Seasonal Variation in Sex Ratio for Gray Bats (Myotis grisescens) at a Hibernaculum

2020 ◽  
Vol 27 (4) ◽  
Author(s):  
Dana M. Green ◽  
Lynn W. Robbins
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Myotis Grisescens

scholarly journals Seasonal variation in the sex ratio of Arctodiaptomus salinus (Copepoda: Calanoida): does it agree with the “cheaper-sex” hypothesis?

2014 ◽  
Vol 36 (6) ◽  
pp. 1413-1418 ◽  
Author(s):  
Raquel Jiménez-Melero ◽  
Juan Diego Gilbert ◽  
Francisco Guerrero
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio

Seasonal Variation of Sex Ratio in Bemisia tabaci on Cotton in Israel

1992 ◽  
Vol 21 (3) ◽  
pp. 556-559 ◽  
Author(s):  
A. R. Horowitz ◽  
D. Gerling
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Bemisia Tabaci

scholarly journals Seasonal variations of childhood Guillain-Barre Syndrome in South west Iran

2018 ◽  
Vol 60 (2) ◽  
pp. 108-112
Author(s):  
Ali A. Momen ◽  
Abdolhussein Shakurnia ◽  
Mahsa Sarrami
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Seasonal Variations ◽  
Acute Flaccid Paralysis ◽  
Guillain Barre Syndrome ◽  
Khuzestan Province ◽  
South West ◽  
Guillain Barré Syndrome ◽  
Different Seasons ◽  
Guillain Barré

Background: It was found that the occurrence of Guillain-Barre Syndrome (GBS) varies in respect tothe month and season; this variation has not been adequately studied.Objective: To determine the month and seasonal variation of GBS in children in the Khuzestanprovince, south west Iran, during a 10-year period (2006-2015).Patients and methods: We extracted data retrospectively from acute flaccid paralysis committeefrom healthcare centers in all cities of the province, over a 10-year period (from January 1, 2006 toDecember 31, 2015). In this study all children under 15 years of age with Guillain-Barre syndromewere surveyed. In order to compare the frequency of GBS in different seasons and months we used theChi Square test.Results: From 187 cases of GBS, 101 (54%) were males, 86 (46%) females with sex ratio 1.17:1. Themean age of the children was 5.39 ± 4.02 years. The highest occurrence of GBS was observed inautumn (32.1%) followed by winter (27.3%). The highest number of cases (28; 15%) occurred inDecember and the lowest (8; 4.3%) in September. There was seasonal (P=0.006) and monthly(P=0.036) variation in occurrence of GBS throughout the year with more prevalence in autumn ,September and December.Conclusion: Our study showed that there is a significant monthly and seasonal variation in childrenwith GBS in Khuzestan province.

scholarly journals Ecology of Phallotorynus pankalos (Cyprinodontiformes: Poeciliidae) in a first-order stream of the upper Paraná Basin

2009 ◽  
Vol 7 (1) ◽  
pp. 49-54 ◽  
Author(s):  
Yzel R. Súarez ◽  
João Paulo da Silva ◽  
Lilian P. Vasconcelos ◽  
William Fernando Antonialli-Júnior
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Population Ecology ◽  
Female Mortality ◽  
Order Stream ◽  
Female Population ◽  
First Order ◽  
Ovary Weight ◽  
Adult Females ◽  
First Reproduction

Some aspects of the population ecology of Phallotorynus pankalos in a first-order stream of the Iguatemi River Basin are described based on samples taken from March/2007 to February/2008. A total of 2680 individuals, including 948 males and 1732 females was collected. Adult females are larger than males; theirs mean fecundity was estimated as 6.5 embryos/female. There was a strong correlation between standard length and ovary weight, relative ovary weight, and number of embryos. The size of the first maturation of 50% of female population was estimated as 18.24 mm of standard lenght. High female mortality was observed after the first reproduction and sex ratio presents seasonal variation with higher female proportion in the winter.

Adaptive Seasonal Variation in the Sex Ratio of Kestrel Broods

1990 ◽  
Vol 4 (2) ◽  
pp. 143 ◽  
Author(s):  
C. Dijkstra ◽  
S. Daan ◽  
J. B. Buker
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio

scholarly journals SEASONAL VARIATION IN SEX RATIO OF FLEDGLING AMERICAN KESTRELS: A LONG TERM STUDY

2002 ◽  
Vol 114 (4) ◽  
pp. 474-478 ◽  
Author(s):  
MATTEO GRIGGIO ◽  
FRANCES HAMERSTROM ◽  
ROBERT N. ROSENFIELD ◽  
GIACOMO TAVECCHIA
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Term Study ◽  
Long Term Study ◽  
American Kestrels

scholarly journals EFFECTS OF STRESSFUL EVENTS IN FRANCE (1968) AND JAPAN (1995) ON THE SEX RATIO AT BIRTH

2016 ◽  
Vol 49 (5) ◽  
pp. 664-674 ◽  
Author(s):  
Victor Grech ◽  
Dorota Zammit ◽  
Hagen Scherb
Keyword(s):  
Public Health ◽  
Seasonal Variation ◽  
Sex Ratio ◽  
Perinatal Mortality ◽  
Stressful Events ◽  
Terrorist Attacks ◽  
Public Health Issue ◽  
Small Male ◽  
Sex Ratio At Birth ◽  
Aum Shinrikyo

SummaryMales are usually born in excess of females. The sex ratio at birth (SR) is often expressed as the ratio of male to total births. A wide variety of factors have been shown to influence SR, including terrorist attacks, which have been shown to reduce SR. This paper reviews the effects on SR outcomes of the stressful events in France in 1968 (in association with the student and worker riots) and in Japan following the Aum Shinrikyo religious cult’s attack on the Tokyo subway using sarin nerve gas in 1995. Both countries displayed seasonal variation in SR. France exhibited a decline in SR in 1968 (p=0.042), with a particularly strong dip in May of that year (p=0.015). For Japan, there was no statistically significant dip for 1995 but there was a significant dip in June of that year (p=0.026). The SR dips follow catastrophic or tragic events if these are perceived to be momentous enough by a given populace. It is believed that SR slumps may be caused by population stress, which is known to lead to the culling of frail/small male fetuses. It has been observed that these fluctuations are comparable in intensity to a substantial proportion of quoted values for perinatal mortality, potentially making this a public health issue.

Responses of three sympatric snake species to tropical seasonality in northern Australia

2002 ◽  
Vol 18 (4) ◽  
pp. 549-568 ◽  
Author(s):  
Gregory P. Brown ◽  
Richard Shine ◽  
Thomas Madsen
Keyword(s):  
Seasonal Variation ◽  
Sex Ratio ◽  
Body Condition ◽  
Reproductive Activity ◽  
Generalist Predator ◽  
Feeding Rates ◽  
Wet Season ◽  
Snake Species ◽  
Dry Tropics ◽  
Biological Attributes

In the Australian wet–dry tropics, temperatures are high year-round but rainfall is concentrated in a 4-mo wet season. Regular nightly surveys in the Fogg Dam Nature Reserve provided data on temporal (monthly, seasonal) variation in biological attributes of three snake species: water pythons (Liasis fuscus, Pythonidae), keelbacks (Tropidonophis mairii, Colubridae) and slatey-grey snakes (Stegonotus cucullatus, Colubridae). Adults of all three taxa were encountered more frequently during the dry season than the wet season, whereas juveniles were more commonly encountered in the wet season. The sex ratio among adult snakes also shifted seasonally, but in different ways in different species. These sex-ratio shifts probably reflect reproductive activity (mate-searching by males, oviposition migrations by females) and were accompanied by increased encounter rates. Feeding rates and body condition of keelbacks (a frog specialist) were highest during the wet season when frogs were most abundant. Rats migrated away from Fogg Dam during the wet season, and most pythons (rat specialists) left this area to follow their prey. The pythons that remained at Fogg Dam exhibited low feeding rates and poor body condition. Slatey-grey snakes (a generalist predator) showed less seasonal variation in feeding rates or body condition. Our data show that tropical seasonality induces strong fluctuations in many attributes of snake populations, and that patterns of response differ both among and within species.

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