Morphology, population size and environmental factors of two morphotypes in Euglena geniculata (Euglenophyceae) in Korea

1998 ◽  
Vol 91 ◽  
pp. 27-36
Author(s):  
Jun Tae Kim ◽  
Sung Min Boo
Keyword(s):  
Environmental Factors ◽  
Population Size

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 Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic

2009 ◽  
Vol 67 (2) ◽  
pp. 304-315 ◽  
Author(s):  
Becky Sjare ◽  
Garry B. Stenson
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Sexual Maturity ◽  
Reproductive Parameters ◽  
Northwest Atlantic ◽  
Pagophilus Groenlandicus ◽  
Long Term Trends ◽  
The Mean ◽  
The 1950S

Abstract Sjare, B., and Stenson, G. B. 2010. Changes in the reproductive parameters of female harp seals (Pagophilus groenlandicus) in the Northwest Atlantic. – ICES Journal of Marine Science, 67: 304–315. Changes in female harp seal (Pagophilus groenlandicus) reproductive parameters from 1980 to 2004, and long-term trends since the early 1950s, are evaluated. Estimates of the total number of seals in the Northwest Atlantic declined from ∼3.0 million in the 1950s to 1.8 million in the early 1970s, then increased steadily to 5.5 million in 1996, at which relatively stable level it has remained since. Pregnancy rates increased from ∼86% in the 1950s to a high of 98% in the mid-1960s, then declined to ∼65–70% by the early 1990s; the rate then varied between 45 and 70% from 2000 to 2004. Concurrently, the mean age at sexual maturity decreased from 5.8 (s.e = 0.02) years in the mid-1950s to 4.1 (s.e. = 0.02) in the late 1970s, increased to 5.5 (s.e. = 0.03) years by the early 1990s, and peaked at 5.7 (s.e. = 0.01) in 1995. From 2000 to 2004, mean age varied from 4.9 (s.e. = 0.01) to 6.0 (s.e. = 0.01) years. Although the direction of change in each of the parameters was consistent with a density-dependent response, changes in population size explained relatively little of the variability observed, suggesting that other ecological or environmental factors were influential.

scholarly journals Ukuran Populasi Koloni dan Daya Jelajah Rayap Coptotermes Curvignathus Holmgren di Pertanaman Pala di Kecamatan Meukek Kabupaten Aceh Selatan

2017 ◽  
Vol 2 (1) ◽  
pp. 1-10
Author(s):  
Fachrizal Yusmar ◽  
Muhammad Sayuthi ◽  
Alfian Rusdy
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Nile Blue ◽  
Neutral Red ◽  
Mark Recapture ◽  
Nile Blue A ◽  
The World ◽  
Termite Attack

Abstrak. Pala (M. fragans) merupakan salah satu komoditas rempah unggulan yang bernilai tinggi, sebagaimana Indonesia menjadi salah satu produsen terbesar di dunia (70 – 75 %). Saat ini dalam membudidayakan tanaman pala, petani mengalami kendala yang salah satunya disebabkan oleh serangan rayap. Penelitian ini bertujuan untuk mengetahui ukuran populasi koloni dan daya jelajah rayap C. curvignathus pada tanaman pala (M. fragans) di kecamatan Meukek dengan menggunakan teknik triple mark recapture. Rayap C. curvignathus dikoleksi dari pertanaman pala (M. fragans) yang ditentukan dalam enam blok (I, II, III, IV, V, VI). Koleksi rayap diwarnai dengan neutral red 0,25% dan nile blue A 0,05% di laboratorium . Hasil pengamatan menunjukan bahwa Total ukuran populasi koloni sebesar 347719.06 individu dari 23 koloni yang tersebar dalam luas areal 7325 m². Rata-rata daya jelajah maksimum Rayap C. curvignathus sejauh 35 m yang diduga pengaruh dari beberapa faktor lingkungan terutama makanan (mengandung selulosa) yang tersedia sangat terbatas.Abstract. Nutmeg (M. Fragans) is one of commodity of superior spices which has high value, as Indonesia became one of the largest manufacturers in the world (70-75%).  Currently in cultivate a nutmeg crop, farmers faced some obstacles and termite attack is one of causes. The purpose of this research is to know the population size of colony and cruising termites C.Curvignathus on nutmeg crop (M. Fragans) in Meukek, South Aceh by using triple mark recapture technique. Termites C. Curvignathus collected from nutmeg crop (M. Fragans) which determined in six block (I, II, III, IV, V, and VI), the termites collection colored with neutral red 0.25% and nile blue A 0.05% in laboratory. The result of observation shows that total of population size of colony is 347.719,06 individual from 23 colonies scattered in the area of 7.325 m2.  The average of cruising termites C.Curnignathus as far as 35 m that suspected influence of some environmental factors especially a food (containing cellulose) very limited available.

scholarly journals The empirical case against the ‘demographic turn’ in Palaeolithic archaeology

2016 ◽  
Vol 371 (1698) ◽  
pp. 20150242 ◽  
Author(s):  
Mark Collard ◽  
Krist Vaesen ◽  
Richard Cosgrove ◽  
Wil Roebroeks
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Human Evolution ◽  
Archaeological Record ◽  
Cultural Complexity ◽  
Hunter Gatherers ◽  
Major Transitions ◽  
Archaeological Data ◽  
Competing Hypotheses ◽  
Palaeolithic Archaeology

Recently, it has become commonplace to interpret major transitions and other patterns in the Palaeolithic archaeological record in terms of population size. Increases in cultural complexity are claimed to result from increases in population size; decreases in cultural complexity are suggested to be due to decreases in population size; and periods of no change are attributed to low numbers or frequent extirpation. In this paper, we argue that this approach is not defensible. We show that the available empirical evidence does not support the idea that cultural complexity in hunter–gatherers is governed by population size. Instead, ethnographic and archaeological data suggest that hunter–gatherer cultural complexity is most strongly influenced by environmental factors. Because all hominins were hunter–gatherers until the Holocene, this means using population size to interpret patterns in the Palaeolithic archaeological record is problematic. In future, the population size hypothesis should be viewed as one of several competing hypotheses and its predictions formally tested alongside those of its competitors. This article is part of the themed issue ‘Major transitions in human evolution’.

scholarly journals Seasonal variation in environmental DNA in relation to population size and environmental factors

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Andrew S. Buxton ◽  
Jim J. Groombridge ◽  
Nurulhuda B. Zakaria ◽  
Richard A. Griffiths
Keyword(s):  
Seasonal Variation ◽  
Environmental Factors ◽  
Population Size ◽  
Environmental Dna

3. Populations

2020 ◽  
pp. 30-47
Author(s):  
Jaboury Ghazoul
Keyword(s):  
Environmental Factors ◽  
Population Size ◽  
Carrying Capacity ◽  
Population Control ◽  
Insect Population ◽  
Trade Offs ◽  
Population Outbreaks ◽  
Persuasive Argument ◽  
Dependent Processes ◽  
Available Resources

‘Populations’ considers the factors behind animal, plant, and insect population outbreaks. Influenced by weather and food, population outbreaks fast exceed available resources and populations crash. It is difficult to determine whether predators control the prey population or vice versa. Competition is a more persuasive argument for population control, acting through density-dependent processes. Carrying capacity is the population size that can be maintained given available resources, which might well be affected by environmental factors. Ecologists define two types of species—r species which reproduce early and produce many offspring, and k species which inhabit more tranquil environments. The picture is complicated by life trade-offs between two variables, such as reproduction and growth or survival.

scholarly journals Environmental factors and public health policy associated with human and rodent infection by leptospirosis: a land cover-based study in Nan province, Thailand

2015 ◽  
Vol 144 (7) ◽  
pp. 1550-1562 ◽  
Author(s):  
P. DELLA ROSSA ◽  
K. TANTRAKARNAPA ◽  
D. SUTDAN ◽  
K. KASETSINSOMBAT ◽  
J.-F. COSSON ◽  
...  
Keyword(s):  
Public Health ◽  
Land Use ◽  
Environmental Factors ◽  
Population Size ◽  
Forest Cover ◽  
Geographical Information ◽  
Health Campaigns ◽  
Sloping Ground ◽  
Public Health Campaigns

SUMMARYLeptospirosis incidence has increased markedly since 1995 in Thailand, with the eastern and northern parts being the most affected regions, particularly during flooding events. Here, we attempt to overview the evolution of human prevalence during the past decade and identify the environmental factors that correlate with the incidence of leptospirosis and the clinical incidence in humans. We used an extensive survey of Leptospira infection in rodents conducted in 2008 and 2009 and the human incidence of the disease from 2003 to 2012 in 168 villages of two districts of Nan province in Northern Thailand. Using an ad-hoc developed land-use cover implemented in a geographical information system we showed that humans and rodents were not infected in the same environment/habitat in the land-use cover. High village prevalence was observed in open habitat near rivers for the whole decade, or in 2008–2009 mostly in rice fields prone to flooding, whereas infected rodents (2008–2009) were observed in patchy habitat with high forest cover, mostly situated on sloping ground areas. We also investigated the potential effects of public health campaigns conducted after the dramatic flood event of 2006. We showed that, before 2006, human incidence in villages was explained by the population size of the village according to the environmental source of infection of this disease, while as a result of the campaigns, human incidence in villages after 2006 appeared independent of their population size. This study confirms the role of the environment and particularly land use, in the transmission of bacteria, emphasized by the effects of the provincial public health campaigns on the epidemiological pattern of incidence, and questions the role of rodents as reservoirs.

scholarly journals Genomic signatures of drift and selection driven by predation and human pressure in an insular lizard

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marta Bassitta ◽  
Richard P. Brown ◽  
Ana Pérez-Cembranos ◽  
Valentín Pérez-Mellado ◽  
José A. Castro ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Environmental Factors ◽  
Population Size ◽  
Genetic Drift ◽  
Explanatory Power ◽  
Human Pressure ◽  
Podarcis Lilfordi ◽  
Genomic Divergence ◽  
The Impact

AbstractGenomic divergence was studied in 10 small insular populations of the endangered Balearic Islands lizard (Podarcis lilfordi) using double digest restriction-site associated DNA sequencing. The objectives were to establish levels of divergence among populations, investigate the impact of population size on genetic variability and to evaluate the role of different environmental factors on local adaptation. Analyses of 72,846 SNPs supported a highly differentiated genetic structure, being the populations with the lowest population size (Porros, Foradada and Esclatasang islets) the most divergent, indicative of greater genetic drift. Outlier tests identified ~ 2% of loci as candidates for selection. Genomic divergence-Enviroment Association analyses were performed using redundancy analyses based on SNPs putatively under selection, detecting predation and human pressure as the environmental variables with the greatest explanatory power. Geographical distributions of populations and environmental factors appear to be fundamental drivers of divergence. These results support the combined role of genetic drift and divergent selection in shaping the genetic structure of these endemic island lizard populations.

The influence of food resources on population dynamics in Columbian ground squirrels

1985 ◽  
Vol 63 (9) ◽  
pp. 2095-2104 ◽  
Author(s):  
F. Stephen Dobson ◽  
Julia D. Kjelgaard
Keyword(s):  
Population Dynamics ◽  
Environmental Factors ◽  
Population Size ◽  
Ground Squirrel ◽  
Food Resources ◽  
Ground Squirrels ◽  
Limiting Factors ◽  
Supplemental Food ◽  
Survival And Reproduction ◽  
Population Processes

Determining the environmental factors that limit the size of populations and examining the influence of environmental factors on population processes (immigration, emigration, survival, and reproduction) are fundamental problems for population ecologists. We conducted an experimental study of population dynamics in the Columbian ground squirrel, Spermophilus columbianus, from 1981 to 1983, in southwestern Alberta, Canada. We supplemented the food resources of two local populations of ground squirrels at different elevations and also monitored two reference (unsupplemented) populations. Population size increased by about 85% annually and population biomass increased by about 94% annually where supplemental food was provided. Reference populations varied in numbers and biomass by less than 40% annually. Because the increase in size of supplemented populations was dramatic, we concluded that food resources probably limited the size of the ground squirrel populations before we began the experiments and that other possible limiting factors were insufficient to check the increases stimulated by supplemental food. Several population processes were influenced by the increased food resources. Immigration of all age-classes was higher to supplemented than to reference populations and favored females. Survival of resident young was higher in supplemented than in reference populations. Reproduction was greatly increased in supplemented populations compared with reference populations, with surviving young residents of 1982 making the greatest contribution to increases in population size. The results were generally similar in the two replicates of the experiment. Competition for food resources appeared to be strongest among yearling and adult females and among young of both sexes.

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