scholarly journals Postponed reproduction as an adaptation to winter conditions in Drosophila melanogaster : evidence for clinal variation under semi-natural conditions

2001 ◽  
Vol 268 (1481) ◽  
pp. 2163-2168 ◽  
Author(s):  
Paul Mitrovski ◽  
Ary A. Hoffmann
Keyword(s):  
Drosophila Melanogaster ◽  
Clinal Variation ◽  
Natural Conditions ◽  
Winter Conditions

scholarly journals GENETIC DIFFERENTIATION BETWEEN GEOGRAPHICALLY DISTANT POPULATIONS OF DROSOPHILA MELANOGASTER

Genetics ◽  
1982 ◽  
Vol 101 (2) ◽  
pp. 235-256
Author(s):  
Rama S Singh ◽  
Donal A Hickey ◽  
Jean David
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Differentiation ◽  
Gene Frequency ◽  
Natural Populations ◽  
Allozyme Variation ◽  
Clinal Variation ◽  
Significant Genetic Differentiation ◽  
African Populations ◽  
Latitudinal Clines ◽  
North And South

ABSTRACT We have studied allozyme variation at 26 gene loci in nine populations of Drosophila melanogaster originating on five different continents. The distant populations show significant genetic differentiation. However, only half of the loci studied have contributed to this differentiation; the other half show identical patterns in all populations. The genetic differentiation in North American, European and African populations is correlated with the major climatic differences between north and south. These differences arise mainly from seven loci that show gene-frequency patterns suggestive of latitudinal clines in allele frequencies. The clinal variation is such that subtropical populations are more heterozygous than temperate populations. These results are discussed in relation to the selectionist and neutralist hypotheses of genetic variation in natural populations.

scholarly journals A Method for the Direct Study of Natural Selection

1939 ◽  
Vol 16 (3) ◽  
pp. 278-285
Author(s):  
CECIL GORDON
Keyword(s):  
Drosophila Melanogaster ◽  
Natural Selection ◽  
Wild Type ◽  
Natural Conditions ◽  
Direct Study ◽  
Recessive Type ◽  
Selection Of

1. Decisive experiments on selection of mutants of Drosophila melanogaster can be carried out under natural conditions in Britain where this species is not indigenous. 2. This communication records an experiment in which a balanced population containing 25% ebony mutants was released in South Devon. 3. The frequency of the genotype among the descendants was estimated after a period equivalent to six discrete generations, by testing trapped flies, most of which were wild type in appearance, for heterozygosis. 4. The frequency estimated was very close to what would be deduced on the assumption that elimination of the recessive type before maturity was complete.

scholarly journals Budbreak Number in Apple Seedlings as Selection Criterion for Improved Adaptability to Mild Winter Climates

HortScience ◽  
2003 ◽  
Vol 38 (6) ◽  
pp. 1186-1190 ◽  
Author(s):  
Iwan F. Labuschagné ◽  
J.H. Louw ◽  
Karin Schmidt ◽  
Annalene Sadie
Keyword(s):  
Environmental Conditions ◽  
Selection Criterion ◽  
Shoot Length ◽  
Natural Conditions ◽  
Mild Winter ◽  
Winter Conditions ◽  
Important Symptom ◽  
Selection For ◽  
Prolonged Dormancy

Absence or long delay of budbreak, also known as prolonged dormancy, is the most important symptom during incomplete dormancy. Budbreak number was evaluated to quantify seedling response to chilling and selection on excised and intact 1-year-old apple (Malus ×domestica Borkh.) seedlings under controlled and natural environmental conditions. Indices based on: 1) the number and distribution of budbreak (prolonged dormancy grade = PDG); 2) the number of buds breaking, including shoot length with increased budbreak as part of the calculation (prolonged dormancy index = PDI); and 3) budbreak number per 100-cm shoot (NB) were tested in association with budbreak time (TB). The indices expressed the effects of cold treatments that induce earlier and higher numbers of budbreak. PDI and NB, but not PDG, identified families with increased budbreak. Seedlings with high PDG and NB were also associated with families in which high chill requiring parents were used, indicating that TB as pre-selection criterion may fail to identify seedlings with increased budbreak. Response to pre-selection for increased budbreak using PDG could be verified with the PDS and NB indices in seedlings and seedling clones. The NB of intact 1-year-old shoots under natural conditions is recommended as a pre-selection criterion against prolonged dormancy in suboptimal winter conditions.

A proline repeat polymorphism of the Frost gene of Drosophila melanogaster showing clinal variation but not associated with cold resistance

2012 ◽  
Vol 21 (4) ◽  
pp. 437-445 ◽  
Author(s):  
A. A. Hoffmann ◽  
M. J. Blacket ◽  
S. W. McKechnie ◽  
L. Rako ◽  
M. Schiffer ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Cold Resistance ◽  
Clinal Variation ◽  
Repeat Polymorphism

scholarly journals Seasonal stability of SARS-CoV-2 in biological fluids

2021 ◽  
Author(s):  
Taeyong Kwon ◽  
Natasha N Gaudreault ◽  
Juergen A Richt
Keyword(s):  
Breast Milk ◽  
Potential Risk ◽  
Half Life ◽  
Close Contact ◽  
Biological Fluids ◽  
Seasonal Pattern ◽  
Climatic Conditions ◽  
Natural Conditions ◽  
Winter Conditions ◽  
Different Types

Transmission of SARS-CoV-2 occurs by close contact with infected persons through droplets, the inhalation of infectious aerosols and the exposure to contaminated surface. Previously, we determined the virus stability on different types of surfaces under indoor and seasonal climatic conditions. SARS-CoV-2 survived the longest on surfaces under winter conditions, followed by spring/fall and summer conditions, suggesting the seasonal pattern of stability on surfaces. However, under natural conditions, the virus is secreted in various biological fluids from infected humans. In this respect, it remains unclear how long the virus survives in various types of biological fluids. This study explored the SARS-CoV-2 stability in human biological fluids under different environmental conditions and estimated the half-life. The virus was stable for up to 21 days in nasal mucus, sputum, saliva, tear, urine, blood, and semen; it remained infectious significantly longer under winter and spring/fall conditions than under summer conditions. In contrast, the virus was only stable up to 24 hours in feces and breast milk. These findings demonstrate the potential risk of infectious biological fluids in SARS-CoV-2 transmission and have implications for its seasonality.

Absence of clinal variation in virgin retention capacity in Australian Drosophila melanogaster

2006 ◽  
Vol 20 (5) ◽  
pp. 407-413 ◽  
Author(s):  
Carla M. Sgrò ◽  
Andréa Magiafoglou ◽  
Laetitia Faine ◽  
Ary A. Hoffmann
Keyword(s):  
Drosophila Melanogaster ◽  
Clinal Variation ◽  
Retention Capacity
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