bluuebunny/crossref_metadata_2025 huggingface dataset:
Demography and Behavior of the Damselfly, Argia Apicalis (Say), (Odonata: Coenagriidae)
Authors: Bick George H. , Bick Juanda C.
Published: May 2006

Demography, movement to and from water, reproductive behavior, behavior, localization, and spacing of single males were studies. All marked and unmarked individuals at water were counted on 47 consecutive days and hourly on three days. Simultaneous counts were tallied at pond and in a roosting area on nine days of varied weather. Behavior of 33 pairs, seven observed constantly from seizure until female left the pond, and of 17 unpaired males, each constantly observed for 30 min, is presented. Daily counts of matures and occurrence of tenerals throughout indicated a summer species and a population of diverse age. Mean minimum reproductive age for males were 8.4 days, for females 7.0 Maximum activity was near noon. Males were at water on 44% of their days lived, females on 20%. Repeat matings during the same day were very rate in both sexes. Males mated on 20% of their days at water, females on 89%. Because of this reciprocal relationship between frequency at water and frequency of mating, the mean total number of matings for both sexes was approximately equal. Movement from roosting area to pond was characterized by random shifting. Males arrived at water earlier than females and became spaced at six—foot intervals. Males recognized kind and sex and seized either flying or perched females immediately when they arrived without courtship or display by either sex. Copulation and oviposition were at sites other than those defended earlier in the day by the unpaired male. Copulation was a short distance away from the main concentration of single males and lasted 16 min. Ovipositing females were gregarious and single males tolerant of pairs, so that egg laying occurred at a few communal sites: willow roots, boards and sticks, horizontal Helenium. Egg laying consisted of three sequential phases: exploration (25 min), oviposition in tandem (65), oviposition alone (21). The male was the active partner in seizure and copulation, the female in oviposition. Most females avoided a second seizure during the same day by rapid escape flight if captured a second time, copulation of oviposition was unsuccessful. A particular male was not associated with a particular six—foot interval from day to day, but in any one day, most males remained within the same interval for 76% of their total time at water. They maintained these areas by aggressive activity which was in no way sexual and which warded off 87% of all intruders. Most important were strong flights toward intruders without physical contact and patrols of an area.
The Annual Seed Rain of Adventive Herbs in a Radiation Damaged Forest
Authors: Wagner Richard H.
Published: May 2006

The seasonal and numerical distribution of seeds of adventive species entering the central 50—m zone of the irradiated forest facility of Brookhaven National Laboratory was studied by the exposure plate method. Adventive seeds were collected from 15 August to 10 December 1963 and 7 May to 1 September 1964 and the cumulative total per hectare noted. The species found on the traps matched fairly well those species established in the study area, suggesting that successional patterns in the 50—m zone are dependent on the availability of aerially borne seeds from surrounding areas.
Measurement of Background Radiation in Lakes
Authors: Likens Gene E.
Published: May 2006

Measurements of background radiation were made in five lakes–two Wisconsin, two New Hampshire, and one antarctic. These lakes were characterized by a small amount of ionizing radiation in mid—water and increasing quantities near the air and sediment boundaries. Moreover, the radioactivity of the sediments in the Wisconsin and New Hampshire lakes usually increased toward the shore line. Count—rate values for the sediments near the shore line were up to ten times higher than the values recorded near the bottom in deep water. A similar pattern of radioactivity distribution in the sediments was not apparent in Lake Vanda, a perennially ice—covered antarctic lake. Various hypotheses were suggested to explain the origin of the anomalous distribution of ionizing radiation in these lakes and its possible role as an environmental factor.
Autecology of the Adult Horn Fly, Haematobia Irritans (L.), (Diptera: Muscidae)
Authors: Morgan Neal O.
Published: May 2006

During the horn fly seasons of 1959 and 1960, experiments were conducted to determine the relationship of weather conditions to horn fly populations on three breeds of dairy heifers, to correlate the effect of the macroenvironment on the microenvironment within the 1/2 in. mantle of a heifer, and also to correlate the locations of horn flies within this mantle with various factors of the microenvironment. Usually there was a significant difference between the number of horn flies on Holstein and that on Guernsey and Jersey heifers. The flies generally preferred the dark—colored areas of biocolored cattle during daylight hours, and the black of the Holstein to the tan of the Guernsey. When the macrotemperature was above 85°C, many of the flies were found on the white skin of the belly and udder area of heifers. During inclement weather the flies were observed on both the white and dark—colored areas of all heifers. Macrotemperature and relative humidity influenced the horn fly populations within the biocenose. The apparently preferred macroclimate for macroclimate for horn flies was: temperature 73 to 80°F, relative humidity 65 to 90%, scattered light showers, and no wind. The flies apparently sought certain microenvironmental conditions most commonly observed on Holsetin heifers. Within the mantle of microenvironment, horn flies appeared to prefer an air temperature of about 85°F, a skin temperature of about 97°F, and a relative humidity of about 65%. When such conditions were not available to the flies on the sides and backs of Holstein heifers, the flies were usually found in near—optimum conditions along the belly midline for each of the three breeds of heifers.
Interspecific Territories of Birds
Authors: Orians Gordon H. , Willson Mary F.
Published: May 2006

Territories of birds, usually defended against conspecific individuals, are sometimes defended against individuals of other species. Since such behavior is demanding both of time and energy, natural selection should favor ecological should favor ecological divergence, the establishment of overlapping territories, and the reduction of aggression. Lack of divergence in modes of exploitation could mean that insufficient time has elapsed for the changes to be completed or that the environment imposes some limitation preventing the evolution of the required degree of divergence. Such environmental limitation can be predicted in (a) structurally simple environments, (b) when feeding sites are strongly stratified in structurally complex vegetation, or (c) when the presence of other species in the environment prevents divergence in certain directions. The known cases of interspecific territoriality in birds are analyzed and shown to be largely in accordance with these predictions, although several cases of overlapping territories in situations where interspecific territoriality has been predicted provide relationships worthy of further study. We suggest that Darwinian selection at the level of the individual permits an understanding of the known structure of avian communities and that there is no need at present to invoke new selective mechanisms at the level of the community or ecosystem.
Ecology of Sponges in Hatteras Harbor, North Carolina
Authors: Wells Harry W. , Wells Mary Jane , Gray I. E.
Published: May 2006

Patterns of settling, growth, gemmule formation, and disappearance of sponges in Hatteras Harbor are presented for a one—year period and related to water temperature. Ten species are represented in the harbor, of which eight were recorded settling on submerged clam shells. Certain water temperatures, critical for some sponges, are realized two months earlier than in Milford Harbor, Long Island Sound. In response to these temperatures, certain events in the life cycles of Microciona prolifera and Haliclona loosanoffi occur two months earlier in Hatteras Harbor. In Hatteras Harbor, the latter species persists throughout the winter, exhibits two periods of settling, and relies on gemmules to survive adverse summer conditions, whereas in Long Island Sound it exhibits a single period of settling and relies on gemmules to survive adverse winter conditions. Observations are also made on competition for space by sponges and by the compound ascidian, Botryllus schlosseri, and on other aspects of the ecology of sponges in Hatteras Harbor.
Arctostaphylos Myrtifolia, Its Biology and Relationship to the Problem of Endemism
Authors: Gankin Roman , Major Jack
Published: May 2006

Arctostaphylos myrtifolia is a California endemic plant limited to only certain outcrops of an Eocene laterite in the Sierra Nevada foothills near Ione and to a kaolin—altered rhyolite and an acid sericitic schist eastward at higher altitudes of 500 m. Taxonomically the diploid species is isolated. Morphologically it resembles a low, sclerophyllous heath. The plants are killed by fire, but seedlings are favored by the ensuing bare areas. It flowers in late winter or very early spring. The climate where A. myrtifolia occurs is dry in summer, wet in winter. Frosts are infrequent and slight, but summer heat is severe. Only some 350 mm of actual evapotranspiration of water is calculated to take place in these environments, but leaching may amount to 200 mm at lower elevations and to 400 mm at higher. The stations for A. myrtifolia do not differ greatly in climate from surrounding areas where the plant does not occur, but they have a somewhat more maritime temperature regime. The soils at these stations are acid and presumably so low in nutrients as to exclude the normal, zonal, climax vegetation. The endemic plant thus is presumed to be a better competitor on the nonzonal sites of acid soil parent material. Many cases of similarly disjunct plant distribution can be related to regionally peculiar soil parent materials whose evident effect is to exclude the regionally climax vegetation. With competition by zonal vegetation thus weakened, disjunct plants can and do occur. The vegetation associated with A. myrtifolia is poor, therophytic, and adapted to acid, seasonally wet sites. Its shows similarities to the Cisto—Lavanduletea of the Mediterranean region. Historical factors of some kind, and not the contemporaneously acting ecologicalfactors alone, are assumed to help account for the limited distribution of the species.
Inhibition of Nitrogen‐Fixing and Nitrifying Bacteria by Seed Plants (I.)
Authors: Rice Elroy L.
Published: May 2006

To determine whether the rate of plant succession on abandoned fields is due in part to the production by the pioneer species of substances inhibitory to nitrogen—fixing or nitrifying bacteria, plant extracts were tested for inhibitory activity by the diffusion technique on solid medium against two strains of Azotobacter, two strains of Rhizobium, one strain of Nitrobacter, and two strains of Nitrosomonas. Of 20 species tested, 13 exhibited considerable inhibitory activity against most of the test organisms. There was considerable variability among the species as to the organ containing the greatest amount of the inhibitor. Of 14 species tested, root extracts of all were inhibitory to at least some of the test organisms. Three of four species tested had more inhibitory activity in young leaves than old. Three of five species had greater activity in young inflorescences than old. Fifteen of 50 plant extracts tested completely prevented any detectable nitrite production by both strains of Nitrosomonas. Eleven other extracts completely prevented nitriteproduction by one of the strains. Leachates of the pots of 10 species of 12 grown in sand culture were inhibitory to one or more of the test organisms. No change in inhibitory activity occurred in sterile extracts of four of eight species due to inherent enzymatic activity or autoxidation at 24.5°C or 37°C. Three species had slight to moderate decreases in activity, and there was an increase in activity of the Digitaria sanguinalis extract against the nitrifiers. There was little loss in inhibitory activity in nonsterile extracts of four of eight species after 6 days at 37°C. Considerable loss of activity occurred in three species after 6 days, and a slight increase occurred after 24 hours at 37°C in one species. Inhibitors in extracts of seven species were at least slightly adsorbed by kaolin or activated charcoal. An extract of Aristida oligantha resulted in a statistically significant reduction in the number of nodules produced on stringless greenpod bean plants. Living plants of Ambrosia elatior, Bromus japonicus, and Digitaria sanguinalis brought about a reduction in the number of nodules produced on inoculated red kidney bean and black valentine bean plants. Older plants of Aristida oligantha significantly inhibited nodulation in black valentine beans. The occurrence of inhibitors of nitrogen—fixing and nitrifying bacteria in pioneer species of abandoned cultivated field in Oklahoma suggests that this mechanism may be important in competition and succession among plants.
Effects of Denudation on the Productivity of Grassland
Authors: Penfound Wm. T.
Published: May 2006

Denudation (close mowing and removal of mulch) of ungrazed prairie and ungrazed cropland plots near Norman, Oklahoma, did not result in significant change in composition, but increased the biomass in both the priarie and cropland during the growing season. Total biomass in all plots was low in February—March, increased to a maximum in late July, and declined rapidly thereafter. Although 115 species were sampled, only the following six species contributed significantly to the total biomass: Andropogon gerardi, Panicum virgatum, Sorghastrum nutans, Andropogon scoparius, Leptoloma cognatum, and Panicum scribnerianum. Average daily productivity was very low in February—March, moderate in April, relatively high and approximately equal in May, June, and July, and negative in August and September. The cumulative productivity was moderate for April, approximately equal but relatively high during May, June, and July, but declined rapidly thereafter. The terminal standing crop of living material (early September) was considerably lower than the maximum biomass in late July. In the denuded plots, the much increased steadily in weight throughout the period of the study. The amount of mulch attained a relatively steady state in the denuded prairie by the end of the third year, and in the denuded cropland by the end of the fourth year.
Bimodal Occurrence of Breeding in an Equatorial Land Snail
Authors: Owen D. F.
Published: May 2006

Near the equator in Uganda, Limicolaria martensiana, an herbivorous land snail, breeds in all months of the year with peaks in January—February and July. This bimodality in breeding pattern appears associated with the two annual and wet and dry seasons.
Vagility of P32‐Labeled Isopods in Grassland
Authors: Paris Oscar H.
Published: May 2006

The nocturnal activity of Armadillidium vulgare in California grassland suggests that this cryptozoan may be very vagile, but earlier attempts to study its lateral movements failed because of its secretive habits. In the present study, assimilated radiophosphorus was used to label isopods and make the recovery of hidden individuals possible. In each of four experiments, cohorts of about 1,000 radioactive animals were released in a grassland area, and the movements and dispersal of the tagged individuals were followed for as long as 25 days. Two of the experiments were conducted during the rainy season and two during summer drought. Activity of the labeled animals, as reflected in their dispersal rates, was greater in summer than in winter. A maximum dispersal rate of 13 m in 12 hr was observed in one of the summer experiments, as contrasted to a maximum of only 10 m in six days in one of the winter experiments. The greatest dispersal distance observed was 25 m (after 20 days in one of the winter experiments). The dispersal patterns can be described by the equation Y = a + c/r, where Y is a measure of the density of labeled animals at distance, r, from point of release, and c is a proportionality constant. A geometrical analogue for this equation, plus a modified dispersal experiment with Porcellio scaber, shows that c/r accounts for density decrease due to the dilution of tagged animals by the increasing area into which they move the constant a is interpreted as affording a relative measure of dropouts, individuals which disappear from the dispersal pattern. Foraging appears to account for the activity of Armadillidium during the winter. In the summer, on the other hand, isopods must search for shelter from desiccative daytime conditions following nightly forages. The search for shelter in addition to the search for food appears primarily responsible for the greater dispersal rate observed during the summer. The physical environment seems to interact importantly with food availability for these isopod populations.
Effect of Fire on Bunchgrasses of the Sagebrush‐Grass Region in Southern Idaho
Authors: Wright Henry A. , Klemmedson James O.
Published: May 2006

Four species of bunchgrass were experimentally burned in a portable combustion chamber to determine their resistance to fire as a function of season of burning (June, July, August), intensity of burn (200°F, 400°F), and plant size. Poa secunda was not affected by burning. Sitanion hystrix proved comparatively resistance to burning; it was damaged in July only. This seasonal response correlates with air temperature and relative humidity, which appear to influence the amount of applied heat required to cause damage. Of the species tested, Stipa comata appeared to be most susceptible to fire. The plants suffered high mortality in June, were extremely susceptible to damage from burning in July, but were relatively resistant to fire in August. The seasonal response of Stipa thurberiana was similar to that of Stipa comata, but damage was less severe. Season of burn was the primary determinant of the extent of damage to Stipa species during June and July, but size of plant became increasingly important in determining the effect of burning during the latter part of summer. The difference between maximum soil surface temperatures of 200°F and 400° was apparent only for small Stipa thurberiana plants burned in June.
Vegation Changes During a 30‐Year Period in Grassland Communities Near Hays, Kansas
Authors: Albertson F. W. , Tomanek G. W.
Published: May 2006

Three plant communities near Hays, Kansas, showed considerable change in the composition of their dominant vegetation over the 30—year period from 1932 to 1961. The short grass community was dominated by Buchloe dactyloides and Bouteloua gracilis in 1932 and dominated only by Bouteloua gracilis in 1961. The little bluestem community was dominated by Andropogon scoparius during favorable years but by Bouteloua curtipendula and Bouteloua gracilis during drought years. The dominants of the little bluestem—big bluestem community were Andropogon scoparius and Andropogon gerardi in 1932 but by 1961 Andropogon gerardi was the only dominant. Two droughts periods, 1933—39 and 1952—56, were important in affecting these vegetation changes.
Relation of Castration to Fat Stores in Male Pheasants
Authors: Nagra Clarence L. , Breitenbach Robert P. , Meyer Roland K.
Published: May 2006

During 1958 and 1959 we studied the effect of castration on lipids in male gamefarm pheasants confined to outdoor pens. In both years the visceral fat stores of control birds decreased from January to June and then increased. Among the orchidectomized pheasants, visceral fat was minimum from February to April 1958 and maximum thereafter, but did not change seasonally in 1959. Liver and plasma lipid showed no regular periodicity and were not associated with levels of visceral fat nor influenced by castration. The weight of the adrenals in intact pheasants increased 20% from February to June 1958 and then decreased. During 1959 the adrenals of these birds weighed most in April, when they were 30% heavier than in January; subsequently they involuted. In 1958 the seasonal pattern of adrenal weight in gonadectomized pheasants was opposite to that of controls, whereas in 1959 the pattern was like that of intact birds. Thyroid weight was stable seasonally.
Root Grafting in Quercus Turbinella Greene
Authors: Saunier Richard E. , Wagle Robert F.
Published: May 2006

Apparent widespread self—grafting and intra—specific grafting roots of Quercus turbinella have been noted in north—central Arizona. Grafting occurred on roots varying in size from 0.1 inch to 1.5 inches in diameter and varying in depth below the soil surface from a few inches to over 25 ft. Cross sections of the grafts indicated sufficient fusion to allow translocation across the unions. Implications of the phenomenon are discussed.
Effects of Altitude on Carbohydrate Content of Mountain Plants
Authors: Mooney H. A. , Billings W. D.
Published: May 2006

Sugar and starch contents of roots or rhizomes of Polygonum bistortoides, Saxifraga rhomboidea, and Calyptridium umbellatum were measured at different altitudes in the Sierra Nevada of California and in the Medicine Bow Mountains of Wyoming. Carbohydrate reserves appear to be higher near the lower altitudinal limits of a species. Ploygonum bistortoides, Caltha howellii, and Sibbaldia procumbens transplanted to lower and warmer elevations used up stored carbohydrates more rapidly than at the elevation of origin. The higher carbohydrate content of individuals in natural populations near the lower altitudinal limits of an alpine species thus appears to be an ecotypic or ecoclinal adaptation.
Methods of pH Determination and Seasonal pH Fluctuations in Quebec Forest Humus
Authors: Vezina Paul E.
Published: May 2006

Seasonal fluctuations of humus pH of three commonly occurring forest soils in Quebec were assessed to determine which of four different methods was best suited for comparisons of pH among sites. Seasonal variations of 1.1 to 1.3 unites were observed on all soil types tested. Humus pH was highest in midsummer and decreases as winter approached. Different pH values were obtained from the same soil at the same time by the different methods used. Reproducibility of pH measurements is briefly discussed.
Absorption of Radiant Energy by Leaves
Authors: Loomis Walter E.
Published: May 2006

Leaves of common plants absorb 80—95% of the blue (400—500 mμ, 60—80% of the green (500—600 mμ, and 80—90% of the red (600—700 mμ. Absorption in the infrared is about 5% at 800 to 1,200 mμ and increases to near 100% beyond, 3,000 m(μ) or 3 μ. Absorption at 550 mμ by equal quantities of leaf pigments was two to six times greater for intact leaves than for methanol solutions. Shifts of the absorption bands toward shorter wavelengths, which are characteristic of chlorophyll solutions, were not observed in isolated whole or sonically disintegrated chloroplasts. Leaves in sunlight are heated from a few degrees above air temperature for thin leaves to 30 degrees C or more for very thick leaves before reaching a steady temperature. The heating and cooling curves shown by wilted leaves were not significantly different from those of transpiring leaves. Dried leaves heated less and cooled faster than normal, transpiring leaves. Leaves in sunshine were cooled quickly toward air temperature by wind at 5 mph. It is concluded that leaves tend to assume the temperature of the surrounding air; that they are heated rapidly by radiant energy, and cooled primarily by conduction of energy to the air.
Further Experiments on Competition Between Strains of House Flies
Authors: Sullivan Robert L. , Sokal Robert R.
Published: May 2006

Experiments on competition in house flies reported here extend two previous studies by Sullivan and Sokal (1963) and Sokal and Sullivan (1963). The wild typed OL strain, the autosomal recessive bwb, and the reciprocal crosses bwb x OL (called A for short) and OL x bwb (called B) were reared at seven densities ranging from 40 to 2,560 eggs per 36 g of CSMA larval medium, both in pure and mixed cultures. Three possible mixtures, OL: bwb, A: bwb, and B: bwb, were set up in three proportions, 10:90, 50:50, and 90:10 parts of wild phenotype to mutants, respectively. The nine possible combinations were replicated minimally five times per density. The numbers, dry weights, and times of emergence of adults were recorded by genotype. The responses of the hybrids resembled those established previously for the wild type flies. The reciprocal heterozygotes were not markedly different from each other. In mixed culture the emergence of bwb flies is affected more severely by an increase in density than that of their competitors. Hence the relative fitness of the wild phenotype increases markedly with density. At the highest densities hybrids weigh more in competition than they do in pure culture. Crowding increases the mean and variance of duration of adult emergence. Mutants emerged fastest in pure culture, whereas the wild phenotypes are fastest in mixed culture. Competition reduces the variance of duration of emergence in the wild type, though increasing it in the mutant. When the wild phenotype is present in low proportions in dense mixed culture its survival, weight, and duration of emergence are better than when it is frequent. These findings are Reviewed and discussed from the point of view of genetic factors in competition, genetic facilitation, and gene frequency dependent changes in components of fitness. A brief comparison is made with a related study of the ge strain in the house fly.
Continuous Breeding in Populations of Two Tropical Crustaceans, Mysidium Columbiae (Zimmer) and Emerita Portoricensis Schmidt
Authors: Goodbody Ivan
Published: May 2006

Mysidium columbiae is a mysid found commonly in mangrove lagoons in Jamaica. Samples collected at approximately fortnightly intervals over a period of 15 months show that eggs and embryos are carried at all seasons of the year and suggest that the population as a whole is reproducing continuously. Emerita portoricensis is a mole crab occurring in dense populations in alluvial sands. Samples taken over a period of two years indicate that young animals enter the population through out the years and that females in berry are found at all seasons. It is concluded that breeding is also continuous in populations of this species.
Use of Miniature Glass Rod Dosimeters in Radiation Ecology
Authors: Kaye Stephen V.
Published: May 2006

A system is discussed for radiation dose measurements in ecological studies with 1 x 6 mm silver—activated metaphosphate glass rods. The miniature size of the dosimeters, their low cost, simplicity of use, and wide range of sensitivity make them especially well suited for use in radiation ecology. The system measures radiation dose by the principle of radiophotoluminescence, whereby ionizing radiation entering the glass matrix reduces ionic silver to its ground state. This change is directly proportional to dose and is easily measured in a fluorometer which can be calibrated to give the actual dose that was received by the rods. Two important radioecological applications are (1) the measurement of exposure, and (2) the measurement of absorbed dose in media of interest such as tissue, soil, and water. Air exposure can be measured at particular locations around gamma irradiation facilities or above an infinite plane source (radioactive fallout on soil or radionuclides mixed with soil). Glass rods used to measure the exposure above the radioactive White Oak Lake bed showed that the exposure rate at five feet is reduced to only one half of the dose rate at the soil surface. Cotton rats tagged with glass rod dosimeters on White Oak Lake bed had an absorbed dose rate of approximately 2.8 rads/day in mid—June of 1962, but the dose rate decreased to 1.5 rads/day by mid—December. This decrease in dose rate was attributed to the gradually rising water table which filtered low energy photons and caused a corresponding decrease of the dose rate above the soil surface. The miniature fluorods were successfully implanted in acorns, in an on living plants, and in soil. Many other applications are possible in radiation ecology including the use of glass rods to monitor wildlife.
Plant Communities and Associated Soil and Water Factors of Shale‐Derived Soil in Northeastern Montana
Authors: Branson F. A. , Miller R. F. , McQueen I. S.
Published: May 2006

Sites on different strata of Bearpaw shale and on alluvium derived from the shale in a small basin in northeastern Montana supported strikingly different plant communities, including three Nuttall saltbush, three big sagebrush, two greasewood, one western wheatgrass, one blue grama, one silver sagebrush, one foxtail, one buckwheat, and a community of mixed shrubs. Several soil factos were measured, but only total soil—moisture stress and soil—moisture volume gave rational ordinations of the communities studied. Total soil—moisture stress at the average root depth ranged from a high of 96 bars for a Nuttall saltbush community to only 19 bars for a mixed shrub community. The Nuttall saltbush community was found on soils having a high soluble salt content, high soluble sodium percentages, high total soil—moisture stress, and low infiltration rates. Soils at the big sagebrush site had low soluble salt content, relatively high soluble sodium, and intermediate total soil—moisture stress values. The wettest site, subject to spring flooding, was occupied by western wheatgrass. Quantities of water evapotranspired from each habitat (calculated as maximum soil moisture minus minimum plus increments added to soils by summer storms) when related to precipitation provided approximations of runoff from, or run—in moisture for, each habitat.
Nonsynchronous Spatial Overlap of Lizards in Patchy Habitats
Authors: Schoener Thomas W.
Published: May 2006

Sympatric native Anolis species with similar structural habitats but contrasting climatic habitats are closer in head and body size on species—rich than on depauperate islands. In two localities, sympatric Anolis species with differential occurrences in sun or shade sought lower, more shaded perches during midday, resulting in partly nonsynchronous utilization of the vegetation by the two species. The second observation may be related to the first in the following way: nonsynchronous spatial overlap could dictate relatively great resource overlap for species coinhabiting patchy or edge areas, requiring great differences between the species in prey size in addition to those in climatic habitat. The extent of such overlap on small depauperate islands could be greater if these contained a greater proportion of patchy or edge habitats (with respect to insolation), or if climatic preferences were broader and more overlapping than on large, species—rich islands. In each locality, the relatively more shade—inhabiting species occurred more often on larger perches and on lower perches than did the other species. In both species of the Bermudan pair, adult males occupied higher and larger perches, and in grahami, shadier perches, than did female—sized individuals. The statistical significance of these and other differences was evaluated using several unweighted g2 procedures, Cochran's weighted g2 test and a partitioning technique for analyzing interactions among variables in complex contingency tables. The last method is described in detail in the papaer by Fienberg, immediately following this one.
Characteristic Permitting Coexistence Among Parasitoids of a Sawafly in Quebec
Authors: Price Peter W.
Published: May 2006

–Six poarasitoid species (Hymenoptera: 5 Ichneumonidae, 1 Eulophidae) coexist on cocoon populations of the Swaine jack pine sawfly, Neodiprion swainei Midd. in Quebec. Their distribution between plant communities was related to host availability except for Gelis urbanus (Brues) which has alternative hosts. Pleolophus basizonus (Grav.) was dominant at high host densities, tending to displace Pleolophus indistinctus (Prov.) which was dominant at low host densities. Mastrus aciclatus (Prov.) occupied dry open sites at high host densities, where other species were less numerous. The highest species diversity of cocoon parasitoids occurred at the ecotone around jack pine stands and at moderate host densities in increasing host populations. Furthermore, parasitoids attacking larvae were well represented in moderately dense host populations. As the host density increased, P. basizonus became so dominant that it reduced species diversity, particularly among the parasitoids attacking the host larvae. Species diversity can be predicted from the proportion of P. basizonus present. This parasitoid acts as an organizer species within the parasitoid complex because of its superior coimpetitive ability. Parasitoids of larvae have a conservative strategy for host exploitation that appears adapted for utilizing low host populations. In contrast, the parasitoids attacking cocoons gain dominance only when host—finding is easy in high host populations.
The Estimation of a Time Function of Ecological Use
Authors: Ricklefs Robert E.
Published: May 2006

A general model is formulated relating the outcome of a series of events such as the capture or escape of a prey item to the probability, time and outcome of each kind of event. Application of the model and its derivation are demonstrated for predator hunting behavior and the nesting biology of birds.
Competition for Moisture among Seedlings of Annual and Perennial Grasses as Influenced by Root Elongation at Low Temperature
Authors: Harris Grant A. , Wilson A. M.
Published: May 2006

Rapidly elongating Bromus tectorum and Taeniatherum asperum roots penetrated the soil ahead of Agropyron spicatum roots and used available moisture. In contrast, Agropyron desertorum roots penetrated the soil almost as rapidly as B. tectorum and T. asperum and remained in favorable moisture. These differences in root penetration resulted in lower leaf water potentials and poorer survival in A. desertorum. The results suggest that in areas where root growth occurs at low temperatures and where lands are infested with B. tectorum and T. asperum, seedlings of A. desertorum would be more successful than seedlings of A. spicatum.
Tritium Collection and Extraction Techniques for Plant‐Water Relationship Studies
Authors: Young S. E. , Dodd J. D. , Ibert E. R.
Published: May 2006

Techniques are described for quantitatively determining water movement and loss in pricklypear plants with tritiated water. Transpired vapor from plants which were injected with tritium was collected with a system that passed dry air over the pad surface and into collecting vials. Water was extracted from tissue samples by a modified freeze—drying technique. Combustion of tissue samples following extraction showed that the method was efficient for tritiated water recovery from the plant material when the extraction time was 8 hours and a warm—water bath temperature of 55°C was maintained.
Principal Component Ordination and Simulated Vegetational Data
Authors: Noy-Meir I. , Austin M. P.
Published: May 2006

Curvilinear ordinations similar to those of Swan (1970) are obtained by using principal component analysis on the same single—gradient models of vegetation. Any non—linear relationships between species will produce such a result.
Effect of Grass Competition and Depth to Water Table on Height Growth of Coniferous Tree Seedlings
Authors: Sims H. P. , Mueller-Dombois D.
Published: May 2006

Pinus banksiana, P. resinosa, Picea glauca, and P. mariana seedlings were grown in combination with three grasses on a loamy sand and on a sand, each forming a small catena with a controlled water table. A much greater total vegetative production was achieved on the loamy sand than on the sand with equal water supply. The greater production on the loamy sand, however, did not result in greater tree—seedling heights. On the contrary, at optimum depth to water table (where maximum heights had occurred when grown without grasses in an earlier experiment) for seedlings on the loamy sand the grasses grew more vigorously and suppressed the tree seedlings. On the sand, seedling height trends were not significantly altered from those observed without competition in a previous experiment. Characteristics of competition are elucidated in relation to root— and shoot—growth patterns of seedlings.
Surface Activities of Some North American Scorpions in Relation to Feeding
Authors: Hadley Neil F. , Williams Stanley C.
Published: May 2006

Field and laboratory studies were conducted on the nocturnal surface activities any feeding behavior of scorpions, using ultraviolet light. Two species, Vejovis confusus and V. mesaensis, showed a decrease in surface occurrence as the evening progressed, while Centruroides sculpturatus showed a random occupation throughout the night. Increased intensity of moonlight resulted in a significant decrease in surface occurrence in V. confuses and V. mesaensis; C. sculpturatus showed no significant response to increased illumination. Species differences in the amount of surface activity and feeding behavior were noted. Potential prey, food preferences, and mechanisms used in prey detection are also discussed.
Seasonal Pattern of Reproduction of the Sand Crab, Emerita Analoga, in Southern California
Authors: Cox George W. , Dudley Gordon H.
Published: May 2006

Reproductive activity was studied over a 20—month period in a population of the sand crab, Emerita analog, at Whale View Point in La Jolla, California, through collections made at monthly or semimonthly intervals. Marked animals were also observed in tanks containing only females, only males, and both males and females. Males over 5 mm in size were potentially fertile and were present in this population throughout the year. Oviferous females were observed in the field from February (1967) or March (1966) the beginning of September. The failure of isolated females to produce eggs, and the low frequency of oviferous females at Whale View Point in the early spring of 966, when the ratio of fertile males to potentially fertile females was very low, suggested that some stimulus by the male is necessary for egg production. Females of the largest modal size classes showed the highest average frequency of egg carrying and initiated egg production earliest in the season. Laboratory observations showed that egg masses were usually produced soon after molting, and were carried for an average of 22.5 days. Individual females produced up to four consecutive egg masses in the laboratory. In field populations, considerations of the percentage of oviferous females, the length of time eggs were carried, and the duration of the breed season, suggested that the larger females breed repeatedly if conditions are favorable. Production of egg masses in the Whale View Point population was synchronized for individuals within each modal class so that the frequency of oviferous females fluctuated cyclically during the season.
Relationships between Assimiliation Efficiencies and Growth Efficiencies for Aquatic Consumers
Authors: Welch Harold E.
Published: May 2006

Relationships between the growth efficiencies and assimilation efficiency of an animal are presented, using energy budgets compiled from the literature. Net growth efficiency is negatively correlated with assimilation efficiency and may range from 20% to 90%. Gross growth efficiencies normally fluctuate between 15% and 35% and demonstrate a nonlinear correlation with assimilation efficiency. Carnivores tend to have high assimilation efficiencies and low net growth efficiencies; herbivore/detritivores have lower assimilation efficiencies and higher net growth efficiencies. Implications of the relationships are discussed.
Persistence of DDT in Crayfish in a Natural Environment
Authors: Dimond John B. , Kadunce Raymond E. , Getchell A. Stanley , Blease John A.
Published: May 2006

DDT residues were measured by gas chromatography in crayfish collected in streams sprayed a single time but in various past years, in streams sprayed two and three times, and in streams never sprayed. Residues in the year of treatment ranged from 0.5 to 2.5 ppm. By 2 yr after treatment, residues had declined to about 0.1 ppm but remained near this level through 9 yr after treatment. Grayfish in unsprayed streams carries uniformly low residues, 0.009—0.014 ppm. Prolonged contamination in crayfish in sprayed watersheds apparently derives from highly persistent soil residues. Ecological significance of these residue levels is discussed.
An Experimental Investigation of Habitat Selection and Water Loss in Some Anoline Lizards
Authors: Sexton Owen J. , Heatwole Harold
Published: May 2006

The distribution of a forest—dwelling, iguanid lizard, Anolis limifrons, relative to overhead structure was studied in a screened cage with simulated canopy. The lizards did not distribute themselves within the cage relative to overhead configuration per se but to some secondary factor. Simultaneous measurements of water loss and activity were made on aA. limifrons and compared with those made on A. auratus, a grassland form. The latter survived significantly longer than the former. Activity increased rate of loss. When the effect of activity was eliminated, A. limifrons had significantly higher rates of loss than A. auratus (and higher ones than most other lizards which been studied). Vital limit and moisture content at fully hydration were not significantly different between the two species.
An Unusual Chelonian Feeding Niche
Authors: Belkin Daniel A. , Gans Carl
Published: May 2006

The feeding mechanisms of the pelomedusid turtle Podocnemis unifilis include a surface—skimming behavior, termed neustophagia, which permits utilization of fine particulate food associated with the water surface (neuston). This behavior and its mechanics are described.
Mobility in Tribolium Confusum
Authors: McDonald Daniel J.
Published: May 2006

The mobility of adult—flour beetles in their natural environment (a flour medium) was measured for 2 genetic strains and both sexes of Tribolium confusum. (When the sexes were observed separately, the mobility of a mutant and a wild strain did not differ in the males, but in females the mutants were nearly 10 times as mobile as the wild individuals. If males and females of the wild strain are observed together, the mobility of the males appears to approach that of the females.
A Determination of the Caloric Density and Major Body Components of Large Birds
Authors: Brisbin I. Lehr
Published: May 2006

A procedure is described for determining the live—weight caloric density and major body components of large birds by using a series of random homogeneous aliquots of the total biomass. The procedure is illustrated with data from 6 adult mourning doves. Statistical analyses indicate that the procedure described is capable of producing uniform aliquots with respect to the percentage composition of the major body components of water, fat and lean dry weight. In future biomass analyses of large birds, it may be possible to obtain reliable estimates of the live—weight caloric density and major body components by processing 10% or less of the bird's total live weight, providing that the carcass is sufficiently homogenized to produce a series of uniform aliquots. The lean dry biomass of the 6 doves had an average energy content of 5.14kcal/g,and using this figure, an average caloric density of 2.61kcal/g live weight was calculated.
Floating in Hydra Littoralis
Authors: Lomnicki Adam , Slobodkin L. B.
Published: May 2006

Starved or poorly fed Hydra will produce a bubble and float to the surface of the medium. Richly fed Hydra will not. The fraction of Hydra that will float is related to the degree to which they are crowded by other Hydra. Water which has been conditioned by either starved or well—fed Hydra will elicit floating. Excessively crowded animals are less effective in eliciting floating than are less crowded animals. Laboratory populations from which floating animals are periodically removed come to a steady state with approximately one—seventh as many animals as in confined populations with the same food supply. The implication of these phenomena is that Hydra in nature are relatively mobile within a lake. The evolution of the floating mechanism in Hydra does not require group selection, but it does illustrate the danger of an overemphasis on abundance as a criterion of adaptive success.
Influence of Soil Type on the Distribution of Two Closely Related Species of Erigeron
Authors: Mooney H. A.
Published: May 2006

On soils derived from a uniform bedrock two closely related species of Erigeron replace each other elevationally in the White Mountains of California. Populations of the two species occur side—by—side at places at the same elevation but on dissimilar soils because of compensations provided by the interactions of substrate color, temperature, moisture, and chemistry. The altitudinal distribution of the species is controlled by temperature at the upper limits and moisture at the lower.
Vegetation of Saline Areas in Saskatchewan
Authors: Dodd J. D. , Coupland R. T.
Published: May 2006

The vegetation of uncultivated saline soils in the grassland zone of Saskatchewan was examined at 270 sites; in each from two to eight plant communities were recognized. Saline Gleysol soil surrounding the permanently flooded center of depressions is occupied by amphibious species, particularly Scripus paludosus. With decreasing salinity from the wet center to the dry margin of depressions a sequence of vegetation types occurs which are characterized by dominance of Salicornia rubra on Saline Gleyed Regosol soil, Triglochin maritima, Puccinellia airoides, Distlichlis stricta, and Hordeum jubatum on Saline Meadow soil, and Sarcobatus vermiculatus, Muhlenbergia richardsonis, and Agropyron spp. on Saline Calcareous Chernozem soil. Saline Rego Chernozem soil occupies the transition to upland and supports a mixture of upland and salt—tolerant species.
Annual Reproductive Patterns of Lizards from a Bornean Rain Forest
Authors: Inger Robert F. , Greenberg Bernard
Published: May 2006

Males and females of four species of lizards from a Bornean rain forest appear to breed continuously through the year. Testes of these species, Cyrtodactylus malayanus, C. pubisulcus, Draco melanopogon, and Draco quinquefasciatus, produce sperm at all times. Production of eggs by the females shows no seasonal pattern. Females of six other species from the same area also appear to breed continuously. Clutch size in these rain forest species is distinctly smaller than that in lizards from the tropical parts of Asia having strongly marked dry seasons. The continuous reproductive patterns of the rain forest species probably increase interactions between species as temporal isolation is eliminated. Whatever effects these have on their community are not pulse—like, in contrast to the effects of lizards in seasonal climates. Year—round reproduction probably buffers population fluctuations and may be one of the factors contributing to the great diversity of rain forest faunas.
Convexity, Desert Lizards, and Spatial Heterogeneity
Authors: Pianka Eric R.
Published: May 2006

The number of lizard species in the flatland desert habitat is correlated with several different structural attributes of the vegetation. It is shown that both the horizontal and vertical components of spatial heterogeneity are correlated with the number of lizard species. The habits of the twelve component species are considered briefly as they relate to the partitioning of the biotope space. Three species are food specialists, eight display various substrate specificities, and only one species appears to be truly "convex." Two tests of the present interpretation of these results are proposed, and some speculations concerning Australian flatland desert lizards are made.