Exploring sub-individual variability: role of ontogeny, abiotic environment and seed-dispersing birds.

Within-individual trait variation - otherwise known as sub-individual variation - is an important component of phenotypic variation, with both a genetic and epigenetic basis. We explore its adaptive value and the effects of ontogeny and the environment on sub-individual variability. We conducted a field study to analyse the effects of tree age, soil pH, soil water content and soil nutrients on sub-individual variability in fruit size of hawthorn (Crataegus monogyna) in three sites in northwest Spain. Additionally, we examined how bird-mediated selection influences average and sub-individual variation in fruit size. Results show that average and sub-individual variations in fruit size were related to fitness affecting seed dispersal. Older trees produced larger fruits, but tree age did not affect sub-individual variation in fruit size. Abiotic environmental factors differently affected sub-individual variation and average fruit size. Seed-dispersing birds exerted correlated selection on average and variation in fruit size, favouring trees with larger and less variable fruit size at one site. Our work suggests that the fruit size variation within individual trees, the sub-individual variation, is modified by abiotic environmental factors and, additionally, is an adaptive trait that responds to natural selection.

Antioxidant activity of Crataegus pentaegyna subsp. elburensis fruits extracts used in traditional medicine in Iran.

In this study, the antioxidant activity of methanol and aqueous extracts of Crataegus pentaegyna subsp. elburensis (CP) were examined by various in vitro assay systems, i.e., DPPH and nitric oxide radical scavenging, reducing power, linoleic acid and iron ion chelating power. IC50 for DPPH radical-scavenging activity was 341.29 +/- 1.29 for methanol and 269.31 +/- 2.11 microg mL(-1) for aqueous extract. Reducing powers of extracts also increased with the increase of their concentrations. Both extracts exhibited a weak reducing power at 25-800 microg mL(-1). Extracts exhibited weak nitric oxide radical scavenging and Fe2+ chelating ability. Methanol extract showed higher Fe2+ chelating ability (IC50 = 1.84 +/- 0.01 mg mL(-1)). Both tested extracts exhibited high antioxidant activity. Extracts showed high total phenolic content.

Polyphenol contents and antioxidant activities of extracts from flowers of two Crataegus azarolus L. varieties.

Phenolic contents of the ethyl acetate extracts prepared from floral buds and opened flowers harvested on Crataegus azarolus trees native in two localities were performed. The antioxidant activity was measured by DPPH' (2,2-diphenyl-picrylhydrazyl), ABTS+ (2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals scavenging using spectrophotometric method. The C. azarolus var. aronia (Willd.) Batt., producing yellow fruits, was richer in total phenols (1638.7 +/- 89.9 mg acid gallic/100 g dry weight) according to C. azarolus var. eu-azarolus Maire (1415.5 +/- 23.8 mg acid gallic/100 g dry weight), producing red ones. Ethyl acetate extract from opened flowers has less content in total phenols, proanthocyanidins and flavonoids compared to this from floral buds. Floral buds from the two C. azarolus varieties occurring in Siliana-Djebel Serdj showed the highest radical scavenging activities (2431.8 +/- 32.7 and 2267.7 +/- 22.7 micromol Trolox/100 g dry weight). Hawthorn from Tunisia contains eight antioxidants of phenolic type (chlorogenic acid, hyperoside, rutin, spiraeoside, isoquercitrin, quercetin, (-)-epicatechin and the dimer procyanidin B2). These compounds identified specially in floral bud extracts presented a strong radical-scavenging activity.

The mathematical treatment of leaf venation: the variation in secondary vein length along the midrib.

BACKGROUND AND AIMS: In some dicotyledonous leaves and leaflets, the secondary veins run more-or-less straight to the margins and have well-defined lengths. For a given half-lamina of length L, an equation, previously proposed, relates the lengths of these veins, p, to the distances, l, between the leaf tip and their insertions on the midrib: p = B2(x+y)l(x)(L - l)(y)/L(x+y-1), where B, x and y are fitted parameters. Aspects of the formula are re-examined, including its general applicability, significance and usefulness. METHODS: Length measurements were made on leaves of various dicotyledons, notably Ulmus glabra, U. procera, Alnus viridis, A. glutinosa, Corylus avellana and Crataegus monogyna. Equations were fitted by non-linear regression. KEY RESULTS: The equation has now been applied descriptively to 23 species of eight families, but it is sometimes preferable or necessary to replace the measured length, L, with a fourth parameter that may differ significantly from it. Within a given species, values of the indices x and y are positively correlated. Leaves of some U. glabra depart qualitatively from the general pattern. As an example of hypothesis testing, the equation was used to show that the retuse or emarginate leaf tips of A. glutinosa are not due to stunting. CONCLUSIONS; That the equation applies to many species suggests that the underlying processes of leaf growth are quantitatively similar. Although relevant knowledge of these is scant, consideration of mathematical relationships may help their elucidation.