Simulated climate warming scenarios lead to earlier emergence and increased weight loss but have no effect on overwintering survival in solitary bees

Insect pollination is critical for both wildflower stability and agricultural yields, with solitary bees being a group of pollinators of fundamental importance. However, documented declines in populations, exacerbated by environmental pressures, including climate change, pose significant threats to the provision of ecosystem services. Exposure to elevated temperatures during periods of dormancy, such as overwintering, is predicted to lead to phenological shifts, changes in condition, and impacts on survival. However, we currently lack studies that inform how such aspects are affected in future climate change scenarios. Using simulated temperature regimes informed by predictions of the Intergovernmental Panel on Climate Change, we exposed overwintering mason bees (Osmia species) to three field-relevant temperature profiles based on either present-day overwintering temperatures or future temperatures predicted under two major climate warming scenarios (SSP2-4.5 and SSP5-8.5) and measured how temperature exposure affected emergence timing, weight loss, and survival. We found that exposure to temperatures under intermediate and worst-case climate warming scenarios led to earlier emergence by approximately three and six weeks, respectively, with increasing divergences in timing of emergence between the sexes of Osmia bicornis, which may lead to intraspecific phenological mismatches. While we found no effect of temperature on overwintering survival rates, we observed increased weight loss prior to emergence but found that in contrast to other studies, it only mildly mediated shifts in emergence timing brought about by temperature exposure, suggesting that weight loss is unlikely to play a major role as a trigger of emergence timing in mason bees. Our study contributes to the growing literature highlighting the impact that temperatures under climate change models will have on the timing of key life events for essential pollinators, which may have consequences at the population and community levels.

Impact of high temperature in 2023 and 2024 on spring leaf flush phenology in Japan derived by GCOM-C satellite

In Japan, the exceptionally high temperatures in 2023 and 2024 may have impacted vegetation phenology. We investigated the timing of the spring leaf flush (SOS) of non-evergreen plants using satellite remote sensing. We utilized data from the SGLI sensor on JAXA's GCOM-C satellite. Compared to NASA's MODIS sensors, which are widely used for phenology studies, GCOM-C/SGLI offers two advantages: more stable orbital control in recent years and a higher spatial resolution (250 m) in the green channel which allows to calculate the Chlorophyll Carotenoid Index (CCI), a more robust index than NDVI against snowmelt. We defined the onset of SOS as the point where CCI exceeds zero during spring, and estimated SOS over seven years (2018-2024) in Japan, validated with ground-based time-lapse camera data. On average (2018-2022), SOS tended to occur later in northern or inland mountainous areas. Compared to the average, SOS in 2023 and 2024 occurred earlier in most of northern Japan. Specifically, an earlier SOS by 3 to 7 days occurred in the southern Tohoku, Kanto, and Chubu in 2023, and across the entire Tohoku and Hokuriku in 2024. These responses of SOS to temperature anomalies align with previous studies on future phenology in Japan.

Floral reward traits change between sexual phases in two Helleborus species

Nectar and pollen attractants as well as visitors in Helleborus viridis ssp. viridis and H. purpurascens (Ranunculaceae), i.e. European species, were studied during two flowering seasons. The long-lived flowers of these species are characterized by long nectar availability lasting 15-17 days, i.e. until the end of pollen presentation. On average, approx. 2-fold more nectar and sugar mass was available in the flowers of H. viridis ssp. viridis compared to H. purpurascens. Both species are protogynous, having an initial female phase lasting for 3 days. The nectar and sugar mass was consistently male-biased. At the end of the flower's life span, the nectar mass and the sugar concentration decreased considerably. In both species, sucrose predominated in the nectar, which also contained small quantities of other disaccharides (maltose and trehalose) and monosaccharides (glucose and fructose). The chemical composition of the nectar sugar varied between the sexual phases; sucrose in the female-phase nectar was replaced mainly by fructose. In addition to nectar, the flowers offered pollen (between 2 and 4 and 10-17 days of anthesis). In the study area, both Helleborus species were foraged by queens of bumble bees and honey bees; however, their distribution differed between the species. Bumble bees dominated in H. viridis subsp. viridis, whereas both pollinator groups were noted with a similar frequency in H. purpurascens.

Development and Application of Novel SSR Markers to Assess the Genetic Diversity and Population Structure of Phacelia secunda Along an Altitudinal Gradient in the Central Chile Andes

Phacelia secunda J.F. Gmel. (Boraginaceae) is a widely distributed insect-pollinated perennial herb. In central Chile (33° S), it occurs from the sea level up to 3600 m in the Andes, exhibiting broad morphological variation. In this study, we developed and characterized novel polymorphic microsatellites for this species, using an Illimina MiSeq sequencing platform. Nineteen polymorphic loci were obtained, with alleles numbers ranging from 3 to 13 per locus (mean = 5.84). Observed (HO) and expected heterozygosities (HE) ranged from 0.050 to 0.900 and from 0.049 to 0.825, respectively. These markers were applied to assess the genetic diversity and population structure along an altitudinal spanning from 1600 to 3600 m. The highest elevation population exhibited significantly lower within-population genetic diversity compared to lower-elevation populations. Significant population differentiation was observed along the gradient. Gene flow estimates support a stepping-stone like mode of migration, with greater exchange between adjacent elevations. These new microsatellites provide a valuable tool for elucidating the influence of altitude on genetic diversity and structure, and for evaluating the roles of local adaptation and phenotypic plasticity in shaping population variation.

Floral freezing tolerance is tied to flowering time in North American woody plant species

BACKGROUND AND AIMS

As winter and spring temperatures continue to increase, the timing of flowering and leaf-out is advancing in many seasonally cold regions. This advancement could put plants that flower early in the spring at risk of decreased reproduction in years when there are late freeze events. Unfortunately, relatively little is known about floral freezing tolerance in forest communities. In this study, we examined the impact of freezing temperatures on the flowers of woody plants in a region where there is rapid winter warming in North America.

METHODS

We subjected the flowers of 25 woody species to a hard (-5 °C) and a light freeze (0 °C). We assessed tissue damage using electrolyte leakage. In a subset of species, we also examined the impact of a hard freeze on pollen tube growth. To determine if the vulnerability of flowers to freezing damage relates to flowering time and to examine the responsiveness of flowering time to spring temperature, we recorded the date of first flower for our study species for 3 years.

KEY RESULTS AND CONCLUSIONS

Across species, we found that floral freezing tolerance was strongly tied to flowering time, with the highest freezing tolerance occurring in plants that bloomed earlier in the year. We hypothesize that these early blooming species are unlikely to be impacted by a false spring. Instead, the most vulnerable species to a false spring should be those that bloom later in the season. The flowering time in these species is also more sensitive to temperature, putting them at a great risk of experiencing a false spring. Ultimately, floral damage in one year will not have a large impact on species fitness, but if false springs become more frequent, there could be long-term impacts on reproduction of vulnerable species.

Flowering time responses to warming drive reproductive fitness in a changing Arctic

BACKGROUND AND AIMS

The Arctic is warming at an alarming rate, leading to earlier spring conditions and plant phenology. It is often unclear to what degree changes in reproductive fitness (flower, fruit and seed production) are a direct response to warming versus an indirect response through shifting phenology. The aim of this study was to quantify the relative importance of these direct and indirect pathways and project the net effects of warming on plant phenology and reproductive fitness under current and future climate scenarios.

METHODS

We used two long-term datasets on 12 tundra species in the Canadian Arctic as part of the International Tundra Experiment (ITEX). Phenology and reproductive fitness were recorded annually on tagged individual plants at both Daring Lake, Northwest Territories (64° 52' N, - 111° 35' W) and Alexandra Fiord, Nunavut (78° 49' N, - 75° 48' W). The plant species encompassed a wide taxonomic diversity across a range of plant functional types with circumpolar/boreal distributions. We used hierarchical Bayesian structural equation models to compare the direct and indirect effects of climate warming on phenology and reproductive fitness across species, sites and years.

KEY RESULTS

We found that warming, both experimental and ambient, drove earlier flowering across species, which led to higher numbers of flowers and fruits produced, reflecting directional phenotypic selection for earlier flowering phenology. Furthermore, this indirect effect of climate warming mediated through phenology was generally about two to three times stronger than the direct effect of climate on reproductive fitness. Under future climate predictions, individual plants showed a ~2- to 4.5-fold increase in their reproductive fitness (flower counts) with advanced flowering phenology.

CONCLUSIONS

Our results suggest that, on average, the benefits of early flowering, such as increased development time and subsequent enhanced reproductive fitness, might outweigh its risks. Overall, this work provides important insights into population-level consequences of phenological shifts in a warming Arctic over multi-decadal time scales.

Species that require long-day conditions to flower are not advancing their flowering phenology as fast as species without photoperiod requirements

BACKGROUND AND AIMS

Over the last few decades, many plant species have shown changes in phenology, such as the date on which they germinate, bud or flower. However, some species are changing more slowly than others, potentially owing to daylength (photoperiod) requirements.

METHODS

We combined data on flowering-time advancement with published records of photoperiod sensitivity to try to predict which species are advancing their flowering time. Data availability limited us to the Northern Hemisphere.

KEY RESULTS

Cross-species analyses showed that short-day plants advanced their flowering time by 1.4 days per decade and day-neutral plants by 0.9 days per decade, but long-day plants delayed their flowering by 0.2 days per decade. However, photoperiod-sensitivity status exhibited moderate phylogenetic conservation, and the differences in flowering-time advancement were not significant after phylogeny was accounted for. Both annual and perennial herbs were more likely to have long-day photoperiod cues than woody species, which were more likely to have short-day photoperiod cues.

CONCLUSIONS

Short-day plants are keeping up with plants that do not have photoperiod requirements, suggesting that daylength requirements do not hinder changes in phenology. However, long-day plants are not changing their phenology and might risk falling behind as competitors and pollinators adapt to climate change.

Does pollination interact with the abiotic environment to affect plant reproduction?

BACKGROUND AND AIMS

Abiotic and biotic components of the environment both limit plant reproduction, but how they interact with one another in combination is less understood. Understanding these interactions is especially relevant because abiotic and biotic environmental components respond differently to various drivers of global change. Here, we aim to understand whether the effects of pollination (biotic component) on plant reproduction depend on soil moisture (abiotic component), two factors known to affect plant reproduction and that are changing with global change.

METHODS

We conducted pollen supplementation experiments for two plant species, Delphinium nuttallianum and Hydrophyllum fendleri, in subalpine meadows in the Western USA across 4 years that varied in soil moisture. In a separate 1-year field experiment, we crossed water addition with pollen supplementation factorially. We measured the proportion of fruit set, seeds per fruit and seeds per plant, in addition to stomatal conductance, to determine whether plant physiology responded to watering.

KEY RESULTS

In the 4-year study, only H. fendleri reproduction was pollen limited, and this occurred independently of soil moisture. Experimental water addition significantly increased soil moisture and stomatal conductance for both species. The effect of pollen addition on reproduction depended on the watering treatment only for H. fendleri fruit production. Reproduction in D. nuttallianum was not significantly affected by pollen addition or water addition, but it did respond to interannual variation in soil moisture.

CONCLUSIONS

Although we found some evidence for the effect of a biotic interaction depending on abiotic conditions, it was only for one aspect of reproduction in one species, and it was in an unexpected direction. Our work highlights interactions between the abiotic and biotic components of the environment as an area of further research for improving our understanding of how plant reproduction responds to global change.

The Late Orchid Catches the Bee: Frost Damage and Pollination Success in the Face of Global Warming in a European Terrestrial Orchid

Global warming changes flowering times of many plant species, with potential impacts on frost damage and their synchronization with pollinator activity. These effects can have severe impacts on plant fitness, yet we know little about how frequently they occur and the extent of damage they cause. We addressed this topic in a thermophilic orchid with a highly specific pollination mechanism, the Small Spider Orchid, Ophrys araneola RchB, in six populations in Northern Switzerland. We measured flowering time, frost damage, and fruiting success in 1250 individually marked plants during 3 years, and documented spring temperatures. Using regression models with historical climate data, we estimated past and future frost damage. In addition, we analyzed historical records of the orchid and its only verified pollinator, the solitary bee Andrena combinata in Northern Switzerland, to estimate potential desynchronization between flowering and pollinator activity due to climate change. Increased spring temperatures accelerated flowering time, and together with the number of frost days explained frost damage well. Frost damage was severe and early-flowering plants were more likely to be damaged. Historical climate data suggested frost damage has increased in the last decades and may increase further in the future. All populations but one had very low fruit set, and plants that flowered earlier were less likely to set fruit. The historical data from between 1970 and 2019 showed a significant advance of flowering- and pollinator occurrence time in the last decades, but to a similar degree in orchids and bees. Our study shows that the orchid, despite being limited to warm habitats in central Europe, suffers under global warming by increased frost damage caused by earlier flowering. We did not detect an effect of accelerated flowering on desynchronization in flowering time and pollinator activity in this orchid species.

Warming induces short-term phenological shifts in pollinator-plant interactions that enhance larval development in honey bee

Climate warming can precipitate mismatches in plant-pollinator interactions by altering their phenologies of both parties, impacting ecosystem services. While most studies have focused on long-term, seasonal phenological shifts, the effect of warming on short-term phenological match-mismatch in these interactions remains unclear. Here, we investigate how experimental warming affects within-day foraging behavior of the honey bee (Apis mellifera) and plant anthesis, and whether the resulting changes in bee pollen composition, in terms of the relative abundance of pollen from different plant species, influences larval development. Experimental warming advanced both the within-day foraging by bees and anthesis of Bidens pilosa-the predominant pollen source among all plant species represented in the collected pollen. Through experimental manipulation of pollen composition, we demonstrated that an increased proportion of B. pilosa pollen in the diet enhanced bee larval growth efficiency. Overall, our study demonstrates that warming may influence pollinator interactions with the many plant species by affecting pollinator behaviors and plant anthesis on short-term temporal scales, with potential implications for pollinator larval development.

Dying of thirst: Osmoregulation by a hawkmoth pollinator in response to variability in ambient humidity and nectar availability

Climate-induced shifts in flowering phenology can disrupt pollinator-floral resource synchrony, especially in desert ecosystems where rainfall dictates both. However, baseline metrics to gauge pollinator health in the wild amidst rapid climate change are lacking. Our laboratory-based study establishes a baseline for pollinator physiological state by exploring how osmotic conditions influence survivorship in a desert hawkmoth pollinator, Manduca sexta. We sampled hemolymph osmolality from over 1000 lab-grown moths at 20 %, 50 %, and 80 % ambient humidity levels. Starved moths maintained healthy osmolality of 350-400 mmol/kg for 1-3 days after eclosion regardless of ambient humidity, but it sharply rose to 550 mmol/kg after 4-5 days in low and moderate humidity, and after 5 days in high humidity. Starved moths in low humidity conditions perished within 5 days, while those in high humidity survived twice as long. Moths fed synthetic Datura wrightii nectar, synthetic Agave palmeri nectar, or water, maintained osmolality within a healthy range of 350-400mmol/kg. The same was true for moths fed authentic floral nectars from Datura and Agave plants, although moths consumed more synthetic than authentic nectars, possibly due to non-sugar constituents. Simulating a 4-day mismatch between pollinator emergence and nectar availability, a single nectar meal osmotically rescued moths under dry ambient conditions. Our findings highlight hemolymph osmolality as a rapid and accurate biomarker distinguishing dehydrated from hydrated states in insect pollinators.

Warm Spring Days are Related to Shorter Durations of Reproductive Phenophases for Understory Forest Herbs

As plants continue to respond to global warming with phenological shifts, our understanding of the importance of short-lived heat events and seasonal weather cues has lagged relative to our understanding of plant responses to broad shifts in mean climate conditions. Here, we explore the importance of warmer-than-average days in driving shifts in phenophase duration for spring-flowering woodland herbs across one growing season. We harnessed the combined power of community science and public gardens, engaging more than 30 volunteers to monitor shifts in phenology (documenting movement from one phenophase to the next) for 198 individual plants of 14 species twice per week for the 2023 growing season (March-October) across five botanic gardens in the midwestern and southeastern US. Gardens included the Holden Arboretum, Kirtland, OH; Dawes Arboretum, Newark, OH; Chicago Botanic Garden, Glencoe, IL; Missouri Botanical Garden, St. Louis, MO; and Huntsville Botanical Garden, Huntsville, AL. We tested: (1) that higher-than-average daily temperatures (deviation from 30-year historical mean daily temperatures for each location) would be related to truncated phenophase durations; and (2) that phenophase durations would vary among species. Our findings support both hypotheses. We documented significant inverse relationships between positive deviations in daily temperature from historic means (e.g., warmer-than-average days) and durations of three reproductive phenophases: "First Bud," "First Ripe Fruit," and "Early Fruiting." Similar (non-significant) trends were noted for several other early-season phenophases. Additionally, significant differences in mean phenophase durations were detected among the different species, although these differences were inconsistent across plant parts (vegetative, flowering, and fruiting). Results underscore the potential sensitivity of understory herb reproductive phenophases to warmer-than-average daily temperatures early in the growing season, contributing to our understanding of phenological responses to short-term heat events and seasonal weather cues.

Climate change impacts flowering phenology in Gongga Mountains, Southwest China

Flowering phenology of plants, which is important for reproductive growth, has been shown to be influenced by climate change. Understanding how flowering phenology responds to climate change and exploring the variation of this response across plant groups can help predict structural and functional changes in plant communities in response to ongoing climate change. Here, we used long-term collections of 33 flowering plant species from the Gongga Mountains (Mt. Gongga hereafter), a biodiversity hotspot, to investigate how plant flowering phenology changed over the past 70 years in response to climate change. We found that mean flowering times in Mt. Gongga were delayed in all vegetation types and elevations over the last 70 years. Furthermore, flowering time was delayed more in lowlands than at high elevations. Interestingly, we observed that spring-flowering plants show earlier flowering times whereas summer/autumn plants show delayed flowering times. Non-synchronous flowering phenology across species was mainly driven by changes in temperature and precipitation. We also found that the flowering phenology of 78.8% plant species was delayed in response to warming temperatures. Our findings also indicate that the magnitude and direction of variation in plant flowering times vary significantly among species along elevation gradients. Shifts in flowering time might cause trophic mismatches with co-occurring and related species, affecting both forest ecosystem structure and function.

Flowering in the Northern Hemisphere is delayed by frost after leaf-out

Late spring frosts, occurring after spring phenological events, pose a dire threat to tree growth and forest productivity. With climate warming, earlier spring phenological events have become increasingly common and led to plants experiencing more frequent and severe frost damage. However, the effect of late spring frosts after leaf-out on subsequent flowering phenology in woody species remains unknown. Utilizing 572,734 phenological records of 640 species at 5024 sites from four long-term and large-scale in situ phenological networks across the Northern Hemisphere, we show that late spring frosts following leaf-out significantly delay the onset of the subsequent flowering by approximately 6.0 days. Late-leafing species exhibit greater sensitivity to the frosts than early-leafing species, resulting in a longer delay of 2.5 days in flowering. Trees in warm regions and periods exhibit a more pronounced frost-induced flowering delay compared to those in cold regions and periods. A significant increase in the frequency of late spring frost occurrence is observed in recent decades. Our findings elucidate the intricate relationships among leaf-out, frost, and flowering but also emphasize that the sequential progression of phenological events, rather than individual phenological stages, should be considered when assessing the phenological responses to climate change.

Interannual temperature rise leads to more uniform phenological matching between invasive Stellera chamaejasme and pollinators across elevations

Exploring how environmental changes induce alterations in the phenology matching between plants and pollinators is significant for predicting species' reproductive output and population dynamics. Our study focused on the invasive poisonous weed Stellera chamaejasme, widely distributed in the Qilian Mountains, China. By continuously monitoring its flowering phenology and flower visitors' activities across different elevational ranges, we compared phenological matching patterns between S. chamaejasme and its potential pollinators across years with varying environmental temperatures. We found that S. chamaejasme, a typical early-flowering alpine species, begins its flowering in early June. Despite variations in the composition of flower-visiting insects across elevations and years, it maintained stable interactions with four major groups: Meloidae, Tachinidae, Scarabaeidae, and Noctuidae. Phenological mismatches between the peak flowering period of S. chamaejasme and the peak abundance of major potential pollinators were generally observed across its range, with higher phenological matching at higher elevations. This enhanced matching at higher elevations may drive the rapid invasion of S. chamaejasme in these areas. In the year with higher ambient temperature, phenological matching increased across its range, and its elevational sensitivity decreased, potentially contributing to its ongoing expansion in different elevations. The results of our study advance a new insight into the population expansion of invasive species in mountain ecosystems.

Warming reduces mid-summer flowering plant reproductive success through advancing fruiting phenology in an alpine meadow

Changes in reproductive phenology induced by warming are happening across the globe, with significant implications for plant sexual reproduction. However, the changes in plant reproductive output (number of flowers and fruits) and success (successful fruits/total flowers) in response to climate change have not been well characterized. Here, we conducted a warming and altered precipitation experiment in an alpine meadow on the eastern Tibetan Plateau to investigate the effects of climate change on the reproductive phenology and success of six common species belonging to two flowering functional groups. We found that warming advanced the start of flowering and the start of fruiting in mid-summerflowering plants. Warming reduced the reproductive output of early-spring flowering plants but did not change their reproductive success. The effects of warming and altered precipitation on the reproductive output and success of mid-summer flowering plants were year-dependent, and the fruiting phenology regulated the response of the mid-summer flowering plant's reproductive success to climate change. These findings highlight the critical role of fruiting phenology in the reproductive success of alpine plants and imply that alpine plants may reduce their fitness by producing fewer flowers and fruits under climate warming, especially for later flowering plants.

The potential for evolutionary rescue in an Arctic seashore plant threatened by climate change

The impacts of climate change may be particularly severe for geographically isolated populations, which must adjust through plastic responses or evolve. Here, we study an endangered Arctic plant, Primula nutans ssp. finmarchica, confined to Fennoscandian seashores and showing indications of maladaptation to warming climate. We evaluate the potential of these populations to evolve to facilitate survival in the rapidly warming Arctic (i.e. evolutionary rescue) by utilizing manual crossing experiments in a nested half-sibling breeding design. We estimate G-matrices, evolvability and genetic constraints in traits with potentially conflicting selection pressures. To explicitly evaluate the potential for climate change adaptation, we infer the expected time to evolve from a northern to a southern phenotype under different selection scenarios, using demographic and climatic data to relate expected evolutionary rates to projected rates of climate change. Our results indicate that, given the nearly 10-fold greater evolvability of vegetative than of floral traits, adaptation in these traits may take place nearly in concert with changing climate, given effective climate mitigation. However, the comparatively slow expected evolutionary modification of floral traits may hamper the evolution of floral traits to track climate-induced changes in pollination environment, compromising sexual reproduction and thus reducing the likelihood of evolutionary rescue.

Distinct latitudinal patterns of shifting spring phenology across the Appalachian Trail Corridor

Warming associated with climate change will advance the onset of spring phenology for many forest plants across the Eastern United States. Understory forbs and spring ephemerals that fix a disproportionate amount of carbon during early spring may be negatively affected by earlier canopy closure; however, information on the spatial patterns of phenological change for these communities is still lacking. To assess the potential for changes in spring phenological windows, we synthesized observations from the Appalachian Mountain Club's (AMCs) Mountain Watch (MW) project, the National Phenology Network (NPN), and AMC's iNaturalist projects between 2004 and 2022 (n = 118,250) across the length of the Appalachian Trail (AT) Corridor (34° N-46° N latitude). We used hierarchical Bayesian modeling to examine the sensitivity of spring flowering and leaf-out for 11 understory species and 14 canopy tree species to mean spring temperature (April-June). We conducted analyses across the AT Corridor, partitioned by regions of 4° latitude (south, mid-Atlantic, and north). Spring phenologies for both understory plants and canopy trees advanced with warming (~6 and ~3 days/°C, respectively). However, the sensitivity of each group varied by latitude, with the phenology of trees and understory plants advancing to a greater degree in the mid-Atlantic region (~10 days/°C) than in the southern or northern regions (~5 days/°C). While we find evidence that phenological windows remain stable in the southern and mid-Atlantic portions of the AT, we observed an expansion of the spring phenological window in the north where there was greater understory forb temperature sensitivity compared with trees (~2.7 days/°C). Our analyses indicate the differential sensitivity of forest plant phenology to potential warming across a large latitudinal gradient in the Eastern United States. Further, evidence for a temperature-driven expansion of the spring phenological window suggests a potential beneficial effect for understory plants in the northern AT, although phenological mismatch with potential pollinators and increased vulnerability to late winter frosts are possible. Using extensive citizen-science datasets allows us to synthesize regional- and continental-scale data to explore spatial and temporal trends in spring phenology related to warming. Such data can help to standardize approaches in phenological research and its application to forest climate resiliency.

Pollinator behaviour and prevalence of the anther smut Antherospora vindobonensis in its host, the Hungarian two-leaf squill (Scilla vindobonensis)

Anther smuts are fungal diseases that have detrimental effects on the biology of their host plants. We investigated the transmission of Anther smut Antherospora vindobonensis to its host, Scilla vindobonensis under natural and laboratory conditions. Plants flowering early in spring were less vulnerable to disease (∼ 20-30% of plants which appeared early in the season were diseased) than flowers that bloom at the end of the season (∼ 60% of plants which appeared late in the season were diseased) which contradicts the patterns observed for other anther smuts species. Diseased plants showed thicker stems, lower nectar production and smaller flower radius than healthy plants. The disease prevalence in S. vindobonensis was not influenced by plant density. The production of spores in diseased flowers was 125 times higher than the production of pollen in healthy flowers. The number of pollen grains attached to pollinator bodies from healthy plants under controlled conditions was similar to the number of spores attached from diseased plants. Experienced honeybees in the field showed almost identical preferences for healthy plants (65%) over diseased ones, as did naïve bumblebees under controlled laboratory conditions (69%). eDNA metabarcoding revealed that healthy flowers attracted a significantly higher number of arthropod species (M = 6.23, SE = 1.48) than diseased flowers (M = 2.32, SE = 0.31). Strong seasonal differences in the risk of infection suggest that S. vindobonensis solves the trade-off between low pollinator availability and low risk of infection at the beginning of the season and high risk of infection and high pollinator availability at the end of season. By reproducing early in the season, plants can reduce the risk of disease.

Climate change increases flowering duration, driving phenological reassembly and elevated co-flowering richness

Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly). We combined long-term field (1937-2012) and herbarium records (1850-2017) of 68 species in a flowering plant community in central North America and used a novel application of Bayesian quantile regression to estimate changes to flowering season length, altered richness and composition of co-flowering assemblages, and whether phenological shifts exhibit seasonal trends. Across the past century, phenological shifts increased species' flowering durations by 11.5 d on average, which resulted in 94% of species experiencing greater flowering overlap at the community level. Increases to co-flowering were particularly pronounced in autumn, driven by a greater tendency of late season species to shift the ending of flowering later and to increase flowering duration. Our results demonstrate that species-level phenological shifts can result in considerable phenological reassembly and highlight changes to flowering duration as a prominent, yet underappreciated, effect of climate change. The emergence of an autumn co-flowering mode emphasizes that these effects may be season-dependent.

Biological macromolecules mediated by environmental signals affect flowering regulation in plants: A comprehensive review

Flowering time is a crucial developmental stage in the life cycle of plants, as it determines the reproductive success and overall fitness of the organism. The precise regulation of flowering time is influenced by various internal and external factors, including genetic, environmental, and hormonal cues. This review provided a comprehensive overview of the molecular mechanisms and regulatory pathways of biological macromolecules (e.g. proteins and phytohormone) and environmental factors (e.g. light and temperature) involved in the control of flowering time in plants. We discussed the key proteins and signaling pathways that govern the transition from vegetative growth to reproductive development, highlighting the intricate interplay between genetic networks, environmental cues, and phytohormone signaling. Additionally, we explored the impact of flowering time regulation on plant adaptation, crop productivity, and agricultural practices. Moreover, we summarized the similarities and differences of flowering mechanisms between annual and perennial plants. Understanding the mechanisms underlying flowering time control is not only essential for fundamental plant biology research but also holds great potential for crop improvement and sustainable agriculture.

Ecological perspectives on female and male reproductive success with competition in two Serapias species

BACKGROUND AND AIMS

The deceptive strategies by which orchids are pollinated and how these are capable of attracting pollinators remain understudied with regard to their implications for plant fitness. Despite their ecological importance, limited investigations have been conducted on sexual deception and shelter mimicry in orchid species, making this a compelling avenue in orchid biology research. To expand the knowledge of these reproductive mechanisms, we studied the pollination of Serapias lingua and S. parviflora in co-occurring and isolated sites in the Balearic Islands (Spain), further accentuated by the presence of a hybrid, indicating shared pollinators.

METHODS

We employed bagging and hand pollination experiments to examine the reproductive biology of the two species. Furthermore, we evaluated the influence of phenotypical and ecological factors on reproductive success, including biometric measurements, reproductive performance and neighbourhood diversity (co-flowering and pollinator communities).

KEY RESULTS

Reproductive mechanisms between these two orchid species exhibit substantial disparities. Serapias lingua relies primarily on insect-mediated pollination, while S. parviflora demonstrates self-reproduction capacity. Although events of open pollination are rare, hybridization occurs predominantly when S. lingua is the pollen donor. Fruit set in S. parviflora was positively correlated with plant height, while in S. lingua it was negatively associated with flower size. The coexistence of the two species positively affected pollinium removal in S. parviflora, but did not exert an influence on reproductive traits in S. lingua. Overall, biometric parameters were diminished in isolated compared with co-occurring sites. At the community level, the increased diversity of co-flowering species in the vicinity exhibited an inhibitory effect on pollinium removal in S. parviflora.

CONCLUSIONS

Under a context of pollinator loss or phenological mismatch between pollinator presence and flowering, the selfing capacity of S. parviflora would guarantee reproduction whereas S. lingua survival would be compromised. Furthers studies are needed to assess the effects of phenotypical and ecological factors on reproductive success of S. lingua in pollinator-decline scenarios.

To live or let die? Epigenetic adaptations to climate change-a review

Anthropogenic activities are responsible for a wide array of environmental disturbances that threaten biodiversity. Climate change, encompassing temperature increases, ocean acidification, increased salinity, droughts, and floods caused by frequent extreme weather events, represents one of the most significant environmental alterations. These drastic challenges pose ecological constraints, with over a million species expected to disappear in the coming years. Therefore, organisms must adapt or face potential extinctions. Adaptations can occur not only through genetic changes but also through non-genetic mechanisms, which often confer faster acclimatization and wider variability ranges than their genetic counterparts. Among these non-genetic mechanisms are epigenetics defined as the study of molecules and mechanisms that can perpetuate alternative gene activity states in the context of the same DNA sequence. Epigenetics has received increased attention in the past decades, as epigenetic mechanisms are sensitive to a wide array of environmental cues, and epimutations spread faster through populations than genetic mutations. Epimutations can be neutral, deleterious, or adaptative and can be transmitted to subsequent generations, making them crucial factors in both long- and short-term responses to environmental fluctuations, such as climate change. In this review, we compile existing evidence of epigenetic involvement in acclimatization and adaptation to climate change and discuss derived perspectives and remaining challenges in the field of environmental epigenetics. Graphical Abstract.

Plant Molecular Phenology and Climate Feedbacks Mediated by BVOCs

Climate change profoundly affects the timing of seasonal activities of organisms, known as phenology. The impact of climate change is not unidirectional; it is also influenced by plant phenology as plants modify atmospheric composition and climatic processes. One important aspect of this interaction is the emission of biogenic volatile organic compounds (BVOCs), which link the Earth's surface, atmosphere, and climate. BVOC emissions exhibit significant diurnal and seasonal variations and are therefore considered essential phenological traits. To understand the dynamic equilibrium arising from the interplay between plant phenology and climate, this review presents recent advances in comprehending the molecular mechanisms underpinning plant phenology and its interaction with climate. We provide an overview of studies investigating molecular phenology, genome-wide gene expression analyses conducted in natural environments, and how these studies revolutionize the concept of phenology, shifting it from observable traits to dynamic molecular responses driven by gene-environment interactions. We explain how this knowledge can be scaled up to encompass plant populations, regions, and even the globe by establishing connections between molecular phenology, changes in plant distribution, species composition, and climate.

Climate change is poised to alter mountain stream ecosystem processes via organismal phenological shifts

Climate change is affecting the phenology of organisms and ecosystem processes across a wide range of environments. However, the links between organismal and ecosystem process change in complex communities remain uncertain. In snow-dominated watersheds, snowmelt in the spring and early summer, followed by a long low-flow period, characterizes the natural flow regime of streams and rivers. Here, we examined how earlier snowmelt will alter the phenology of mountain stream organisms and ecosystem processes via an outdoor mesocosm experiment in stream channels in the Eastern Sierra Nevada, California. The low-flow treatment, simulating a 3- to 6-wk earlier return to summer baseflow conditions projected under climate change scenarios in the region, increased water temperature and reduced biofilm production to respiration ratios by 32%. Additionally, most of the invertebrate species explaining community change (56% and 67% of the benthic and emergent taxa, respectively), changed in phenology as a consequence of the low-flow treatment. Further, emergent flux pulses of the dominant insect group (Chironomidae) almost doubled in magnitude, benefitting a generalist riparian predator. Changes in both invertebrate community structure (composition) and functioning (production) were mostly fine-scale, and response diversity at the community level stabilized seasonally aggregated responses. Our study illustrates how climate change in vulnerable mountain streams at the rain-to-snow transition is poised to alter the dynamics of stream food webs via fine-scale changes in phenology-leading to novel predator-prey "matches" or "mismatches" even when community structure and ecosystem processes appear stable at the annual scale.

Decadal-scale variability and warming affect spring timing and forest growth across the western Great Lakes region

The Great Lakes region of North America has warmed by 1-2 °C on average since pre-industrial times, with the most pronounced changes observable during winter and spring. Interannual variability in temperatures remains high, however, due to the influence of ocean-atmosphere circulation patterns that modulate the warming trend across years. Variations in spring temperatures determine growing season length and plant phenology, with implications for whole ecosystem function. Studying how both internal climate variability and the "secular" warming trend interact to produce trends in temperature is necessary to estimate potential ecological responses to future warming scenarios. This study examines how external anthropogenic forcing and decadal-scale variability influence spring temperatures across the western Great Lakes region and estimates the sensitivity of regional forests to temperature using long-term growth records from tree-rings and satellite data. Using a modeling approach designed to test for regime shifts in dynamic time series, this work shows that mid-continent spring climatology was strongly influenced by the 1976/1977 phase change in North Pacific atmospheric circulation, and that regional forests show a strengthening response to spring temperatures during the last half-century.

Decoupling of bird migration from the changing phenology of spring green-up

The green-up of vegetation in spring brings a pulse of food resources that many animals track during migration. However, green-up phenology is changing with climate change, posing an immense challenge for species that time their migrations to coincide with these resource pulses. We evaluated changes in green-up phenology from 2002 to 2021 in relation to the migrations of 150 Western-Hemisphere bird species using eBird citizen science data. We found that green-up phenology has changed within bird migration routes, and yet the migrations of most species align more closely with long-term averages of green-up than with current conditions. Changing green-up strongly influenced phenological mismatches, especially for longer-distance migrants. These results reveal that bird migration may have limited flexibility to adjust to changing vegetation phenology and emphasize the mounting challenge migratory animals face in following en route resources in a changing climate.

Understanding how environmental degradation, microclimate, and management shape honey production across different spatial scales

Although the abundance, survival, and pollination performance of honeybees are sensitive to changes in habitat and climate conditions, the processes by which these effects are transmitted to honey production and interact with beekeeping management are not completely understood. Climate change, habitat degradation, and beekeeping management affect honey yields, and may also interact among themselves resulting in indirect effects across spatial scales. We conducted a 2-year, multi-scale study on Chiloe Island (northern Patagonia), where we evaluated the most relevant environmental and management drivers of honey produced by stationary beekeepers. We found that the effects of microclimate, habitat, and management variables changed with the spatial scale. Among the environmental variables, minimum temperature, and cover of the invasive shrub, gorse (Ulex europaeus) had the strongest detrimental impacts on honey production at spatial scales finer than 4 km. Specialized beekeepers who adopted conventional beekeeping and had more mother colonies were more productive. Mean and minimum temperatures interacted with the percentage of mother colonies, urban cover, and beekeeping income. The gorse cover increased by the combination of high temperatures and the expansion of urban lands, while landscape attributes, such as Eucalyptus plantation cover, influenced beekeeping management. Results suggest that higher temperatures change the available forage or cause thermal stress to honeybees, while invasive shrubs are indicators of degraded habitats. Climate change and habitat degradation are two interrelated environmental phenomena whose effects on beekeeping can be mitigated through adaptive management and habitat restoration.

Forest understorey flowering phenology responses to experimental warming and illumination

Species are altering their phenology to track warming temperatures. In forests, understorey plants experience tree canopy shading resulting in light and temperature conditions, which strongly deviate from open habitats. Yet, little is known about understorey phenology responses to forest microclimates. We recorded flowering onset, peak, end and duration of 10 temperate forest understorey plant species in two mesocosm experiments to understand how phenology is affected by sub-canopy warming and how this response is modulated by illumination, which is related to canopy change. Furthermore, we investigated whether phenological sensitivities can be explained by species' characteristics, such as thermal niche. We found a mean advance of flowering onset of 7.1 d per 1°C warming, more than previously reported in studies not accounting for microclimatic buffering. Warm-adapted species exhibited greater advances. Temperature sensitivity did not differ between early- and later-flowering species. Experimental illumination did not significantly affect species' phenological temperature sensitivities, but slightly delayed flowering phenology independent from warming. Our study suggests that integrating sub-canopy temperature and light availability will help us better understand future understorey phenology responses. Climate warming together with intensifying canopy disturbances will continue to drive phenological shifts and potentially disrupt understorey communities, thereby affecting forest biodiversity and functioning.

The contemporary nexus of medicines security and bioprospecting: a future perspective for prioritizing the patient

Reacting to the challenges presented by the evolving nexus of environmental change, defossilization, and diversified natural product bioprospecting is vitally important for advancing global healthcare and placing patient benefit as the most important consideration. This overview emphasizes the importance of natural and synthetic medicines security and proposes areas for global research action to enhance the quality, safety, and effectiveness of sustainable natural medicines. Following a discussion of some contemporary factors influencing natural products, a rethinking of the paradigms in natural products research is presented in the interwoven contexts of the Fourth and Fifth Industrial Revolutions and based on the optimization of the valuable assets of Earth. Following COP28, bioprospecting is necessary to seek new classes of bioactive metabolites and enzymes for chemoenzymatic synthesis. Focus is placed on those performance and practice modifications which, in a sustainable manner, establish the patient, and the maintenance of their prophylactic and treatment needs, as the priority. Forty initiatives for natural products in healthcare are offered for the patient and the practitioner promoting global action to address issues of sustainability, environmental change, defossilization, quality control, product consistency, and neglected diseases to assure that quality natural medicinal agents will be accessible for future generations.

Elevational and seasonal patterns of plant pollinator networks in two highland tropical ecosystems in Costa Rica

Many plant species in high montane ecosystems rely on animal pollination for sexual reproduction, however, our understanding of plant-pollinator interactions in tropical montane habitats is still limited. We compared species diversity and composition of blooming plants and floral visitors, and the structure of plant-floral visitor networks between the Montane Forest and Paramo ecosystems in Costa Rica. We also studied the influence of seasonality on species composition and interaction structure. Given the severe climatic conditions experienced by organisms in habitats above treeline, we expected lower plant and insect richness, as well as less specialized and smaller pollination networks in the Paramo than in Montane Forest where climatic conditions are milder and understory plants are better protected. Accordingly, we found that blooming plants and floral visitor species richness was higher in the Montane Forest than in the Paramo, and in both ecosystems species richness of blooming plants and floral visitors was higher in the rainy season than in the dry season. Interaction networks in the Paramo were smaller and more nested, with lower levels of specialization and modularity than those in the Montane Forest, but there were no seasonal differences within either ecosystem. Beta diversity analyses indicate that differences between ecosystems are likely explained by species turnover, whereas within the Montane Forest differences between seasons are more likely explained by the rewiring of interactions. Results indicate that the decrease in species diversity with elevation affects network structure, increasing nestedness and reducing specialization and modularity.

Climate change impacts on insect pests for high value specialty crops in California

California is a global leader in production and supply of walnuts and almonds, and the state is the largest producer of peaches in the U.S. These crops have an important contribution to the California's agricultural economy. Damages to these crops from lepidopteran pests, mainly from Codling moth (Cydia pomonella) (family: Tortricidae), Peach twig borer (Anarsia lineatella) (family: Gelechiidae) and Oriental fruit moth (Grapholita molesta) (family: Tortricidae), are still high, despite the improvement in pest management activities. Given that temperature increase can directly impact the rate of growth and development of these pests, it is important to understand to what extent dynamics of these pests will change in future in California. The objective of this study was to quantify changes in the biofix, lifecycle length, and number of generations for these pests for the entire Central Valley of California. Using a well-established growing-degree days (GDD) model calibrated and validated using observations from orchards of California, and climate change projections from the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5 and CMIP6) General Circulation Models, we found that biofix dates of these pests are expected to shift earlier by up to 28 days, and length of generations is expected to be shortened by up to 19 days, and up to 1.4 extra generations of these pests can be added by the end of the century depending on the scenario. Results from this work would enable industries to prioritize development of practices that are more effective in the long run, such as developing better cultural and biological pest solutions and insect tolerant varieties. Growers and researchers can take proactive actions to minimize future risks associated with these damaging pests. This work can be scalable to other pests and regions to understand regional dynamics of damaging agricultural pests under climate change.

Forest herb species with similar European geographic ranges may respond differently to climate change

Many phenological studies have shown that spring geophytes are very sensitive to climate change, responding by shifting flowering and fruiting dates. However, there is a gap in knowledge about climatic drivers of their distributions and range shifts under climate change. Here we aimed to estimate climate niche shifts for four widely distributed and common geophytes of the nemoral zone of Europe (Anemone nemorosa, Anemone ranunculoides, Convallaria majalis and Maianthemum bifolium) and to assess the threat level under various climate change scenarios. Using MaxEnt species distribution models and future climate change scenarios we found that the precipitation of the warmest quarter was the most important factor shaping their ranges. All species studied will experience more loss in the 2061-2080 period than in 2041-2060, and under more pessimistic scenarios. M. bifolium will experience the highest loss, followed by A. nemorosa, A. ranunculoides, and the smallest for C. majalis. A. ranunculoides will gain the most, while M. bifolium will have the smallest potential range expansion. Studied species may respond differently to climate change despite similar current distributions and climatic variables affecting their potential distribution. Even slight differences in climatic niches could reduce the overlap of future ranges compared to present. We expect that due to high dependence on the warmest quarter precipitation, summer droughts in the future may be particularly severe for species that prefer moist soils. The lack of adaptation to long-distance migration and limited availability of appropriate soils may limit their migration and lead to a decline in biodiversity and changes in European forests.

Plant phenology shifts under climate warming: a systematic review of recent scientific literature

Climate warming-driven temporal shifts in phenology are widely recognised as the foremost footprint of global environmental change. In this regard, concerted research efforts are being made worldwide to monitor and assess the plant phenological responses to climate warming across species, ecosystems and seasons. Here, we present a global synthesis of the recent scientific literature to assess the progress made in this area of research. To achieve this, we conducted a systematic review by following PRISMA protocol, which involved rigorous screening of 9476 studies on the topic and finally selected 215 studies for data extraction. The results revealed that woody species, natural ecosystems and plant phenological responses in spring season have been predominantly studied, with the herbaceous species, agricultural ecosystems and other seasons grossly understudied. Majority of the studies reported phenological advancement (i.e., preponement) in spring, followed by also advancement in summer but delay in autumn. Methodology-wise, nearly two -third of the studies have employed direct observational approach, followed by herbarium-based and experimental approaches, with the latter covering least temporal depth. We found a steady increase in research on the topic over the last decade with a sharp increase since 2014. The global country-wide scientific output map highlights the huge geographical gaps in this area of research, particularly in the biodiversity-rich tropical regions of the developing world. Based on the findings of this global synthesis, we identify the current knowledge gaps and suggest future directions for this emerging area of research in an increasingly warming world.

Earlier and more uniform spring green-up linked to lower insect richness and biomass in temperate forests

Urbanization and agricultural intensification are considered the main causes of recent insect decline in temperate Europe, while direct climate warming effects are still ambiguous. Nonetheless, higher temperatures advance spring leaf emergence, which in turn may directly or indirectly affect insects. We therefore investigated how Sentinel-2-derived start of season (SOS) and its spatial variability (SV-SOS) are affected by spring temperature and whether these green-up variables can explain insect biomass and richness across a climate and land-use gradient in southern Germany. We found that the effects of both spring green-up variables on insect biomass and richness differed between land-use types, but were strongest in forests. Here, insect richness and biomass were higher with later green-up (SOS) and higher SV-SOS. In turn, higher spring temperatures advanced SOS, while SV-SOS was lower at warmer sites. We conclude that with a warming climate, insect biomass and richness in forests may be affected negatively due to earlier and more uniform green-up. Promising adaptation strategies should therefore focus on spatial variability in green-up in forests, thus plant species and structural diversity.

Phenology and foraging bias contribute to sex-specific foraging patterns in the rare declining butterfly Argynnis idalia idalia

Variation in pollinator foraging behavior can influence pollination effectiveness, community diversity, and plant-pollinator network structure. Although effects of interspecific variation have been widely documented, studies of intraspecific variation in pollinator foraging are relatively rare. Sex-specific differences in resource use are a strong potential source of intraspecific variation, especially in species where the phenology of males and females differ. Differences may arise from encountering different flowering communities, sex-specific traits, nutritional requirements, or a combination of these factors. We evaluated sex-specific foraging patterns in the eastern regal fritillary butterfly (Argynnis idalia idalia), leveraging a 21-year floral visitation dataset. Because A. i. idalia is protandrous, we determined whether foraging differences were due to divergent phenology by comparing visitation patterns between the entire season with restricted periods of male-female overlap. We quantified nectar carbohydrate and amino acid contents of the most visited plant species and compared those visited more frequently by males versus females. We demonstrate significant differences in visitation patterns between male and female A. i. idalia over two decades. Females visit a greater diversity of species, while dissimilarity in foraging patterns between sexes is persistent and comparable to differences between species. While differences are diminished or absent in some years during periods of male-female overlap, remaining signatures of foraging dissimilarity during implicate mechanisms other than phenology. Nectar of plants visited more by females had greater concentrations of total carbohydrates, glucose, and fructose and individual amino acids than male-associated plants. Further work can test whether nutritional differences are a cause of visitation patterns or consequence, reflecting seasonal shifts in the nutritional landscape encountered by male and female A. i. idalia. We highlight the importance of considering sex-specific foraging patterns when studying interaction networks, and in making conservation management decisions for this at-risk butterfly and other species exhibiting strong intraspecific variation.

Geographical patterns and determinants in plant reproductive phenology duration

Biodiversity is and always has been an important issue in ecological research. Biodiversity can reflect niche partitioning among species at several spatial and temporal scales and is generally highest in the tropics. One theory to explain it is that low-latitude tropical ecosystems are dominated by species that are generally only distributed over a narrow area. This principle is known as Rapoport's rule. One previously unconsidered extension of Rapoport's rule may be reproductive phenology, where variation in flowering and fruiting length may reflect a temporal range. Herein, we collected reproductive phenology data for more than 20,000 species covering almost all angiosperm species in China. We used a random forest model to quantify the relative role of seven environmental factors on the duration of reproductive phenology. Our results showed that the duration of reproductive phenology decreased with latitude, although there was no obvious change across longitudes. Latitude explained more of the variation in the duration of flowering and fruiting phases in woody plants than in herbaceous plants. Mean annual temperature and the length of the growing season strongly influenced the phenology of herbaceous plants, and average winter temperature and temperature seasonality were important drivers of woody plant phenology. Our result suggests the flowering period of woody plants is sensitive to temperature seasonality, while it does not influence herbaceous plants. By extending Rapoport's rule to consider the distribution of species in time as well as space, we have provided a novel insight into the mechanisms of maintaining high levels of diversity in low-latitude forests.

Impacts of inter-annual climate variability on reproductive phenology and postnatal development of morphological features of three sympatric bat species

Inter-annual variation in weather conditions has been shown to affect the reproductive phenological patterns of many organisms. Because of their relatively small body size and dependence on ectothermic prey, temperate-zone insectivorous bats are particularly sensitive to adverse spring environmental conditions that affect the duration of gestation and timing of parturition in these animals. This study aimed to compare phenological recruitment, birth seasonality and synchrony and morphological changes during postnatal growth in Rhinolophus euryale, Rhinolophus ferrumequinum and Myotis emarginatus in two consecutive years representing a typical dry (2015) and an extremely wet climatic event (2016) in a nursing colony in Kerend cave, western Iran. Females of these three bat species arrived from their wintering cave to the nursing colony in late April to mid-May each year. Synchrony of parturition as defined by amount clustering of births within a year assessed by circular statistics showed that for R. euryale and R. ferrumequinum the angular variance in dry year were significantly (P < 0.05) lower than in wet year, indicating a low level of synchrony in 2016. Similar comparison showed that births from M. emarginatus were highly synchrony, and there were no significant differences in timing of births among years (P > 0.05). Generalized estimating equation (GEE) for R. euryale indicated that for body mass and forearm length tests of parallelism (interaction term or growth rate) and tests for equal intercepts (y-intercepts or group term) were significant (P < 0.001). In R. ferrumequinum, the initial (y-intercepts) forearm length and body mass were not significantly (P > 0.05) different between the 2 years, but the tests for parallelism showed a significant decrease in growth rates of body mass and forearm length in the wet year (P < 0.05). Similar comparison in M. emarginatus indicated that for body mass, tests of parallelism were significantly different (P = 0.004), while tests for equal intercepts were not (P = 0.23). Our results suggest that climate changes may have unequal effects on different bat species due to differences in foraging habitat, niche partitioning, reproductive requirements and foraging strategies.

Applied winter biology: threats, conservation and management of biological resources during winter in cold climate regions

Winter at high latitudes is characterized by low temperatures, dampened light levels and short photoperiods which shape ecological and evolutionary outcomes from cells to populations to ecosystems. Advances in our understanding of winter biological processes (spanning physiology, behaviour and ecology) highlight that biodiversity threats (e.g. climate change driven shifts in reproductive windows) may interact with winter conditions, leading to greater ecological impacts. As such, conservation and management strategies that consider winter processes and their consequences on biological mechanisms may lead to greater resilience of high altitude and latitude ecosystems. Here, we use well-established threat and action taxonomies produced by the International Union of Conservation of Nature-Conservation Measures Partnership (IUCN-CMP) to synthesize current threats to biota that emerge during, or as the result of, winter processes then discuss targeted management approaches for winter-based conservation. We demonstrate the importance of considering winter when identifying threats to biodiversity and deciding on appropriate management strategies across species and ecosystems. We confirm our expectation that threats are prevalent during the winter and are especially important considering the physiologically challenging conditions that winter presents. Moreover, our findings emphasize that climate change and winter-related constraints on organisms will intersect with other stressors to potentially magnify threats and further complicate management. Though conservation and management practices are less commonly considered during the winter season, we identified several potential or already realized applications relevant to winter that could be beneficial. Many of the examples are quite recent, suggesting a potential turning point for applied winter biology. This growing body of literature is promising but we submit that more research is needed to identify and address threats to wintering biota for targeted and proactive conservation. We suggest that management decisions consider the importance of winter and incorporate winter specific strategies for holistic and mechanistic conservation and resource management.

Differences in individual flowering time change pollen limitation and seed set in three montane wildflowers

PREMISE

Changes to flowering time caused by climate change could affects plant fecundity, but studies that compare the individual-level responses of phenologically distinct, co-occurring species are lacking. We assessed how variation in floral phenology affects the fecundity of individuals from three montane species with different seasonal flowering times, including in snowmelt acceleration treatments to increase variability in phenology.

METHODS

We collected floral phenology and seed set data for individuals of three montane plant species (Mertensia fusiformis, Delphinium nuttallianum, Potentilla pulcherrima). To examine the drivers of seed set, we measured conspecific floral density and conducted pollen limitation experiments to isolate pollination function. We advanced the phenology of plant communities in a controlled large-scale snowmelt acceleration experiment.

RESULTS

Differences in individual phenology relative to the rest of the population affected fecundity in our focal species, but effects were species-specific. For our early-season species, individuals that bloomed later than the population peak bloom had increased fecundity, while for our midseason species, simply blooming before or after the population peak increased individual fecundity. For our late-season species, blooming earlier than the population peak increased fecundity. The early and midseason species were pollen-limited, and conspecific density affected seed set only for our early-season species.

CONCLUSIONS

Our study shows that variation in individual phenology affects fecundity in three phenologically distinct montane species, and that pollen limitation may be more influential than conspecific density. Our results suggest that individual-level changes in phenology are important to consider for understanding plant reproductive success.

Coat color mismatch improves survival of a keystone boreal herbivore: Energetic advantages exceed lost camouflage

Climate warming is causing asynchronies between animal phenology and environments. Mismatched traits, such as coat color change mismatched with snow, can decrease survival. However, coat change does not serve a singular adaptive benefit of camouflage, and alternate coat change functions may confer advantages that supersede mismatch costs. We found that mismatch reduced, rather than increased, autumn mortality risk of snowshoe hares in Yukon by 86.5% when mismatch occurred. We suggest that the increased coat insulation and lower metabolic rates of winter-acclimatized hares confer energetic advantages to white mismatched hares that reduce their mortality risk. We found that white mismatched hares forage 17-77 min less per day than matched brown hares between 0°C and -10°C, thus lowering their predation risk and increasing survival. We found no effect of mismatch on spring mortality risk, during which mismatch occurred at warmer temperatures, suggesting a potential temperature limit at which the costs of conspicuousness outweigh energetic benefits.

Ecological traits explain long-term phenological trends in solitary bees

Across taxa, the timing of life-history events (phenology) is changing in response to warming temperatures. However, little is known about drivers of variation in phenological trends among species. We analysed 168 years of museum specimen and sighting data to evaluate the patterns of phenological change in 70 species of solitary bees that varied in three ecological traits: diet breadth (generalist or specialist), seasonality (spring, summer or fall) and nesting location (above-ground or below-ground). We estimated changes in onset, median, end and duration of each bee species' annual activity (flight duration) using quantile regression. To determine whether ecological traits could explain phenological trends, we compared average trends across species groups that differed in a single trait. We expected that specialist bees would be constrained by their host plants' phenology and would show weaker phenological change than generalist species. We expected phenological advances in spring and delays in summer and fall. Lastly, we expected stronger shifts in above-ground versus below-ground nesters. Across all species, solitary bees have advanced their phenology by 0.43 days/decade. Since 1970, this advancement has increased fourfold to 1.62 days/decade. Solitary bees have also lengthened their flight period by 0.44 days/decade. Seasonality and nesting location explained variation in trends among species. Spring- and summer-active bees tended to advance their phenology, whereas fall-active bees tended to delay. Above-ground nesting species experienced stronger advances than below-ground nesting bees in spring; however, the opposite was true in summer. Diet breadth was not associated with patterns of phenological change. Our study has two key implications. First, an increasing activity period of bees across the flight season means that bee communities will potentially provide pollination services for a longer period of time during the year. And, since phenological trends in solitary bees can be explained by some ecological traits, our study provides insight into mechanisms underpinning population viability of insect pollinators in a changing world.

The Resilience of Plant-Pollinator Networks

There is growing awareness of pollinator declines worldwide. Conservation efforts have mainly focused on finding the direct causes, while paying less attention to building a systemic understanding of the fragility of these communities of pollinators. To fill this gap, we need operational measures of network resilience that integrate two different approaches in theoretical ecology. First, we should consider the range of conditions compatible with the stable coexistence of all of the species in a community. Second, we should address the rate and shape of network collapse once this safe operational space is exited. In this review, we describe this integrative approach and consider several mechanisms that may enhance the resilience of pollinator communities, chiefly rewiring the network of interactions, increasing heterogeneity, allowing variance, and enhancing coevolution. The most pressing need is to develop ways to reduce the gap between these theoretical recommendations and practical applications. This perspective shifts the emphasis from traditional approaches focusing on the equilibrium states to strategies that allow pollination networks to cope with global environmental change.

Current and lagged climate affects phenology across diverse taxonomic groups

The timing of life events (phenology) can be influenced by climate. Studies from around the world tell us that climate cues and species' responses can vary greatly. If variation in climate effects on phenology is strong within a single ecosystem, climate change could lead to ecological disruption, but detailed data from diverse taxa within a single ecosystem are rare. We collated first sighting and median activity within a high-elevation environment for plants, insects, birds, mammals and an amphibian across 45 years (1975-2020). We related 10 812 phenological events to climate data to determine the relative importance of climate effects on species' phenologies. We demonstrate significant variation in climate-phenology linkage across taxa in a single ecosystem. Both current and prior climate predicted changes in phenology. Taxa responded to some cues similarly, such as snowmelt date and spring temperatures; other cues affected phenology differently. For example, prior summer precipitation had no effect on most plants, delayed first activity of some insects, but advanced activity of the amphibian, some mammals, and birds. Comparing phenological responses of taxa at a single location, we find that important cues often differ among taxa, suggesting that changes to climate may disrupt synchrony of timing among taxa.

Pollinators exert selection on floral traits in a pollen-limited, narrowly endemic spring ephemeral

PREMISE

Floral traits are frequently under pollinator-mediated selection, especially in taxa subject to strong pollen-limitation, such as those reliant on pollinators. However, antagonists can be agents of selection on floral traits as well. The causes of selection acting on spring ephemerals are understudied though these species can experience particularly strong pollen-limitation. I examined pollinator- and antagonist-mediated selection in a narrowly endemic spring ephemeral, Trillium discolor.

METHODS

I measured pollen limitation in T. discolor across two years and evaluated its breeding system. I compared selection on floral traits (display height, petal size, petal color, flowering time) between open-pollinated, and pollen-supplemented plants to measure the strength and mode of pollinator-mediated selection. I assessed whether natural levels of antagonism impacted selection on floral traits.

RESULTS

Trillium discolor was self-incompatible and experienced pollen limitation in both years of the study. Pollinators exerted negative disruptive selection on display height and petals size. In one year, pollinator-mediated selection favored lighter petals but in the second year pollinators favored darker petals. Antagonist damage did not alter selection on floral traits.

CONCLUSIONS

Results demonstrate that pollinators mediate the strength and mode of selection on floral traits in T. discolor. Interannual variation in the strength, mode, and direction of pollinator-mediated selection on floral traits could be important for maintaining of floral diversity in this system. Observed levels of antagonism were weak agents of selection on floral traits.

Wildflower phenological escape differs by continent and spring temperature

Temperate understory plant species are at risk from climate change and anthropogenic threats that include increased deer herbivory, habitat loss, pollinator declines and mismatch, and nutrient pollution. Recent work suggests that spring ephemeral wildflowers may be at additional risk due to phenological mismatch with deciduous canopy trees. The study of this dynamic, commonly referred to as "phenological escape", and its sensitivity to spring temperature is limited to eastern North America. Here, we use herbarium specimens to show that phenological sensitivity to spring temperature is remarkably conserved for understory wildflowers across North America, Europe, and Asia, but that canopy trees in North America are significantly more sensitive to spring temperature compared to in Asia and Europe. We predict that advancing tree phenology will lead to decreasing spring light windows in North America while spring light windows will be maintained or even increase in Asia and Europe in response to projected climate warming.

Predicting the Geographical Distribution Shift of Medicinal Plants in South Africa Due to Climate Change

There has been a recent rise in the number of medicinal plant users in Southern Africa, with approximately a million users reported to utilize these plants for various health conditions. Unfortunately, some of these plants are reportedly endangered and facing extinction due to harvesting pressure. In addition, climate change is likely to negatively affect the geographical distribution of these medicinal plants. In the current study, future greenhouse gas emission scenarios of the representative concentration pathways, RCP2.6 and RCP8.5, for future projections to 2050 and 2080 were used to simulate the effect of climate change on three medicinal plants’ (Aloe ferox, Bowiea volubilis, and Dioscorea elephantipes) distribution in South Africa. We studied these plant species as the International Union for Conservation of Nature stated that A. ferox is currently of least concern in South Africa, while B. volubilis and D. elephantipes are categorised as declining and vulnerable, respectively. Specifically, we utilised a species distribution model (i.e., the maximum entropy: MaxEnt) to investigate the effect of climate change on the future spatial distribution of medicinal plants in South Africa. In 2050 and 2080, under both RCP scenarios, the suitable habitat of the studied plant species will reduce in the country’s northern parts. Specifically, the habitat for D. elephantipes will totally disappear in the country’s northern parts. However, there will be slight additions of suitable habitats for the species in the country’s southern parts. Model validation indicated that the area under curve (AUC) for A. ferox was 0.924 ± 0.004, while for B. volubilis and D. elephantipes it was 0.884 ± 0.050 and 0.944 ± 0.030, respectively. Using the results from this study, there is a need for the long-term in situ and ex situ conservation of these medicinal plants. The results of the present study could guide the development of effective and efficient policies and strategies for managing and conserving medicinal plants in South Africa.

Anthropogenic habitat modification alters calling phenology of frogs

Anthropogenic habitat modification significantly challenges biodiversity. With its intensification, understanding species' capacity to adapt is critical for conservation planning. However, little is known about whether and how different species are responding, particularly among frogs. We used a continental-scale citizen science dataset of >226,000 audio recordings of 42 Australian frog species to investigate how calling-a proxy for breeding-phenology varied along an anthropogenic modification gradient. Calling started earlier and breeding seasons lengthened with increasing modification intensity. Breeding seasons averaged 22.9 ± 8.25 days (standard error) longer in the most modified compared to the least modified regions, suggesting that frog breeding activity was sensitive to habitat modification. We also examined whether calls varied along a modification gradient by analysing the temporal and spectral properties of advertisement calls from a subset of 441 audio recordings of three broadly distributed frog species. There was no appreciable effect of anthropogenic habitat modification on any of the measured call variables, although there was high variability. With continued habitat modification, species may shift towards earlier and longer breeding seasons, with largely unknown ecological consequences in terms of proximate and ultimate fitness.