scholarly journals Individual boldness is life stage-dependent and linked to dispersal in a hermaphrodite land snail

2017 ◽  
Author(s):  
Maxime Dahirel ◽  
Alexandre Vong ◽  
Armelle Ansart ◽  
Luc Madec
Keyword(s):  
Evolutionary Dynamics ◽  
Life Stage ◽  
Reproductive Investment ◽  
Land Snail ◽  
Life History Strategies ◽  
Life Stages ◽  
Dispersal Tendency ◽  
Cornu Aspersum ◽  
Animal Personalities ◽  
Over Time

ABSTRACTBoth individual variation in dispersal tendency and animal personalities have been shown to be widespread in nature. They are often associated in personality-dependent dispersal, and both have major but underappreciated consequences for ecological and evolutionary dynamics. In addition, personalities are not stable over time and changes can appear through ontogeny, leading to life stage-dependent behaviours. We investigated relationships between dispersal, life stage and boldness in an invertebrate with between- and within-life stages variation in dispersal tendency, the land snail Cornu aspersum. Latency to exit the shell following a simulated attack was repeatable, indicating boldness is a personality trait in Cornu aspersum. Subadults were bolder and more dispersive than adults. Dispersers were bolder than non-dispersers, independently of boldness changes between life stages. We discuss how these results can be explained in relation with life history strategies in this hermaphrodite species, in particular risk management in the context of reproductive investment.

scholarly journals Capital structure and the firm’s life stage

2005 ◽  
Vol 36 (4) ◽  
pp. 9-18 ◽  
Author(s):  
A. Frielinghaus ◽  
B. Mostert ◽  
C. Firer
Keyword(s):  
Pilot Study ◽  
Capital Structure ◽  
Life Stage ◽  
Order Theory ◽  
Life Stages ◽  
Stage Model ◽  
Pecking Order ◽  
Pecking Order Theory ◽  
The Relationship ◽  
Over Time

In this paper we argue the case for a relationship between capital structure and a firm’s life stage. We provide an overview of the two sets of theories and follow this with a proposed linkage between the life stage and capital structure. We use the Adizes life stage model to assess the life stage of the firms in our sample. Our pilot study found a statistically significant relationship between life stage and the capital structure of respondents. The nature of the relationship (more debt in the early and late life stages than in prime) supports the pecking order theory of capital structure and suggests a practical use of the life stage model in helping firms to understand how their financing is likely to change over time.

Composition of body storage compounds influences egg quality and reproductive investment in the land snail Cornu aspersum

2012 ◽  
Vol 90 (9) ◽  
pp. 1161-1170 ◽  
Author(s):  
Annegret Nicolai ◽  
Juliane Filser ◽  
Roman Lenz ◽  
Briand Valérie ◽  
Maryvonne Charrier
Keyword(s):  
Clutch Size ◽  
Energy Content ◽  
Reproductive Investment ◽  
Land Snail ◽  
The Body ◽  
Nutrient Allocation ◽  
Energy Investment ◽  
Storage Compounds ◽  
Investment In Reproduction ◽  
Cornu Aspersum

In invertebrates, resources available for growth and reproduction might influence the composition of body stores and subsequently nutrient allocation to eggs, thereby adjusting energy investment in reproduction. We investigated in the land snail Cornu aspersum (Müller, 1774) the efficiency of growth and the main storage compounds in the body and in eggs with respect to lipid content in food (5.5% versus 2.5%). The high body dry mass density of snails fed on lipid-rich diet underlined the high storage capacity of neutral lipids acquired during growth (high growth efficiency) without changing energy content because of the prevailing carbohydrate storage compounds. Reproductive investment was lower in these snails, and maternal effects decreased clutch size. Triglyceride allocation to eggs might enhance survival probability of offspring and therefore compensate for smaller clutch size. Snails fed on lipid-poor diet maximized their investment in clutch size whatever the amount of body stores, and allocated a higher amount of cholesterol to eggs. Cholesterol could be essential for embryo growth, as it ensures membrane functioning. In conclusion, the availability of resources can differentially affect nutrient allocation and energy investment in reproduction. Thus, the investigation of physiological processes becomes essential to understand population dynamics in fluctuating or changing habitats.

scholarly journals Individual behaviour in firebugs ( Pyrrhocoris apterus )

2010 ◽  
Vol 278 (1705) ◽  
pp. 628-633 ◽  
Author(s):  
Enikő Gyuris ◽  
Orsolya Feró ◽  
András Tartally ◽  
Zoltán Barta
Keyword(s):  
Life History ◽  
Reproductive Investment ◽  
Recent Model ◽  
Life History Strategies ◽  
Reproductive Value ◽  
Pyrrhocoris Apterus ◽  
Major Interest ◽  
Theoretical Predictions ◽  
Future Reproduction ◽  
Animal Personalities

The concept of animal personalities has recently become of major interest as researchers began to wonder why animals within a given population show consistent behaviour across situations and contexts, what led to the evolution of such behavioural inflexibility and what mechanisms might underlie the phenomenon. A recent model explains individual differences in a population as the result of trade-off between present and future reproduction. We tested this model on the two wing morphs, i.e. short-winged (brachypterous) and long-winged (macropterous) specimens of the firebug ( Pyrrhocoris apterus ). Since it has been already demonstrated that the two wing morphs differ in their life-history strategies, this species is an ideal subject to test whether the specimens with different life-history strategies have different personalities as well. The results show that individuals behave consistently over time and across contexts, meaning observed bugs do have personalities. We also have found that in females, the two wing morphs have different personalities supporting the theoretical predictions, i.e. winged ones, which are supposed to have lower future reproductive value, are braver and more exploratory. We found no difference between the morphs in males. Differences in reproductive investment might explain this discrepancy between the sexes.

scholarly journals Contrasting selection at multiple life stages maintains divergent adaptation between sunflower ecotypes

2020 ◽  
Author(s):  
April M. Goebl ◽  
Nolan C. Kane ◽  
Daniel F. Doak ◽  
Loren H. Rieseberg ◽  
Kate L. Ostevik
Keyword(s):  
Sequence Data ◽  
Life Stage ◽  
Natural Populations ◽  
Common Garden ◽  
Life History Strategies ◽  
Frequency Change ◽  
Life Stages ◽  
Fitness Components ◽  
Demographic Models ◽  
Genomic Studies

AbstractConspecific populations living in adjacent, but contrasting, microenvironments represent excellent systems for studying natural selection. These systems are valuable because gene flow maintains genetic homogeneity except at loci experiencing strong, divergent selection. A history of reciprocal transplant and common garden studies in such systems, and a growing number of genomic studies, have contributed to understanding how selection operates in natural populations. While selection can vary across different fitness components and life stages, few studies have investigated how this ultimately affects allele frequencies and persistence of divergent populations. Here, we study two sunflower ecotypes in distinct, adjacent habitats by combining demographic models with genome-wide sequence data to estimate fitness components, absolute fitness, and allele frequency change at multiple life stages. This framework allows us to demonstrate that only local ecotypes experience positive population growth (lambda>1) and that the maintenance of divergent adaptation is mediated via habitat- and life stage-specific selection. We identify genetic variation, significantly driven by loci in chromosomal inversions, associated with different life history strategies in neighbouring ecotypes that optimize different fitness components and contribute to the persistence of each ecotype in its respective habitat.

Do dietary carotenoids improve the escape-response performance of southern corroboree frog larvae?

Behaviour ◽  
2020 ◽  
Vol 157 (12-13) ◽  
pp. 987-1006
Author(s):  
Emma P. McInerney ◽  
Aimee J. Silla ◽  
Phillip G. Byrne
Keyword(s):  
Larval Development ◽  
Treatment Effect ◽  
Escape Response ◽  
Life Stage ◽  
High Dose ◽  
Life Stages ◽  
Response Performance ◽  
Developmental Point ◽  
Early Larval Development ◽  
Over Time

Abstract Dietary antioxidants can improve escape-response performance in adult vertebrates, but whether juveniles receive similar benefits remains untested. Here, we investigated the effect of two dietary carotenoids (β-carotene and lutein) on the escape-response of juvenile corroboree frogs (Pseudophryne corroboree) at two developmental points (early and late larval development). We found that burst speed was lower during late larval development compared to early larval development, particularly in the low- and high-dose lutein treatments. These findings suggest that performance decreased over time, and was reduced by lutein consumption. At each developmental point we found no treatment effect on escape-response, providing no evidence for carotenoid benefits. A previous study in corroboree frogs demonstrated that carotenoids improved adult escape-response, so our findings suggest that benefits of carotenoids in this species may be life-stage dependent. Continued investigation into how carotenoids influence escape-response at different life-stages will provide insights into mechanistic links between nutrition and behaviour.

‘And all my children?’

2018 ◽  
Author(s):  
Charlotte Scott
Keyword(s):  
Early Modern ◽  
Life Stage ◽  
Early Modern Period ◽  
Life Stages ◽  
Cultural Imagination ◽  
Modern Period

Beginning with an exploration of the role of the child in the cultural imagination, Chapter 1 establishes the formative and revealing ways in which societies identify themselves in relation to how they treat their children. Focusing on Shakespeare and the early modern period, Chapter 1 sets out to determine the emotional, symbolic, and political registers through which children are depicted and discussed. Attending to the different life stages and representations of the child on stage, this chapter sets out the terms of the book’s enquiry: what role do children play in Shakespeare’s plays; how do we recognize them as such—age, status, parental dynamic—and what are the effects of their presence? This chapter focuses on how the early moderns understood the child, as a symbolic figure, a life stage, a form of obligation, a profound bond, and an image of servitude.

scholarly journals Cost of autotomy drives ontogenetic switching of anti-predator mechanisms under developmental constraints in a land snail

2012 ◽  
Vol 279 (1748) ◽  
pp. 4811-4816 ◽  
Author(s):  
Masaki Hoso
Keyword(s):  
High Efficiency ◽  
Shell Growth ◽  
Land Snail ◽  
Life History Strategies ◽  
Body Parts ◽  
Developmental Constraint ◽  
Developmental Constraints ◽  
Evolution Of Life ◽  
Snake Range ◽  
In The Wild

Autotomy of body parts offers various prey animals immediate benefits of survival in compensation for considerable costs. I found that a land snail Satsuma caliginosa of populations coexisting with a snail-eating snake Pareas iwasakii survived the snake predation by autotomizing its foot, whereas those out of the snake range rarely survived. Regeneration of a lost foot completed in a few weeks but imposed a delay of shell growth. Imprints of autotomy were found in greater than 10 per cent of S. caliginosa in the snake range but in only less than 1 per cent out of it, simultaneously demonstrating intense predation by the snakes and high efficiency of autotomy for surviving snake predation in the wild. However, in experiments, mature S. caliginosa performed autotomy less frequently. Instead of the costly autotomy, they can use defensive denticles on the inside of their shell apertures. Owing to the constraints from the additive growth of shells, most pulmonate snails can produce these denticles only when they have fully grown up. Thus, this developmental constraint limits the availability of the modified aperture, resulting in ontogenetic switching of the alternative defences. This study illustrates how costs of adaptation operate in the evolution of life-history strategies under developmental constraints

scholarly journals Variación en la abundancia de árboles maderables por efecto de borde en un bosque tropical subcaducifolio

2019 ◽  
Vol 97 (1) ◽  
pp. 35 ◽  
Author(s):  
Víctor Abraham Vargas-Vázquez ◽  
Crystian Sadiel Venegas-Barrera ◽  
Arturo Mora-Olivo ◽  
José Guadalupe Martínez-Ávalos ◽  
Eduardo Alanís-Rodríguez ◽  
...  
Keyword(s):  
Edge Effect ◽  
Environmental Conditions ◽  
Life Stage ◽  
Life Stages ◽  
Cedrela Odorata ◽  
Economic Implications ◽  
Bursera Simaruba ◽  
Environmental Requirements ◽  
Guazuma Ulmifolia ◽  
Favorable Conditions

<p><strong>Background: </strong>The edge effect differentially affects the species in their life stages. We analyzed the environmental conditions associated with the abundance by life stage of four species of timber trees on the edge of a subdeciduous tropical forest.<strong></strong></p><p><strong>Hypothesis:</strong> The edges have higher light incidence and temperature, favorable conditions for the seedlings, so it is expected that the edge will have more abundance of seedlings with respect to the forest interior.</p><p><strong>Species under study:</strong> <em>Bursera simaruba</em> (L.) Sarg.<em>, Cedrela odorata</em> L.<em>, Guazuma ulmifolia </em>Lam.<em>, Lysiloma divaricatum </em>(Jacq.) J.F. Macbr.</p><p><strong>Study site and dates:</strong> Reserva de la Biosfera "El Cielo" (Tamaulipas), Mexico. January-December 2016.</p><p><strong>Methods: </strong>The abundance by life stages and environmental conditions were quantified within the gradient. These variables were correlated, in addition the requirements between stages were contrasted and they were associated with the identified environments.</p><p><strong>Results:</strong> <em>Guazuma ulmifolia</em> showed a negative response to the edge effect, while <em>Cedrela</em> <em>odorata</em> responded positively. The environmental requirements differed between the first life stages and adults. The abundance of the seedlings was associated to conditions of higher light incidence.</p><strong>Conclusions:</strong> Environmental requirements differentially affect each life stage. The abundance of seedlings increases in conditions of higher light incidence, but not in the rest of the stages, except in <em>C. odorata</em>. The loss of cover and the consequent formation of borders can lead to a reduction in the abundance of these species, with economic implications.

scholarly journals Seed Banks Alter the Rate and Direction of Molecular Evolution in Bacillus subtilis

2021 ◽  
Author(s):  
William R. Shoemaker ◽  
Evgeniya Polezhaeva ◽  
Kenzie B. Givens ◽  
Jay T. Lennon
Keyword(s):  
Bacillus Subtilis ◽  
Molecular Evolution ◽  
Seed Bank ◽  
Negative Selection ◽  
Evolutionary Dynamics ◽  
Genetic Manipulation ◽  
Seed Banks ◽  
Rate Of Molecular Evolution ◽  
Over Time ◽  
Growth And Reproduction

Fluctuations in the availability of resources constrains the growth and reproduction of individuals, which in turn effects the evolution of their respective populations. Many organisms are able to respond to fluctuations by entering a reversible state of reduced metabolic activity, a phenomenon known as dormancy. This pool of dormant individuals (i.e., a seed bank) does not reproduce and is expected to act as an evolutionary buffer, though it is difficult to observe this effect directly over an extended evolutionary timescale. Through genetic manipulation, we analyze the molecular evolutionary dynamics of Bacillus subtilis populations in the presence and absence of a seed bank over 700 days. We find that the ability to enter a dormant state increases the accumulation of genetic diversity over time and alters the trajectory of mutations, findings that are recapitulated using simulations based on a simple mathematical model. While the ability to form a seed bank does not alter the degree of negative selection, we find that it consistently alters the direction of molecular evolution across genes. Together, these results show that the ability to form a seed bank affects the direction and rate of molecular evolution over an extended evolutionary timescale.

scholarly journals Bile acid production is life-stage and sex-dependent and affected by primer pheromones in the sea lamprey

2021 ◽  
pp. jeb.229476
Author(s):  
Yu-Wen Chung-Davidson ◽  
Ugo Bussy ◽  
Skye D. Fissette ◽  
Anne M. Scott ◽  
Weiming Li
Keyword(s):  
Bile Salt ◽  
Bile Salts ◽  
Life Stage ◽  
Sea Lamprey ◽  
Life Stages ◽  
Pheromone Production ◽  
Primer Pheromone ◽  
Petromyzonol Sulfate ◽  
Sea Lampreys ◽  
Primer Pheromones

Pheromonal bile salts are important for sea lampreys (Petromyzon marinus Linnaeus) to complete their life cycle. The synthesis and release of a releaser/primer pheromone 3-keto petromyzonol sulfate (3kPZS) by spermiating males have been well characterized. 3kPZS evokes sexual behaviors in ovulatory females, induces immediate 3kPZS release in spermiating males, and elicits neuroendocrine responses in prespawning adults. Another primer pheromone released by spermiating males, 3-keto allocholic acid (3kACA), antagonizes the neuroendocrine effects of 3kPZS in prespermiating males. However, the effects of 3kACA and 3kPZS on pheromone production in prespawning adults is unclear. To understand the foundation of pheromone production, we examined sea lamprey bile salt levels at different life stages. To investigate the priming effects of 3kACA and 3kPZS, we exposed prespawning adults with vehicle or synthetic 3kACA or 3kPZS. We hypothesized that endogenous bile salt levels were life-stage and sex-dependent, and differentially affected by 3kACA and 3kPZS in prespawning adults. Using ultra-performance liquid chromatography tandem mass spectrometry, we found that sea lampreys contained distinct mixtures of bile salts in the liver and plasma at different life stages. Males usually contained higher amounts of bile salts than females. Petromyzonamine disulfate was the most abundant C27 bile salt and petromyzonol sulfate was the most abundant C24 bile salt. Waterborne 3kACA and 3kPZS exerted differential effects on bile salt production in the liver and gill, their circulation and clearance in the plasma, and their release into water. We conclude that bile salt levels are life-stage and sex-dependent and differentially affected by primer pheromones.

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