Hummingbirds (order Apodiformes, family Trochilidae) Hummingbirds are the only bird pollinators found in Missouri. They are important pollinators for tubular flowers, into which they insert their beaks and then use their tongues to lap up nectar. Pollen collects mainly on a hummingbird’s head while it is feeding and is then transferred to the pistils of other flowers. Missouri’s only resident hummingbird is the ruby-throated hummingbird (Archilochus colubris) (Figure 22), although other species may travel through Missouri during migration. Because they are larger than other pollinators, hummingbirds can move pollen over long distances. To attract hummingbirds to a garden, plant native wildflowers with bright and long-tubed flowers, such as cardinal flower (Lobelia cardinalis), jewelweed (family Balsaminaceae) and trumpet creeper (Campsis radicans). You can also use a hummingbird feeder to dispense sugar water for hummingbirds in the early spring as they return from their annual migration when flowers are scarce.
Studies carried out in a wide array of ecosystems and regions in East Asia are required because the research on plant- pollinator interactions done so far has not been evenly distributed geographically. The majority of pollination studies in China have conducted in mountainous regions (Ren et al. 2018). In East Asia, relatively few studies have been conducted in the subtropics, coastal ecosystems, and wetland ecosystems. Although the Korean peninsula and Taiwan are biologically diverse and biogeographically important components of East Asia (Kong & Watts 1999; Choe et al. 2016; Zhu 2016; Tojo et al. 2017), very few studies on plant- pollinator interactions have been conducted in these regions. The relationship between habitat type and the composition of pollinator fauna in East Asia is still unclear because few community-level studies that were comparable among habitat types have been conducted. However, some trends can be observed (Fig. 2). Although very few studies have been conducted in wetland habitats, dipteran pollinators are known to be abundant in wetland habitats (Kato & Miura 1996). Bees, especially bumblebees, and Diptera are dominant flower visitors in alpine regions (Yumoto 1986; Fang & Huang 2012; Mizunaga & Kudo 2017; Ishii et al. 2019). Wasps tend to be more abundant in coastal sand dunes than in other habitats (Inoue & Endo 2006b; Hiraiwa & Ushimaru 2017). More studies are needed to definitively elucidate the relationships between different habitat types and their pollinator fauna.
First, analysis of the effects of socio-economic factors on floral quality and subsequent effects on bee abundance was handled using single-variable linear models. Estimates of the beta coefficients of these more straightforward single–variable linear models were verified through residualization in multivariate models. The results presented in this work stem from this analysis, as they are more widely accessible to readers with varying degrees of statistical exposure. Given the use of linear models, skewed variables were log transformed to meet conditions of normality (see Appendix C.1 for more detail). Data was also standardized to z-scores given that each variable was measured across significantly different ranges and scales, streamlining comparison of effect size across variables. Second, to more directly address multivariate models and to corroborate coefficient estimates garnered from single variate models, we utilized partial linear square regressions (PLS regressions) to create multivariate regressions. PLS regression is often used when predictor variables are highly collinear (Mevik and Wehrens 2007). In our analysis, PLS regressions acted as a degree of authentication of the relationships found between socio- economic variables and dependent variables (see Appendix C.2 for further details).
In contrast, the negative relationship recorded here between forest cover and network size differs from the results obtained by Ferreira et al. [ 32 ] in the Atlantic Forests of Brazil, where the converse trend was observed. It is important to note that the simulated networks presented here differ from these field situations, as they incorporated pollination interactions across the entire landscape (i.e. including both forest and non-forest vegetation), rather than being lim- ited to a single environment type, as was the case in the field studies. This highlights the need for field data for pollinator networks to be collected from both inside and outside forest patches along deforestation gradients; such data are currently lacking. A further difference is that the species richness and abundance of both bees and flower species was constant across the modelled gradient of forest cover, which contrasts with the field situation. In field studies, as habitat area increased, networks tended to become larger and more diverse [ 14 , 32 ]. The variation in network size encountered in the model results is attributable to stochastic pro- cesses, such as chance interactions between bees and flowers arising from pollinator behaviour. As evidence of this, it is notable that in none of the model experiments conducted did all possi- ble interactions between bee and flower species actually occur. It should also be noted, how- ever, that some field studies have reported results that were consistent with the model outputs presented here. For example, working in temperate woodlands, Vanbergen et al. [ 49 ] found that plant-pollinator networks from relatively disturbed sites were less connected, but were also more speciose and therefore larger. This was attributed to the effects of disturbance on the size and distribution of interspecific interactions in the networks, and the influence of these factors on robustness to co-extinction cascades. Similar mechanisms were identified by Grass et al. [ 50 ] in calcareous grassland fragments, where plant–pollinator communities were found to respond to the loss of species associated with habitat fragmentation by opportunistic partner switches. While such processes have not yet been documented in Atlantic Forest, these results suggest they might usefully be examined in future field investigations.
species is globally stable. That is, if the feedback control is small enough, the population may remain stable. Wang et al.  have shown that the system (.) is globally stable, and our work shows that the feedback controls have no inﬂuence on the attractivity of the sys- tem. The obtained results may be helpful to maintain the plant-pollinator cooperation and provide insight in the mechanisms by which pollination mutualism could persist and we have global attractivity, which may be helpful for understanding the complexity of these systems.
Aspects of arti ﬁ cial lighting also affected both the number of seeds produced per seed capsule and the total dry mass of seeds per seed capsule, though the two would be expected to correlate. Speci ﬁ cally, an interaction between lamp type and lighting regime meant that seed count increased under PN HPS lighting and decreased under PN LED lighting, relative to unlit controls (Fig. 3) and both FN lighting treatments. How- ever, an interaction between lamp type and dis- tance meant that seed mass increased with distance from the light under HPS lighting but decreased with distance from the light under LEDs (Fig. 6). Again, the cause of these effects is unclear, and it should be noted that both effects were non-signi ﬁ cant when lighting was treated as a ﬁ ve-level categorical variable (Appendix S1: Table S4). Possibly, these effects could be the result of changes in duration of feeding by moths under different lamp types; moths spend less time feeding under arti ﬁ cial light than in dark- ness, and the effect is strongest for lighting con- taining a high proportion of short wavelengths (van Langevelde et al. 2017), such as many com- mercially available LEDs, including those used in our study (Fig. 1). The strength of any effect of light can clearly be expected to reduce with dis- tance from the light. However, it is not clear how such effects would interact with lighting regime. A physiological response by the plant (i.e., increased photosynthesis under lighting treat- ments) appears unlikely because seed capsules mostly developed after all ﬂ owers were returned to the glasshouse, when they were no longer exposed to the experimental lights. There is a possibility that differences between lit treatments and unlit controls could have been in ﬂ uenced by low-level noise and/or air pollution from the pet- rol generators used to power the experimental lights, as generators were not operated at the unlit control plots. Nevertheless, further research
and where they are located within a given landscape. They also vary depending on the time of year and day when you sample. Documenting changes in bee communities using this protocol will allow you to assess the efficacy of best management practices aimed at increasing pollinator abun- dance and diversity. Best management practices may in- clude enhancing floral resources and/or nesting sites, reduc- ing tillage and reducing the non-target impact of pesticides. Alternatively, using this protocol to monitor pollinators in field crops or orchards can provide insights into which na- tive species provide farmers with free pollination services. To develop an accurate picture of how a bee community is changing, however, it is important to keep in mind the fol- lowing two points:
and pollen deposition was found at the community level, it rarely applied to individual visitor groups. Some frequent visitors were poor pollen depositors as they only collected nectar from the flowers and/or were poor morphological matches with the flowers (e.g. male Anthophora bees visiting Asphodelus aestivus or Diptera visit- ing Tordilium carmeli), a situation detected in numerous studies of single plant species (e.g. refs 23 and 24). Such visits will only influence plant fitness if the removal of floral rewards influences the behaviour of more effective pollinators. Others have also cautioned against relying solely on interaction frequencies to estimate the struc- ture of plant-pollinator interactions 25–27 , as high numbers of low quality visits need not necessarily translate into
This paper has investigated whether an increase in diamond prices leads to more violent activity in African countries that are diamond abundant, and if so through which mecha- nism. Potentially, a rise in diamond price could increase conflict activity through changing the wage rate, thereby impacting the opportunity costs of conflict (Dal Bó and Dal Bó, 2004) and/or through weak property rights protection, increasing the expected revenue from conflict (Garfinkel et al., 2008). The two theoretical models formalizing these mechanisms make opposite predictions for primary diamonds (characterized by a capital intensive pro- duction process and relatively secure property rights) and secondary diamonds (labour in- tensive and relatively insecure property rights). Exploiting this, I interact both primary and secondary diamond abundance with diamond price and investigate whether these terms are related to violent activity. This research, based on explicit theoretical models, using an exogenous indicator for primary and secondary diamond abundance and employing a country-fixed effects model, intends to avoid some of the pitfalls of earlier work, hopefully arriving at more consistent and reliable results.
The degree and direction of heterogeneity of light distribution within natural plant communities is strongly determined by the density, species composition and growth rates of the constituent plants, all of which differ substantially in time and space (Grime, 1994). This suggests that plants must have evolved fine-tuned detection mechanisms and transduction pathways that enable them to respond to the thus produced variation in light cues such that they can optimize their light capture. Physiological research indeed indicates that such mechanisms exist (Smith, 2000; Stamm and Kumar, 2010). However, few studies have analysed how the functional significance of plasticity in architectural traits, triggered by intra- and interspecific interactions, contributes to species performance in real plant communities. This study shows how a strong plasticity in tillering enables wheat to adjust its architecture strongly so as to improve its light acquisition in contrasting light environments. This may likely apply to other grasses as well. Tillering helps grasses to occupy space at an early time and maintain high rates of leaf area production which is essential in competition for light. In addition, the production of surviving tillers and the associated root production help to increase the uptake of available resources, as shown in higher N yields in the border row (Table 2.1). The senescence of tillers in dense canopies would balance the cost and benefits of tiller production (Fig. 2.4). In addition, the top leaves, which are vital for the production of grain filling, were larger (Fig. 2.5 A, B) and contained a higher chlorophyll concentration (Fig. 2.6). Together these results indicate the importance of plasticity in architectural traits for the success of tillering grasses. Conclusions
Roads have become an important landscape feature (Watkins et al. 2003) that may influence ecological pro- cesses in a surrounding habitat. It is still unclear how distance from roads can affect the diversity of understory vegetation in a forest, and the ecological impacts of roads and traffic, however, have become a great concern (Spellerberg 1998), especially on understory plant rich- ness (Enoki et al. 2014). Guirado et al. (2007) studying Mediterranean forests found that the total species rich- ness of understory vegetation increased with distance to the main roads. Pollutants affecting plants and animals range from noise, light, sand, dust to other particulates, metals, and gases (Spellerberg 1998). Also, road dust could be an important factor for plant diversity. Dust that are mobilized and spread by the road traffic can re- strict photosynthesis, respiration, and transpiration of plants (Trombulak and Frissell 2000). According to Wong et al. (1984, in Watkins et al. 2003), plant mate- rials sampled from a site with a high traffic density showed a significant decrease in root growth whereas in- creased root growth was found for plants sampled from low-traffic-density areas. In addition to physiological stress generated from roads, the closer the habit is to a road, the more disturbances on vegetation by human in- fluence there may be. On the other hand, Watkins et al. (2003) found higher richness of understory vegetation on the roadside edge since lower canopy cover of the edge allows more light to reach understory. Thus, road density, vehicle transportation, and distribution of roads around the area of interest may interplay, affecting the richness of understory vegetation.
Mutualism is ubiquitous in nature, and nursery pollination mutualisms provide a system well suited to quantifying the benefits and costs of symbiotic interactions. In nursery pollination mutualisms, pollinators reproduce within the inflorescence they pollinate, with benefits and costs being measured in the numbers of pollinator offspring and seeds produced. This type of mutualism is also typically exploited by seed-consuming non- pollinators that obtain resources from plants without providing pollination services. Theory predicts that the rate at which pollen-bearing “foundresses” visit a plant will strongly affect the plant's production of pollinator offspring, non-pollinator offspring, and seeds. Spatially aggregated plants are predicted to have high rates of foundress visitation, increasing pollinator and seed production, and decreasing non-pollinator production; very high foundress visitation may also decrease seed production indirectly through the production of pollinators. Working with a nursery mutualism comprised of the Sonoran Desert rock fig, Ficus petiolaris, and host-specific pollinating and non- pollinating fig wasps, we use linear models to evaluate four hypotheses linking species interactions to benefits and costs: 1) foundress density increases with host-tree
Pollinator Frocks was publicly tested over a three week period through a series of public engagement events and performative video ‘walkabouts’ in New Zealand’s Pukekura Parklands as part of the art, technology and ecology event SCANZ 2011, which included exhibitions, workshops and talks, and a symposium and screening of the Pollinator Frocks film at the Govett-Brewster Art Gallery, New Plymouth NZ, in January 2011.
The reproductive success of plants is often limited by pollen availability (reviewed in Burd 1994; Larson & Barrett 2000; Ashman et al. 2004; Knight et al. 2005). This occurs when the quantity and/or quality of pollen that a plant receives during pollination is insufficient to fertilize available ovules, resulting in a reduction in fruit and/or seed production (Burd 1995; Aizen & Harder 2007). The fitness consequences of pollen limitation in variable pollination environments are diverse, and chronic pollen limitation can affect the evolution of a range of life history and reproductive traits in plant populations (Haig & Westoby 1988; Ashman et al. 2004; Morgan et al. 2005; Porcher & Lande 2005; Harder & Aizen 2010). Extended floral longevity is one trait that can increase opportunities for pollinators to visit flowers and buffer fertility in stochastic environments with few pollinators (Kerner von Marilaun 1895; Primack 1985; Ashman & Schoen 1994; Charnov 1996). Theoretical models have examined the factors influencing optimal floral longevities (Ashman & Schoen 1994; Schoen & Ashman 1995), but relatively few studies have experimentally examined the direct consequences of floral longevities on female reproductive success (but see Ashman & Schoen 1997; Rathcke 2003; Alonso 2004).
Brittlebush population and community dynamics in cities The phenological and pollinator differences may affect population and community dynamics in urban ecosystems. There is overlap in blooming period between mesiscaped urban and desert sites, so there is still the potential for gene flow between these populations if brittlebush pollinators travel far enough. However, if pollinators do not travel far enough, then there is the potential for isolated genetic changes and the development of ecotypes (Franks et al. 2007). Furthermore, mesiscaped urban land cover types are significantly depauperate in abundance and richness of pol- linators, which may also decrease the potential for gene flow. Because mesiscaped patches and desert remnant patches are scattered throughout the Phoenix metropolitan area, the spatiotemporal pattern of flowering and pollinator abundance and richness does not reflect an even gradient from the desert fringe to the urban core. This study indi- cates that the flowering pattern and pollinator community is much more heterogeneous across both space and time and that desert remnants appear to vary in their similarity of arthropod pollinators to surrounding native areas de- pending on community measurement. A multiyear investi- gation of flowering phenology patterns will help clarify the overall long-term effects of urbanization on patchiness of flowering.
Crop plants are exposed to several environmental stresses, all affecting plant growth and development, which consequently hamper crop productivity. Among all stresses drought is considered the single most devastating environmental stress. During germination phase, the water absorbed is required for several enzymatic reactions, for solubilization and transport of metabolites and as a reagent in the hydraulic digestion of proteins, carbohydrates and lipids from the tissue reserve of the seed towards the embryo. Drought stress negatively impacts growth, yield, membrane integrity, pigment content, osmotic adjustment, water relationsand photosynthetic activity. It causes not only a significant damage to photosynthetic pigments, but also affects thylakoid membranes. The generation of reactive oxygen species (ROS) is one of the earliest biochemical responses of eukaryotic cells to biotic and abiotic stresses. Being highly reactive, ROS can seriously damage plants by increasing lipid peroxidation, protein degradation, DNA fragmentation and ultimately cell death. Escape from drought is attained when phenological growth is effectively coordinated with periods of water availability, where the growing season is shorter and terminal drought stress predominates. Drought avoiders maintain water status through stomatal closure to minimize transpirational water loss and maintains water uptake through an extensive and prolific root system, osmoregulation and anti-oxidant enzymes. Both conventional and molecular breeding have paved the way towards tolerance and plant scientists have developed new line of crop plants that can cope with water stressed environment without sacrificing yield.
Plant growth is usually linear or circumferential (Steeves and Sussex, 1989) but in some cases it results in twists, spirals or coils; these patterns are generally categorised as helical (see Glossary, Box 1) growth. Well-known examples of plant organs that exhibit helical growth are the tendrils of climbing plants (Jaffe and Galston, 1968), but many other forms have been described (Fig. 1). For example, the tips of growing stems and other organs exhibit circumnutation (see Glossary, Box 1) as they extend and interact with components of the environment, be it light, other vegetation, or soil (Darwin, 1880; Baillaud, 1962a,b). Less well known are the specialised twists of leaf and flower stems that occur to invert their dorsal-ventral orientation (resupination; see Glossary, Box 1) (Hill, 1939), the spiral insertion of petals (contortion; see Glossary, Box 1) in the flower template (Endress, 1999), the coiling (see Glossary, Box 1) of pods and awns during seed dispersal, and the twisting (see Glossary, Box 1) of flat leaves that ensures their rigidity. It should be noted that one common form of helical arrangement, namely the placement of leaves and flowers on stems ( phyllotaxy), represents a different category of helical patterning involving organ initiation rather than subsequent organ growth. The properties and mechanisms of phyllotaxy are relatively well known (Reinhardt et al., 2003; reviewed by Traas, 2013) and will not be discussed here.
Fig. 5. A molecular framework for plant regeneration. (A) A schematic model showing how Arabidopsis explants regenerate shoots in vitro. Wounding induces WIND1-4 expression to promote the acquisition of pluripotency at cut sites. Culturing plant explants on auxin-rich callus-inducing medium upregulates the expression of PLT3, PLT5 and PLT7, which subsequently promotes the acquisition of pluripotency through the induction of PLT1, PLT2, CUC1 and CUC2. Upon transfer to cytokinin-rich shoot-inducing medium, the WUS, ESR1 and ESR2 genes are induced, conferring cells with shoot fate. CUC2 expression becomes spatially confined to promeristems, in which STM and PIN1 further regulate patterning and formation of the meristems (red arrowheads). (B) A schematic model showing how root regeneration is controlled in Arabidopsis leaf explants. Accumulation of auxin at cut sites promotes the fate conversion from leaf procambium/parenchyma cells to root founder cells by activating WOX11 and WOX12 expression. WOX11 and WOX12 subsequently induce the expression of LBD16, LBD29, and then WOX5 to initiate root meristem formation (red arrowhead). (C) A schematic model showing how indirect somatic embryogenesis is regulated in Arabidopsis. A gradient of auxin in the embryonic callus specifies WUS expression to low auxin response domains. WUS subsequently induces expression of LEC1, LEC2 and FUS3, which together with AGL15 modulate the endogenous levels of auxin, GA and ABA to promote embryogenesis. Solid black lines indicate direct transcriptional regulation demonstrated by molecular evidence and dotted black lines indicate direct or indirect transcriptional regulation inferred from genetic evidence. Proteins that promote cellular competency are in blue; those that mediate shoot fate are in green, root fate in orange or brown, and embryonic fate in pink or purple.
to activate transcription upon hormonal inductions and stresses. Despite its main localisation and place of action in the cytoplasm, AGO1 was found to be associated to the chromatin of around 940 loci. The guiding of AGO1 to chromatin relies on 21-nt sRNA as the association of AGO1 to the targeted loci is decreased in the dcl1 mutant. A positive regulation of chromatin-bound AGO1 on transcription was observed when comparing the transcript abun- dance between the control and ago1 mutants. In addition, inves- tigation of active Pol II abundance on AGO1 bound loci showed that AGO1 has a direct effect on transcription and suggests that AGO1 might facilitate the recruitment of Pol II to the locus. How AGO1 acts to regulate transcription is not fully understood, but the direct interaction of AGO1 with a SWI/SNF chromatin remod- elling complex could facilitate Pol II accessibility to chromatin. Interestingly, Liu et al. further showed that association of AGO1 to chromatin as well as associated transcriptional activation is regulated by plant hormones, abiotic and biotic stimuli.