Miracle-dz/UniFAR-FTUs huggingface dataset:
Does risk of predation influence population dynamics? Evidence from cyclic decline of snowshoe hares

Like most heavily preyed-upon animals, snowshoe hares (Lepus americanus) have to balance conflicting demands of obtaining food at a high rate and avoiding predators. Adopting foraging behaviours to minimise predation risk may also lead to a decline in condition, and hence fecundity. Predictions of three hypotheses (condition constraint hypothesis, predator-avoidance constraint hypothesis, predation-sensitive foraging (PSF) hypothesis) were tested by comparing changes in the survival and condition of snowshoe hares on four experimental areas in winter during a cyclic peak and decline (1989–1993) near Kluane Lake, Yukon, Canada, where (i) predation risk was reduced by excluding terrestrial predators (FENCE), (ii) food supply was supplemented with rabbit chow ad libitum (FOOD), (iii) these two treatments were combined (FENCE+FOOD), and (iv) an unmanipulated CONTROL was used. Different pattems of survival and changes in body mass were observed in the presence and absence of terrestrial predators. On the CONTROL area, female body mass and fecundity declined, even though sufficient winter forage was apparently available in all years. A similar decrease in body mass was observed on the FOOD treatment, but only during the third year of the population decline. In contrast, female body mass remained high throughout the decline in the absence of terrestrial predators in the FENCE+FOOD and FENCE treatments. Winter survival declined on CONTROL and FENCE areas during the first year of the population decline (1991), but remained higher on FOOD until 1992 and FENCE+FOOD until 1993. These results generally supported the PSF hypothesis where terrestrial predators were present (CONTROL and FOOD grids). Where terrestrial predators were absent (FENCE and FENCE+FOOD), the results supported the alternative condition constraint hypothesis. The evidence suggests that a cascade of sublethal behavioural and physiological effects associated with increased predation risk contribute to the population decline and delayed recovery of cyclic low-phase populations of snowshoe hares.
Habitats used by Juvenile Flagtails (Kuhlia spp.; Perciformes: Kuhliidae) on the Island of Hawai'i1

Abstract: Patterns of juvenile habitat use by two species of kuhliid fishes (āholehole) on the island of Hawai'i were examined. Kuhlia sandvicensis was observed in marine habitat types only, but juvenile K. xenura were observed in freshwater streams, estuaries, on reef flats, along rocky shorelines, and in tide-pool habitats. Principal components analysis indentified nonrandom microhabitat selection by juvenile K. sandvicensis and K. xenura. Both species selected microhabitats that were higher in salinity and temperature and nearer to the open ocean than were areas randomly available to them. Although distributions of juvenile K. sandvicensis and K. xenura overlapped in marine habitats, characteristics of the marine microhabitats used by each species differed. Along rocky shorelines, K. sandvicensis used microhabitats that were characteristic of high-energy surge zones—deep areas close to the open ocean that had high salinities. The rocky shorelines most frequently inhabited by K. xenura, conversely, were shallower areas that were farther from the open ocean with lower salinity. A similar pattern was observed in tide-pool habitats, with K. sandvicensis using microhabitats typical of surge zones, and K. xenura utilizing protected tide pools with low salinities. Protection of a variety of inshore habitats is important for conservation of juvenile Hawaiian kuhliid fishes.
Factors Involved in Spontaneous Discharge of Gonadal Germ Cells from Developing Gonad of 7-day-old Chick Embryos

A series of experiments was conducted to elucidate the factor(s) involved in the spontaneous gonadal germ cells (GGCs) discharge from chick embryonic gonads. The developing gonads recovered from 7-day-old White Leghorn (WL) embryos were incubated for 1 h in Dulbecco’s phosphate-buffered saline (PBS) supplemented with Ca 2+ and/or Mg 2+ at temperatures of 4-42°C. The number of GGCs spontaneously discharged from gonads into PBS was negatively correlated with Ca 2+ concentration and positively correlated with incubation temperature (P<0.05). Effects of Mg 2+ on spontaneous GGCs discharge into PBS[‒] was observed to be minimal (P>0.05). Gonadal germ cells discharged into PBS was observed when divalent cations in the medium were chelated using EDTA. In conclusion, it was revealed that spontaneous discharge of GGCs from gonad of 7-day-old chick embryo into PBS was primarily affected by Ca 2+ concentration and incubation temperature.
Greenhouse Assessment of Differences in Clomazone Tolerance among Sweetpotato Cultivars

Abstract Differences in clomazone tolerance among sweetpotato cultivars were first observed in April 2007 after use of the herbicide for weed control in fields containing the sweetpotato breeding project at the U.S. Vegetable Laboratory. Susceptible cultivars and experimental clones exhibited severe foliar chlorosis and reduced growth, whereas the most tolerant were not injured. Twelve cultivars and experimental clones were included in a greenhouse experiment to quantify the differences in clomazone tolerance. In the greenhouse, the clomazone concentration that caused moderate injury or reduction in shoot growth to the most tolerant clones was approximately 10 times the concentration that caused a similar response in the most susceptible clones. Two older cultivars, Excel and Sumor, that were developed before the registration of clomazone for use in sweetpotato were susceptible. Clomazone is an important component in sweetpotato weed management, and susceptibility is an undesirable trait that should be avoided in new sweetpotato cultivars. Nomenclature: Clomazone; sweetpotato, Ipomoea batatas (L.) Lam.
Filamentous algal endophytes in macrophytic Antarctic algae: prevalence in hosts and palatability to mesoherbivores

Amsler C.D. , Amsler M.O. , McClintock J.B. and Baker B.J. 2009. Filamentous algal endophytes in macrophytic Antarctic algae: prevalence in hosts and palatability to mesoherbivores. Phycologia 48: 324–334. DOI: 10.2216/08-79.1. Five individuals, each from 13 common species of large macroalgae (‘macrophytes’) from the western Antarctic Peninsula, were surveyed for the presence of filamentous algal endophytes both macroscopically and microscopically using dissecting and compound microscopes. Of the 13 species surveyed, endophytes were either rare or absent in five. The remaining species all supported endophytes in most or usually all individuals with maximum endophyte densities per species ranging from 3% to 75% of the thallus area. Thallus fragments from all individuals with endophytes were placed into culture, and 99 unialgal, filamentous brown algal strains were isolated. The ITS1 gene was sequenced in each strain to sort these into distinct genotypes. Brown algal endophytes grew well in culture, and 10 distinct filamentous genotypes were present. The green endophytes did not grow well in culture, and only two green algal species present in the thallus fragments were isolated. No-choice feeding rate bioassays were performed with thallus fragments of all 13 macrophyte species and with cultures of seven filamentous brown endophytes and both green endophytes. Feeding rates on the endophytes were 2–3 orders of magnitude higher than rates on 12 of the macrophyte species and 2- to 6-fold higher than on the only truly palatable macrophyte, Palmaria decipiens. These data support the hypothesis that Antarctic macrophytes are commonly endophytized and that the endophytes benefit from the association by being protected, at least in part, from amphipod herbivory.
Acceptance by the splendid fairy-wren of parasitism by Horsfield's bronze-cuckoo: further evidence for evolutionary equilibrium in brood parasitism

Horsfield's bronze-cuckoo (Chrysococcyx basalis) is one of several highly specialized Australian brood parasites that lay eggs adapted toward those of their hosts. Although parasitized at a mean rate of 20% over 17 years, one primary host, the splendid fairy-wren (Malurus splendens), does not reject the cuckoo's egg or nesding, despite evidence that this host-parasite association is one of long standing. Long-term reproductive and survival data for the splendid fairy^vren showed that (1) the least successful host females were more likely to be parasitized; (2) die most successful host females were more dian able to compensate for the effects of parasitism when lifetime reproduction was considered; and (3) the parasitism had no apparent adverse effect on the survival of breeding females despite the fact that parasitized birds laid more clutches dian diose not parasitized. We suggest that a long coevolutionary history of brood parasitism and nest predation has favored adjustment to the host's life-history pattern, to the point where total acceptance of the cuckoo egg is now an evolutionarily stable strategy. The implications of these findings widi respect to other host species are discussed. In particular, we challenge the current concept of the cuckoo-host association as a classic example of an escalating coevolutionary arms race. Key xuords: arms race, brood parasitism, coevolution, evolutionary equilibrium, life-history strategy, rejection behavior. [Behav Ecol 7:395—407 (1996)]
Field studies on zooplankton‐cyanobacteria interactions

Abstract Correlative field evidence suggests that large grazers such as Daphnia pulex promote the growth of colonial cyanobacteria by selectively eating competitive phytoplankton. This is supported by experimental evidence that (1) in eutrophic lakes dominated by cyanobacteria grazing by zooplankton on small particles is often > 100% day‐1, and (2) colonial cyanobacteria are generally not grazed as rapidly as smaller phytoplankton. Cyanobacteria generally have deleterious effects on grazing zooplankton. Filamentous cyanobacteria such as Anabaena and Oscillatoria can inhibit filtering by cladocerans, reducing growth and reproduction. Detrimental effects on zooplankton via nutritional deficiencies and toxins of cyanobacteria have been demonstrated in the laboratory but not in the field. Grazing on colonial cyanobacteria by zooplankton appears to be an important trophic link in tropical lakes. Generally, calanoid copepods seem best adapted to utilising large cyanobacteria. The generalisation that, with incre.
Trophic State of Clear and Colored, Soft- and Hardwater Lakes with Special Consideration of Nutrients, Anoxia, Phytoplankton and Fish

ABSTRACT Idiosyncrasies, erroneous assumptions and gaps are still hampering lake evaluations, despite several decades of defining the trophic state of lakes. I reevaluated nutrient and algal biomass limits that group lakes into oligo-, meso-, eu- and hyper eutrophic lakes at transition concentrations of 10, 30 and 100 μg · L−1 average total phosphorus concentration of the summer epilimnion. I investigated the direct and indirect effects of general lake characteristics like morphometry and geochemistry (water hardness and color) on lake trophic state and formulated models to deal with their significant influences. Nutrient and biomass concentrations as well as quantitative measures of anoxia were used to determine the trophic state. I demonstrated that the number of coldwater fish species may be used to classify the lower trophic levels in geographically constraint areas. Limits and models were established with data from well-studied lakes and verified with literature data from worldwide lakes. Trophic sta.
The components of the upper thoracic sympathetic nerves

The anatomical and functional relationships of the sympathetic and vagus nerves and their distribution to the thoracic viscera have long been subjects of investigation. Many of the data regarding these nerves have been derived from anatomical investigations ; others from physiological experiments. Surgical procedures for sympathectomy of the upper extremity and for the relief of pain of cardiac origin also have contributed to our knowledge of the anatomical relationships and the functional importance of both the cervical and thoracic sympathetic and vagus nerves. The sympathetic trunk gives rise in the cervical and thoracic segments to rami which extend to the thoracic and abdominal viscera. These include the cervical and thoracic cardiac, the pulmonary and the splanchnic nerves. The sympathetic cardiac nerves may for convenience be divided into two categories; those which arise from the cervical segments of the sympathetic trunk and those which arise from the thoracic segments. The cervical ca.rdiac nerves descend through the cervical region to enter the thorax and join the cardiac plexuses. The thoracic cardiac nerves in general are arranged segmentally and only those arising in the upper four or five thoracic segments enter the cardiac plexuses directly. Those which arise at lower levels join the aortic plexus. These nerves vary in sizes and numbers and in the manner in which they reach the cardiac plexuses in different specimens and bilaterally in the same specimen.
Estudio Ontogenico Comparativo de la Lamina epitelial de los Compartimentos Gastricos no Glandulares en Ovinos Merinos

A total of 74 embryos and fetuses were used in a comparative analysis of the epithelium of the non‐glandular stomach compartments of merino sheep during development. The mechanical protection showed by the tegumentary epithelium in the superficial layers of the rumen, reticulum and omasum is supported by a buffer system of neutral mucopolysaccharides secreted by the deeper strata. Neutral mucopolysaccharides first appeared in epithelial cells at 46 days of fetal life. Acid mucopolysaccharides, mucins, and mucoid compounds were not detected. Growth curves and formulas were constructed for the epithelial layers.
Slatted versus Solid Floors in the Dung Area of Farrowing Pens: Effects on Hygiene and Pig Performance, Birth to Weaning

The effect of slatted versus solid floors in the dung area of farrowing pens on the health and production of pigs from birth to weaning was studied. In half of the farrowing pens, evenly distributed within a unit, the plastic slats were glued together to form a solid surface and only urine drainage was allowed. A total of 201 litters were studied. Pen hygiene in the slatted floor pens in general was significantly better in all trials, and there was a demonstrably higher amount of bacteria in the solid floor pens. Total mortality from birth to weaning was significantly higher for the solid floor treatment group, primarily due to more traumatic injuries and more infection losses. No significant treatment effects on morbidity and daily weight gain were observed. In conclusion, even in a closed herd with batch farrowing, good general hygiene level and good herd immunity, a small change such as solid flooring in the dung area can negatively affect pig health and production before weaning.
Beneficial effects of flower-dwelling predators on their host plant

We examined the effects of the sit-and-wait spider Misumenops argenteus (Thomisidae) on the herbivore assemblage and fitness of the perennial woody shrub Trichogoniopsis adenantha (Asteraceae). Because crab spiders prey on both pollinators and phytophagous insects, they can have potentially negative and positive effects on plants. In a manipulative experiment using paired plants, spiders decreased the density of sucking and some endophagous herbivores on the leaves and capitula and reduced the number of damaged achenes produced by the plants. Damaged capitula had a higher proportion of fertilized achenes in plants with spiders than without spiders, but not undamaged capitula. These results indicate that M. argenteus exerted a double positive effect on seed production in T. adenantha. The effect of M. argenteus on herbivores may be taxon specific and vary among years with different herbivore abundances.
A New Species of Sigmatostalix (Orchidaceae: Oncidiinae) from Northern Ecuador

ABSTRACT A new species of the genus Sigmatostalix, S. uncinata, is described and illustrated from the province of Carchi in northern Ecuador. Sigmatostalix uncinata is compared with S. aristulifera, from which it mainly differs by the subquadrate lateral lobes of the lip having an apical, linear, uncinate appendix (vs. narrowly dolabriform and apically emarginate-bilobed); and a semilunate, rounded, concave callus (vs. absent or reduced to a low keel). The phylogenetic position of Sigmatostalix is discussed, and previous infrageneric schemes of classification are reviewed.
Foraging Ecology of the Tropical Giant Hunting Ant Dinoponera australis (Hymenoptera: Formicidae)—Evaluating Mechanisms for High Abundance

A central goal of ecology is to understand the mechanisms behind variation in the abundance of species. Food web theory predicts higher biomass for animals at lower trophic levels. However, some high trophic level species may reach great abundance via highly efficient foraging behaviors. We evaluated ecological and behavioral traits of the giant tropical ant Dinoponera australis related to these mechanisms. We determined its distribution and abundance, documented its foraging behavior, and measured its trophic position in a population at P.N. Iguazú, Argentina. We report that D. australis colonies are overdispersed, and the species reaches a wet biomass of more than 2.5 kg/ha at this site. Dinoponera australis foraging behavior is characterized by route fidelity of individual workers, with different individuals specializing on different areas around the nest. Finally, stable isotopic evidence and direct observation suggest these ants are among the top predators in this terrestrial invertebrate community. We interpret our findings in the context of how the behavior of an abundant top predator creates an exception to the usual trade‐off between biomass and trophic level. Together these data provide insight into the biology of one of the world's largest ants and why they may be able to attain such high densities where they occur.
Genetic differentiation in the viability of sibling species of Rhagoletis fruit flies on host plants, and the influence of reduced hybrid viability on reproductive isolation

Prior theoretical studies have analyzed host‐associated factors restricting gene flow between phytophagous insect species, and simulated evolutionary changes in components of fitness contributing to the adaptation of species to distinct host plants. However, there is relatively little empirical information on these topics. In this paper we report data on two host‐associated sibling species of tephritid fruit flies, Rhagoletis mendax (Curran) and R. pomonella (Walsh) which infest ericaceous and rosaceous host plants, respectively. To test the hypothesis that these species have evolved viability differences on alternate hosts which can contribute to the restriction of gene flow between them, we measured the larval‐to‐adult viability of R. mendax, R. pomonella and F1 interspecific hybrid progeny reared on naturally‐growing, highbush blueberry (Vaccinium corymbosum L.) and apple (Malus pumila Miller = Pyrus malus L.) plants in the field. Our results indicate that genetic changes associated with the adaptation of these species to distinct host plants could also cause reduced fitness of interspecific hybrids, and thereby restrict interspecific gene flow. Fewer interspecific hybrids survived to adulthood than either R. pomonella progeny reared in apples or R. mendax progeny reared in blueberries. These differences in the viability of progeny from hybrid versus conspecific crosses can substantially restrict gene flow between R. mendax and R. pomonella flies, and may be an important factor influencing their reproductive isolation. Genetic differences among hybrid and conspecific crosses were also detected for the lengths, widths and weights of pupae reared from blueberries and apples. In a second experiment, the ovipositional preferences of R. mendax and R. pomonella flies were recorded on host plants inside a field cage. R. mendax flies had a strong ovipositional preference for blueberries over apples, whereas R. pomonella flies readily oviposited in both host fruits. Other studies have determined that R. pomonella flies also oviposit in the fruits of several other plants which are not hosts under field conditions; this behavior can promote host shifts to new plants by flies with suitable plant‐finding and viability traits. Our results support the theoretical assumption that divergence in host‐acceptance behaviors and viabilities on host plants are key aspects of evolutionary differentiation among closely‐related taxa of phytophagous parasitic insects. We discuss our results in the context of other traits that can restrict gene flow between R. mendax and R. pomonella, and in relation to the findings of other studies on the evolution of host plant use.
Breeding seasons of sea‐birds in the Galapagos Islands

The sea-birds breeding in the Galapagos Islands show a diversity of breeding cycles. Some species have rigidly fixed annual breeding while others breed throughout the year but have peaks of breeding at less than annual intervals. The eight species which have non-annual breeding are probably breeding as often as possible with the interval between the end of a breeding attempt and the start of the next being the time needed to moult the wing and tail feathers. Only one species is definitely known to breed and moult at the same time. Although there are well marked seasonal fluctuations in the sea temperature, regular sampling failed to demonstrate any regular fluctuations in the surface plankton. The available evidence suggests that food for some sea-birds is erratic and unpredictable. Some non-annual breeding species have their breeding synchronized by severe food shortages which delay breeding, presumably because females cannot find enough food to form eggs, until conditions improve. Timing of the breeding season in annual breeders is less easily explained but some species may be feeding well away from the islands in areas where there is a regular fluctuation in the food supply. Most of the annual breeders have prolonged breeding seasons and in two species breeding is out of phase on different islands. Perhaps species are influenced by some weak annual variation in food supply which makes it disadvantageous to breed in a few months of the year.
Aquatic Ecosystem Health and Integrity: Problems and Potential Solutions

Stable URL:http://links.jstor.org/sici? sici=0887-3593%28199606%2915%3A2%3C254%3AAEHAIP%3E2.0. CO%3B2-6Journal of the North American Benthological Society is currently published by The North American Benthological Society.Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available athttp://www.jstor.org/about/terms.html. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtainedprior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content inthe JSTOR archive only for your personal, non-commercial use.Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained athttp://www.jstor.org/journals/nabs.html. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printedpage of such transmission.JSTOR is an independent not-for-profit organization dedicated to and preserving a digital archive of scholarly journals. Formore information regarding JSTOR, please contact support@jstor.org. http://www.jstor.orgSat Jun 9 14:08:22 2007