Flowering Synchrony Research Articles

Hybrid grain production in wheat benefits from synchronized flowering and high female flower receptivity.

The performance of plant hybrids relative to line breeding types is generally associated with higher yields, better adaptation, and improved yield stability. In bread wheat (Triticum aestivum L.), however, a broad commercial success for hybrids has not been accomplished until now largely due to the low efficiency of hybrid grain production, which is highly attributable to its self-pollinating nature. To better understand how hybrid wheat grains can be produced more effectively, we investigated the influence of synchronized flowering between female, i.e. male-sterile, lines and their male cross-pollinator lines as well as of the duration of flowering on hybrid grain production. We found that synchronization of flowering in combination with the longest possible temporal overlap had the largest positive effect on hybrid grain production. However, despite sufficient spatial and temporal synchronization of flowering, we also found that some female lines had lower hybrid grain set than others, suggesting genetic differences in female floral receptivity. To better assess female receptivity, we established a new phenotyping scale of male-sterile wheat flowers that provides the floral basics for effective cross-pollination. Applying this scale in our field and greenhouse trials revealed that better performing female lines remained longer in the pollen-receptive phase.

Natural and anthropogenic factors influence flowering synchrony and reproduction of a dominant plant in an inter-Andean scrub.

Agriculture expansion, livestock, and global change have transformed biological communities and altered, through aerosols and direct deposition, N:P balance in soils of inter-Andean valleys, potentially affecting flowering phenology of many species and thereby flowering synchrony and plant reproduction. We evaluated the influence of variation in temperature and moisture along the local elevational gradient and treatments with the addition of N and P and grazing on flowering synchrony and reproduction of Croton, a dominant shrub of the inter-Andean dry scrub. Along the elevational gradient (300 m difference between the lowest and highest site), we set up plots with and without grazing nested with four nutrient treatments: control and addition of N or P alone or combined N + P. We recorded the number of female and male flowers in bloom monthly from September 2017 to August 2019 to calculate flowering synchrony. We assessed fruiting, seed mass, and pre-dispersal seed predation. Higher growing-season soil temperatures, which were negatively associated with local elevation and higher nitrogen availability promoted flowering synchrony of Croton, particularly among larger plants. Greater flowering synchrony, high soil temperatures, and addition of N + P resulted in production of more fruits of Croton, but also intensified pre-dispersal seed predation. Temperature, availability of moisture throughout the elevational gradient, and nutrient manipulation affected flowering synchrony, which subsequently affected production of fruits in Croton. These results emphasize the critical role of current anthropogenic changes in climate and nutrient availability on flowering synchrony and reproduction of Croton, a dominant plant of the inter-Andean scrub.

Morphological and phenological variation of flower colour morphs in a wild population of Opuntia streptacantha (Cactaceae)

Background and aims – Opuntia s.s. (Cactaceae) is one of the most diverse genera in the subfamily Opuntioideae, with approximately 220 species. The considerable morphological and anatomical diversity among these species has resulted in a remarkable adaptative plasticity, evident in both intra- and interspecific variability. Our study system is Opuntia streptacantha, which has two flower colour morphs: yellow and orange. The objective is to determine if there are morphological differences in the reproductive and vegetative structures between floral morphs. Material and methods – We measured 8 cladode traits (n = 20 cladodes for each floral morph) and 17 flower traits (n = 30 flowers per morph), and reproductive phenology was recorded for both morphs to describe their phenophases (n = 10 individuals per morph). Key results and conclusion – We found that floral colour morphs of O. streptacantha showed significant differences mostly associated with flower traits. Principal component analysis revealed seven components that explained 80% of the total variation, namely total flower length, number of stamens, distance between anther and stigma, number of pollen grains, style length, equatorial diameter of the ovarian chamber, pericarp width, and number of areole lines. Some individuals of O. tomentosa were classified as floral morphs of O. streptacantha, not having a clear separation between the species. The phenology of the floral colour morphs showed a slight lag in their peak flowering and fruiting. Very high flowering synchrony was found for each floral morph and between them. The modifications found in the flowers of O. streptacantha may be associated with a possible hybridization with O. tomentosa favouring the appearance of the two floral morphs.

Is staggered flowering phenology favoured by phenotypic selection? The case of two co-occurring Cnidoscolus species

Staggered flowering phenology in sympatric plant species that share pollinators is often considered the ultimate strategy for avoiding pollinator competition or a facilitative strategy to maintain pollinators throughout the year. Some factors of the abiotic environment may also contribute to the maintenance of staggered flowering. Flowering (a)synchrony among conspecifics is recognized as a trait with selective value. However, little research has addressed phenotypic selection for (a)synchrony with other plant species. Here, I experimentaly examined the flowering phenology of two sympatric congeneric species (Cnidoscolus aconitifolius & C. souzae) that share pollinators and measured phenotypic selection on this trait. Preliminary field observation suggests that these species exhibit staggered flowering, so my main goal was to assess phenotypic selection on flowering (a)synchrony between the two study species (interspecific synchrony). I predicted that the plants that present greater interspecific synchrony would be selected against and would thus contribute to the maintenance of staggered flowering. However, the patterns of phenotypic selection found were counterintuitive: individuals of C. souzae with greater intraspecific synchrony were selected against, while those with greater interspecific synchrony with C. aconitifolius were favoured by phenotypic selection. I also found the opposite pattern of flower production response to temperature in this system, implying that the abiotic environment could partly explain the occurrence of staggered flowering. Since the phenotypic selection found in this study may select against the observed staggered flowering, reciprocal phenotypic selection between co-occurring plants cannot be invoked as a mechanism underlying staggered flowering phenology in these two Cnidoscolus species.

What are the drivers of female success in food-deceptive orchids?

A large suite of floral signals, and environmental and biotic characteristics influence the behavior of pollinators, affecting the female success of food-deceptive orchids. In this study, we examined the many factors shaping the reproductive output of three orchid taxa: Dactylorhiza majalis, D. incarnata var. incarnata, and D. fuchsii. We applied a statistical model to correlate female success (number of fruit sets) with individual characteristics (plant and inflorescence height, number of flowers, and spur length), number of pollinaria removed, flowering time, and density of floral units of co-flowering rewarding plants. Our findings suggested that the broad spectrum of variations in Dactylorhiza's morphological traits, floral display, and flowering phenology within different environmental contexts has a significant impact on their reproductive success. The number of fruits increased with an increase in the number of pollinaria removed in the studied Dactylorhiza taxa. In contrast, a higher number of flowers per inflorescence and higher inflorescences in relation to individual height always decreased fruit set. We observed that low number of co-flowering rewarding plants in populations could affect the Dactylorhiza reproductive output as magnets and competitor plants. The synchronization of flowering, or lack thereof, between Dactylorhiza and rewarding plants can limit reproductive success. This demonstrates that the food deception strategy is multidirectional, and reproductive output can vary considerably both spatially and temporally within the context of this strategy.

Exploring the molecular regulation of vernalization-induced flowering synchrony in Arabidopsis.

Many plant populations exhibit synchronous flowering, which can be advantageous in plant reproduction. However, molecular mechanisms underlying flowering synchrony remain poorly understood. We studied the role of known vernalization-response and flower-promoting pathways in facilitating synchronized flowering in Arabidopsis thaliana. Using the vernalization-responsive Col-FRI genotype, we experimentally varied germination dates and daylength among individuals to test flowering synchrony in field and controlled environments. We assessed the activity of flowering regulation pathways by measuring gene expression across leaves produced at different time points during development and through a mutant analysis. We observed flowering synchrony across germination cohorts in both environments and discovered a previously unknown process where flower-promoting and repressing signals are differentially regulated between leaves that developed under different environmental conditions. We hypothesized this mechanism may underlie synchronization. However, our experiments demonstrated that signals originating from sources other than leaves must also play a pivotal role in synchronizing flowering time, especially in germination cohorts with prolonged growth before vernalization. Our results suggest flowering synchrony is promoted by a plant-wide integration of flowering signals across leaves and among organs. To summarize our findings, we propose a new conceptual model of vernalization-induced flowering synchrony and provide suggestions for future research in this field.

Among-individual variation in flowering phenology affects flowering synchrony and mating opportunity.

The timing and pattern of a plant's flowering can have important consequences for reproductive success. Variation in flowering phenology may influence the number of prospective mates, the risk of mating with lower quality individuals, and the likelihood of self-pollination. Here we use a common garden experiment to explore within- and among-population variation in phenology. Our work provides new insights into how flowering phenology shapes mating opportunity and flowering synchrony in a self-compatible perennial. To quantify variation in flowering phenology we raised progeny from nine populations of Mimulus ringens in a common garden. For each individual, we measured phenological traits including age at flowering onset, daily floral display size, total flower number, and flowering synchrony with other members of the population, and related these traits to mating opportunity. We also tested how individual flowering schedules influence the magnitude of synchrony. Flowering phenology and synchrony varied substantially within and among populations. From day to day, plants often oscillated between large and small daily floral displays. Additionally, flowering schedules of individual plants strongly influenced flowering synchrony and, along with the number of flowering days, markedly affected plants' mating opportunity. Phenological traits such as flowering synchrony can affect the quantity of mating opportunities and may be important targets of natural selection. Our results highlight the need for studies that quantify flowering patterns of individuals as well as populations.

Agro-climatic requirements and reproductive potentials of pistachio pollinator specimens grown in warm area in North Africa

The success of pistachio production depends on the best selection of female and male trees combined with perfect flowering synchronization. In warm areas, flowering is highly affected by climate change and selecting an appropriate pollinator for a female cultivar is challenging. In this study, seventeen local pistachio pollinators were under study in the arid Central Tunisian region. Bloom timing and chilling and heat requirements were determined based on 17 years of phenology records and using the Partial Least Squares (PLS) regression. Pollen production and quality were assessed. Three pollinator groups as early-, intermediate- and late-flowering ones were delineated and their median bloom dates spanned from DOY84 to DOY110, with bloom dates spread over 27 and 37 days, allowing perfect coverage of the bloom period of the female cultivar Mateur. Within the three groups, the most interesting candidates were H23a and H26a as intermediate-flowering males, H3a, H3b, H18, H23b and H26b as late-flowering ones and H30 as an early-flowering male covering the first flowers blooming. The pollen viability was high in all the studied pollinators (92–98 %). However, great differences existed in inflorescence density (in the range of 2–4) and pollen production per inflorescence (in the range of 191–424 mg). Based on flowering synchronization, the suitable ones had less variable chilling requirements in the range of 33–37 Chill Portions (CP) in warm areas against a significant variability of the heat needs (8783–17,302 GDH). This supported the key role of increased heat accumulation to compensate for the lack of chill and when chilling requirements are not fully fulfilled in warm areas until the chill threshold value of 25 CP. A significant delayed flowering period occurred for all pistachio pollinators when chill accumulation dropped below 25 CP, which may cause asynchronous flowering, leading to poor pollination. In conclusion, bloom timing and pollen production are common variables to characterize pistachio pollinators. The agroclimatic needs could be a relevant tool for planning the best combination linked to local conditions, while estimation improvement is required for warm areas. However, pistachio cultivation in warmer areas will be viable until a certain chill level. Pistachio cultivars will be able to grow, while lack of chill will be overcome with heat accumulation key role for chill compensation until a threshold of 25CP. These findings are of high interest for the warmest orchards, which will cover many important fruit-growing regions with Mediterranean climates all over the world with the expected climate change.

Dynamics of pollen-generating environment producing impact on society based on the relative humidity of the previous year and flowering synchrony

An area with the potential of producing high concentrations of airborne pollen is defined as the ‘potential pollinosis area’. However, the detailed dynamics of pollen dispersion are not fully understood. Further, studies on the detailed dynamics of the pollen-generating environment are limited. This study aimed to determine the relationship between the dynamics of potential pollinosis areas and annual meteorological factors with high spatiotemporal resolution. We visualised and analysed the dynamics of the potential polliosis area based on 11–year high-spatial-density observation data for the atmospheric concentrations of Cryptomeria japonica pollen. The results showed that the potential pollinosis area headed northeast with repeated expansion and contraction, while the centre of the potential pollinosis area leaped to the north in mid-March. The variance in the fluctuation of the coordinates for the potential pollinosis area before the northward leap was strongly related to the variance in the relative humidity of the previous year. These results indicated that the pollen grains of C. japonica across Japan are distributed based on the meteorological conditions of the previous year until mid-March, after which, the pollen grains are distributed through flowering synchrony. Our results suggest that daily nationwide flowering synchrony has a significant annual impact, and changes in relative humidity caused by, for example, global warming would affect the occurrence and predictability of seasonal changes in the pollen dispersion dynamics of C. japonica and other pollen-producing species. Our study showed that pollen production by C. japonica through flowering synchrony is a major cause of nationwide pollinosis and other allergy-related health problems.

Oak masting drivers vary between populations depending on their climatic environments

Large interannual variation in seed production, called masting, is very common in wind-pollinated tree populations and has profound implications for the dynamics of forest ecosystems and the epidemiology of certain human diseases.1,2,3,4,5 Comparing the reproductive characteristics of populations established in climatically contrasting environments would provide powerful insight into masting mechanisms, but the required data are extremely scarce. We built a database from an unprecedented fine-scale 8-year survey of 150 sessile oak trees (Quercus petraea) from 15 populations distributed over a broad climatic gradient, including individual recordings of annual flowering effort, fruiting rate, and fruit production. Although oak masting was previously considered to depend mainly on fruiting rate variations,6,7 we show that the female flowering effort is highly variable from year to year and explains most of the fruiting dynamics in two-thirds of the populations. What drives masting was found to differ among populations living under various climates. In soft-climate populations, the fruiting rate increases initially strongly with the flowering effort, and the intensity of masting results mainly from the flowering synchrony level between individuals. By contrast, the fruiting rate of harsh-climate populations depends mainly on spring weather, which ensures intense masting regardless of the flowering synchronization level. Our work highlights the need for jointly measuring flowering effort and fruit production to decipher the diversity of masting mechanisms among populations. Accounting for such diversity will be decisive in proposing accurate, and possibly contrasted, scenarios about future reproductive patterns of perennial plants with ongoing climate change and their numerous cascading effects.

Development of morphological marker on natural interspecific hybrid seedling of Acacia (Acacia mangium × Acacia auriculiformis) verified by molecular marker

Development of the hybridization between two different species of Acacia mangium and Acacia auriculiformis in Indonesia started in 2009 by establishing an open-pollinated orchard to produce the natural Acacia hybrid seed in Wonogiri District, Central Java Province. The design of the orchard was an alternate row between A. mangium and A. auriculiformis with a spacing of 5 × 5 meters. The orchard produced putative Acacia hybrid seeds firstly in 2013. Based on flowering synchronization between the two species, seeds from 38 sample trees of A. mangium were taken to identify their character seedling morphology to obtain the Acacia putative hybrid. The seedling morphological characteristics observed were leaf development patterns from the emergence of a true leaf (pinnate) until the pseudo leaf (phyllode) emerged. Acacia putative hybrid was then verified using a Simple Sequence Repeat (SSR) marker and Sequence Characterized Amplified Region (SCAR) to obtain the hybrid of A. mangium × A. auriculiformis. The result showed that the presence of 4-pinnate on the seedling development pattern was verified as 100% pure species of A. mangium and the opposite was 100% hybrid. In comparison, the presence of a true leaf of phyllode + 4-pinnate was verified as a 40% hybrid. The final estimation of Acacia hybrid seed production at the hybrid seed orchard on the first flowering was about 3.1% approximately based on the seedling leaf development pattern.

Warming reduced flowering synchrony and extended community flowering season in an alpine meadow on the Tibetan Plateau.

The timing of phenological events is highly sensitive to climate change, and may influence ecosystem structure and function. Although changes in flowering phenology among species under climate change have been reported widely, how species-specific shifts will affect phenological synchrony and community-level phenology patterns remains unclear. We conducted a manipulative experiment of warming and precipitation addition and reduction to explore how climate change affected flowering phenology at the species and community levels in an alpine meadow on the eastern Tibetan Plateau. We found that warming advanced the first and last flowering times differently and with no consistent shifts in flowering duration among species, resulting in the entire flowering period of species emerging earlier in the growing season. Early-flowering species were more sensitive to warming than mid- and late-flowering species, thereby reducing flowering synchrony among species and extending the community-level flowering season. However, precipitation and its interactions with warming had no significant effects on flowering phenology. Our results suggest that temperature regulates flowering phenology from the species to community levels in this alpine meadow community, yet how species shifted their flowering timing and duration in response to warming varied. This species-level divergence may reshape flowering phenology in this alpine plant community. Decreasing flowering synchrony among species and the extension of community-level flowering seasons under warming may alter future trophic interactions, with cascading consequences to community and ecosystem function.

Recent advances in seed priming strategies for enhancing planting value of vegetable seeds

Vegetable crops benefit from seed priming technology by their low volume and high value. Early sowing of vegetables under suboptimal environments is practised often to fetch better remuneration in the market, although simultaneously it compels the farmers to use high seed rates to compensate for poor seedling emergence. To tackle this problem, farmers and seed companies world over practice on-farm and wet/dry priming techniques of seeds as it facilitates synchrony in flowering and fruiting, resulting in improved yields. The various priming strategies used for seed treatment are classified into: conventional/invasive (hydro-, osmo-, hormonal, halo-, solid matrix, nutrient, bio- or nano-priming) and physical/non-invasive (magneto, UV-irradiation, γ-radiation, cold plasma, electron and laser priming). The farmers can reap the benefits of seed priming as it minimizes (i) the time for plant emergence, (ii) expense of re-seeding, (iii) additional irrigation and fertilization, (iv) weed management, (v) ineffectiveness of cultural practices used on a stand of non-uniform growth. This review discusses the recent details about various seed priming techniques used for the enhancement of germination rate as well as vigor in vegetable crops. The biochemical and molecular mechanisms underlying the priming effects have also been comprehensively reviewed to explain the scientific basis of the technology.

Flowering in Hylocereus spp.: comparative analysis and self-incompatibility

Objective: To know the variables of the reproductive component of materials for manual cross-pollination purposes, for which the search for sexual synchrony is emphasized. Design/methodology/approach: Four materials were analyzed, two with white pulp and two with red pulp, about which it is unknown if they present sexual self-incompatibility, and the synchrony in flowering is also unknown. The flowering phase and the variables that can shed light on its reproductive behavior were analyzed Results: It was found that the red materials present strong hercogamy, they cannot self-fertilize. There is also no floral synchrony, but there is closeness between the date of anthesis in a pitahaya with white pulp and a red one, which would allow promoting cross-pollination. Study limitations /implications: Hylocereus spp. is consumed in a large part of the world and has acquired a very strong importance since the industrial demand is increasing; however, several of the genotypes used in commercial production in Mexico show low fruit set compared to high floral emission, which is considered self-incompatibility. Findings/conclusions: The presence of hercogamy, stronger in the red-fleshed materials, indicates the existence of sexual self-incompatibility, explaining the fact that the materials emit a large number of flowers, but do not achieve fruit setting.

Long-term flowering intensity of European tree species under the influence of climatic and resource dynamic variables

• European tree species exhibited increasing flowering intensities in last 66 years. • Flowering synchrony increased in time and decreases spatially between species. • GAMLSS model explained flowering well with weather cues and provenances. • Previous flowering significantly influenced flowering intensities in most species. • Flower masting regulated by sufficient resource and prevailing optimal climate. Mast flowering and seeding is a well-known reproductive strategy of tree species with many ecological consequences regulating synchronous year-to-year flowering intensity variations at the population level. In contrast to flowering timing, the effects of climate change on flowering intensity across space, time, and species are largely unexplored. In this study, a long-term data set on flowering intensities for eight common tree species ( Alnus glutinosa, Fagus sylvatica, Larix decidua, Picea abies, Pinus sylvestris, Pseudotsuga menziesii, Quercus petraea , and Quercus robur ) in Germany was reassembled to analyse flowering mechanisms and strategies by applying GAMLSS (Generalised Additive Models for Location Scale and Shape) models together with climatic data (temperature, precipitation, and drought) and various time-lagged effects. All species showed increasing flowering intensities in the period 1954–2019. The flowering intensity of Larix and Pinus differed significantly across their respective ecological provenances. Time series revealed higher synchrony among broadleaf than conifer species, although correlation coefficients of both their flowering intensities generally increased over time. GAMLSS modelling mainly explained flowering intensities well, with R 2 ranging between 0.58 ( Pseudotsuga ) and 0.25 ( Alnus ). Flowering intensity of almost all species was significantly influenced by flowering in previous years, indicating autocorrelative influences pointing to resource depletion and accumulation. Growing season temperature was modelled to be the main factor among weather cues, with the general pattern of flower masting being correlated negatively with temperature two years before masting and positively with temperature one year before masting. In addition, the short-term drought estimated by Standardised Precipitation-Evapotranspiration Index (12 months) increased flowering intensity in almost all cases. Therefore, it can be inferred that the heavy flowering of European common tree species has been regulated by sufficient resources and prevailing optimal climatic conditions.

Honey bee (Apis mellifera) hive placement is more influential than orchard layout on the fruit set of a dioecious crop

Managers of insect-pollinated orchards face many decisions that can significantly influence crop yields, including managing pollination through use of beehives or the layout of cultivars in the orchard. Understanding the relative importance and interactions between these multiple decisions through empirical field trials is rarely possible, so modeling approaches can provide valuable insights and generate new hypotheses. Based on kiwifruit (Actinidia chinensis var. deliciosa (A. Chev.) A. Chev. ‘Hayward’), a dioecious fruiting vine, as an exemplar, we used a spatially-explicit system of differential equations on a lattice to explore the effects of overlap of male and female flowers, hive placements within the orchard, and orchard layout on the predicted pollination success. In our model, hive placement and orchard layout influenced the proportion of fruit set in an orchard more strongly than male and female flowering synchrony. Simulations with hives distributed evenly around the orchard had the most fruit set, while hives located at a single point resulted in relatively low fruit set. Our model showed that the effect of hive distribution was more important for fruit production than planting regime. We have demonstrated how such a model can be used to provide key information for orchardists to optimize their yields. Our model predicts that while orchard planting decisions are important, the consideration of hive placement during flowering is likely to have greater influence on final orchard productivity in functionally dioecious crops.

Photoperiodic Induction and Synchronization of Flowering in Sugarcane Hybrids for Breeding Programs

Photoperiodic Induction and Synchronization of Flowering in Sugarcane Hybrids for Breeding Programs

Reproductive biology of Myrtillocactus geometrizans (Cactaceae) flowers with contrasting orientation

AbstractIn columnar cacti, a higher production of reproductive structures on branches oriented towards the Equator has been explained by their higher interception of photosynthetic active radiation (PAR) as well as resource availability. The goal of this study was to evaluate the effect of orientation on diverse aspects of the reproductive biology of Myrtillocactus geometrizans. Phenology was studied in north‐ and south‐facing branches. Floral cycle events, floral visitors, reproductive traits associated with sexual and attraction functions, and reproductive success were estimated from reproductive structures with contrasting orientation. Pollination experiments were conducted to evaluate the effect of orientation on mating system. Our results showed that south‐facing branches had a longer duration of the mature fruit phenophase. Moreover, flower synchrony, production of reproductive structures, and floral traits associated with the male (number of anthers and pollen grains per floral bud), female (number and size of ovules and dimensions of both ovary and ovary cavity), and attraction (petal size) functions had higher values in south‐facing flowers. The beginning and ending of the male function and the end of flower anthesis occurred earlier in south‐facing flowers. Diversity of floral visitors was similar between orientations, except for beetles whose abundance was greater in flowers oriented towards the south. North‐ and south‐facing flowers had a mixed mating system, with similar reproductive success. Our results showed strong differences in the reproductive biology of an intertropical columnar cactus, probably in response to the uneven PAR interception and resource availability in branches and flowers with contrasting orientation.

Fire influences reproductive outcomes by modifying flowering phenology and mate-availability.

A recent study posited that fire in grasslands promotes persistence of plant species by improving mating opportunities and reproductive outcomes. We devised an investigation to test these predicted mechanisms in two widespread, long-lived perennials. We expect fire to synchronize flowering, increase mating and boost seed set. We quantified individual flowering phenology and seed set of Liatris aspera and Solidago speciosa for 3yr on a preserve in Minnesota, USA. The preserve comprises two management units burned on alternating years, allowing for comparisons between plants in burned and unburned areas within the same year, and plants in the same area across years with and without burns. Fire increased flowering synchrony and increased time between start date and peak flowering. Individuals of both species that initiated flowering later in the season had higher seed set. Fire was associated with substantially higher flowering rates and seed set in L. aspera but not S. speciosa. In L. aspera, greater synchrony was associated with increased mean seed set. Although fire affected flowering phenology in both species, reproductive success improved only in the species in which fire also synchronized among-year flowering. Our results support the hypothesis that reproduction in some grassland species benefits from fire.

Are Temperate Alpine Plants With Distinct Phenology More Vulnerable to Extraordinary Climate Events Than Their Continuously Flowering Relatives in Tropical Mountains?

Alpine plants are perceived as some of the most vulnerable to extinction due to the global climate change. We expected that their life history strategies depend, among others, on the latitude they live in: those growing in temperate regions are likely to have a distinct phenology with short seasonal peaks, while tropical alpine plants can potentially exploit favorable year-round growing conditions and different individuals within a population may flower at different times of the year. In species, whose flowering is synchronized into short seasonal peaks, extraordinary climate events, which may become stronger and more frequent with climate change, can potentially destroy reproductive organs of all synchronized individuals. This may result in reducing fitness or even extinction of such species. We studied field populations of five groups of closely related Andean alpine plant species to test our expectations on their latitude-dependent synchronization of flowering. Our results confirmed these expectations: (i) Tropical alpine species were least synchronized and flowering peaks of different individuals in their populations were distributed across many months. Thus, in tropical alpine species, if an extraordinary event happens, only some individuals are affected and other members of the population successfully reproduce in other parts of the long season. (ii) Higher synchronicity in flowering of temperate and subtropical alpine plants resulted even in some of these species using only a part of the short growing season to reproduce, which increases their vulnerability to extraordinary climatic events. However, we did not find any unique pattern valid for all species, groups and regions. The diversity in flowering phenology (i.e., different levels of seasonality and synchronicity) that we found increases the likelihood of plants successfully coping with climate change.