Sex Ratio and the Timing of Pubertal Maturation in Girls: A Life History Approach

2011 ◽  
Author(s):  
Sarah Feingold
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Pubertal Maturation ◽  
History Approach

scholarly journals The impact of sex ratio and economic status on local birth rates

2013 ◽  
Vol 9 (2) ◽  
pp. 20130027 ◽  
Author(s):  
A. Chipman ◽  
E. Morrison
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Economic Status ◽  
Life History Strategy ◽  
Reproductive Behaviour ◽  
Female Competition ◽  
Birth Rates ◽  
Economically Deprived ◽  
Human Mating ◽  
The Impact

Human mating and reproductive behaviour can vary depending on various mechanisms, including the local sex ratio. Previous research shows that as sex ratios become female-biased, women from economically deprived areas are less likely to delay reproductive opportunities to wait for a high-investing mate but instead begin their reproductive careers sooner. Here, we show that the local sex ratio also has an impact on female fertility schedules. At young ages, a female-biased ratio is associated with higher birth rates in the poorest areas, whereas the opposite is true for the richest areas. At older ages, a female-biased ratio is associated with higher birth rates in the richest, but not the poorest areas. These patterns suggest that female–female competition encourages poorer women to adopt a fast life-history strategy and give birth early, and richer women to adopt a slow life-history strategy and delay reproduction.

Population dynamics of Stenothoe valida Dana, 1852 (Amphipoda, Stenothoidae) at Cheongsapo beach of Busan, Republic of Korea

Crustaceana ◽  
2021 ◽  
Vol 94 (4) ◽  
pp. 413-429
Author(s):  
Ye Ji Lee ◽  
Won Gyu Park
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Sex Ratio ◽  
Brood Size ◽  
Ovigerous Female ◽  
Seasonal Pattern ◽  
Recruitment Rate ◽  
Republic Of Korea ◽  
Female Size ◽  
History Of

Abstract The population dynamics of Stenothoe valida Dana, 1852 were studied at Cheongsapo beach of Busan, Republic of Korea, from March 2019 to March 2020. Sampling was conducted once a month at low tide during spring tides. Specimens were grouped by the cephalic length at 0.025 mm intervals, and classified into four categories: females, ovigerous females, males and juveniles. The sex ratio, defined as females : total males + females, exceeded 0.5 during most of the study period. Brood size was significantly coupled with ovigerous female size. Two to four cohorts appeared at each study period. New cohorts occurred at almost every sampling except in the samples Jun-2, and Nov-2. Life span was estimated at 1-2 months. The juvenile ratio, the ratio of ovigerous females, and the recruitment rate estimated by FiSAT were commonly high in summer and winter. The life history of S. valida was not coupled with water temperature, but had a strong seasonal pattern.

Reproductive Ecology of The Allied Rock-wallaby, Petrogale assimilis.

1996 ◽  
Vol 19 (2) ◽  
pp. 209
Author(s):  
R. Delaney
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Sexual Maturity ◽  
Post Partum ◽  
Reproductive Ecology ◽  
Oestrous Cycle ◽  
Embryonic Diapause ◽  
Minimum Age

Petrogale assimilis has a typical life history and reproductive ecology for a macropodid of its size. Both sexes are capable of reproducing continuously; gestation is about the same length as the oestrous cycle (approximately one month); a single young is born and, a post-partum oestrus and embryonic diapause probably occurs. The sex ratio of young is unbiased. Pouch young remain permanently attached to the teat until 110 - 143 days (n=11). Permanent exit from the pouch occurs at 180 - 231 days (mean=201 days, n=25), and weaning occurs between 267 - 387 days (n=5). Sexual maturity occurs at a minimum age of 17.5 months in females and 23 months in males.

scholarly journals Nesting Biology of Podium angustifrons Kohl (Hymenoptera, Sphecidae) in an Araucaria Forest Fragment

2014 ◽  
Vol 74 (2) ◽  
pp. 493-500
Author(s):  
MLT. Buschini ◽  
CE. Buss
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Wild Species ◽  
Development Time ◽  
Forest Fragment ◽  
Nesting Biology ◽  
Araucaria Forest ◽  
Trap Nests ◽  
French Guyana ◽  
Coated Surfaces

Podium angustifrons Kohl 1902 is a species of solitary wasp which nests in pre-existing cavities, with neotropical distribution in Argentina, Bolivia, Brazil, Colombia, Guyana and French Guyana. The aim of this study was to investigate the nesting biology of P. angustifrons, discussing aspects of their life history. To capture its nests, wooden trap-nests were installed in the Parque Municipal das Araucárias, Guarapuava (PR), Brazil, from January 2003 to April 2009. A total of 29 nests were collected, all during the warmer months. These showed no vestibular and intercalary cells, and their closures were made up of chewed plants and mud mixed with organic materials and resin-coated surfaces, sometimes showing a layer of lichens. The cells were provisioned with various wild species of cockroaches (Chorisoneura sp, Riata sp and Helgaia sp) in the nymph stage and/or adults. The sex ratio was 4.6 females per male, significantly higher that the expected 1:1. Most pre-pupae entered diapause in winter with development time ranging from 187 to 283 days for females and 180 to 283 days for males. Deaths occurred in 41.66% of cells provisioned, 33.33% were attributed to faulty development and 8.33% to Chrysididae.

The effect of childhood unpredictability on co-parenting relationships during the transition to parenthood: A life history approach

2020 ◽  
Vol 37 (8-9) ◽  
pp. 2438-2458
Author(s):  
Ohad Szepsenwol
Keyword(s):  
Life History ◽  
Early Life ◽  
Life History Theory ◽  
Transition To Parenthood ◽  
Life Experiences ◽  
Parental Behaviors ◽  
Childhood Socioeconomic Status ◽  
Environmental Unpredictability ◽  
History Approach

Recent extensions to life history theory posit that exposure to environmental unpredictability during childhood should forecast negative parental behaviors in adulthood. In the current research, this logic was extended to co-parental behaviors, which refer to how parents coordinate, share responsibility, and support each other’s parental efforts. The effects of early-life unpredictability on individual and dyadic co-parental functioning were examined in a sample of 109 families (two parents and their firstborn child) who were followed longitudinally from before the child’s birth until the age of two. Greater early-life unpredictability (family changes, residential changes, and parents’ occupational changes by age 8) experienced by mothers, but not fathers, predicted more negative co-parental behaviors in triadic observations 6 months post birth, and lower couple-reported co-parenting quality assessed 3, 9, 18, and 24 months post birth. These effects were not explained by parents’ childhood socioeconomic status or current relationship quality. These findings highlight the role of mothers in shaping co-parenting relationships and how these relationships might be influenced by mothers’ early-life experiences.

The effect of different diet on life history parameters and growth of Oppia denticulata (Acari: Oribatida: Oppiidae)

2017 ◽  
Vol 22 (5) ◽  
pp. 749 ◽  
Author(s):  
Anna Seniczak ◽  
Stanisław Seniczak ◽  
Mariola Słowikowska ◽  
Zbigniew Paluszak
Keyword(s):  
Life History ◽  
Sex Ratio ◽  
Population Growth ◽  
Laboratory Experiment ◽  
Green Algae ◽  
Penicillium Chrysogenum ◽  
Trichoderma Viride ◽  
Population Parameters ◽  
Good Population ◽  
Fungal Hyphae

The effect of different diet on Oppia denticulata was studied during a 4-month laboratory experiment, based on daily observations. This species is known as microphytophagous (i.e. feeding on bacteria and/or fungal hyphae and/or algae), like other species of Oppiidae, but our observations show its wider diet. We tested 11 types of food, including homogenous diet [green algae, lichens, fungi (dry yeasts, Trichoderma viride, Penicillium chrysogenum), nematodes], and combined diet [green algae and nematodes, lichens and nematodes, dry yeasts and nematodes, T. viride and nematodes, P. chrysogenum and nematodes]. The basic population parameters (fertility, mortality, sex ratio), time of development, population growth in four months and body length were compared between all groups. Observations on biology of O. denticulata were also made. The most favourable diet for O. denticulata was a combination of T. viride and nematodes, which allowed the highest population growth (about 50 times higher than the least favourable food, a combination of P. chrysogenum and nematodes), due to highest fertility and shortest development. Good population parameters and largest size were obtained on yeasts (served alone or with nematodes). This species did not do well on P. chrysogenum, probably because it produces penicillin.

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