Effects of Nutrient Supply on Pre-emergence Growth and Nutrient Absorption in Wheat (Triticum aestivumL.) and Sugarbeet (Beta vulgarisL.)

Nutrient absorption in wheat and sugarbeet was studied duringpre-emergence growth by adding 0, 7, 10.5 or 14 mol m^-3nitrogen(N) to the growth medium. Seedling growth and carbon, N and¹⁵Ncontents of the seedling parts were measured. Differences betweenthe natural abundance of¹⁵N in seeds and in nutrient solutionwere used to determine the proportion of N in the organs originatingfrom seed reserves and from absorption. Absorption began laterfor wheat than for sugarbeet and had less effect on seedlinggrowth. The absorbed N was found mainly in roots. Compared towheat, sugarbeet seedling N content was greatly altered andthe hypocotyl showed increased elongation when nutrients wereadded. Most of the absorbed N was found in the radicle and hypocotylwith less in the cotyledons. Sugarbeet seedling emergence andearly growth could be decreased by adverse conditions occurringafter sowing by affecting mineral availability in the soil orthrough altered root absorption.Copyright 1998 Annals of BotanyCompany Triticum aestivumL., wheat,Beta vulgarisL., emergence, natural isotopic composition, seedling, seed reserves     

Ontogenesis of internal secretory cells in leaves of Lantana camara (Verbenaceae)

Internal secretory cells may be morphologically indistinguishable from their neighbours except for the presence of secreted material, or they may differ to such an extent that could be classified as secretory idioblasts. Several authors have reported the presence of glandular trichomes secreting essential oil in Verbenaceae, including Lantana . However, none have reported internal secretory cells. Anatomical and histochemical methods applied to Lantana camara leaves revealed the occurrence of internal secretory cells whose ontogenesis and chemical nature are described in this paper. According to leaf developmental analysis, L. camara secretory cells originated from the ground meristem, started to differentiate in the third node leaves, and were actively secreting in the fourth node leaves. The content of the secretory cells was of a lipidic nature, and a terpenoid essence of their secretion was also identified. Based upon differences in size and shape from neighbouring cells and on detection of nonvolatile terpenes, they were confirmed as true internal secretory idioblasts.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 148 , 427–431.     

Strong founder effects and low genetic diversity in introduced populations of Coqui frogs

The success of non-native species may depend on the genetic resources maintained through the invasion process. The Coqui ( Eleutherodactylus coqui ), a frog endemic to Puerto Rico, was introduced to Hawaii in the late 1980s via the horticulture trade, and has become an aggressive invader. To explore whether genetic diversity and population structure changed with the introduction, we assessed individuals from 15 populations across the Hawaiian Islands and 13 populations across Puerto Rico using six to nine polymorphic microsatellite loci and five dorsolateral colour patterns. Allelic richness ( R _T) and gene diversity were significantly higher in Puerto Rico than in Hawaii populations. Hawaii also had fewer colour patterns (two versus three to five per population) than Puerto Rico. We found no isolation by distance in the introduced range, even though it exists in the native range. Results suggest extensive mixing among frog populations across Hawaii, and that their spread has been facilitated by humans. Like previous research, our results suggest that Hawaiian Coquis were founded by individuals from sites around San Juan, but unlike previous research the colour pattern and molecular genetic data (nuclear and mtDNA) support two separate introductions, one on the island of Hawaii and one on Maui. Coquis are successful invaders in Hawaii despite the loss of genetic variation. Future introductions may increase genetic variation and potentially its range.     

Population structure and conservation biology of the endangered fern Trichomanes speciosum Willd. (Hymenophyllaceae) at its northern distributional limit

Genetic diversity in the Killarney fern, Trichomanes speciosum Willd. has been investigated in south-western Scotland, the northern-most limit of the distribution of the sporophyte. T. speciosum is unique amongst European pteridophytes in that both phases of the life cycle are perennial and capable of vegetative propagation. Within sites no variation was revealed by allozyme electrophoresis, even where both generations were growing together. In contrast, diversity was observed among sites, with seven different multilocus phenotypes (MLPs) present in the area. Two of these MLPs covered large areas while the others were restricted to one, or few localities. Asexual reproduction of the gametophyte via gemmae is assumed to be the main means of dispersal in recent times, allowing single clones to become widespread, while the overall genetic variability may be attributed to sexual reproduction and spore dispersal in historic times under more favourable climatic conditions. We suggest that it is not inbreeding, nor lack of genetic variation that limits sporophyte production, but rather the prevailing climatic conditions. The sporophyte is extremely rare and vulnerable. However, when the gametophyte is considered, the species is neither threatened with extinction, nor does it appear to face the danger of marked genetic erosion, because the long-lived gametophyte stage contains all of the genetic variability present in the area and can be regarded as a valuable 'seed-bank'.     

Evidence of a latitudinal gradient in spider diversity in Australian cotton

The most common explanation for species diversity increasing towards the tropics is the corresponding increase in habitats (spatial heterogeneity). Consequently, a monoculture (like cotton in Australia) which is grown along a latitudinal gradient, should have the same degree of species diversity throughout its range. We tested to see if diversity in a dominant cotton community (spiders) changed with latitude, and if the community was structurally identical in different parts of Australia. We sampled seven sites extending over 20° of latitude. At each site we sampled 1–3 fields 3–5 times during the cotton growing season using pitfall traps and beatsheets, recording all the spiders collected to family. We found that spider communities in cotton are diverse, including a large range of foraging guilds, making them suitable for a conservation biological control programme. We also found that spider diversity increased from high to low latitudes, and the communities were different, even though the spiders were in the same monocultural habitat. Spider beatsheet communities around Australia were dominated by different families, and responded differently to seasonal changes, indicating that different pest groups would be targeted at different locations. These results show that diversity can increase from high to low latitudes, even if spatial heterogeneity is held constant, and that other factors external to the cotton crop are influencing spider species composition. Other models which may account for the latitudinal gradient, such as non‐equilibrium regional processes, are discussed.     

Activity of the Pentose Phosphate and Glycolytic Pathways During Anaerobic Germination of Echinochloa crus-galli (barnyard grass) Seeds

Changes in the activity of key enzymes in glycolysis and theoxidative pentose phosphate pathway were studied in Echinochloacrus-galli (L.) Beauv. var. oryzicola seeds during germinationin air or nitrogen. In addition, the metabolism of specificallylabelled [^I4C]glucose was followed to evaluate the activityof both pathways during anaerobic germination. During the 7 d time period studied there was no difference betweenair and nitrogen in phosphofructokinase activity. Under anaerobicconditions, fructose-1, 6-bisphosphate aldolase increased morethan two-fold in 7 d; whereas in air, it decreased. The activityof the pentose phosphate pathway enzyme, glucose-6-phosphatedehydrogenase, increased under N₂ until day three, when it levelledoff, whilst it continued to increase up to day seven in air. Incubation of Echinochloa seedlings with specifically labelledglucose also resulted in differences between anaerobic- andair-grown seedlings. Labelling of phosphorylated sugars andlipids predominated under N₂; whereas in air, malate and fumaratewere the most heavily labelled compounds. In both air and N₂,there was a greater percentage of label in CO2 from [l-¹⁴C]glucose,while [6-14C] resulted in a greater percentage label in ethanol.These differences were more pronounced under N2, especiallyduring the first 24 h of imbibition, suggesting increased activityof the pentose phosphate pathway. Key words: Echinochloa, Anaerobic metabolism, Oxidative pentose phosphate pathway     

Loss of Butt-End Leg Bands on Male Wild Turkeys

ABSTRACT We estimated loss of butt-end leg bands on male wild turkeys (Meleagris gallapavo) captured in New York, Ohio, and Pennsylvania (USA) during December-March, 2006–2008. We used aluminum rivet leg bands as permanent marks to estimate loss of regular aluminum, enameled aluminum, anodized aluminum, and stainless steel butt-end leg bands placed below the spur. We used band loss information from 887 turkeys recovered between 31 days and 570 days after release (x̄ = 202 days). Band loss was greater for turkeys banded as adults (>1 yr old) than juveniles and was greater for aluminum than stainless steel bands. We estimated band retention was 79–96%, depending on age at banding and type of band, for turkeys recovered 3 months after release. Band retention was <50% for all age classes and band types 15 months after banding. We concluded that use of butt-end leg bands on male wild turkeys is inappropriate for use in mark-recapture studies.     

Non-glaucousness, a probable aphid-resistance character of wheat

Cuticular waxes from wheat cultivars that have a bluish-green waxy bloom under field conditions were compared with those of non-glaucous (NG) variants that appeared dark green and glossy in the field. Cuticular wax from NG variants was deficient in diketones and hydroxydiketones, and did not form the micro-spicules of epicuticular wax which were characteristic of the normal bloom. Typically, NG wheats were resistant to Sitobion avenae in the field, but in environments where wax secretion was diminished, resistance was reduced or absent. Possible causes of this resistance, which appears likely to be easy to exploit, are discussed.     

Microhabitat use by Blennius fluviatilis in the Río Matarraña, Spain

SUMMARY.

• 1 Microhabitat use by Blennius fluviatilis in the Río Matarraña, Spain, varied significantly among dates during a 19-month study. Most temporal variation, however, was attributable to changes in microhabitat availability.
• 2 B. fluviatilis demonstrated non-random use of available microhabitats during each sampling period, and generally occupied deeper microhabitats with higher average current velocities dominated by rubblegravel substrates.
• 3 B. fluviatilis also demonstrated non-random use of available nest sites; males generally nested under the largest available pieces of rubble, in areas with less gravel or sand. Water column depth influenced nest site use in two of four study areas.
• 4 We found few microhabitat differences between spawning and nonspawning periods, or between males and females. In addition, microhabitat use was similar among B. fluviatilis size-groups.
• 5 Although B. fluviatilis often were over-represented in deeper, erosional areas, blennies necessarily inhabited a wide range of microhabitats because average current velocities and water depths fluctuated greatly during the study. Tolerance of a broad range of environmental conditions may contribute to the species' persistence in habitats that exhibit extreme seasonal changes in discharge such as the Matarraña.