scholarly journals The life-history trade-off between fertility and child survival

2012 ◽  
Vol 279 (1748) ◽  
pp. 4755-4764 ◽  
Author(s):  
David W. Lawson ◽  
Alexandra Alvergne ◽  
Mhairi A. Gibson
Keyword(s):  
Life History ◽  
Parental Investment ◽  
Socioeconomic Development ◽  
Child Survival ◽  
Relative Magnitude ◽  
Individual Characteristics ◽  
Human Reproduction ◽  
African Countries ◽  
Trade Off ◽  
Fertility Limitation

Evolutionary models of human reproduction argue that variation in fertility can be understood as the local optimization of a life-history trade-off between offspring quantity and ‘quality’. Child survival is a fundamental dimension of quality in these models as early-life mortality represents a crucial selective bottleneck in human evolution. This perspective is well-rehearsed, but current literature presents mixed evidence for a trade-off between fertility and child survival, and little empirical ground to evaluate how socioecological and individual characteristics influence the benefits of fertility limitation. By compiling demographic survey data, we demonstrate robust negative relationships between fertility and child survival across 27 sub-Saharan African countries. Our analyses suggest this relationship is primarily accounted for by offspring competition for parental investment, rather than by reverse causal mechanisms. We also find that the trade-off increases in relative magnitude as national mortality declines and maternal somatic (height) and extrasomatic (education) capital increase. This supports the idea that socioeconomic development, and associated reductions in extrinsic child mortality, favour reduced fertility by increasing the relative returns to parental investment. Observed fertility, however, falls considerably short of predicted optima for maximizing total offspring survivorship, strongly suggesting that additional unmeasured costs of reproduction ultimately constrain the evolution of human family size.

scholarly journals Determinants of life-history traits in a fish ectoparasite: a hierarchical analysis

Parasitology ◽  
2011 ◽  
Vol 138 (7) ◽  
pp. 848-857 ◽  
Author(s):  
G. LOOT ◽  
N. POULET ◽  
S. BROSSE ◽  
L. TUDESQUE ◽  
F. THOMAS ◽  
...  
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Size ◽  
Life History Traits ◽  
Abiotic Factors ◽  
Individual Characteristics ◽  
Trade Off ◽  
Individual Fitness ◽  
Parasite Number ◽  
Egg Number

SUMMARYObjective. Unravelling the determinants of parasite life-history traits in natural settings is complex. Here, we deciphered the relationships between biotic, abiotic factors and the variation in 4 life-history traits (body size, egg presence, egg number and egg size) in the fish ectoparasite Tracheliastes polycolpus. We then determined the factors affecting the strength of the trade-off between egg number and egg size. Methods. To do so, we used 4-level (parasite, microhabitat, host and environment) hierarchical models coupled to a field database. Results. Variation in life-history traits was mostly due to individual characteristics measured at the parasite level. At the microhabitat level (fins of fish hosts), parasite number was positively related to body size, egg presence and egg number. Higher parasite number on fins was positively associated with individual parasite fitness. At the host level, host body size was positively related to the individual fitness of the parasite; parasites were bigger and more fecund on bigger hosts. In contrast, factors measured at the environmental level had a weak influence on life-history traits. Finally, a site-dependent trade-off between egg number and egg size existed in this population. Conclusion. Our study illustrates the importance of considering parasite life-history traits in a hierarchical framework to decipher complex links between biotic, abiotic factors and parasite life-history traits.

Number and Size of Offspring

2021 ◽  
pp. 115-128
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Clutch Size ◽  
Parental Investment ◽  
Adaptive Significance ◽  
Offspring Size ◽  
Structural Constraints ◽  
Offspring Survival ◽  
Trade Off ◽  
Offspring Number ◽  
Parental Fitness

Offspring number and size are two of the most variable life-history traits. Among species, much of this variability can be attributed to genetic, developmental, physiological, or structural constraints. Some trait combinations are not possible because of differences associated with a species’ evolutionary history. Substantial variation in propagule number and size can exist among populations of the same species, generating questions concerning the adaptive significance of this variability. The most influential models are those attributed to Lack on clutch size and to Smith and Fretwell on offspring size. Fundamental to both sets of models is a trade-off between offspring number and parental investment per offspring. When offspring survival or fitness continuously varies with offspring size, the fitness of the parent depends on both offspring size and the number of offspring of that size that the parent can produce. If offspring survival is independent of offspring size, parental fitness is maximized when individuals maximize the production of minimally sized propagules.

scholarly journals The offspring quantity–quality trade-off and human fertility variation

2016 ◽  
Vol 371 (1692) ◽  
pp. 20150145 ◽  
Author(s):  
David W. Lawson ◽  
Monique Borgerhoff Mulder
Keyword(s):  
Evolutionary Ecology ◽  
Reproductive Behaviour ◽  
Low Fertility ◽  
Human Reproduction ◽  
Trade Off ◽  
Trade Offs ◽  
Human Fertility ◽  
Fertility Variation ◽  
Fertility Limitation ◽  
Economic Perspectives

The idea that trade-offs between offspring quantity and quality shape reproductive behaviour has long been central to economic perspectives on fertility. It also has a parallel and richer theoretical foundation in evolutionary ecology. We review the application of the quantity–quality trade-off concept to human reproduction, emphasizing distinctions between clutch size and lifetime fertility, and the wider set of forces contributing to fertility variation in iteroparous and sexually reproducing species like our own. We then argue that in settings approximating human evolutionary history, several factors limit costly sibling competition. Consequently, while the optimization of quantity–quality trade-offs undoubtedly shaped the evolution of human physiology setting the upper limits of reproduction, we argue it plays a modest role in accounting for socio-ecological and individual variation in fertility. Only upon entering the demographic transition can fertility limitation be clearly interpreted as strategically orientated to advancing offspring quality via increased parental investment per child, with low fertility increasing descendant socio-economic success, although not reproductive success. We conclude that existing economic and evolutionary literature has often overemphasized the centrality of quantity–quality trade-offs to human fertility variation and advocate for the development of more holistic frameworks encompassing alternative life-history trade-offs and the evolved mechanisms guiding their resolution.

Ghana: the State of Agriculture and Prospects for Food Security in the Context of Achieving SDGs

2018 ◽  
pp. 16-31
Author(s):  
Tatyana Denisova
Keyword(s):  
Food Security ◽  
Socioeconomic Development ◽  
Agricultural Sector ◽  
Well Being ◽  
The State ◽  
Successful Implementation ◽  
Careful Study ◽  
African Countries ◽  
Development Goals ◽  
The Government

For the first time in Russian African studies, the author examines the current state of agriculture, challenges and prospects for food security in Ghana, which belongs to the group of African countries that have made the most progress in achieving the Sustainable Development Goals (SDGs). The SDGs are a collection of 17 global goals adopted by UN member states in 2015 with a view of achieving them by 2030. The SDGs include: ending poverty in all its forms everywhere (Goal 1); ending hunger, achieving food security and improved nutrition, and promoting sustainable agriculture (2); ensuring healthy lives and promoting well-being for all at all ages (3), etc. These goals are considered fundamental because the achievement of a number of other SDGs – for example, ensuring quality education (4), achieving gender equality (5), ensuring sustainable consumption and production patterns (12), etc. – largely depends on their implementation. Ghana was commended by the world community for the significant reduction in poverty, hunger and malnutrition between 2000 and 2014, i.e. for the relatively successful implementation of the first of the Millennium Development Goals (MDGs, 2000–2015) – the eradication of extreme poverty and hunger. However, SDGs require more careful study and planning of implementation measures. In order to achieve the SDGs, the Government of Ghana has adopted a number of programs, plans and projects, the successful implementation of which often stumbles upon the lack of funding and lack of coordination between state bodies, private and public organizations, foreign partners – donors and creditors, etc., which are involved in the processes of socioeconomic development of Ghana. The author determines the reasons for the lack of food security in Ghana, gives an assessment of the state of the agricultural sector, the effective development of which is a prerequisite for the reduction of poverty and hunger, primarily due to the engagement of a significant share (45%) of the economically active population in this sector. The study shows that the limited growth in food production is largely due to the absence of domestic markets and necessary roads, means of transportation, irrigation and storage infrastructure, as well as insufficient investment in the agricultural sector, rather than to a shortage of fertile land or labor.

scholarly journals Transcriptomic analyses of the termite, Cryptotermes secundus, reveal a gene network underlying a long lifespan and high fecundity

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Silu Lin ◽  
Jana Werle ◽  
Judith Korb
Keyword(s):  
Life History ◽  
Social Insects ◽  
Social Communication ◽  
Gene Network ◽  
Social Insect ◽  
Nutrient Sensing ◽  
Model Organisms ◽  
Termite Species ◽  
High Fecundity ◽  
Trade Off

AbstractOrganisms are typically characterized by a trade-off between fecundity and longevity. Notable exceptions are social insects. In insect colonies, the reproducing caste (queens) outlive their non-reproducing nestmate workers by orders of magnitude and realize fecundities and lifespans unparalleled among insects. How this is achieved is not understood. Here, we identified a single module of co-expressed genes that characterized queens in the termite species Cryptotermes secundus. It encompassed genes from all essential pathways known to be involved in life-history regulation in solitary model organisms. By manipulating its endocrine component, we tested the recent hypothesis that re-wiring along the nutrient-sensing/endocrine/fecundity axis can account for the reversal of the fecundity/longevity trade-off in social insect queens. Our data from termites do not support this hypothesis. However, they revealed striking links to social communication that offer new avenues to understand the re-modelling of the fecundity/longevity trade-off in social insects.

Brand Africa – A Guidebook to Strengthen the Competitiveness of African Tourism

2021 ◽  
Author(s):  
Keyword(s):  
Socioeconomic Development ◽  
African Countries ◽  
Destination Branding ◽  
Present Book ◽  
Tourism Experience ◽  
Operational Frameworks

Africa is a diverse continent, with each of its countries endowed with unique features. This offers visitors a wide variety of opportunities to connect with different people, traditions and cultures, making for an unequaled tourism experience. The present book offers guidance on possible strategies and actions that African countries can adopt and implement with a view to strengthening their destination brands and rebuild their tourism sectors stronger. Prepared in collaboration with Africa Tourism Partners, the guidebook collects valuable insights and expertise from African national tourism organizations as well as examples of effective destination branding from Africa and beyond. It concludes with recommendations, operational frameworks and practical tools aimed at supporting African countries in advancing their branding and strengthening their competitiveness towards a stronger Brand Africa and the socioeconomic development of the continent through tourism.

scholarly journals Maternal Education, Fertility, and Child Survival in Comoros

2018 ◽  
Vol 15 (12) ◽  
pp. 2814 ◽  
Author(s):  
Abayomi Samuel Oyekale ◽  
Thonaeng Charity Maselwa
Keyword(s):  
Child Mortality ◽  
Socioeconomic Development ◽  
Formal Education ◽  
Maternal Education ◽  
Child Survival ◽  
Regression Method ◽  
Probit Regression ◽  
Two Stage ◽  
Reduce Child Mortality ◽  
Household Headship

Reduction in child mortality is a demographic progress of significant socioeconomic development relevance in Africa. This paper analyzed the effect of maternal education and fertility on child survival in the Islands of Comoros. The 2012 Demographic and Health Survey (DHS) data were used. A two-stage probit regression method was used for data analysis. The results showed that about 75% of the children’s mothers had given birth to between one and five children, while more than half did not have any form of formal education. The results of the two-stage probit regression showed that while child survival reduced significantly (p < 0.05) with the age of the heads of households, residence in the Ngazidja region, being born as twins, mother’s number of business trips, and number of marital unions, it increased with maternal education, fertility, male household headship, and the child being breastfed immediately after birth. It was concluded that efforts to enhance maternal education would reduce child mortality. It is also critical to promote child breastfeeding among women, while regional characteristics promoting differences in child mortality in Comoros Islands should be properly addressed with keen focus on the Ngazidja region.

scholarly journals Enzymatic antioxidants but not baseline glucocorticoids mediate the reproduction–survival trade-off in a wild bird

2018 ◽  
Vol 285 (1892) ◽  
pp. 20182141 ◽  
Author(s):  
Stefania Casagrande ◽  
Michaela Hau
Keyword(s):  
Life History ◽  
Body Condition ◽  
Redox State ◽  
Reproductive Investment ◽  
Redox System ◽  
Reactive Oxygen Metabolites ◽  
Enzymatic Antioxidants ◽  
Trade Off ◽  
Trade Offs ◽  
Nest Provisioning

The trade-off between reproductive investment and survival is central to life-history theory, but the relative importance and the complex interactions among the physiological mechanisms mediating it are still debated. Here we experimentally tested whether baseline glucocorticoid hormones, the redox system or their interaction mediate reproductive investment–survival trade-offs in wild great tits ( Parus major ). We increased the workload of parental males by clipping three feathers on each wing, and 5 days later determined effects on baseline corticosterone concentrations (Cort), redox state (reactive oxygen metabolites, protein carbonyls, glutathione peroxidase [GPx], total non-enzymatic antioxidants), body mass, body condition, reproductive success and survival. Feather-clipping did not affect fledgling numbers, chick body condition, nest provisioning rates or survival compared with controls. However, feather-clipped males lost mass and increased both Cort and GPx concentrations. Within feather-clipped individuals, GPx increases were positively associated with reproductive investment (i.e. male nest provisioning). Furthermore, within all individuals, males that increased GPx suffered reduced survival rates. Baseline Cort increases were related to mass loss but not to redox state, nest provisioning or male survival. Our findings provide experimental evidence that changes in the redox system are associated with the trade-off between reproductive investment and survival, while baseline Cort may support this trade-off indirectly through a link with body condition. These results also emphasize that plastic changes in individuals, rather than static levels of physiological signals, may mediate life-history trade-offs.

scholarly journals Plasmodium infection decreases fecundity and increases survival of mosquitoes

2012 ◽  
Vol 279 (1744) ◽  
pp. 4033-4041 ◽  
Author(s):  
J. Vézilier ◽  
A. Nicot ◽  
S. Gandon ◽  
A. Rivero
Keyword(s):  
Life History ◽  
Insecticide Resistance ◽  
Life History Traits ◽  
Experimental System ◽  
Adaptive Strategy ◽  
Genetic Variations ◽  
The Other ◽  
Plasmodium Infection ◽  
Trade Off ◽  
The One

Long-lived mosquitoes maximize the chances of Plasmodium transmission. Yet, in spite of decades of research, the effect of Plasmodium parasites on mosquito longevity remains highly controversial. On the one hand, many studies report shorter lifespans in infected mosquitoes. On the other hand, parallel (but separate) studies show that Plasmodium reduces fecundity and imply that this is an adaptive strategy of the parasite aimed at redirecting resources towards longevity. No study till date has, however, investigated fecundity and longevity in the same individuals to see whether this prediction holds. In this study, we follow for both fecundity and longevity in Plasmodium- infected and uninfected mosquitoes using a novel, albeit natural, experimental system. We also explore whether the genetic variations that arise through the evolution of insecticide resistance modulate the effect of Plasmodium on these two life-history traits. We show that (i) a reduction in fecundity in Plasmodium- infected mosquitoes is accompanied by an increase in longevity; (ii) this increase in longevity arises through a trade-off between reproduction and survival; and (iii) in insecticide-resistant mosquitoes, the slope of this trade-off is steeper when the mosquito is infected by Plasmodium (cost of insecticide resistance).

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