scholarly journals Now you see him, now you don't: experience, not age, is related to reproduction in kittiwakes

2011 ◽  
Vol 278 (1721) ◽  
pp. 3060-3066 ◽  
Author(s):  
Marine Desprez ◽  
Roger Pradel ◽  
Emmanuelle Cam ◽  
Jean-Yves Monnat ◽  
Olivier Gimenez
Keyword(s):  
Growth Rate ◽  
Process Model ◽  
Population Growth Rate ◽  
Rissa Tridactyla ◽  
Factors Influencing ◽  
Important Constraint ◽  
Wide Range ◽  
In The Wild ◽  
Intermittent Breeding

In long-lived species, individuals can skip reproduction. The proportion of breeders affects population growth rate and viability, there is a need to investigate the factors influencing intermittent breeding. The theory predicts that if lack of experience is an important constraint, breeding probabilities should increase with experience for individuals of the same age, whereas under the so-called restraint hypothesis, breeding probabilities should increase with age regardless of experience. However, because the probability of detecting individuals in the wild is generally less than 1, it is difficult to know exactly the number of previous breeding episodes (breeding experience). To cope with this issue, we developed a hidden process model to incorporate experience as a latent state possibly influencing the probability of breeding. Using a 22-year mark-recapture dataset involving 9970 individuals, we analysed simultaneously experience and age effects on breeding probabilities in the kittiwake ( Rissa tridactyla ). We did not detect an influence of age on adult breeding probabilities. We found that inexperienced birds breed less frequently than experienced birds. Our approach enables us to highlight the key role of experience on adults breeding probabilities and can be used for a wide range of organisms for which detection is less than 1.

Turning Discounts Into Profits: Factors Influencing Online Purchasing Decisions for Hotel Add-on Items

2020 ◽  
pp. 193896552093539 ◽  
Author(s):  
Esther L. Kim ◽  
Sarah Tanford
Keyword(s):  
Process Model ◽  
Mental Accounting ◽  
Thinking Styles ◽  
Impulse Buying ◽  
Purchasing Decisions ◽  
Price Discount ◽  
Mediating Role ◽  
Factors Influencing ◽  
Impulse Buying Tendency

A hotel website exclusive discount is widely adopted by major chain hotels to increase the volume of direct bookings. Although the traditional purpose of a discount promotion is to attract customers to the business, this research suggests that a hotel website exclusive price discount can induce consumers’ additional spending. Principles of mental accounting and two thinking styles (analytic vs. holistic) predict different effects of a price discount and the add-on product type by individual thinking styles. A quasi-experiment investigated the effect of an unexpected discount, relatedness of add-on item to a hotel stay, and individual thinking styles on add-on purchasing. The mediating role of impulse buying was subsequently examined using the PROCESS model. The effect of a price discount and the relatedness of add-on item are significant for analytic thinkers, whereas holistic thinkers report higher likelihood to purchase add-on items regardless of relatedness. Holistic thinkers’ likelihood to purchase is enhanced through an impulse buying tendency. The findings provide further evidence for the role of individual differences in response to pricing tactics by suggesting that a price promotion increases add-on purchases for analytic thinkers, whereas promoting a sense of impulsiveness can be more effective for holistic thinkers.

scholarly journals Scaling rules for the final decline to extinction

2009 ◽  
Vol 276 (1660) ◽  
pp. 1361-1367 ◽  
Author(s):  
Blaine D Griffen ◽  
John M Drake
Keyword(s):  
Growth Rate ◽  
Carrying Capacity ◽  
Population Growth Rate ◽  
Current Theory ◽  
Theoretical Explanation ◽  
Standard Theory ◽  
Current Standard ◽  
Population Extinction ◽  
Time Scaling ◽  
Wide Range

Space–time scaling rules are ubiquitous in ecological phenomena. Current theory postulates three scaling rules that describe the duration of a population's final decline to extinction, although these predictions have not previously been empirically confirmed. We examine these scaling rules across a broader set of conditions, including a wide range of density-dependent patterns in the underlying population dynamics. We then report on tests of these predictions from experiments using the cladoceran Daphnia magna as a model. Our results support two predictions that: (i) the duration of population persistence is much greater than the duration of the final decline to extinction and (ii) the duration of the final decline to extinction increases with the logarithm of the population's estimated carrying capacity. However, our results do not support a third prediction that the duration of the final decline scales inversely with population growth rate. These findings not only support the current standard theory of population extinction but also introduce new empirical anomalies awaiting a theoretical explanation.

scholarly journals Mental Distress during the Coronavirus Pandemic in Israel: Who Are the Most Vulnerable?

2021 ◽  
Vol 19 (1) ◽  
pp. 124
Author(s):  
Tehila Refaeli ◽  
Michal Krumer-Nevo
Keyword(s):  
Process Model ◽  
Mental Distress ◽  
Linear Models ◽  
Economic Effects ◽  
Stress Process Model ◽  
Current Crisis ◽  
Economic Distress ◽  
The Social ◽  
Wide Range

Based on Pearlin’s stress process model and the social inequality approach to health, this study used a social lens to explore the role of socioeconomic inequities in mental distress during the COVID-19 pandemic in Israel. Specifically, we examined people’s pre-pandemic sociodemographic characteristics and economic situation, and the economic effects of the pandemic itself on mental distress. A real-time survey was conducted in May 2020 among 273 adults (ages 20–68), and hierarchical linear models were employed. Findings indicated that groups vulnerable to mental distress in routine times (e.g., women, people with economic difficulties) showed the same pattern during the pandemic. Not only was unemployment related to mental distress, so too was a reduction in work hours. The pandemic’s economic effects (e.g., needing to take out loans, having a worsening financial situation) were also associated with increased mental distress. This study is one of very few studies to explore a wide range of socioeconomic factors and their association with mental distress during the current crisis. The findings call for broader interventions to alleviate the economic distress caused by the pandemic to promote mental health, especially for groups that were vulnerable before the crisis and those most affected economically following the pandemic.

scholarly journals Population growth rates: issues and an application

2002 ◽  
Vol 357 (1425) ◽  
pp. 1307-1319 ◽  
Author(s):  
H. Charles J. Godfray ◽  
Mark Rees
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Growth Rates ◽  
Population Growth Rate ◽  
Population Change ◽  
Evolutionarily Stable Strategy ◽  
Model Systems ◽  
Population Growth Rates

Current issues in population dynamics are discussed in the context of The Royal Society Discussion Meeting 'Population growth rate: determining factors and role in population regulation'. In particular, different views on the centrality of population growth rates to the study of population dynamics and the role of experiments and theory are explored. Major themes emerging include the role of modern statistical techniques in bringing together experimental and theoretical studies, the importance of long-term experimentation and the need for ecology to have model systems, and the value of population growth rate as a means of understanding and predicting population change. The last point is illustrated by the application of a recently introduced technique, integral projection modelling, to study the population growth rate of a monocarpic perennial plant, its elasticities to different life-history components and the evolution of an evolutionarily stable strategy size at flowering.

scholarly journals Role of Spore Coat Proteins in the Resistance of Bacillus subtilis Spores to Caenorhabditis elegans Predation

2008 ◽  
Vol 190 (18) ◽  
pp. 6197-6203 ◽  
Author(s):  
Maria-Halima Laaberki ◽  
Jonathan Dworkin
Keyword(s):  
Bacillus Subtilis ◽  
Caenorhabditis Elegans ◽  
Spore Coat ◽  
Coat Proteins ◽  
Host Interaction ◽  
Wide Range ◽  
In The Wild

ABSTRACT Bacterial spores are resistant to a wide range of chemical and physical insults that are normally lethal for the vegetative form of the bacterium. While the integrity of the protein coat of the spore is crucial for spore survival in vitro, far less is known about how the coat provides protection in vivo against predation by ecologically relevant hosts. In particular, assays had characterized the in vitro resistance of spores to peptidoglycan-hydrolyzing enzymes like lysozyme that are also important effectors of innate immunity in a wide variety of hosts. Here, we use the bacteriovorous nematode Caenorhabditis elegans, a likely predator of Bacillus spores in the wild, to characterize the role of the spore coat in an ecologically relevant spore-host interaction. We found that ingested wild-type Bacillus subtilis spores were resistant to worm digestion, whereas vegetative forms of the bacterium were efficiently digested by the nematode. Using B. subtilis strains carrying mutations in spore coat genes, we observed a correlation between the degree of alteration of the spore coat assembly and the susceptibility to the worm degradation. Surprisingly, we found that the spores that were resistant to lysozyme in vitro can be sensitive to C. elegans digestion depending on the extent of the spore coat structure modifications.

SOME MICRO-ECOLOGICAL FACTORS INFLUENCING THE POPULATION DYNAMICS OF SCHISTOSOMIASIS INTERMEDIATE HOST SNAILS IN KHARTOUM STATE, SUDA

2016 ◽  
Vol 4 (8) ◽  
pp. 147-151
Author(s):  
A. Zakaria Mohamed ◽  
Azzam Afifi ◽  
Yassir Sulieman ◽  
Theerakamol Pengsakul
Keyword(s):  
Growth Rate ◽  
Population Dynamics ◽  
Population Growth ◽  
Intermediate Host ◽  
Population Growth Rate ◽  
Ecological Factors ◽  
Water Bodies ◽  
Snail Population ◽  
Factors Influencing ◽  
High Turbidity

This study was conducted to determine the role of some micro-ecological factors influencing the population dynamics of schistosomiasis intermediate host snails in the water bodies of Khartoum State, Sudan. The results show that the air and water temperature play a significant role in the determination of snail growth, a gradual increase of air and water temperate causing an increase in the snail population growth rate with the peak in summer. Water of high turbidity and high current speed caused a drop in the snail population. Vegetation cover in water bodies showed a significant effect on the snail population, the denser the cover the higher the snail population growth rate.

scholarly journals Does variation in photosynthetic rate explain variation in growth rate and yield?

1987 ◽  
Vol 35 (4) ◽  
pp. 505-519 ◽  
Author(s):  
H. Lambers
Keyword(s):  
Growth Rate ◽  
Photosynthetic Rate ◽  
Leaf Anatomy ◽  
Photosynthetic Characteristics ◽  
Rubp Carboxylase ◽  
N Distribution ◽  
Wide Range ◽  
Crop Performance ◽  
Leaf Canopy

The basis of variation in growth rate and production between and within species is discussed. Examples taken from a wide range of literature and species are used to investigate the role of NAR and the pattern of photosynthate investment in such variation. Variation in photosynthesis is considered in terms of RuBP-carboxylase and N compound concn and leaf anatomy and morphology. Patterns of N distribution within the leaf canopy are briefly discussed together with the potential for improving crop performance by altering plant photosynthetic characteristics. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The role of hatchling size in generating the intrinsic size-at-age variability of cephalopods: extending the Forsythe Hypothesis

2004 ◽  
Vol 55 (4) ◽  
pp. 387 ◽  
Author(s):  
G. T. Pecl ◽  
M. A. Steer ◽  
K. E. Hodgson
Keyword(s):  
Growth Rate ◽  
Incubation Temperature ◽  
Adult Size ◽  
Daily Growth ◽  
Wide Range ◽  
Extreme Variability ◽  
Effects Of Temperature ◽  
Size At Age ◽  
Hatchling Size

Cephalopods are characterised by extreme variability in size-at-age, with much of this variation attributed to effects of temperature and food. However, even siblings reared under identical conditions display a wide range of sizes after a period of growth. Hatchling size may represent a source of variation encompassed within adult size-at-age data (i) within a given cohort (variation in hatchling size suggests that a cohort’s growth trajectory will have a ‘staggered start’) and (ii) as hatchling size also varies as a function of incubation temperature this will vary across broader scales (i.e. between cohorts). Field-hatchling size data for Sepioteuthis australis were used in simple deterministic simulations, extending Forsythe’s (1993) temperature hypothesis, to investigate the influence of hatchling size on adult size-at-age variability. Within a cohort, our growth projections suggest that after 90 days, a large hatchling growing at a specific constant percentage daily growth rate (%BW day–1), would be approximately double the size of the small hatchling growing at exactly the same rate, irrespective of the growth rate used. When considering growth of different cohorts, decreases in hatchling size, as temperatures increase during a spring/summer spawning season, may be partially counteracting the ‘Forsythe-effect’ of increased growth rate at higher temperatures.

scholarly journals Density dependence or climatic variation? Factors influencing survival, recruitment, and population growth rate of Virginia opossums

2014 ◽  
Vol 95 (2) ◽  
pp. 421-430 ◽  
Author(s):  
Elizabeth M. Troyer ◽  
Susan E. Cameron Devitt ◽  
Melvin E. Sunquist ◽  
Varun R. Goswami ◽  
Madan K. Oli
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Density Dependence ◽  
Population Growth Rate ◽  
Climatic Variation ◽  
Factors Influencing
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