Fledgling sex-ratio is biased towards the helping sex in a Neotropical cooperative breeder, the brown-and-yellow marshbird (Pseudoleistes virescens)

Behaviour ◽  
2021 ◽  
pp. 1-26
Author(s):  
Myriam E. Mermoz ◽  
Cecilia Villarruel ◽  
Alicia de la Colina ◽  
Bettina Mahler
Keyword(s):  
Sex Ratio ◽  
Breeding Success ◽  
Population Level ◽  
Adaptive Strategy ◽  
Individual Level ◽  
Cooperatively Breeding ◽  
Nestling Survival ◽  
Biased Sex Ratio ◽  
Communal Areas ◽  
Breeding Seasons

Abstract In many cooperatively breeding species, helpers increase the breeding success of their parents. The repayment hypothesis predicts a skewed sex-ratio towards the helping sex at population level; at individual level bias would increase in broods attended by a smaller number of helpers. We studied a brown-and-yellow marshbird (Pseudoleistes virescens) population during 11 breeding seasons. We found that 90% of helpers were males and that they increased nestling survival, although this effect disappeared in presence of parasitic shiny cowbirds. Helpers sometimes helped at nests of adults other than their parents. Population sex-ratio of fledglings was highly skewed towards males (1.4:1). At individual level, male-biased sex-ratio of fledglings was more pronounced early in the season and increased with brood losses but was not affected by number of helpers. Marshbirds feed at communal areas so retaining helpers would not be costly. Therefore, a general skew towards males might be the best adaptive strategy.

scholarly journals Is earlier reproduction associated with higher or lower survival? Antagonistic results between individual and population scales in the blue tit

2021 ◽  
Author(s):  
Olivier Bastianelli ◽  
Anne Charmantier ◽  
Clotilde Biard ◽  
Suzanne Bonamour ◽  
Céline Teplitsky ◽  
...  
Keyword(s):  
Breeding Success ◽  
Positive Association ◽  
Population Level ◽  
Adult Survival ◽  
Breeding Density ◽  
Cyanistes Caeruleus ◽  
Individual Level ◽  
Population Scale ◽  
Individual Scale ◽  
The Individual

ABSTRACTAlthough it has been shown that phenology can respond to temporal environmental variation in free ranging populations of several species, little is known about the mechanisms of these responses and their effects on demography, and in particular on survival. Exploring phenological responses and their associated consequences on survival can be achieved at two distinct scales: the population scale, which focusses on a set of common responses to environmental conditions, and the individual scale, focusing on the relative position of each individual in the distribution of survival and phenology under particular conditions. In this study, we apply capture-mark-recapture multistate modelling on a 38-year monitoring dataset of blue tits (Cyanistes caeruleus) to investigate the effects of breeding phenology and some demographic covariates (breeding density, average and individual breeding success) on adult survival, at both population and individual scales. Our analysis revealed that (i) at the population scale, early breeding years are followed by lower average adult survival. (ii) At the individual level, earlier breeders within the population have higher subsequent survival than later breeders, although this relationship is reversed in years with very harsh conditions, e.g. warm spring and high breeding density. (iii) High individual relative breeding success is also associated with higher subsequent survival and explains more survival variation than relative phenology. Overall, our study indicates that, although earlier breeding is associated with a survival cost at the population level, substantial intrapopulation hererogeneity shapes a positive association between earlier breeding, breeding success and survival at the individual level.

scholarly journals Demography of Brown-Headed Cowbirds at Delta Marsh, Manitoba

The Auk ◽  
2001 ◽  
Vol 118 (1) ◽  
pp. 156-166 ◽  
Author(s):  
Bonnie E. Woolfenden ◽  
H. Lisle Gibbs ◽  
Spencer G. Sealy
Keyword(s):  
Sex Ratio ◽  
Site Fidelity ◽  
Breeding Site ◽  
Adult Survival ◽  
Parameter Estimates ◽  
Delta Marsh ◽  
The Social ◽  
Biased Sex Ratio ◽  
Breeding Seasons

Abstract Available estimates of demographic parameters for Brown-headed Cowbirds (Molothrus ater) vary geographically. However, few estimates are based on long-term studies of marked individuals. We conducted a mark–recapture study on the population of cowbirds at Delta Marsh, Manitoba during the 1993–1998 breeding seasons. We estimated annual survival, breeding site fidelity, and sex ratio, and compared those parameter estimates to other populations of Brown-headed Cowbirds. The Delta Marsh population had higher adult survival (male 90.1%; female 69.6%) and breeding site fidelity (males 66.9%, female 59.5%) than reported for other populations, and the sex ratio was significantly different from unity (1.9 males:1 female). We suggest that differences in survival and breeding-site fidelity between the Delta Marsh population and others may be due to differences in methods used to calculate parameter estimates. In contrast, variation in sex ratios is likely real and due to differences in the local ecological conditions. In our population, high survivorship and breeding-site fidelity may lead to low recruitment of new birds into the resident population and intense competition for limited breeding opportunities. The highly male biased sex ratio may result in strong sexual-selection pressure on males competing for the limited breeding opportunities. Those circumstances have implications for the social behavior and mating system of cowbirds.

scholarly journals Sex allocation and field population sex ratio of Apanteles taragamae Viereck (Hymenoptera: Braconidae), a larval parasitoid of the cucumber moth Diaphania indica Saunders (Lepidoptera: Crambidae)

2021 ◽  
Vol 6 (1) ◽  
pp. 673-681
Author(s):  
Ihsan Nurkomar ◽  
Azru Azhar ◽  
Damayanti Buchori
Keyword(s):  
Sex Ratio ◽  
Brood Size ◽  
Sex Allocation ◽  
Natural Habitat ◽  
Adult Emergence ◽  
Female Offspring ◽  
Individual Level ◽  
Apanteles Taragamae ◽  
Larval Parasitoid ◽  
Biased Sex Ratio

Abstract Sex ratio is one of the most important biological characteristics of arthropods. In a parasitoid population, sex ratio can influence the suppression of host populations or the stability of host–parasitoid interactions in the field. In this study, a survey was carried out to determine the sex allocation through the sequence of male/female adult emergence and calculate the sex ratio of selected populations of Apanteles taragamae in their natural habitat. Assessment of sex ratio at the population and individual level (brood size per female) was examined. We found no difference in the likelihood that either sex would emerge before the other. Observations of sex ratio at the population and individual level reveal a females biased sex ratio. Analysis of the relationship between brood size and sex ratio of A. taragamae shows that brood size may influence the proportion of male to female offspring yielded. A male-biased sex ratio tends to be found in smaller brood size. However, sex ratio is shifted to female biased in larger brood size.

scholarly journals The endangered Brown Shrike subspecies Lanius cristatus superciliosus has a male-biased sex ratio and only early arriving males are paired

2021 ◽  
pp. 1-8
Author(s):  
HARUKA MIZUMURA ◽  
KOHEI KUBOTA ◽  
HIROYOSHI HIGUCHI
Keyword(s):  
Sex Ratio ◽  
East Asian ◽  
Long Distance ◽  
Breeding Range ◽  
Passerine Species ◽  
Biased Sex Ratio ◽  
Breeding Seasons

Summary Along with many long-distance migrant passerine species in the East Asian-Australasian Flyway, the migratory Brown Shrike Lanius cristatus superciliosus has been sharply declining throughout its breeding range. Its breeding range in Japan shrank by 90.9% between the 1910s and 2010s. In contrast, the closely related but resident Bull-headed Shrike L. bucephalus bucephalus has been gradually declining but is still a common resident in Japan. To better understand the drastic decline of Brown Shrike, we compared the pairing success during three consecutive breeding seasons of these two species. About 60–70% of Brown Shrike males were unpaired, which was much higher than the percentage of unpaired male Bull-headed Shrike (c.0–20%). Brown Shrike males arriving later did not pair because the population’s sex proportion is heavily biased toward males. One of the factors of male-biased population of Brown Shrike may be female-biased mortality in wintering sites, or on the migratory journey, and tracking studies will be required to test this.

scholarly journals Blood Pressure Trajectories Across the Life Course

2021 ◽  
Vol 34 (3) ◽  
pp. 234-241
Author(s):  
Norrina B Allen ◽  
Sadiya S Khan
Keyword(s):  
Blood Pressure ◽  
Measurement Errors ◽  
Clinical Care ◽  
Population Level ◽  
Cumulative Exposure ◽  
Older Adulthood ◽  
Individual Level ◽  
The Life Course ◽  
Level Group ◽  
Improve Health

Abstract High blood pressure (BP) is a strong modifiable risk factor for cardiovascular disease (CVD). Longitudinal BP patterns themselves may reflect the burden of risk and vascular damage due to prolonged cumulative exposure to high BP levels. Current studies have begun to characterize BP patterns as a trajectory over an individual’s lifetime. These BP trajectories take into account the absolute BP levels as well as the slope of BP changes throughout the lifetime thus incorporating longitudinal BP patterns into a single metric. Methodologic issues that need to be considered when examining BP trajectories include individual-level vs. population-level group-based modeling, use of distinct but complementary BP metrics (systolic, diastolic, mean arterial, mid, and pulse pressure), and potential for measurement errors related to varied settings, devices, and number of readings utilized. There appear to be very specific developmental periods during which divergent BP trajectories may emerge, specifically adolescence, the pregnancy period, and older adulthood. Lifetime BP trajectories are impacted by both individual-level and community-level factors and have been associated with incident hypertension, multimorbidity (CVD, renal disease, cognitive impairment), and overall life expectancy. Key unanswered questions remain around the additive predictive value of BP trajectories, intergenerational contributions to BP patterns (in utero BP exposure), and potential genetic drivers of BP patterns. The next phase in understanding BP trajectories needs to focus on how best to incorporate this knowledge into clinical care to reduce the burden of hypertensive-related outcomes and improve health equity.

scholarly journals Examining the Effects of the Sacramento Dockless E-Bike Share on Bicycling and Driving

2021 ◽  
Vol 13 (1) ◽  
pp. 368
Author(s):  
Dillon T. Fitch ◽  
Hossain Mohiuddin ◽  
Susan L. Handy
Keyword(s):  
Travel Behavior ◽  
Regression Models ◽  
Population Level ◽  
Panel Survey ◽  
Multilevel Regression ◽  
Combine Data ◽  
Cross Sectional ◽  
Individual Level ◽  
Before And After ◽  
Bike Share

One way cities are looking to promote bicycling is by providing publicly or privately operated bike-share services, which enable individuals to rent bicycles for one-way trips. Although many studies have examined the use of bike-share services, little is known about how these services influence individual-level travel behavior more generally. In this study, we examine the behavior of users and non-users of a dockless, electric-assisted bike-share service in the Sacramento region of California. This service, operated by Jump until suspended due to the coronavirus pandemic, was one of the largest of its kind in the U.S., and spanned three California cities: Sacramento, West Sacramento, and Davis. We combine data from a repeat cross-sectional before-and-after survey of residents and a longitudinal panel survey of bike-share users with the goal of examining how the service influenced individual-level bicycling and driving. Results from multilevel regression models suggest that the effect of bike-share on average bicycling and driving at the population level is likely small. However, our results indicate that people who have used-bike share are likely to have increased their bicycling because of bike-share.

No room for males in caves: Female‐biased sex ratio in subterranean amphipods of the genus Niphargus

2021 ◽  
Author(s):  
Ester Premate ◽  
Špela Borko ◽  
Simona Kralj‐Fišer ◽  
Michael Jennions ◽  
Žiga Fišer ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Biased Sex Ratio

Medication Adherence: Expanding the Conceptual Framework

2021 ◽  
Author(s):  
Marie Krousel-Wood ◽  
Leslie S Craig ◽  
Erin Peacock ◽  
Emily Zlotnick ◽  
Samantha O’Connell ◽  
...  
Keyword(s):  
Older Adults ◽  
Medication Adherence ◽  
Conceptual Framework ◽  
Clinical Outcomes ◽  
Implicit Attitudes ◽  
Explanatory Power ◽  
Population Level ◽  
Time Preferences ◽  
Adherence Behavior ◽  
Individual Level

Abstract Interventions targeting traditional barriers to antihypertensive medication adherence (AHMA) have been developed and evaluated, with evidence of modest improvements in adherence. Translation of these interventions into population-level improvements in adherence and clinical outcomes among older adults remains suboptimal. From the Cohort Study of Medication Adherence among Older adults (CoSMO), we evaluated traditional barriers to AHMA among older adults with established hypertension (N=1544; mean age=76.2 years, 59.5% women, 27.9% Black, 24.1% and 38.9% low adherence by proportion of days covered (i.e., PDC<0.80) and the 4-item Krousel-Wood Medication Adherence Scale (i.e., K-Wood-MAS-4≥1), respectively), finding that they explained 6.4% and 14.8% of variance in pharmacy refill and self-reported adherence, respectively. Persistent low adherence rates, coupled with low explanatory power of traditional barriers, suggest that other factors warrant attention. Prior research has investigated explicit attitudes toward medications as a driver of adherence; the roles of implicit attitudes and time preferences (e.g., immediate versus delayed gratification) as mechanisms underlying adherence behavior are emerging. Similarly, while associations of individual-level social determinants of health (SDOH) and medication adherence are well-reported, there is growing evidence about structural SDOH and specific pathways of effect. Building on published conceptual models and recent evidence, we propose an expanded conceptual framework that incorporates implicit attitudes, time preferences and structural SDOH, as emerging determinants that may explain additional variation in objectively and subjectively measured adherence. This model provides guidance for design, implementation and assessment of interventions targeting sustained improvement in implementation medication adherence and clinical outcomes among older women and men with hypertension.

Male-biased sex ratio in Argulus canadensis Wilson, 1916 (Crustacea: Branchiura) ectoparasitic on sticklebacks

1989 ◽  
Vol 67 (8) ◽  
pp. 2078-2080 ◽  
Author(s):  
Robert Poulin ◽  
Gerard J. FitzGerald
Keyword(s):  
Salt Marsh ◽  
Sex Ratio ◽  
Laboratory Experiments ◽  
Fish Predation ◽  
Reproductive Behaviour ◽  
Egg Deposition ◽  
Alternative Hypotheses ◽  
Biased Sex Ratio ◽  
The Difference ◽  
Fish Hosts

Females of the ectoparasitic crustacean Argulus canadensis must leave their fish hosts at least temporarily to deposit their eggs on the substrate. To test the hypothesis that this difference in reproductive behaviour between the two sexes could result in male-biased sex ratios on their stickleback hosts, we sampled sticklebacks in tide pools of a Quebec salt marsh from early July to early September 1986. During this period, fish harboured significantly more male than female A. canadensis. Laboratory experiments were done to test two alternative hypotheses offered to explain this biased sex ratio. The first hypothesis was that male A. canadensis were more successful than females in attacking their stickleback hosts; however, we found no differences in attack success on their hosts between the two parasite sexes. The second hypothesis was that sticklebacks ate more female than male A. canadensis. Although males were less vulnerable to fish predation than females, the difference was not significant. We conclude that sexual differences in reproductive behaviour, i.e., egg deposition behaviour of females, can account for the male-biased sex ratio of A. canadensis on sticklebacks.

Female-Biased Sex Ratio at Hatching in the Green Woodhoopoe

The Auk ◽  
1990 ◽  
Vol 107 (4) ◽  
pp. 765-771 ◽  
Author(s):  
J. David Ligon ◽  
Sandra H. Ligon
Keyword(s):  
Sex Ratio ◽  
Biased Sex Ratio
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