A simple and nondestructive method for estimation of worker population size in Myrmica ant nests

A method to estimate the number of workers in Myrmica ant nests on abandoned meadows was developed based on removal of workers. Ant workers have a tendency to climb up on wooden sticks put into their nests, therefore, assuming that the number of workers removed on sticks is related to the total number of workers within the nests, regression models for Myrmica rubra, M. ruginodis and M. scabrinodis may be built. We used a general regression model to perform a backward stepwise elimination of explanatory variables. These were the number of workers removed on sticks, temperature at the nest and site (a categorical variable). In case of each species the final model contained only the number of workers removed as a significant variable. The method is apparently non-destructive as we did not observe decreased survival of nests surveyed as compared to control nests. The method can be a very useful tool in population studies of ants as well as in biodiversity projects, where ants are used as bioinidcators. Received 10 February 2005; revised 4 August 2005; accepted 24 August 2005.     

Double-observer approach to estimating egg mass abundance of pool-breeding amphibians

Interest in seasonally flooded pools, and the status of associated amphibian populations, has initiated programs in the northeastern United States to document and monitor these habitats. Counting egg masses is an effective way to determine the population size of pool-breeding amphibians, such as wood frogs (Rana sylvatica) and spotted salamanders (Ambystoma maculatum). However, bias is associated with counts if egg masses are missed. Counts unadjusted for the proportion missed (i.e., without adjustment for detection probability) could lead to false assessments of population trends. We used a dependent double-observer method in 2002–2003 to estimate numbers of wood frog and spotted salamander egg masses at seasonal forest pools in 13 National Wildlife Refuges, 1 National Park, 1 National Seashore, and 1 State Park in the northeastern United States. We calculated detection probabilities for egg masses and examined whether detection probabilities varied by species, observers, pools, and in relation to pool characteristics (pool area, pool maximum depth, within-pool vegetation). For the 2 years, model selection indicated that no consistent set of variables explained the variation in data sets from individual Refuges and Parks. Because our results indicated that egg mass detection probabilities vary spatially and temporally, we conclude that it is essential to use estimation procedures, such as double-observer methods with egg mass surveys, to determine population sizes and trends of these species.     

Use of SSR fragment length homozygotes for orangutan systematics

The use of simple sequence repeat (SSR) loci lacking length polymorphisms among their alleles (defined here as homozygotes) in systemtic studies has thus far been largely ignored due to their apparent lack of genetic heterogeneity. However, in this paper we show that point mutations, insertions, and deletions within SSR loci of identical size can be highly informative for population genetic and evolutionary studies. Our preliminary study of the von Willebrand factor (vWF) locus shows that there is a significant level of divergence among the Bornean Orangutans which implies that present orangutan subbopulations in Borneo are genetically isolated from each other. However, our findings do not confirm that the Bornean and Sumatran Orangutans form two separate clades.     

TrackBeam, a simple tool for estimating potential exposure to the solar beam underneath tree canopies

A simple tool, TrackBeam, for rapid in situ estimates of potential exposure to the solar beam of objects underneath tree canopies is presented, tested and demonstrated to be useful in insect conservation studies. The tool can be used whenever accurate data on sun exposure is of use e.g., in ecological studies of saproxylic insects. TrackBeam draws upon the principles behind the analysis of hemispherical photographs but its use is much less dependent on the weather at the time of sampling. It may be used for detecting canopy openings in directions corresponding to the solar path. Based on this, periods of time with potential beam exposure and/or the proportion of sky that is not obscured by canopy for objects such as dead wood may be estimated. The results of using TrackBeam compares well between operators and with the corresponding results of analysed hemispherical photographs. Results are presented which show that TrackBeam was successfully used to characterise the habitat light requirements of the saproxylic beetle Melanotus castanipes (Coleoptera: Elateridae).     

A simple system for pea transformation

The lateral cotyledonary meristems of germinatingPisum sativum cv. Puget seeds were used to develop a reproducibleAgrobacterium tumefaciens-mediated transformation system. This procedure exhibits distinct advantages over those previously reported, in that it uses dry seed as starting material, and the highly regenerable cotyledonary meristems rapidly produce transgenic shoots without an intermediate callus phase. This transformation regime facilitates the rapid generation of phenotypically normal, self-fertile plants containing functional transgenes inherited in a Mendelian fashion.Abbreviations bar Bialaphos resistance gene - BAP 6-Benzylaminopurine - GA₃ Gibberellic acid - IBA Indole-3-butyric acid - PAT Phosphinothricin acetyltransferase - PPT Phosphinothricin     

The benefit to some minnows of spawning in the nests of other species

Synopsis Fishes that act as nest associates spawn simultaneously with nest-building hosts and then abandon their eggs. The proposed benefit for this behavior is increased brood survivorship, arising from the physical environment provided by the nest or the parental care provided by the host. Field and enclosure experiments indicated that associates benefit from the parental care provided by the host, and not from the physical environment provided by the nests of hosts. This information, along with the effect of nest association on host reproductive success, is necessary before the nature of this nesting symbiosis can be characterized.     

A preliminary study of food selection by the orangutan in relation to plant quality

We observed the foraging behavior of orangutans in Central Indonesian Borneo during October, November, and December 1980, and analyzed food and nonfood items for water content, neutral detergent fiber, crude protein, available crude protein, and protein:fiber ratio and the presence of alkaloids and tannins. The diet of the orangutan during this season was unusual because it consisted predominantly of seeds and unripe, rather than ripe, fruits. Also, the major diet item, the seeds ofIrvingia malayana, had been ignored in previous years when it had fruited. In leaves, protein content was more closely associated with food choice than either neutral detergent fiber or the protein:fiber ratio. Flowers had the highest protein content and protein:fiber ratio of any food item. Tannins were found in most food items, but the presence of alkaloids was found in only one.     

A simple method for isolation of high-molecular-weight DNA from Rhodotorula gracilis

Unsheared DNA has been isolated from Rhodotorula and Rhodosporidium yeasts using a cell-wall-digesting enzyme preparation from Paecilomyces lilacinus. Pulsed-field gel electrophoresis indicated that at least 11 chromosomes were present in Rhodot. gracilis ATCC 90950. The DNA was amenable to digestion with restriction enzymes.The authors are with the Department of Microbiology, Central Food Technological Research Institute, Mysore-570 013, India.     

A simple procedure to obtain plasmids suitable for transfecting mammalian cell lines

A simple procedure to obtain plasmid preparations, suitable for transfecting mammalian cell lines using a calcium phosphate co-precipitation technique, is described. The protocol is based on the purification of plasmid DNA by double gel-filtration chromatography on Sephacryl S-1000 and additional slight modifications to the original transfection procedure. The purity of plasmid preparation was verified by analytical methods. The resulting preparation efficiently transfected NIH-3T3 cells.The authors are with the National Center for Scientific Research, Molecular Biology Department, Biotechnology Branch, POB 6880, Havana, Cuba.     

A suitable model for the utilization of Duddingtonia flagrans fungus in small-flock-size sheep farms

Effective alternatives to anthelmintic treatment of nematode parasite infections of sheep are required because of the high prevalence of drug resistance. Within this context, the nematode-trapping fungus Duddingtonia flagrans has become a valuable component of various integrated control strategies. Toward this objective, a small quantity of lyophilized D. flagrans chlamydospores (10⁶ spores per animal) was administered to sheep in a one-year plot study. Animals grazing on native pasture were divided into two homogeneous groups and were kept in 1-ha paddocks in the southern region of Brazil. The oral administration of chlamydospores led to a significant reduction (p < 0.05) in the number of nematode eggs per gram of feces and in the larval availability on herbage (difference of 37.6%) in comparison to the control group. Control animals needed to be dewormed three times during the experiment, whereas the fungus-treated animals maintained a low parasite load, independent of seasonal variation. Although D. flagrans cannot serve as a panacea for nematode parasite control of livestock, it represents a significant advance toward rationalizing the use of endoparasitic drugs in small animals.     

A comparison of metrics for estimating phylogenetic signal under alternative evolutionary models

Several metrics have been developed for estimating phylogenetic signal in comparative data. These may be important both in guiding future studies on correlated evolution and for inferring broad-scale evolutionary and ecological processes (e.g., phylogenetic niche conservatism). Notwithstanding, the validity of some of these metrics is under debate, especially after the development of more sophisticated model-based approaches that estimate departure from particular evolutionary models (i.e., Brownian motion). Here, two of these model-based metrics (Blomberg’s K-statistics and Pagel’s λ) are compared with three statistical approaches [Moran’s I autocorrelation coefficient, coefficients of determination from the autoregressive method (ARM), and phylogenetic eigenvector regression (PVR)]. Based on simulations of a trait evolving under Brownian motion for a phylogeny with 209 species, we showed that all metrics are strongly, although non-linearly, correlated to each other. Our analyses revealed that statistical approaches provide valid results and may be still particularly useful when detailed phylogenies are unavailable or when trait variation among species is difficult to describe by more standard Brownian or O-U evolutionary models.     

A simple method for maintaining high multiplication of Narcissus shoot cultures in vitro

A simple method for stimulating and maintaining high in vitro multiplication of Narcissus shoot clump cultures was developed. Shoot clumps were subjected either to normal cutting where leaves were trimmed to 20 mm in length at the beginning of each culture passage or to severe cutting where shoot clumps were cut down to the basal plate region removing all green tissue. Severe cutting at the beginning of each culture passage initially doubled the leaf multiplication, compared to normal cutting, but the difference between cutting treatments declined in successive passages. The improvement in leaf multiplication was maintained when shoot clumps were subjected to severe cutting only at every other culture passage, with no cutting in the alternate recovery passages. In vitro multiplication was increased by severe cutting in all seven Narcissus cultivars which were tested.Abbreviations NAA-1 naphthylacetic acid - BAP benzylaminopurine     

Spatial and temporal patterns of aboveground net primary productivity (ANPP) along two freshwater-estuarine transects in the Florida Coastal Everglades

We present here a 4-year dataset (2001–2004) on the spatial and temporal patterns of aboveground net primary production (ANPP) by dominant primary producers (sawgrass, periphyton, mangroves, and seagrasses) along two transects in the oligotrophic Florida Everglades coastal landscape. The 17 sites of the Florida Coastal Everglades Long Term Ecological Research (FCE LTER) program are located along fresh-estuarine gradients in Shark River Slough (SRS) and Taylor River/C-111/Florida Bay (TS/Ph) basins that drain the western and southern Everglades, respectively. Within the SRS basin, sawgrass and periphyton ANPP did not differ significantly among sites but mangrove ANPP was highest at the site nearest the Gulf of Mexico. In the southern Everglades transect, there was a productivity peak in sawgrass and periphyton at the upper estuarine ecotone within Taylor River but no trends were observed in the C-111 Basin for either primary producer. Over the 4 years, average sawgrass ANPP in both basins ranged from 255 to 606 g m⁻² year⁻¹. Average periphyton productivity at SRS and TS/Ph was 17–68 g C m⁻² year⁻¹ and 342–10371 g C m⁻² year⁻¹, respectively. Mangrove productivity ranged from 340 g m⁻² year⁻¹ at Taylor River to 2208 g m⁻² year⁻¹ at the lower estuarine Shark River site. Average Thalassia testudinum productivity ranged from 91 to 396 g m⁻² year⁻¹ and was 4-fold greater at the site nearest the Gulf of Mexico than in eastern Florida Bay. There were no differences in periphyton productivity at Florida Bay. Interannual comparisons revealed no significant differences within each primary producer at either SRS or TS/Ph with the exception of sawgrass at SRS and the C−111 Basin. Future research will address difficulties in assessing and comparing ANPP of different primary producers along gradients as well as the significance of belowground production to the total productivity of this ecosystem.     

A simple, integrative assay to quantify nutritional quality of browses for herbivores

Many regard the concentrations of nitrogen (N), tannins and plant cell wall constituents (fibre) as key indicators of food quality and habitat suitability for browsing herbivores; yet there is no method for measuring their combined effects. We have developed a simple in vitro assay for measuring the effects of tannins and fibre on N availability in browse. We determined the effects of tannins by measuring the polyethylene glycol (PEG)-binding capacity (PEG-BC) of Eucalyptus leaf samples, followed by a two-stage in vitro digestion with pepsin and cellulase to determine the digestibility of dry matter and N. There was a significant relationship between concentrations of digestible N and the PEG-BC of the leaves. Furthermore, adding PEG significantly improved the digestibility of N. Our results concur with in vivo observations from several mammalian species. This suggests that our method is effective for measuring the nutritional quality of browse and the benefits of adding PEG, providing some index of the detrimental effects of tannins. We further simplified the assay by removing the PEG step, allowing us to quickly analyse samples in bulk. Nevertheless, this simplified method is still not practical for analysing the many samples necessary to compare the nutritional values of different tracts of forest. We used near-infrared reflectance spectroscopy to produce calibration equations and predicted total and digestible N in 322 trees at eleven sites. Both within and between sites, we found a wide variation in concentrations of digestible N but a much lower variation in total N, with either no relationship or poor relationships between the two measures. This confirms the variability in the nutritional quality of eucalypt forests, which may explain the distribution and abundance of mammalian herbivores. Thus, our assay provides a useful tool for understanding how food resources influence herbivore populations at different scales. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

A comparison of alternative methods for estimating population density of the fiddler crab Uca annulipes at Saco Mangrove, Inhaca Island (Mozambique)

Visual counts of surface-active crabs both by binocular and burrow counting methods have been used in many studies to estimate population density. However, their reliability has not yet been assessed comparatively. Three methods for estimating the abundance of fiddler crabs Uca annulipes in a mangrove forest (Inhaca Island, Mozambique) were compared from three different sub-areas: two sub-areas inundated only during spring tides and one sub-area inundated in both spring and neap tides. Burrow, binocular and direct (excavation) counting methods were performed by plotting ten 0.25 m² quadrats in each sub-area over the four moon phases. Overall densities (per 0.25 m²) differed according to method, sub-area and lunar phase. Burrow count overestimated crab density by up to 20%, while binocular count underestimated density by up to 41%. Correlation coefficient estimated for both counting methods showed that burrow count gives better density estimates than binocular count (0.91 and 0.56, respectively). Sex ratios were also investigated within the three sub-areas and at the moon phases. Males are dominant throughout the studied period except during new moon and first quarter, indicating that when the number of gravid females is low, sex ratio bias for binocular count is minimal.     

A comparative structural and functional analysis of cyanobacterial plastocyanin and cytochrome c 6 as alternative electron donors to Photosystem I

Plastocyanin and cytochrome c ₆ are two soluble metalloproteins that act as alternative electron carriers between the membrane-embedded complexes cytochromes b ₆ f and Photosystem I. Despite plastocyanin and cytochrome c ₆ differing in the nature of their redox center (one is a copper protein, the other is a heme protein) and folding pattern (one is a β-barrel, the other consists of α-helices), they are exchangeable in green algae and cyanobacteria. In fact, the two proteins share a number of structural similarities that allow them to interact with the same membrane complexes in a similar way. The kinetic and thermodynamic analysis of Photosystem I reduction by plastocyanin and cytochrome c ₆ reveals that the same factors govern the reaction mechanism within the same organism, but differ from one another. In cyanobacteria, in particular, the electrostatic and hydrophobic interactions between Photosystem I and its electron donors have been analyzed using the wild-type protein species and site-directed mutants. A number of residues similarly conserved in the two proteins have been shown to be critical for the electron transfer reaction. Cytochrome c ₆ does contain two functional areas that are equivalent to those previously described in plastocyanin: one is a hydrophobic patch for electron transfer (site 1), and the other is an electrically charged area for complex formation (site 2). Each cyanobacterial protein contains just one arginyl residue, similarly located between sites 1 and 2, that is essential for the redox interaction with Photosystem I. This revised version was published online in June 2006 with corrections to the Cover Date.     

A simple assay to determine the nutritional suitability of cattle dung for coprophagous beetles

An assay using extracted dung fluid was developed to provide an objective method of assessing the suitability of cattle dung for beetle Euoniticellus intermedius. Fluid was extracted from whole dung by twisting gauze-wrapped samples by hand, or by use of an hydraulic press set sequentially at 2 MPa, 6 MPa and 10 MPa. Artificial dung was made by adding dung fluid to shredded fibre-board in a 15:1 weight ratio. The rate of brood-ball (= egg) production by female E. intermedius fed on the artificial dung made from fluid extracted by the hydraulic press at 2 MPa was the same as that on natural whole dung. Reproductive performance on all artificial dungs was significantly correlated with the percent dry matter content of the dung fluid used in the mixture. Thus the percent dry matter in the fluid extracted at 2 MPa pressure provides an objective measurement for comparing the quality of different dungs as food for adult E. intermedius, without the need for performing bioassays. The results confirm that the fluid component of dung is the major source of nutrition for adult dung beetles.Deceased February 1986.