Influence of habitats, climate, grazing and mining on terrestrial vertebrates at Olympic Dam, South Australia.

1992 ◽  
Vol 14 (2) ◽  
pp. 143 ◽  
Author(s):  
JL Read
Keyword(s):  
Land Use ◽  
Population Size ◽  
Small Mammals ◽  
South Australia ◽  
Terrestrial Vertebrates ◽  
Population Sizes ◽  
Central South ◽  
Heavy Rains ◽  
Capture Rates ◽  
Olympic Dam

Small mammals, reptiles and amphibians were trapped in pitfalls in a range of habitats around the Olympic Dam Operations mine in central South Australia over a five year period (1987-91) to assess the impacts on these groups of climate, mining and grazing. Neobatrachus centralis, a frog, was the most abundant vertebrate in the region but was only recorded after heavy rains. Reptiles were both diverse and abundant in summer samples and in general maintained their population sizes during droughts. Mammals, however, exhibited considerable fluctuations in population size which were associated with climatic cycles. Sites within the mining lease consistently yielded higher species diversities and capture rates of reptiles than sites in pastoral land, but this could not be related directly to land use.

Factors affecting pitfall capture rates of small ground vertebrates in arid South Australia. II. Optimum pitfall trapping effort

2001 ◽  
Vol 28 (1) ◽  
pp. 61 ◽  
Author(s):  
K. E. Moseby ◽  
J. L. Read
Keyword(s):  
Habitat Type ◽  
South Australia ◽  
Trapping Efficiency ◽  
High Rate ◽  
Pitfall Trapping ◽  
Mammal Species ◽  
Terrestrial Vertebrates ◽  
Reptile Species ◽  
Capture Rates ◽  
Olympic Dam

Pitfall trapping is widely used for sampling small terrestrial vertebrates. This study investigated the influence of trapping period, number of trap sites and drift fences on the capture rates of small vertebrates in order to ascertain optimum pitfall trapping efficiency. Capture rates at fenced pits were five times higher than at unfenced pits. Our study indicates that one fenced site established in chenopod shrubland in the Olympic Dam region and trapped for four nights yielded less than one third of the local chenopod shrubland reptile inventory. Capture rates of reptiles at Olympic Dam in arid South Australia were significantly higher on the first three nights of trapping than on the seven subsequent nights. The most efficient number of trap nights for maximising the number of reptile species captured was five nights. Trapping only a single pitfall site per habitat type for 5 nights captured approximately 30% of the reptile species in that habitat compared with 55%, 65% and 73% for three, five and ten sites respectively. Typically, approximately 70% of the reptile species in chenopod shrubland were captured by trapping 5 sites for 7 nights, a method recommended for thorough surveys of species present in chenopod shrublands. Captures of mammals were more variable than those of reptiles and, as a result, sampling of mammal species benefited from more trapping nights than did sampling of reptiles. New mammal species continued to be recorded at a high rate for 8 nights and even 10 sites trapped for 10 nights typically yielded only 60–80% of the species present in chenopod shrubland. Standard 4-night trapping periods adopted by most surveys will fail to detect many rare species, or those that are difficult to trap. Repeated 7-night trapping sessions for up to 21 nights are recommended for surveys where more accurate species inventories are required.

Improved technique for capturing the greater bilby (Macrotis lagotis) using burrow cage traps

2014 ◽  
Vol 36 (2) ◽  
pp. 259 ◽  
Author(s):  
H. M. McGregor ◽  
K. E. Moseby
Keyword(s):  
Cryptic Species ◽  
Capture Rate ◽  
South Australia ◽  
Entire Population ◽  
Improved Method ◽  
Improved Technique ◽  
Central South ◽  
Very High ◽  
Capture Rates

The greater bilby (Macrotis lagotis) is generally trap shy and uninterested in baits, therefore difficult to capture. In order to capture an entire population of bilbies in the Arid Recovery Reserve of central South Australia, we developed an improved method of using burrow cage traps. Traps were set to engulf the entrance of the burrow and the base was camouflaged with sand. We obtained a very high capture rate (6% overall, and 73% for confirmed burrows). Assuming that occupied burrows can be detected, this method should improve capture rates for this endangered and cryptic species.

scholarly journals Effect of Pheromone Blend Components, Sex Ratio, and Population Size on the Mating of Cadra cautella (Lepidoptera: Pyralidae)

2020 ◽  
Vol 20 (6) ◽  
Author(s):  
Abeysinghe Mudiyanselage Prabodha Sammani ◽  
Dissanayaka Mudiyanselage Saman Kumara Dissanayaka ◽  
Leanage Kanaka Wolly Wijayaratne ◽  
William Robert Morrison
Keyword(s):  
Sex Ratio ◽  
Population Size ◽  
Management Practices ◽  
Mating Disruption ◽  
Current Knowledge ◽  
Mating Status ◽  
Cadra Cautella ◽  
Synthetic Chemicals ◽  
Population Sizes ◽  
Lepidoptera Pyralidae

Abstract The almond moth Cadra cautella (Walker), a key pest of storage facilities, is difficult to manage using synthetic chemicals. Pheromone-based management methods remain a high priority due to advantages over conventional management practices, which typically use insecticides. Cadra cautella females release a blend of pheromone including (Z, E)-9,12-tetradecadienyl acetate (ZETA) and (Z)-9-tetradecadien-1-yl acetate (ZTA). The effect of these components on mating of C. cautella and how response varies with the population density and sex ratio remain unknown. In this study, the mating status of C. cautella was studied inside mating cages under different ratios of ZETA and ZTA diluted in hexane and at different population sizes either with equal or unequal sex ratio. The lowest percentage of mated females (highest mating disruption [MD] effects), corresponding to roughly 12.5%, was produced by a 5:1 and 3.3:1 ratio of ZETA:ZTA. Populations with equal sex ratio showed the lowest percentage of mated females, at 20% and 12.5% under lower and higher density, respectively. The next lowest percentage of mated females was produced when the sex ratio was set to 1: 2 and 2:1 male:female, with just 25% and 22.5% of moths mated, respectively. This study shows that mating status of C. cautella is influenced by ZETA:ZTA ratio, sex ratio, and population size. This current knowledge would have useful implications for mating disruption programs.

scholarly journals EFFECTS OF POPULATION SIZE AND SELECTION INTENSITY ON SHORT-TERM RESPONSE TO SELECTION FOR POSTWEANING GAIN IN MICE

Genetics ◽  
1973 ◽  
Vol 73 (3) ◽  
pp. 513-530
Author(s):  
J P Hanrahan ◽  
E J Eisen ◽  
J E Legates
Keyword(s):  
Population Size ◽  
Selection Response ◽  
Selection Intensity ◽  
Realized Heritability ◽  
Family Selection ◽  
Effective Population ◽  
Population Sizes ◽  
Selection For ◽  
Selection Intensities ◽  
Term Response

ABSTRACT The effects of population size and selection intensity on the mean response was examined after 14 generations of within full-sib family selection for postweaning gain in mice. Population sizes of 1, 2, 4, 8 and 16 pair matings were each evaluated at selection intensities of 100% (control), 50% and 25% in a replicated experiment. Selection response per generation increased as selection intensity increased. Selection response and realized heritability tended to increase with increasing population size. Replicate variability in realized heritability was large at population sizes of 1, 2 and 4 pairs. Genetic drift was implicated as the primary factor causing the reduced response and lowered repeatability at the smaller population sizes. Lines with intended effective population sizes of 62 yielded larger selection responses per unit selection differential than lines with effective population sizes of 30 or less.

Estimation of Catchabilities and Population Sizes of Lobsters

1963 ◽  
Vol 20 (1) ◽  
pp. 59-88 ◽  
Author(s):  
J. E. Paloheimo
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Atlantic Coast ◽  
Temperature Data ◽  
New Method ◽  
Bottom Temperature ◽  
Population Size Estimates ◽  
Population Sizes ◽  
Estimate Population Size ◽  
Size Estimates

Techniques of estimating population size, level of fishing, and the degree of dependence of fishing success on environmental factors are examined on the basis of tagging, catch and effort data. A new method is developed to estimate population size from catch, effort, and temperature data when the catchability varies with temperature.The methods of estimation discussed are applied to data collected from a number of lobster fisheries on Canada's Atlantic coast. Analysis confirms a relationship between the catchability of lobsters and bottom temperature. Differences in this relationship are found between areas and between tagged and untagged lobsters within areas. It is suggested that these differences are attributable to the differences in densities as well as to aggregations of lobsters and fishing. The effect of these aggregations on population size estimates is considered.Calculated average catchabilities at comparable temperatures are different for different areas. These differences are correlated with the numbers of trap hauls per day per square miles fished. It is suggested that the differences in the catchabilities might be due to interactions between units of gear not predicted by the customary relationship between catch and effort.

scholarly journals Macroeconomic Impacts of Climate Change Driven by Changes in Crop Yields

2018 ◽  
Vol 10 (10) ◽  
pp. 3673 ◽  
Author(s):  
Shinichiro Fujimori ◽  
Toshichika Iizumi ◽  
Tomoko Hasegawa ◽  
Jun’ya Takakura ◽  
Kiyoshi Takahashi ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Population Size ◽  
Large Population ◽  
Food Prices ◽  
Production Volume ◽  
Total Uncertainty ◽  
Indicator Value ◽  
Macroeconomic Impacts ◽  
Macroeconomic Indicator

Changes in agricultural yields due to climate change will affect land use, agricultural production volume, and food prices as well as macroeconomic indicators, such as GDP, which is important as it enables one to compare climate change impacts across multiple sectors. This study considered five key uncertainty factors and estimated macroeconomic impacts due to crop yield changes using a novel integrated assessment framework. The five factors are (1) land-use change (or yield aggregation method based on spatially explicit information), (2) the amplitude of the CO2 fertilization effect, (3) the use of different climate models, (4) socioeconomic assumptions and (5) the level of mitigation stringency. We found that their global impacts on the macroeconomic indicator value were 0.02–0.06% of GDP in 2100. However, the impacts on the agricultural sector varied greatly by socioeconomic assumption. The relative contributions of these factors to the total uncertainty in the projected macroeconomic indicator value were greater in a pessimistic world scenario characterized by a large population size, low income, and low yield development than in an optimistic scenario characterized by a small population size, high income, and high yield development (0.00%).

scholarly journals DO LANGUAGE CHANGE RATES DEPEND ON POPULATION SIZE?

2008 ◽  
Vol 11 (03) ◽  
pp. 357-369 ◽  
Author(s):  
SØREN WICHMANN ◽  
DIETRICH STAUFFER ◽  
CHRISTIAN SCHULZE ◽  
ERIC W. HOLMAN
Keyword(s):  
Population Size ◽  
Computer Simulations ◽  
Empirical Data ◽  
Language Change ◽  
Strong Dependence ◽  
Language Model ◽  
Population Sizes

An earlier study [24] concluded, based on computer simulations and some inferences from empirical data, that languages will change the more slowly the larger the population gets. We replicate this study using a more complete language model for simulations (the Schulze model combined with a Barabási–Albert network) and a richer empirical dataset [12]. Our simulations show either a negligible or a strong dependence of language change on population sizes, depending on the parameter settings; while empirical data, like some of the simulations, show a negligible dependence.

scholarly journals Polygenic local adaptation in metapopulations: a stochastic eco-evolutionary model

2020 ◽  
Author(s):  
Enikő Szép ◽  
Himani Sachdeva ◽  
Nick Barton
Keyword(s):  
Population Size ◽  
Local Adaptation ◽  
Genetic Drift ◽  
Diffusion Approximation ◽  
Joint Distribution ◽  
Evolutionary Model ◽  
Ecological Niches ◽  
Demographic Stochasticity ◽  
Linkage Disequilibria ◽  
Population Sizes

AbstractThis paper analyses the conditions for local adaptation in a metapopulation with infinitely many islands under a model of hard selection, where population size depends on local fitness. Each island belongs to one of two distinct ecological niches or habitats. Fitness is influenced by an additive trait which is under habitat-dependent directional selection. Our analysis is based on the diffusion approximation and accounts for both genetic drift and demographic stochasticity. By neglecting linkage disequilibria, it yields the joint distribution of allele frequencies and population size on each island. We find that under hard selection, the conditions for local adaptation in a rare habitat are more restrictive for more polygenic traits: even moderate migration load per locus at very many loci is sufficient for population sizes to decline. This further reduces the efficacy of selection at individual loci due to increased drift and because smaller populations are more prone to swamping due to migration, causing a positive feedback between increasing maladaptation and declining population sizes. Our analysis also highlights the importance of demographic stochasticity, which exacerbates the decline in numbers of maladapted populations, leading to population collapse in the rare habitat at significantly lower migration than predicted by deterministic arguments.

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