flora is critical for informing ex situ conservation practices, designing effective reintroduction strategies, and understanding how climate change will impact such species, especially in montane regions with high levels of environmental heterogeneity. In southern Appalachia, USA, the mountain sweet pitcher plant (Sarracenia rubra subsp. jonesii) and mountain purple pitcher plant (Sarracenia purpurea var. montana) inhabit overlapping ranges. These taxa rarely co-occur in the same mountain bogs but frequently hybridize at sites where they do co-occur. We assessed patterns of climatic niche differentiation in these imperiled taxa to explore whether they naturally co-occur or may have been brought into secondary contact through human translocations. In addition, we constructed ecological niche models to evaluate the comparative availability of suitable habitat for each taxon under present and future climates. Sarracenia purpurea var. montana inhabits higher elevation habitats than Sarracenia rubra subsp. jonesii, and these differences in elevation correspond with differences in climatic niche. Under the most likely future climate scenario, models predicted that habitat matching the climatic niche of Sarracenia rubra subsp. jonesii will decline in area by 95% by 2080, while habitat matching the climatic niche of Sarracenia purpurea var. montana will increase in area by 13%. Despite high spatial overlap, these two related taxa exhibit divergent climatic niches, resulting in highly different management needs and conservation approaches. We raise concerns about the future of mountain bog plant assemblages, and the rare species they include, under climate change.

Leaf respiration is a key metabolic process controlling leaf carbon balance. However, empirical data on leaf respiration, particularly in the light (RL), remain scarce for ferns, and no study has systematically compared respiration-trait relationships between ferns and seed plants. We measured seven leaf traits, including leaf respiration in the dark (RD), RL, light-saturated photosynthetic rate (Asat), leaf N and P content, leaf dry mass per unit area (LMA), and leaf dry mass content (LDMC) in 19 ferns. These fern data were analyzed in comparison with seed plant data from the Glopnet data set. Light inhibition of leaf respiration averaged 37%. Ferns had significantly lower LMA, Asat, and RD than seed plants. Standardized major axis analyses (SMA) revealed the slopes of RD vs. LMA, Asat, and P differed significantly between ferns and seed plants, while RD-N relationships shared common slopes, but their intercept differed markedly. Generalized linear models identified LMA and RD as the strongest predictors of RL, jointly explaining 70.6% of its variation. The terrestrial understory ferns employ a distinct "low-cost, slow-cycling" strategy-characterized by a unique combination of low leaf construction cost (LMA) and low metabolic rates (photosynthesis and respiration), which deviates from the traditional fast-slow leaf economics spectrum. The divergent respiration-trait relationships suggest that applying trait-based models parameterized solely for seed plants to ferns may introduce uncertainty into ecosystem models. This highlights the value of incorporating fern-specific trait relationships to refine projections of the global carbon cycle.

Flower color, a key trait influencing plant-pollinator interactions, may be influenced by abiotic factors such as soil. We investigated association between pollinators, soil characteristics, and flower color variations in Digitalis purpurea across native populations in Sweden and introduced populations in Bolivia. We measured floral traits, reflectance of petals and nectar-guide spots, plant size, pollinator visitation, fruit set, seed production, germination, and soil characteristics. Individuals were categorized into violet, pink, and white morphs, which were confirmed by spectral measurements and bee vision modelling. Reflectance of inner nectar-guide spots overlapped across morphs, potentially limiting pollinator discrimination. Bumblebees were the main pollinators in all populations. Although visitation varied among morphs, pollinator visits to different color morphs were population specific. In Bolivia, violet flowers were predominant (70-87%), with pink (13-17%) and white (0-13%) at lower frequencies. In Sweden, morph frequencies were more even (violet 20-43%, pink 38-69%, white 11-30%). Morph frequency was not associated with soil composition, despite differences between regions. Reproductive fitness varied across populations but not consistently among morphs: The largest Swedish population had the highest fruit set but the lowest seed set, while germination was lower in Bolivia. Phosphorus was lower in soil beneath violet individuals; other soil variables, plant size, and floral traits did not differ among color morphs. Floral color variation in D. purpurea was not significantly related to pollinator visitation or soil conditions at the spatial scale examined, suggesting maintenance by local environmental conditions, neutrality, or historical and demographic processes rather than selection.

Touch-sensitive stigmas (TSSs), specialized receptive structures in angiosperms, dynamically respond to mechanical stimulation or pollen deposition. The typical sequence comprises temporary closure, reopening, and permanent closure, which optimize pollen capture, retention, and fertilization success. However, the specific environmental and pollination-related factors regulating these phases are unexplored. Here we systematically investigated the association of environmental (temperature and humidity) and pollination-related factors (amount of pollen deposited [load], position of pollen tube, and growth rate of pollen tube) with the temporal dynamics of stigma movements in Mazus miquelii, a species with TSS. Temporary closure and reopening were primarily associated with temperature and were independent of the pollen load. In contrast, permanent closure was strongly correlated with the pollen load and position and growth rate of pollen tube. Furthermore, temporary closure and reopening time were negatively correlated, although neither were significantly correlated with permanent closure time. Rapid temporary closure and reopening events were primarily associated with environmental cues, whereas irreversible permanent closure was associated with pollination-related signals. These advances in our understanding of the ecological regulation of TSS behavior provide a foundation for future studies into the physiological and molecular mechanisms of touch sensitivity of stigmas.

Interpretations of evolutionary outcomes are limited without incorporation of physiological ecology, and ecophysiological interpretations would benefit from incorporating evolutionary perspectives. Although there has been a rise of studies in the last 20 years between these fields, evolutionary studies that incorporate plant physiology have largely focused on the same traits (e.g., flowering time, specific leaf area), neglecting cellular and developmental traits. This neglect is largely due to the high throughput demands in evolutionary studies and the lack of technological advancements in ecophysiology. However, this bias in measured traits has resulted in limiting our understanding of the evolution of plant form and function. On the other hand, most detailed studies on plant physiological and anatomical responses to the environment are either in applied sciences, focused on economically important plants, or examine model organisms rather than wild populations. These detailed ecophysiological studies generally do not incorporate evolutionary discourse, even though they often study adaptation. The aim of this synthesis is to offer a comprehensive resource, building upon previous works, for researchers to bridge the gap between ecophysiology and evolutionary ecology.

The maintenance of gynodioecy, female and hermaphroditic coexistence in plants, requires females to have a reproductive advantage over hermaphrodites in offspring quality, quantity, or both. Pollinators can influence this by mediating the reproductive success of females and hermaphrodites. We measured differences in pollinator-mediated fitness components between female and hermaphroditic plants in Sidalcea campestris to evaluate the role of pollinator-mediated selection in maintaining gynodioecy. We studied sex-biased pollinator dynamics across 28 gynodioecious populations of S. campestris and conducted pollen supplementation experiments in 20 of these populations. Using pollinator surveys and pollen supplementation experiments, we tested for differences in pollinator visitation rates, pollinator community composition, seed production, and pollen limitation between sexes. Hermaphrodites received an average of 2.24 times more visits than females, although pollinator community composition was similar for both sexes. The estimated average probability of female seed set was 1.7 times higher than hermaphrodites for open-pollinated flowers and 2.0 times higher for hand-pollinated flowers, providing evidence of a female reproductive advantage. Seed set in both sexes was pollen limited, and females were not more limited than hermaphrodites. Female pollen limitation was unaffected by population-level female frequency. These results revealed complex pollinator-mediated fitness differences between females and hermaphrodites. While our study demonstrated that females achieve the expected reproductive advantage for cytonuclear gynodioecy, the lack of differential pollen limitation and frequency-dependent female fitness are inconsistent with expectations of stable gynodioecy. Additional environmental, ecological, and genetic factors may regulate population dynamics in this gynodioecious system.

Species of Deuterocohnia (17 spp.) show extraordinary variation in elevation (0-3900 m a.s.l.) and growth forms, and many have narrow geographic distributions in the west-central Andes and the Peru-Chile coast. Previous research using few plastid and nuclear loci failed to produce well-resolved or supported phylogenies. Here we sequenced 1815 single-copy nuclear genes and whole plastomes to infer relationships, screen for reticulation, reconstruct evolution of vegetative and floral characters, and evaluate species groups and their historical biogeography. We developed the Bromeliad1815 bait set to capture low-copy nuclear genes across Bromeliaceae, producing nuclear and plastome phylogenies for Deuterocohnia and outgroups in six bromeliad subfamilies using maximum likelihood, ASTRAL, and network analyses; test for cytonuclear conflict and its potential causes; and evaluate evolution of morphological characters in relation to each other and elevation using phylogenetic PCA and phylogenetic regression. We produced fully resolved, strongly supported nuclear and plastome phylogenies for Deuterocohnia, with crown ages of 5.5 and 8.0 Mya, respectively. Cytonuclear conflict appears driven mainly by hybridization/introgression, consistent with several species co-occurring in small areas. Vegetative organs and growth form become increasingly compact with elevation, reflecting adaptation to desiccation, wind exposure, and cold soils. Deuterocohnia arose in southeastern Bolivia and repeatedly evolved up- and downslope into other habitats from Andean Yungas at mid-elevation. Our results imply rapid adaptive divergence (e.g., in strobilifera-chrysantha), convergent evolution (two origins of the cushion growth-form), phylogeny consistent with form in some cases (e.g., seramisiana-brevispicata-meziana) and recurrent effects of the Rio Pilcomayo barrier on speciation and chloroplast capture.

A number of ecologically important tropical trees form symbiotic ectomycorrhizal (EcM) fungal associations including the Dipterocarpaceae, that dominate lowland forests of South-east Asia. Whilst numerous pot-based studies have focused on the importance of EcMs for dipterocarp seedling growth and performance, few field studies have been undertaken. In a 20-month field experiment in Malaysian Borneo, two species with contrasting light requirements-shade-tolerant Hopea nervosa and the more light-demanding Parashorea tomentella-were subjected to the factorial addition of fungicide (to reduce EcM colonization) and nutrients. Fungicide addition reduced EcM colonization by a small but significant percentage. Reductions in foliar nitrogen, phosphorus, and chlorophyll concentrations in both species and in calcium and magnesium concentrations in H. nervosa did not translate into reduced biomass in either species. When given additional nutrients, H. nervosa had no increase in foliar nutrient concentrations or biomass, but P. tomentella had an increase in foliar nitrogen, phosphorus, and magnesium concentrations and more than doubled its biomass. When nutrients were added but EcM reduced, P. tomentella did not increase in biomass. EcM fungi can play an important role in influencing dipterocarp seedling mineral nutrition, and P. tomentella may require EcMs to effectively utilize additional mineral nutrient sources. The importance of nutrient uptake for biomass production is less clear and may be confounded by the use of fungicide to control EcM colonization.

Flowers that present their anthers and stigma in close proximity can achieve precise animal-mediated pollen transfer, but risk self-pollination. One evolutionary solution is reciprocal herkogamy. Reciprocity of anther and style positions among different plants (i.e., a genetic dimorphism) is common in distylous plants, but very rare in enantiostylous plants. We investigated the pollination and reproductive system of the enantiostylous Caribbean plant Cubanicula xanthorrhizos (Haemodoraceae). We assessed stylar orientation of flowers and conducted controlled pollination experiments. We used videography of flower visitors and pollen load analysis to determine the pollination mechanism. We also measured floral morphology, pollen production, spectral reflectance, and volatile emissions. Cubanicula xanthorrhizos exhibits dimorphic enantiostyly with c. 50:50 left- to right-styled morphs. Plants are self-compatible, but pollinator dependent for seed production. Intra- and intermorph crosses are equally fertile. The nectarless flowers are pollinated by female carpenter bees (Xylocopa cubaecola) that collect pollen, often by sonication, from two centrally positioned yellow feeding anthers. An inconspicuous deflected pollinating anther deposits pollen on the side of the bee thorax, which contacts the stigma of the mirror-image morph. A yellow-orange "guide" on the white tepals appears to be a visual attractant. Flowers emit methoxy benzenoid volatiles that may also attract bees. Reciprocity of the style with a single pollinating stamen in C. xanthorrhizos appears to promote intermorph pollen export via "safe sites" on pollen-collecting bees. This novel case of dimorphic enantiostyly contributes to understanding of the evolution of floral polymorphisms.