Numerical Changes and Resource Utilization in Orchard Populations of Drosophila.

1985 ◽  
Vol 33 (6) ◽  
pp. 875 ◽  
Author(s):  
KM Nielsen ◽  
AA Hoffmann
Keyword(s):  
Resource Utilization ◽  
Endemic Species ◽  
Seasonal Changes ◽  
Environmental Variables ◽  
Laboratory Experiments ◽  
Climatic Variables ◽  
Partial Agreement ◽  
Larval Stages

Drosophila were collected monthly at a south-east Australian orchard site over 30 months. D, melanogaster was predominant in spring-summer, D. simulans in autumn, and D. immigrans in winter. These seasonal changes are consistent with trends described in an earlier study by McKenzie and Parsons (1974). Numbers of the endemic species D. lativittata tended to follow those of D. melanogaster. Comparisons of numbers of each species with environmental variables indicate that D. melanogaster is positively correlated, and D. immigrans negatively correlated, with temperature parameters. D. simulans and D. lativittata numbers were independent of all climatic variables tested. These associations are consistent with collections by McKenzie and Parsons (1974) from an orchard site, but not from their suburban sites. The associations of numbers of adults of each species with climatic variables are only in partial agreement with results from laboratory experiments on stress in adults. Sampling within the orchard indicates that D. melanogaster and D. simulans are differentially associated with fruit resources at both adult and larval stages, with D. melanogaster predominating on peach resources.

Consistency of patterns between laboratory experiments and field collected fish in otolith chemistry: an example and applications for salinity reconstructions

2005 ◽  
Vol 56 (5) ◽  
pp. 609 ◽  
Author(s):  
T. S. Elsdon ◽  
B. M. Gillanders
Keyword(s):  
Environmental Variables ◽  
Laboratory Experiments ◽  
Juvenile Fish ◽  
Otolith Chemistry ◽  
Ambient Water ◽  
Elemental Concentrations ◽  
Adequate Knowledge ◽  
Black Bream ◽  
Environmental Histories ◽  
The Relationship

Elemental concentrations within fish otoliths can track movements and migrations of fish through gradients of environmental variables. Tracking the movements of fish relies on establishing links between environmental variables and otolith chemistry, with links commonly made using laboratory experiments that rear juvenile fish. However, laboratory experiments done on juvenile fish may not accurately reflect changes in wild fish, particularly adults. We tested the hypotheses that: (1) the relationship between ambient (water) and otolith chemistry is similar between laboratory-reared black bream (Acanthopagrus butcheri) and wild black bream; and (2) ontogeny does not influence otolith chemistry. Field-collected and laboratory-reared fish showed similar effects of ambient strontium : calcium (Sr : Ca) on otolith Sr : Ca concentrations. However, ambient and otolith barium : calcium concentrations (Ba : Ca) differed slightly between laboratory-reared and field-collected fish. Importantly, fish reared in stable environmental variables showed no influence of ontogeny on Sr : Ca or Ba : Ca concentrations. Natural distributions of ambient Sr : Ca showed no clear relationship to salinity, yet, ambient Ba : Ca was inversely related to salinity. The distribution of ambient Sr : Ca and Ba : Ca in estuaries inhabited by black bream, suggest that these elements can answer different questions regarding environmental histories of fish. Reconstructing salinity histories of black bream using otolith Ba : Ca concentrations seems plausible, if adequate knowledge of Ba : Ca gradients within estuaries is obtained.

scholarly journals Distribution Pattern of Gymnosperms’ Richness in Nepal: Effect of Environmental Constrains along Elevational Gradients

Plants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 625
Author(s):  
Bikram Pandey ◽  
Nirdesh Nepal ◽  
Salina Tripathi ◽  
Kaiwen Pan ◽  
Mohammed A. Dakhil ◽  
...  
Keyword(s):  
Species Richness ◽  
Distribution Pattern ◽  
Species Distribution ◽  
Environmental Variables ◽  
Environmental Indicators ◽  
Climatic Variables ◽  
Elevation Gradients ◽  
Hypothesis Model ◽  
Richness Pattern ◽  
Richness Patterns

Understanding the pattern of species distribution and the underlying mechanism is essential for conservation planning. Several climatic variables determine the species diversity, and the dependency of species on climate motivates ecologists and bio-geographers to explain the richness patterns along with elevation and environmental correlates. We used interpolated elevational distribution data to examine the relative importance of climatic variables in determining the species richness pattern of 26 species of gymnosperms in the longest elevation gradients in the world. Thirteen environmental variables were divided into three predictors set representing each hypothesis model (energy-water, physical-tolerance, and climatic-seasonality); to explain the species richness pattern of gymnosperms along the elevational gradient. We performed generalized linear models and variation partitioning to evaluate the relevant role of environmental variables on species richness patterns. Our findings showed that the gymnosperms’ richness formed a hump-shaped distribution pattern. The individual effect of energy-water predictor set was identified as the primary determinant of species richness. While, the joint effects of energy-water and physical-tolerance predictors have explained highest variations in gymnosperm distribution. The multiple environmental indicators are essential drivers of species distribution and have direct implications in understanding the effect of climate change on the species richness pattern.

scholarly journals Dominant Height Model for Site Classification ofEucalyptus grandisIncorporating Climatic Variables

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
José Roberto Soares Scolforo ◽  
Romualdo Maestri ◽  
Antonio Carlos Ferraz Filho ◽  
José Márcio de Mello ◽  
Antônio Donizette de Oliveira ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Eucalyptus Grandis ◽  
Site Index ◽  
Climatic Variables ◽  
Site Classification ◽  
Monthly Precipitation ◽  
Annual Increment ◽  
Dominant Height ◽  
Mean Annual Increment ◽  
Height Model

This study tested the effects of inserting climatic variables inEucalyptus grandisas covariables of a dominant height model, which for site index classification is usually related to age alone. Dominant height values ranging from 1 to 12 years of age located in the Southeast region of Brazil were used, as well as data from 19 automatic meteorological stations from the area. The Chapman-Richards model was chosen to represent dominant height as a function of age. To include the environmental variables a modifier was included in the asymptote of the model. The asymptote was chosen since this parameter is responsible for the maximum value which the dominant height can reach. Of the four environmental variables most responsible for database variation, the two with the highest correlation to the mean annual increment in dominant height (mean monthly precipitation and temperature) were selected to compose the asymptote modifier. Model validation showed a gain in precision of 33% (reduction of the standard error of estimate) when climatic variables were inserted in the model. Possible applications of the method include the estimation of site capacity in regions lacking any planting history, as well as updating forest inventory data based on past climate regimes.

Relative influence of weather and season on anuran calling activity

2013 ◽  
Vol 91 (7) ◽  
pp. 462-467 ◽  
Author(s):  
David A. Steen ◽  
Christopher J.W. McClure ◽  
Sean P. Graham
Keyword(s):  
Seasonal Changes ◽  
Environmental Variables ◽  
Reproductive Activity ◽  
Environmental Variable ◽  
Relative Influence ◽  
Ephemeral Wetlands ◽  
Temperature And Precipitation ◽  
South Central ◽  
Multiple Hypotheses ◽  
Calling Activity

Drivers of anuran reproductive activity may include multiple and independent environmental variables. To determine the relative influence of season, temperature, and precipitation in initiating frog reproduction, we monitored a species-rich frog assemblage in south-central Alabama for 3 years and modeled calling activity of vocalizing males, who call to attract mates. We evaluated multiple hypotheses potentially explaining calling activity and we were able to identify significant influences of calling activity for all 11 anuran species considered in the analysis. Eight species were significantly influenced by month of survey and four of these were influenced by at least one additional environmental variable. In our study, precipitation was relatively unimportant in influencing calling activity, likely because breeding pools at the site are semipermanent and the species we sampled are not generally reliant on ephemeral wetlands. In general, our data suggest that different species within the same wetlands respond to different cues when initiating reproduction and calling activity is largely based on a combination of both environmental conditions and either seasonal changes or endogenous drivers.

Seasonal Changes in Epipelic Diatoms Along an Intertidal Shore, Berrow Flats, Somerset

1991 ◽  
Vol 71 (3) ◽  
pp. 579-596 ◽  
Author(s):  
Deborah R. Oppenheim
Keyword(s):  
Organic Matter ◽  
Salt Marsh ◽  
Water Content ◽  
Seasonal Changes ◽  
Environmental Variables ◽  
Interstitial Water ◽  
Seasonal Pattern ◽  
Environmental Variable ◽  
Assemblage Structure ◽  
Epipelic Diatoms

Seasonal changes in the assemblage structure of dominant epipelic diatoms were studied along a transect crossing a salt marsh, sandflat, and mudflat of an estuarine intertidal shore at Berrow Flats, Somerset, UK. Seasonal changes in cell numbers displayed different patterns in the salt marsh and sandflat/mudflat. At salt marsh sites highest numbers of individuals were recorded in summer followed by a smaller autumn growth, while in the sandflat lower numbers showed no seasonal pattern. Repeated annual patterns in the succession of taxa were not observed as environmental conditions changed at the study site with time. Measurements of salinity, pH, interstitial water content, air and soil temperature were taken together with the diatom samples. A canonical correspondence analysis was employed to relate seasonal changes in assemblage structure to measured environmental variables. Total percentage variation in the first four axes of the species/site-environmental biplots ranged between 54 and 66°. In winter, sites and species separated most significantly along gradients of salinity and levels of organic matter. In spring and autumn, interstitial water content became a more significant environmental variable. By summer steep gradients in pH, levels of organic matter, and hypersaline conditions separated sites and assemblages into more discrete groups when compared to the more even spread of points in the other seasons. The results indicate that different combinations of environmental variables influence diatom assemblage structure seasonally.

The Toxicity of Malathion, Perthane, Maneb and Zineb to Trialeurodes vaporariorum (Westwood)

1964 ◽  
Vol 96 (3) ◽  
pp. 541-549 ◽  
Author(s):  
R. D. McMullen
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Laboratory Experiments ◽  
Trialeurodes Vaporariorum ◽  
Antagonistic Effects ◽  
Larval Stages ◽  
First Instar ◽  
Wettable Powder

AbstractIn laboratory experiments wettable and emulsifiable malathion and Perthane were most toxic to adult T. vaporariorum and progressively less so to the larval stages in order of development. Eggs were not killed. Perthane was most toxic at low temperatures, malathion at high temperatures. Malathion was more toxic than Perthane and the emulsifiable formulations of both more toxic than the wettable formulations. Against first-instar larvae, at the LD50, level, 70% maneb and 50% Perthane wettable powders were equally toxic but 65% zineb wettable powder was less toxic. Against adults, 70% maneb and 65% zineb wettable powders were one-half and one-third as toxic as 50% Perthane wettable powder at the LD50, level. Tests of spray mixtures against larvae with either 25% malathion or 50% Perthane wettable powders added to either 70% maneb or 65% zineb wettable powders showed neither synergistic nor antagonistic effects.

scholarly journals The correspondence between environmental similarity and geographical sympatry in Uromastyx species

2020 ◽  
Vol 41 (2) ◽  
pp. 245-251
Author(s):  
Marwa Kechnebbou ◽  
Jorge M. Lobo ◽  
Mohsen Chammem
Keyword(s):  
Related Species ◽  
Environmental Variables ◽  
Potential Distribution ◽  
Environmental Gradient ◽  
Climatic Variables ◽  
Geographical Isolation ◽  
Speciation Process ◽  
Environmental Similarity ◽  
Eleven Species

Abstract Estimating the realized and potential distribution of species has become a very active field of research with capacity to propose likely speciation mechanisms. Here, environmental variables and point locality data derived from several sources were used to examine the concordance between geographical distributions and environmental niches derived from occurrences for eleven species of the genus Uromastyx (Reptilia, Agamidae). Our results indicate that the degree of geographical overlap is definitively and statistically lower than the degree of environmental similarity. This reinforces the hypothesis that speciation process within the genus Uromastyx will be mainly based on geographical isolation. However, the environmental divergence among some groups of species cannot be excluded; high environmental distances can be obtained for some related species and the environmental gradient represented by two unique climatic variables allows discriminating some species among which an ecological or environmental segregation would be a plausible explanation.

Reproductive diapause in the Argentine stem weevil, Listronotus bonariensis, (Kuschel) (Coleoptera: Curculionidae), in New Zealand

1981 ◽  
Vol 71 (2) ◽  
pp. 275-287 ◽  
Author(s):  
S. L. Goldson
Keyword(s):  
New Zealand ◽  
Juvenile Hormone ◽  
Body Fat ◽  
Seasonal Changes ◽  
Laboratory Experiments ◽  
Reproductive Activity ◽  
Reproductive Diapause ◽  
Reproductive Morphology ◽  
Critical Photoperiod ◽  
Listronotus Bonariensis

AbstractTo improve the precision of understanding of the phenology of Listronotus bonariensis (Kuschel), samples were collected at regular intervals near Canterbury, New Zealand, and the seasonal changes in their reproductive morphology monitored by regular dissection. It was demonstrated that the adult weevils enter hibernatory reproductive diapause in early March and remain in this state until late July when reproductive activity resumes. Adults emerging in February may enter diapause immediately. The existence of diapause was further supported by its associated cessation of mating, increase in body fat and apparent drop in the haemolymph titre of juvenile hormone. Laboratory experiments indicated that a critical photoperiod induces diapause and an eventual reduction in sensitivity to photoperiod allows reproductive activity to resume.

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