Intra- and interspecific interactions in the two coexisting Locustella warblers revealed by song playback experiments.

Males usually come into conflict due to competition for territories and females. However, interference competition can also occur between males of congeneric species when their ecological requirements are overlapping. Using acoustic playback experiments, we investigated male-male interactions within and between Grasshopper (Locustella naevia; GW) and River Warbler (L. fluviatilis; RW). Our objective was to evaluate the song and behavioural response of tested males of both species to conspecific song stimuli in order to compare this with the response to congeneric stimulus, based on which we could assess whether these two commonly co-existing species show interspecific territorialism. A total of nine GW and 11 RW males were tested in May and June 2019 in western Slovakia. The ability to differentiate between the heterospecific (control), congeneric, and conspecific stimuli was similar between the two species. Conspecific playback elicited the strongest non-vocal response and a significant change in vocalization. The GW males shortened the songs, while the RW males shortened the songs and also increased their syllable rate. The congeneric playback elicited a lower intensity of behavioural response than conspecific playback and no change in vocalization in either species. We conclude that interspecific interference competition between GW and RW is rather low, suggesting that the species' ecological requirements are separated, although these two congeneric species commonly share habitat.

Incorporating high-resolution climate, remote sensing and topographic data to map annual forest growth in central and eastern Europe.

To enhance our understanding of forest carbon sequestration, climate change mitigation and drought impact on forest ecosystems, the availability of high-resolution annual forest growth maps based on tree-ring width (TRW) would provide a significant advancement to the field. Site-specific characteristics, which can be approximated by high-resolution Earth observation by satellites (EOS), emerge as crucial drivers of forest growth, influencing how climate translates into tree growth. EOS provides information on surface reflectance related to forest characteristics and thus can potentially improve the accuracy of forest growth models based on TRW. Through the modelling of TRW using EOS, climate and topography data, we showed that species-specific models can explain up to 52 % of model variance (Quercus petraea), while combining different species results in relatively poor model performance (R2 = 13 %). The integration of EOS into models based solely on climate and elevation data improved the explained variance by 6 % on average. Leveraging these insights, we successfully generated a map of annual TRW for the year 2021. We employed the area of applicability (AOA) approach to delineate the range in which our models are deemed valid. The calculated AOA for the established forest-type models was 73 % of the study region, indicating robust spatial applicability. Notably, unreliable predictions predominantly occurred in the climate margins of our dataset. In conclusion, our large-scale assessment underscores the efficacy of combining climate, EOS and topographic data to develop robust models for mapping annual TRW. This research not only fills a critical void in the current understanding of forest growth dynamics but also highlights the potential of integrated data sources for comprehensive ecosystem assessments.

Avian sibling cannibalism: Hoopoe mothers regularly use their last hatched nestlings to feed older siblings.

Sibling cannibalism is relatively common in nature, but its evolution in birds and certain other vertebrates with extended parental care had been discarded. Here, however, we demonstrate its regular occurrence in two European populations of the Eurasian hoopoe (Upupa epops) and explore possible adaptive and non-adaptive explanations. Results showed that sibling cannibalism was more frequently detected in Spain (51.7%) than in Austria (5.9%). In these two populations, the hoopoes laid similar clutch sizes, resulting in similar fledging production, but hatching failures were more frequent in the northern population. Consequently, having more nestlings condemned to die in the southern population may explain the higher incidence of sibling cannibalism. In accordance with this interpretation, hatching span and failure, but not breeding date, explained the probability of sibling cannibalism in the Spanish hoopoes, while all three variables predicted brood reduction intensity. Furthermore, experimental food supply reduced the probability of sibling cannibalism, but not the intensity of brood reduction. Finally, females allocated fewer resources to the smallest nestlings when they were going to starve, but not necessarily when they were going to be used as food for their siblings. These results suggest that hoopoes produce extra eggs that, in the case of reduced hatching failure and food scarcity, produce nestlings that are used to feed older siblings. These findings provide the first evidence that sibling cannibalism occurs regularly in a bird species, thus expanding our evolutionary understanding of clutch size, hatching asynchrony, parent-offspring conflict, infanticide, and sibling cannibalism in the animal kingdom.

Increased wood biomass growth is associated with lower wood density in Quercus petraea (Matt.) Liebl. saplings growing under elevated CO2.

Atmospheric carbon dioxide (CO2) has increased substantially since the industrial revolution began, and physiological responses to elevated atmospheric CO2 concentrations reportedly alter the biometry and wood structure of trees. Additionally, soil nutrient availability may play an important role in regulating these responses. Therefore, in this study, we grew 288 two-year-old saplings of sessile oak (Quercus petraea (Matt.) Liebl.) in lamellar glass domes for three years to evaluate the effects of CO2 concentrations and nutrient supply on above- and belowground biomass, wood density, and wood structure. Elevated CO2 increased above- and belowground biomass by 44.3% and 46.9%, respectively. However, under elevated CO2 treatment, sapling wood density was markedly lower (approximately 1.7%), and notably wider growth rings-and larger, more efficient conduits leading to increased hydraulic conductance-were observed. Moreover, despite the vessels being larger in saplings under elevated CO2, the vessels were significantly fewer (p = 0.023). No direct effects of nutrient supply were observed on biomass growth, wood density, or wood structure, except for a notable decrease in specific leaf area. These results suggest that, although fewer and larger conduits may render the xylem more vulnerable to embolism formation under drought conditions, the high growth rate in sessile oak saplings under elevated CO2 is supported by an efficient vascular system and may increase biomass production in this tree species. Nevertheless, the decreased mechanical strength, indicated by low density and xylem vulnerability to drought, may lead to earlier mortality, offsetting the positive effects of elevated CO2 levels in the future.

Novel Hydraulic Vulnerability Proxies for a Boreal Conifer Species Reveal That Opportunists May Have Lower Survival Prospects under Extreme Climatic Events.

Top dieback in 40-60 years old forest stands of Norway spruce [Picea abies (L.) Karst.] in southern Norway is supposed to be associated with climatic extremes. Our intention was to learn more about the processes related to top dieback and in particular about the plasticity of possible predisposing factors. We aimed at (i) developing proxies for P 50 based on anatomical data assessed by SilviScan technology and (ii) testing these proxies for their plasticity regarding climate, in order to (iii) analyze annual variations of hydraulic proxies of healthy looking trees and trees with top dieback upon their impact on tree survival. At two sites we selected 10 tree pairs, i.e., one healthy looking tree and one tree with visual signs of dieback such as dry tops, needle shortening and needle yellowing (n = 40 trees). Vulnerability to cavitation (P 50) of the main trunk was assessed in a selected sample set (n = 19) and we thereafter applied SilviScan technology to measure cell dimensions (lumen (b) and cell wall thickness (t)) in these specimen and in all 40 trees in tree rings formed between 1990 and 2010. In a first analysis step, we searched for anatomical proxies for P 50. The set of potential proxies included hydraulic lumen diameters and wall reinforcement parameters based on mean, radial, and tangential tracheid diameters. The conduit wall reinforcement based on tangential hydraulic lumen diameters ((t/b ht)(2)) was the best estimate for P 50. It was thus possible to relate climatic extremes to the potential vulnerability of single annual rings. Trees with top dieback had significantly lower (t/b ht)(2) and wider tangential (hydraulic) lumen diameters some years before a period of water deficit (2005-2006). Radial (hydraulic) lumen diameters showed however no significant differences between both tree groups. (t/b ht)(2) was influenced by annual climate variability; strongest correlations were found with precipitation in September of the previous growing season: high precipitation in previous September resulted in more vulnerable annual rings in the next season. The results are discussed with respect to an "opportunistic behavior" and genetic predisposition to drought sensitivity.

Selective inhibitory action of Biginelli-type dihydropyrimidines on depolarization-induced arterial smooth muscle contraction.

OBJECTIVES: Dihydropyridine calcium channel blockers have some disadvantages such as light sensitivity and relatively short plasma half-lives. Stability of dihydropyrimidines analogues could be of advantage, yet they remain less well characterized. We aimed to test four newly synthesized Biginelli-type dihydropyrimidines for their calcium channel blocking activity on rat isolated aorta. METHODS: Dihydropyrimidines (compounds A-D) were prepared by the Biginelli-like three-component condensation of benzaldehydes with urea/thiourea and dimethyl or diethyl acetone-1,3-dicarboxylate, and their physicochemical properties and effects on depolarization-induced and noradrenaline-induced contractions of rat isolated aorta were evaluated. KEY FINDINGS: Dihydropyrimidines A and C blocked KCl-induced contraction only weakly (-log(IC50)=5.03 and 3.73, respectively), while dihydropyrimidine D (-log(IC50)=7.03) was almost as potent as nifedipine (-log(IC50)=8.14). Washout experiments revealed that dihydropyrimidine D may bind strongly to the L-type calcium channel or remains bound to membrane. All tested dihydropyrimidines only marginally inhibited noradrenaline-induced contractions of rat isolated aorta (20% reduction of noradrenaline E(max) ), indicating a more selective action on L-type calcium channel than nifedipine with 75% inhibition of noradrenaline E(max) at 10(-4) m nifedipine). CONCLUSIONS: Compounds A and, particularly, D are potent calcium channel blockers in vitro, with a better selectivity in inhibiting depolarization-induced arterial smooth muscle contraction than nifedipine.

Monastrol analogs: a synthesis of pyrazolopyridine, benzopyranopyrazolopyridine, and oxygen-bridged azolopyrimidine derivatives and their biological screening.

A synthesis of novel pyrazolopyridine, benzopyranopyrazolopyridine, and oxygen-bridged pyrazolo-, tetrazolo-, benzimidazo-, and thiazolopyrimidines via Hantzsch- and Biginelli-like condensations has been developed. The ability of these compounds to inhibit Eg5 activity has been examined. The results indicate that synthetic manipulations in the monastrol thiourea moiety are inefficient.

rac-2-Methyl-3,4,5,6-tetra-hydro-2H-2,6-methano-1,3-benzoxazocin-4-one.

The title compound, C(12)H(13)NO(2), represents a conformationally restricted 2-pyridone analogue of 1,4-dihydro-pyridine-type calcium antagonists and was selected for a crystal structure determination in order to explore some aspects of drug-receptor inter-action. In the mol-ecule, two stereogenic centres are of opposite chirality, whereas a racemate occurs in the crystal. It was found that the formally aminic N atom of the heterocycle is essentially sp(2)-hybridized with the lone-pair electrons partially delocalized through conjugation with the adjacent carbonyl bond. As a result, the central pyridone ring assumes an unsymmetrical half-chair conformation. The critical 4-phenyl ring is fixed in a pseudo-axial and perpendicular orientation [dihedral angle 85.8 (1)°] with respect to the pyridone ring via an oxygen bridge. In the crystal a pair of centrosymmetric N-H⋯O hydrogen bonds connect mol-ecules of opposite chirality into a dimer. The dimers are packed by hydrophobic van der Waals inter-actions.

Methyl 5'-(2-hy-droxy-phen-yl)-4',5',6',7'-tetra-hydro-spiro-[2H-1-benzopyran-2,7'-1,2,4-triazolo[1,5-a]pyrimidine]-3-carboxyl-ate.

There are two crystallographically independent mol-ecules in the asymmetric unit of the title compound, C(21)H(18)N(4)O(4). The substituted benzopyran portion of one of the independent mol-ecules exhibits disorder [occupancy 0.5248 (18):0.4752 (18)], which was modelled by using two sets of atomic positions and restraints on the chemically equivalent bond lengths and angles. The central, partially saturated pyrimidine rings of both independent mol-ecules were found to assume unsymmetrical half-chair conformations. The hy-droxy-phenyl substituent occupies an equatorial position in both mol-ecules, and is rotated by 55.6 (1)° from the mean plane of the pyrimidine ring in one independent mol-ecule, and by 53.4 (1)° in the other. In the crystal, there are two types of inter-molecular hydrogen bond present: reciprocal N-H⋯N inter-actions join the two crystallographically independent mol-ecules into a dimer and O-H⋯N inter-actions link the dimers into sheets in the ab plane.

2-Methyl-1,10b-dihydro-5H-pyrazolo[1,5-c][1,3]benzoxazin-5-one.

In the title compound, C(11)H(10)N(2)O(2), a potential inhibitor of the cyclo-oxygenase-2 isoenzyme, the pyrazoline ring exists in a flat-envelope conformation while the puckering of the central oxazine ring is more severe. As a result, the mol-ecule as a whole is non-planar. The formal sp(3) pyrazoline N atom is sp(2) hybridized, with the lone-pair electrons delocalized through conjugation with the carbonyl group rather than the double bond of the pyrazoline ring.

(5R*,11R*)-5-Methyl-1,2-dihydro-5,11-methano-5H,11H-1,3-thia-zolo[2,3-d][1,3,5]benzoxadiazo-cine.

The title compound, C(13)H(14)N(2)OS, crystallizes as a racemate in a non-chiral space group. It represents a conformationally restricted analogue of so-called Biginelli compounds known to exhibit multiple pharmacological activities and was selected for a single-crystal X-ray analysis in order to probe the chemical and spatial requirements of some kinds of activity. It was found that the state of hybridization of the formally aminic nitro-gen of the heterocycle is between sp(2) and sp(3) with the lone-pair electrons partially delocalized through conjugation with the sulfur atom rather than the double bond of the pyrimidine nucleus. As a result, the thia-zolo ring adopts a flat-envelope conformation and the puckering of the central pyrimidine ring is close to a half-chair. The critical phenyl ring is fixed in a pseudo-axial and perpendicular [dihedral angle 84.6 (1)°] orientation with respect to the pyrimidine ring via an oxygen bridge.

Methyl 6-methoxy-carbonyl-methyl-2-oxo-4-phenyl-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

The title compound, C(15)H(16)N(2)O(5), belongs to the class of monastrol-type anti--cancer agents and was selected for crystal structure determination in order to determine the conformational details needed for subsequent structure-activity relationship studies. The central tetra-hydro-pyrimidine ring has a flat-envelope conformation. The 4-phenyl group occupies a pseudo-axial position and is inclined at an angle of ca 90° to the mean plane of the heterocyclic ring. Of the two methyl ester groups, one (in the 5-position) is in a coplanar and the other (in the 6-position) in a perpendicular orientation with respect to the heterocyclic plane. The coplanar 5-ester group has its carbonyl bond oriented cis with respect to the pyrimidine C=C double bond. By comparison of the structural results for the present compound with those determined previously for its diethyl analogue, we have identified the mol-ecular factors which control the dual course of the Biginelli reaction with salicylaldehyde. The crystal structure is dominated by two hydrogen bonds which link the mol-ecules into chains of dimers.

4-[(5R*,10bR*)-2-Methyl-1,10b-dihydro-pyrazolo[1,5-c][1,3]benzoxazin-5-yl]benzoic acid.

In the title compound, C(18)H(16)N(2)O(3), a potential inhibitor of the cyclo-oxygenase-2 isoenzyme, the pyrazoline ring exists in a flattened envelope conformation with one C atom deviating by 0.463 Šfrom the mean plane of the remaining four atoms. The puckering of the central oxazine ring is more severe, with one N atom and one C atom displaced by 0.235 (6) and 0.370 (2) Å, respectively, on opposite sides of the mean plane defined by the other four atoms; the conformation is that of a half-chair. As a result, the mol-ecule as a whole is not planar. The carboxyl group is involved in an inter-molecular O-H⋯N hydrogen bond, which links the mol-ecules into centrosymmetric dimers.

Ethyl 6-ethoxy-carbonyl-methyl-4-(2-hydroxy-phen-yl)-2-oxo-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

The title compound, C(17)H(20)N(2)O(6), belongs to the monastrol-type of anti-cancer agents and was selected for crystal structure determination in order to confirm its mol-ecular structure and explore some aspects of its structure-activity relationships. The central tetra-hydro-pyrimidine ring has a flat-envelope conformation. The 4-hydroxy-phenyl group occupies a pseudo-axial position and is inclined at an angle of 87.7 (2)° to the mean plane of the heterocyclic ring. Of the two ethyl ester groups, one (in the 5-position) is in a coplanar and the other (in the 6-position) is in a perpendicular orientation with respect to the heterocyclic plane. There is a three-dimensional hydrogen-bonding network in which all hydrogen-bond donors and acceptors are involved.

N-[(1E)-Amino[3-methyl-5-(4-methylphenyl)-4,5-dihydro-1H-pyrazol-1-yl]methylene]-1H-imidazole-1-carboxamide.

In the title compound, C(16)H(18)N(6)O, an N-carbonylimidazole derivative of pyrazoline-1-carboximidamide, the pi-electron density of the N atom in the 1-position on the pyrazoline ring is delocalized through the amidine moiety and the adjacent carbonyl group. The imidazole ring, though coplanar with the rest of the molecule, is deconjugated. The pyrazoline ring adopts a flat-envelope conformation, having the substituted phenyl ring oriented perpendicular to the mean plane of the heterocycle. Both of the two potential hydrogen-bond donors are involved in intramolecular hydrogen-bonding interactions.

4,5-Dihydro-3-methyl-5-(4-methylphenyl)-1H-pyrazole-1-carboxamide.

The reaction between 4-(4-methylphenyl)but-3-en-2-one and aminoguanidine produced an unexpected product of formula C(12)H(15)N(3)O, consisting of a carboxamide moiety joined to a substituted pyrazoline ring at one of the N atoms. The pyrazoline ring adopts a flat-envelope conformation and the substituted phenyl ring is oriented almost perpendicular to the heterocycle. The carbonyl O atom has partial anionic character as a result of the transfer of pi density from the two adjacent sp(2) N atoms and is involved in an intermolecular hydrogen bond with the amide group.

4,5-Dihydro-3-methyl-5-(4-methylphenyl)-1H-pyrazole-1-carboxamidinium acetate acetone hemisolvate.

The X-ray structure analysis of the unexpected product of the reaction between 4-(4-methylphenyl)but-3-en-2-one and aminoguanidine revealed the title compound, C(12)H(17)N(4)(+) x -C(2)H(3)O(2)(-) x 0.5C(3)H(6)O, consisting of a protonated amidine moiety joined to a substituted pyrazoline ring at the N1 atom. The amidine group is protonated and the positive charge is delocalized over the three C[bond]N bonds in a similar manner to that found in guanidinium salts. The amidinium moiety of the cation is linked to the acetate anions through four N[bond]H...O hydrogen bonds, with N...O distances of 2.749 (4), 2.848 (4), 2.904 (4) and 2.911 (4) A. The pyrazoline ring adopts a flattened envelope conformation and the substituted phenyl ring is oriented perpendicular to the attached heterocycle. The acetone solvate molecule lies across a twofold rotation axis.