scholarly journals Influence of flower functionality and pollination system on the pollen size-pistil length relationship

2009 ◽  
Vol 9 (2) ◽  
pp. 75-82 ◽  
Author(s):  
Verónica Andrea Fernández ◽  
Leonardo Galetto ◽  
Julia Astegiano
Keyword(s):  
Pollen Size ◽  
Pollination System ◽  
Length Relationship ◽  
Pistil Length

Evolution of Angiosperm Pollen: 8. Lamiids

2020 ◽  
Vol 105 (3) ◽  
pp. 323-376
Author(s):  
Li-E Yang ◽  
Lu Lu ◽  
Kevin S. Burgess ◽  
Hong Wang ◽  
De-Zhu Li
Keyword(s):  
Maximum Likelihood ◽  
Pollen Morphology ◽  
Pollen Size ◽  
State Transitions ◽  
Character State ◽  
Evolutionary Mechanisms ◽  
Pollen Characters ◽  
Exine Ornamentation ◽  
Shape Class ◽  
Pollen Character

Lamiids, a clade composed of approximately 15% of all flowering plants, contains more than 50,000 species dispersed across 49 families and eight orders (APG IV, 2016). This paper is the eighth in a series that analyzes pollen characters across angiosperms. We reconstructed a maximum likelihood tree based on the most recent phylogenetic studies for the Lamiids, comprising 150 terminal genera (including six outgroups) and covering all eight orders and 49 families within the clade. To illustrate pollen diversity across the Lamiids, pollen grains from 22 species (22 genera in 14 families) were imaged under light, scanning, and transmission electron microscopy. Eighteen pollen characters that were documented from previous publications, websites, and our new observations were coded and optimized onto the reconstructed phylogenetic tree using Fitch parsimony, maximum likelihood, and hierarchical Bayesian analysis. Pollen morphology of the Lamiids is highly diverse, particularly in shape class, pollen size, aperture number, endoaperture shape, supratectal element shape, and tectum sculpture. In addition, some genera show relatively high infrageneric pollen variation within the Lamiids: i.e., Coffea L., Jacquemontia Choisy, Justicia L., Pedicularis L., Psychotria L. nom. cons., Sesamum L., Stachytarpheta Vahl, and Veronica L. The plesiomorphic states for 16 pollen characters were inferred unambiguously, and 10 of them displayed consistent plesiomorphic states under all optimization methods. Seventy-one lineages at or above the family level are characterized by pollen character state transitions. We identified diagnostic character states for monophyletic clades and explored palynological evidence to shed light on unresolved relationships. For example, palynological evidence supports the monophyly of Garryales and Metteniusaceae, and sister relationships between Icacinaceae and Oncothecaceae, as well as between Vahliales and Solanales. The evolutionary patterns of pollen morphology found in this study reconfirm several previously postulated evolutionary trends, which include an increase in aperture number, a transition from equatorially arranged apertures to globally distributed ones, and an increase in exine ornamentation complexity. Furthermore, there is a significant correlation between pollen characters and a number of ecological factors, e.g., pollen size and pollination type, pollen ornamentation and pollination type, and shape class and plant growth form. Our results provide insight into the ecological, environmental, and evolutionary mechanisms driving pollen character state changes in the Lamiids.

Effect of alkali therapy with NaHCO3 or THAM on cardiac contractility

1996 ◽  
Vol 270 (5) ◽  
pp. R955-R962
Author(s):  
C. D. Mazer ◽  
B. Naser ◽  
K. S. Kamel
Keyword(s):  
Myocardial Ischemia ◽  
Contractile Function ◽  
Venous Blood ◽  
Systolic Pressure ◽  
Ischemic Myocardium ◽  
Stroke Work ◽  
Length Relationship ◽  
Alkali Therapy ◽  
Myocardial Contractile ◽  
The Impact

We examined the impact of alkali therapy on myocardial contractility in a model of myocardial ischemia in dogs using direct measurements of myocardial contractile function. Myocardial ischemia in the left anterior descending (LAD) artery territory was induced using a perfusion circuit from the internal carotid artery to the LAD artery. Myocardial contractile function was assessed using sonomicrometry for measurement of percent systolic shortening (%SS), preload recruitable stroke work (PRSW) slope, and end-systolic pressure-length relationship (ESPLR) area. Because the blood flow in LAD artery was diminished by approximately 70%, there was a significant decrease in O2 delivery and uptake by the ischemic myocardium. Ischemia led to a significant fall in LAD regional contractile function with %SS decreasing from 15 +/- 2 to 7 +/- 2%, PRSW slope from 82 +/- 10 to 37 +/- 5 mmHg, and ESPLR area from 121 +/- 2 to 48 +/- 14 mmHg.mm (P < 0.05). In six dogs, the intracoronary administration of NaHCO(3) resulted in a significant increase in pH in LAD arterial and venous blood. There was, however, no significant increase in %SS (6 +/- 2), PRSW slope (43 +/- 10 mmHg), or ESPLR area (60 +/- 13 mmHg.mm). Since administration of NaHCO(3) resulted in a significant increase in PCO2 in LAD arterial and venous blood, similar experiments were carried out in five dogs, but with the intracoronary infusion of the amine buffer THAM [tris(hydroxymethyl)aminomethane (Tris) buffer; 2-amino-2-hydroxyl-1,3-propandiol] instead of NaHCO3. Although administration of THAM resulted in a significant increase in pH and a significant decrease in PCO2, in both LAD arterial and venous blood, there was no significant improvement in any of the parameters used to assess myocardial contractile function. In conclusion, administration of alkali (NaHCO3 or THAM) does not enhance the contractile function of the ischemic myocardium.

scholarly journals Generalized olfactory detection of floral volatiles in the highly specialized Greya-Lithophragma nursery pollination system

2021 ◽  
Author(s):  
Florian P. Schiestl ◽  
Erika A. Wallin ◽  
John J. Beck ◽  
Magne Friberg ◽  
John N. Thompson
Keyword(s):  
Selective Advantage ◽  
Floral Volatiles ◽  
Pollination System ◽  
Allopatric Populations ◽  
Evolutionary Scenario ◽  
Plant Recognition ◽  
Hexahydrofarnesyl Acetone ◽  
Electroantennographic Detection ◽  
Local Host ◽  
Olfactory Detection

AbstractVolatiles are of key importance for host-plant recognition in insects. In the pollination system of Lithophragma flowers and Greya moths, moths are highly specialized on Lithophragma, in which they oviposit and thereby pollinate the flowers. Floral volatiles in Lithophragma are highly variable between species and populations, and moths prefer to oviposit into Lithophragma flowers from populations of the local host species. Here we used gas chromatography coupled with electroantennographic detection (GC-EAD) to test whether Greya moths detect specific key volatiles or respond broadly to many volatiles of Lithophragma flowers. We also addressed whether olfactory detection in Greya moths varies across populations, consistent with a co-evolutionary scenario. We analyzed flower volatile samples from three different species and five populations of Lithophragma occurring across a 1400 km range in the Western USA, and their sympatric female Greya politella moths. We showed that Greya politella detect a broad range of Lithophragma volatiles, with a total of 23 compounds being EAD active. We chemically identified 15 of these, including the chiral 6, 10, 14-trimethylpentadecan-2-one (hexahydrofarnesyl acetone), which was not previously detected in Lithophragma. All investigated Lithophragma species produced the (6R, 10R)-enantiomer of this compound. We showed that Greya moths detected not only volatiles of their local Lithophragma plants, but also those from allopatric populations/species that they not encounter in local populations. In conclusion, the generalized detection of volatiles and a lack of co-divergence between volatiles and olfactory detection may be of selective advantage for moths in tracking hosts with rapidly evolving, chemically diverse floral volatiles.

Does Performance Breed Slack? Ownership as a Contingency to the Performance Feedback and Slack Relationship

2021 ◽  
pp. 014920632110142
Author(s):  
Varkey Titus ◽  
Jonathan P. O’Brien ◽  
Jaya Dixit
Keyword(s):  
Performance Feedback ◽  
Stock Price ◽  
Theory Of The Firm ◽  
Organizational Outcomes ◽  
Organizational Slack ◽  
Length Relationship ◽  
Different Types ◽  
Stakeholder Perspective ◽  
Shareholder Perspective ◽  
The Relationship

Although organizational slack is a prominent construct in strategic management, it is often treated as an antecedent or enabler of other organizational outcomes, and thus our understanding of where slack comes from is underdeveloped. We draw on the behavioral theory of the firm to develop a better understanding about the antecedents of organizational slack. In so doing, we address a gap in the literature on the antecedents of slack by developing base models showing how and why performance feedback influences the three most common types of slack studied in the literature. Moreover, we contend that ownership is an important contingency that influences these relationships because different types of owners are motivated by different norms. Within a “communitarian” culture such as Japan, domestic owners generally have a multifaceted relationship with the firm and hence are motivated by norms of reciprocity and embeddedness, thereby allowing managers to adopt a stakeholder perspective. In contrast, foreign investors typically have only an arm’s-length relationship with the firm and are thus motivated by stock price, thereby putting “contractarian” pressures on managers to adopt a shareholder perspective. This domestic/foreign ownership distinction influences how resources are allocated and therefore the relationship between performance feedback and different types of slack in the firm. We further emphasize that these relationships will vary in accordance to where the slack resides: internal or external to the firm. We find general support for our hypotheses.

Evolution of floral morphology and pollination system in Bignonieae (Bignoniaceae)

2010 ◽  
Vol 97 (5) ◽  
pp. 782-796 ◽  
Author(s):  
Suzana Alcantara ◽  
Lúcia G. Lohmann
Keyword(s):  
Floral Morphology ◽  
Pollination System

scholarly journals The role of ultraviolet reflectance and pattern in the pollination system of Hypoxis camerooniana (Hypoxidaceae)

AoB Plants ◽  
2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Yannick Klomberg ◽  
Raissa Dywou Kouede ◽  
Michael Bartoš ◽  
Jan E J Mertens ◽  
Robert Tropek ◽  
...  
Keyword(s):  
Plant Species ◽  
Central Africa ◽  
Complete Removal ◽  
Reproductive Organs ◽  
Specific Pattern ◽  
Flowering Plant ◽  
Pollination System ◽  
Mount Cameroon ◽  
Uv Reflectance ◽  
Montane Grasslands

Abstract Apart from floral morphology and colours perceived by the human eye, ultraviolet (UV) reflectance acts as an important visual advertisement of numerous flowering plant species for pollinators. However, the effect of UV signalling on attracting pollinators of particular plant species is still insufficiently studied, especially in the Afrotropics. Therefore, we studied the pollination system of Hypoxis camerooniana in montane grasslands of Mount Cameroon, West/Central Africa. We focused mainly on the effects of the flowers’ UV reflectance on its visitors. We experimentally removed UV reflection from petals either completely or partially. Thereafter, flower visitors were recorded and pistils were collected post-flowering to quantify germinated pollen tubes per treatments. The most important visitors were bees, followed by flies. Due to their contacts with reproductive organs bees are considered as the primary pollinators. Visitation rates were lower when UV reflectance was completely removed, whereas the decrease of frequency on half-treated flowers did not differ significantly from control treatments. The complete removal of UV also affected bees’ landing behaviour, but not that of flies. We showed that the presence of UV reflectance is more important than UV pattern for bees visiting flowers of H. camerooniana. We hypothesize that exploiting all flowers irrespective of their pattern can be more efficient for pollinators in the open grasslands of high altitudes to spot these relatively scarce flowers by their UV reflectance. Furthermore, we highlight the necessity of both experimental and natural controls in similar studies to control for additional effects of the used UV manipulations. Many plants advertise their flowers with UV reflectance visible to their insect visitors. By manipulating the UV reflectance and pattern of Hypoxis camerooniana in the Afromontane grasslands of Mount Cameroon, we have shown how crucial it is for the predominant visitor, bees. Both bees' preferences for flowers and their behaviour during visits are influenced by changes in UV reflectance. However, the presence of some UV signal is more important than the specific pattern. Especially in montane grasslands with higher UV irradiation, the UV floral colours are important for recognition of flowers by potential pollinators.

Transfer of pollinaria on birds? feet: a new pollination system in orchids

2004 ◽  
Vol 244 (3-4) ◽  
pp. 181-188 ◽  
Author(s):  
Steven D. Johnson ◽  
Mark Brown
Keyword(s):  
Pollination System

CYTOLOGY OF POPLAR SPECIES AND NATURAL HYBRIDS

1938 ◽  
Vol 16c (11) ◽  
pp. 445-455 ◽  
Author(s):  
F. H. Peto
Keyword(s):  
Size Distribution ◽  
Genetic Factors ◽  
Chromosome Complement ◽  
Pollen Grains ◽  
Pollen Size ◽  
Cell Nuclei ◽  
Good Pollen ◽  
Natural Hybrids ◽  
Pollen Diameter ◽  
High Degree

Complete analyses of pollen-mother-cell nuclei at first metaphase, percentage good pollen, pollen diameter and pollen-size distribution were determired for the following poplar species and natural hybrids: Populus grandidentata Michx., P. tremuloides Michx., P. eugenei Simon Louis, P. alba L., P. canescens Sm., natural hybrids of P. alba × P. grandidentata and of P. alba × P. tremuloides.Both of the P. alba and two of the four P. canescens trees examined were triploids (2n = 57) while all other trees examined were diploids (2n = 38). Meiotic observations on the natural hybrids indicated a high degree of homology between the chromosomes of P. alba and the native aspens (P. grandidentata and P. tremuloides), since 17 to 19 bivalents were usually found at first metaphase. In collections from one triploid P. canescens and two diploid alba-grandidentata hybrid trees, failure of a high proportion of the chromosomes to pair was attributed to genetic factors limiting pairing, rather than to non-homology.Pollen characters such as percentage good pollen, pollen diameter, and pollen size distribution were, in most cases, not indicative of the chromosome number or pairing relations at first metaphase. Consequently, triploids could not be detected by pollen observations under the conditions of this experiment. In spite of the lack of correlation between first metaphase and pollen observations, abnormally large pollen grains were observed in collections from several of the trees, and these were considered to contain the diploid or unreduced chromosome complement. The tendency for the poplars to produce unreduced pollen grains probably accounts for the number of triploid trees discovered in Canada and Sweden.

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