Seasonal variation in numbers of the rabbit flea on the wild rabbit

Parasitology ◽  
1975 ◽  
Vol 70 (1) ◽  
pp. 103-118 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan ◽  
B. D. Rennison
Keyword(s):  
Seasonal Variation ◽  
Population Size ◽  
Wild Rabbit ◽  
Breeding Performance ◽  
Reproductive Condition ◽  
Juvenile Mortality ◽  
Relationship Of ◽  
Host Behaviour ◽  
The Relationship ◽  
Size And Structure

Samples of rabbits were obtained throughout each month over the 4-year period 1967–70. All fleas were removed, sexed and counted and the reproductive condition of the rabbits recorded. Rabbit fleas Spilopsyllus cuniculi (Dale) were present on both sexes of rabbit at all times of the year. In each year significantly high numbers of fleas were found on the rabbits in January, February, March and April and significantly low numbers in August, September and October. Mean flea counts were significantly higher on female rabbits than on males during April, May and June. During the rest of the year counts from each sex of host did not differ significantly. There were significant differences in flea numbers between years. More female than male fleas were found on both sexes of host throughout the year. The rabbit population sampled is shown to be typical of post-myxomatosis populations with regard to breeding performance and juvenile mortality. The relationship of the observed patterns of change in flea numbers to host and flea breeding and to host behaviour, population size and structure is discussed.

Study on Population-Farmland-Settlement in West Hainan at Town Scale

2013 ◽  
Vol 726-731 ◽  
pp. 4823-4826 ◽  
Author(s):  
Tie Chou Shi ◽  
Xiao Hong Xu
Keyword(s):  
Population Size ◽  
Correlation Coefficient ◽  
Research Area ◽  
Moderate Correlation ◽  
Settlement Area ◽  
Low Correlation ◽  
Relationship Of ◽  
The Relationship

The paper chooses West Hainan (Dongfang city and Changjiang county) as the research area, takes the towns as the unit, and analyses the change and relationship of population-farmland-settlement from 1950s to 1970s. The research shows that the correlation coefficient of population size and farmland area is 0.313 in 1950s and 0.417 in 1970s in West Hainans 29 towns, the two belong to low correlation, population and farmland have smaller relationship; the correlation coefficient of farmland area and settlement area is 0.454 in 1950s and 0.598 in 1970s, the two belong to moderate correlation, farmland and settlement have substantive relationship; the correlation coefficient of population size and settlement area is 0.794 in 1950s and 0.710 in 1970s, the two belong to high correlation, the relationship between the population and the settlement is very close.

scholarly journals Effect of Seasonal Variation on the Relationship of Indoor Air Particulate Matter with Measures of Obesity and Blood Pressure in Children

2021 ◽  
Vol 11 (30) ◽  
Author(s):  
Anye Chungag ◽  
Godwill Azeh Engwa ◽  
Constance Rufaro Sewani-Rusike ◽  
Benedicta Ngwenchi Nkeh-Chungag
Keyword(s):  
South Africa ◽  
Blood Pressure ◽  
Particulate Matter ◽  
Seasonal Variation ◽  
Indoor Air ◽  
Rural Areas ◽  
Urban Areas ◽  
Prevalence Of Obesity ◽  
Relationship Of ◽  
The Relationship

Background. Particulate matter (PM) air pollution is an important environmental health risk factor. Although some studies have shown PM to be associated with obesity and hypertension, very few studies have assessed the association of indoor PM specifically with obesity and blood pressure measures in children with respect to seasonal variation. Objectives. The present study investigated the relationship of PM with obesity and blood pressure variables in children across the winter and summer seasons. Methods. A comparative descriptive approach was adopted and school children from 10–14 years of age from selected rural and urban localities of the Eastern Cape Province of South Africa were assessed in winter and summer. Anthropometric measurements were taken, including height, weight, waist circumference, body mass index (BMI), and total fat mass (TFM), while blood pressure variables including systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured. Indoor air PM concentrations were measured in the classrooms in the presence of children. Results. The prevalence of obesity and hypertension in children were 13.4% and 5.1% in winter and 12.9% and 1.0% in summer, respectively. High blood pressure was more prevalent in children in rural areas, while the prevalence of obesity in children was higher in urban areas. Particulate matter was significantly (p<0.05) higher in rural areas compared to urban areas. Obese children in summer had a greater than 3-fold association (AOR: 3.681, p=0.005) with 4th interquartile range (IQR) of PM5 and a greater than 3- and 4-fold association (AOR: 3.08; 4.407; p<0.05) with 2nd and 4th IQR of PM10, respectively, than their overweight, normal weight or underweight counterparts. High blood pressure was not associated (p< 0.05) with PM. Conclusions. High concentrations of indoor PM were positively associated with obesity in children in summer, particularly among rural children. This association could be accounted for by location and seasonal differences. Participant Consent. Obtained Ethics Approval. Ethics approval was obtained from the Health Sciences Ethics Committee of Walter Sisulu University, South Africa (Ref No: CHI011SCHU01). Competing Interests. The authors declare no competing financial interests.

Seasonal, inverse cycling of length- and age-at-recruitment in the diadromous gobies Sicydium punctatum and Sicydium antillarum in Dominica, West Indies

1995 ◽  
Vol 52 (7) ◽  
pp. 1535-1545 ◽  
Author(s):  
Kim N. I. Bell ◽  
Joseph A. Brown ◽  
Pierre Pepin
Keyword(s):  
Growth Rate ◽  
Seasonal Variation ◽  
Field Study ◽  
West Indies ◽  
Temporal Pattern ◽  
Fresh Waters ◽  
Relationship Of ◽  
The Relationship

We report on an 18-month field study of temporal pattern and interrelationships of size- and age-at-recruitment (to fresh waters) for two diadromous hill-stream gobies in Dominica, West Indies (15°30′N, 61°25′W). Recruitment is panseasonal in Sicydium punctatum and Sicydium antillarum and supports a directed fishery similar to other goby fry fisheries. We found both size and age of recruits to vary seasonally, but the relationship of size to age is complex. Although positively related within lunar-monthly recruiting cohorts, the overall relationship of size and age was poor because seasonal variation in size is out of phase with age. Among recruiting cohorts, mean (or predicted) size and age are negatively correlated. Recruitment (fishery yield) also varies seasonally, in phase with size and out of phase with age. Peak fishery yields coincide with the youngest, but largest, recruits; low yields coincide with the reverse, implicating growth rate variations in fishery yield. This is the first such report of systematic seasonal variation in age-at-recruitment. Given these findings, size- and age-at-recruitment (here similar to settlement or metamorphosis) should not be assumed invariant, even for tropical fishes.

Small towns and urban centers: The relationship of distance and population size to community satisfaction

2019 ◽  
Vol 50 (4) ◽  
pp. 389-405
Author(s):  
Matthew L. McKnight ◽  
Benjamin G. Gibbs ◽  
Scott R. Sanders ◽  
Michael R. Cope ◽  
Jorden E. Jackson ◽  
...  
Keyword(s):  
Population Size ◽  
Small Towns ◽  
Community Satisfaction ◽  
Urban Centers ◽  
Relationship Of ◽  
The Relationship

Structure and organization of an avian haemosporidian assemblage in a Neotropical savanna in Brazil

Parasitology ◽  
2012 ◽  
Vol 140 (2) ◽  
pp. 181-192 ◽  
Author(s):  
ALAN FECCHIO ◽  
MARCOS ROBALINHO LIMA ◽  
MARIA SVENSSON-COELHO ◽  
MIGUEL ÂNGELO MARINI ◽  
ROBERT E. RICKLEFS
Keyword(s):  
Life History Traits ◽  
Bird Species ◽  
Bird Community ◽  
Central Brazil ◽  
Avian Haemosporidians ◽  
Differential Exposure ◽  
Relationship Of ◽  
Host Behaviour ◽  
The Relationship ◽  
Nest Type

SUMMARYStudies on avian haemosporidia are on the rise, but we still lack a basic understanding of how ecological and evolutionary factors mold the distributions of haemosporidia among species in the same bird community. We studied the structure and organization of a local avian haemosporidian assemblage (genera Plasmodium and Haemoproteus) in the Cerrado biome of Central Brazil for 5 years. We obtained 790 blood samples from 54 bird species of which 166 (21%) were infected with haemosporidians based on molecular diagnostics. Partial sequences of the parasite cytochrome b gene revealed 18 differentiated avian haemosporidian lineages. We also analysed the relationship of life-history traits (i.e., nesting height, migration status, nest type, sociality, body mass, and embryo development period) of the 14 most abundant bird species with the prevalence of avian haemosporidia. It was found that host species that bred socially presented a higher prevalence of Haemoproteus (Parahaemoproteus) than bird species that bred in pairs. Thus, aspects of host behaviour could be responsible for differential exposure to vectors. The assemblage of avian haemosporidia studied here also confirms a pattern that is emerging in recent studies using molecular markers to identify avian haemosporidians, namely that many lineages are host generalists.

The relationship of the scleractinian corals to the rugose corals

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver
Keyword(s):  
Critical Points ◽  
Scleractinian Corals ◽  
Convincing Evidence ◽  
Early Triassic ◽  
Rugose Corals ◽  
History Of ◽  
The Subject ◽  
Relationship Of ◽  
The Relationship ◽  
Biologic Factors

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Studies on Leukemogenic and Sarcomagenic Viruses

1970 ◽  
Vol 28 ◽  
pp. 156-157
Author(s):  
Leon Dmochowski
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Morphological Properties ◽  
Mode Of Development ◽  
Relationship Of ◽  
The Relationship

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.

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