Tales of lizard tails: effects of tail autotomy on subsequent survival and growth of free-ranging hatchling Uta stansburiana

1997 ◽  
Vol 75 (4) ◽  
pp. 542-548 ◽  
Author(s):  
P. H. Niewiarowski ◽  
J. D. Congdon ◽  
A. E. Dunham ◽  
L. J. Vitt ◽  
D. W. Tinkle
Keyword(s):  
Natural Populations ◽  
Reproductive Investment ◽  
Experimental Manipulation ◽  
Costs And Benefits ◽  
Growth And Survival ◽  
Large Sample ◽  
Uta Stansburiana ◽  
Tail Autotomy ◽  
Trade Offs ◽  
Free Ranging

Potential costs and benefits of tail autotomy in lizards have been inferred almost exclusively from experimental study in semi-natural enclosures and from indirect comparative evidence from natural populations. We present complementary evidence of the costs of tail autotomy to the lizard Uta stansburiana from detailed demographic study of a natural population. On initial capture, we broke the tails of a large sample of free-ranging hatchlings (560) and left the tails of another large sample (455) intact, and then followed subsequent hatchling growth and survival over a 3-year period. Surprisingly, in 1 out of the 3 years of study, survival of female hatchlings with broken tails exceeded that of female hatchlings with intact tails. Furthermore, no effects of tail loss on survivorship were detected for male hatchlings. However, in 2 years when recaptures were very frequent (1961, 1962), growth rates of hatchlings with broken tails were significantly slower than those of their counterparts with intact tails. We discuss our results in the broader context of estimating the relative costs and benefits of tail autotomy in natural populations, and suggest that long-term demographic studies will provide the best opportunity to assess realized fitness costs and benefits with minimum bias. We also describe how experimentally induced tail autotomy can be used as a technique to complement experimental manipulation of reproductive investment in the study of life-history trade-offs.

Effect of body size, age and timing of breeding on clutch and egg size of female Eastern Gray Treefrogs, Hyla versicolor

2021 ◽  
pp. 1-11
Author(s):  
Gerlinde Höbel ◽  
Robb Kolodziej ◽  
Dustin Nelson ◽  
Christopher White
Keyword(s):  
Life History ◽  
Egg Size ◽  
Life History Theory ◽  
Reproductive Investment ◽  
Ecological Factors ◽  
Hyla Versicolor ◽  
Growth And Survival ◽  
Factors Affecting ◽  
Trade Offs ◽  
Gray Treefrogs

Abstract Information on how organisms allocate resources to reproduction is critical for understanding population dynamics. We collected clutch size (fecundity) and egg size data of female Eastern Gray Treefrogs, Hyla versicolor, and examined whether observed patterns of resource allocation are best explained by expectations arising from life history theory or by expected survival and growth benefits of breeding earlier. Female Hyla versicolor showed high between-individual variation in clutch and egg size. We did not observe maternal allocation trade-offs (size vs number; growth vs reproduction) predicted from life history theory, which we attribute to the large between-female variation in resource availability, and the low survival and post-maturity growth rate observed in the study population. Rather, clutches are larger at the beginning of the breeding season, and this variation in reproductive investment aligns with seasonal variation in ecological factors affecting offspring growth and survival.

scholarly journals The costs of standardized apprenticeship curricula for training firms

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Jürg Schweri ◽  
Manuel Aepli ◽  
Andreas Kuhn
Keyword(s):  
Regulatory Element ◽  
Recent Survey ◽  
Skills Development ◽  
Costs And Benefits ◽  
Apprenticeship Training ◽  
Training Costs ◽  
Trade Offs ◽  
Training Content ◽  
Productive Process ◽  
Productive Output

AbstractStandardized curricula define the set of skills that must be trained within a training occupation and thus are a key regulatory element of apprenticeship systems. Although clear economic rationales support the usage of such curricula, they necessarily impose costs, especially on firms that train apprentices, but do not use the full set of skills in their productive process and/or train other skills that are not covered by the curriculum. In this paper, we identify the trade-offs involved in setting up training curricula and use data from the most recent survey on the costs and benefits of apprenticeship training among Swiss firms to quantify the associated costs to training firms. On average, training firms state that they do not use 17% of the training content prescribed by the relevant curriculum, and 11% of the companies train additional skills not covered by the curriculum. We show that both kinds of misfit are associated with higher training costs and lower productive output from apprentices. This shows that the regulator imposes costs on firms in order to guarantee broad skills development for apprentices. It also cautions against overly broad curricula that may impose disproportionate costs on firms.

Sex ratio and life history traits at reaching sexual maturity in the dioecious shrub Fuchsia parviflora: field and common garden experiments

2021 ◽  
pp. 1-6
Author(s):  
Jessica S. Ambriz ◽  
Clementina González ◽  
Eduardo Cuevas
Keyword(s):  
Natural Population ◽  
Sexual Maturity ◽  
Sex Ratios ◽  
Natural Populations ◽  
Common Garden ◽  
Common Garden Experiment ◽  
Trade Offs ◽  
Reproductive Biomass ◽  
Common Garden Experiments ◽  
Growth And Reproduction

Abstract Fuchsia parviflora is a dioecious shrub that depends on biotic pollination for reproduction. Previous studies suggest that the male plants produce more flowers, and male-biased sex ratios have been found in some natural populations. To assess whether the biased sex ratios found between genders in natural populations are present at the point at which plants reach sexual maturity, and to identify possible trade-offs between growth and reproduction, we performed a common garden experiment. Finally, to complement the information of the common garden experiment, we estimated the reproductive biomass allocation between genders in one natural population. Sex ratios at reaching sexual maturity in F. parviflora did not differ from 0.5, except in one population, which was the smallest seedling population. We found no differences between genders in terms of the probability of germination or flowering. When flowering began, female plants were taller than males and the tallest plants of both genders required more time to reach sexual maturity. Males produced significantly more flowers than females, and the number of flowers increased with plant height in both genders. Finally, in the natural population studied, the investment in reproductive biomass was seven-fold greater in female plants than in male plants. Our results showed no evidence of possible trade-offs between growth and reproduction. Despite the fact that female plants invest more in reproductive biomass, they were taller than the males after flowering, possibly at the expense of herbivory defence.

scholarly journals Adult body growth and reproductive investment vary markedly within and across Atlantic and Pacific herring: a meta-analysis and review of 26 stocks

2021 ◽  
Author(s):  
Thassya C. dos Santos Schmidt ◽  
Doug E. Hay ◽  
Svein Sundby ◽  
Jennifer A. Devine ◽  
Guðmundur J. Óskarsson ◽  
...  
Keyword(s):  
Egg Size ◽  
Meta Analysis ◽  
Reproductive Investment ◽  
Body Growth ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Atlantic Herring ◽  
Additional Information ◽  
Trade Offs ◽  
Investment In Reproduction

AbstractLife-history traits of Pacific (Clupea pallasii) and Atlantic (Clupea harengus) herring, comprising both local and oceanic stocks subdivided into summer-autumn and spring spawners, were extensively reviewed. The main parameters investigated were body growth, condition, and reproductive investment. Body size of Pacific herring increased with increasing latitude. This pattern was inconsistent for Atlantic herring. Pacific and local Norwegian herring showed comparable body conditions, whereas oceanic Atlantic herring generally appeared stouter. Among Atlantic herring, summer and autumn spawners produced many small eggs compared to spring spawners, which had fewer but larger eggs—findings agreeing with statements given several decades ago. The 26 herring stocks we analysed, when combined across distant waters, showed clear evidence of a trade-off between fecundity and egg size. The size-specific individual variation, often ignored, was substantial. Additional information on biometrics clarified that oceanic stocks were generally larger and had longer life spans than local herring stocks, probably related to their longer feeding migrations. Body condition was only weakly, positively related to assumingly in situ annual temperatures (0–30 m depth). Contrarily, body growth (cm × y−1), taken as an integrator of ambient environmental conditions, closely reflected the extent of investment in reproduction. Overall, Pacific and local Norwegian herring tended to cluster based on morphometric and reproductive features, whereas oceanic Atlantic herring clustered separately. Our work underlines that herring stocks are uniquely adapted to their habitats in terms of trade-offs between fecundity and egg size whereas reproductive investment mimics the productivity of the water in question.

scholarly journals Between Market Failures and Justice Failures: Trade-Offs Between Efficiency and Equality in Business Ethics

2021 ◽  
Author(s):  
Charlie Blunden
Keyword(s):  
Business Ethics ◽  
Private Firms ◽  
Market Failures ◽  
Costs And Benefits ◽  
Trade Offs ◽  
Efficiency Losses ◽  
Different Types ◽  
Hybrid Theory ◽  
Market Failures Approach ◽  
Ethical Obligations

AbstractThe Market Failures Approach (MFA) is one of the leading theories in contemporary business ethics. It generates a list of ethical obligations for the managers of private firms that states that they should not create or exploit market failures because doing so reduces the efficiency of the economy. Recently the MFA has been criticised by Abraham Singer on the basis that it unjustifiably does not assign private managers obligations based on egalitarian values. Singer proposes an extension to the MFA, the Justice Failures Approach (JFA), in which managers have duties to alleviate political, social, and distributive inequalities in addition to having obligations to not exploit market failures. In this paper I describe the MFA and JFA and situate them relative to each other. I then highlight a threefold distinction between different types of obligations that can be given to private managers in order to argue that a hybrid theory of business ethics, which I call the MFA + , can be generated by arguing that managers have obligations based on efficiency and duties based on equality to the extent that these latter obligations do not lead to efficiency losses. This argument suggests a novel theoretical option in business ethics, elucidates the issues that are at stake between the MFA and the JFA, and clarifies the costs and benefits of each theory.

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 Genome-wide shifts in climate-related variation underpin responses to selective breeding in a widespread conifer

2021 ◽  
Vol 118 (10) ◽  
pp. e2016900118
Author(s):  
Ian R. MacLachlan ◽  
Tegan K. McDonald ◽  
Brandon M. Lind ◽  
Loren H. Rieseberg ◽  
Sam Yeaman ◽  
...  
Keyword(s):  
Gene Flow ◽  
Selective Breeding ◽  
Natural Populations ◽  
Cold Injury ◽  
Nucleotide Polymorphisms ◽  
Phenotypic Differences ◽  
Climatic Regions ◽  
Breeding Populations ◽  
Trade Offs ◽  
Growth Initiation

Locally adapted temperate tree populations exhibit genetic trade-offs among climate-related traits that can be exacerbated by selective breeding and are challenging to manage under climate change. To inform climatically adaptive forest management, we investigated the genetic architecture and impacts of selective breeding on four climate-related traits in 105 natural and 20 selectively bred lodgepole pine populations from western Canada. Growth, cold injury, growth initiation, and growth cessation phenotypes were tested for associations with 18,600 single-nucleotide polymorphisms (SNPs) in natural populations to identify “positive effect alleles” (PEAs). The effects of artificial selection for faster growth on the frequency of PEAs associated with each trait were quantified in breeding populations from different climates. Substantial shifts in PEA proportions and frequencies were observed across many loci after two generations of selective breeding for height, and responses of phenology-associated PEAs differed strongly among climatic regions. Extensive genetic overlap was evident among traits. Alleles most strongly associated with greater height were often associated with greater cold injury and delayed phenology, although it is unclear whether potential trade-offs arose directly from pleiotropy or indirectly via genetic linkage. Modest variation in multilocus PEA frequencies among populations was associated with large phenotypic differences and strong climatic gradients, providing support for assisted gene flow polices. Relationships among genotypes, phenotypes, and climate in natural populations were maintained or strengthened by selective breeding. However, future adaptive phenotypes and assisted gene flow may be compromised if selective breeding further increases the PEA frequencies of SNPs involved in adaptive trade-offs among climate-related traits.

scholarly journals Introduction. Antarctic ecology: from genes to ecosystems. Part 2. Evolution, diversity and functional ecology

2007 ◽  
Vol 362 (1488) ◽  
pp. 2187-2189 ◽  
Author(s):  
Alex D Rogers ◽  
Eugene J Murphy ◽  
Nadine M Johnston ◽  
Andrew Clarke
Keyword(s):  
Climate Change ◽  
Life Histories ◽  
Natural Populations ◽  
Environmental Parameters ◽  
Functional Ecology ◽  
Antarctic Species ◽  
Trade Offs ◽  
Genes To Ecosystems ◽  
Micro Organisms ◽  
The Antarctic

The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.

Ecological immunology

2021 ◽  
pp. 109-142
Author(s):  
Paul Schmid-Hempel
Keyword(s):  
Energy Consumption ◽  
Natural Selection ◽  
Ecological Immunology ◽  
Costs And Benefits ◽  
Response Delay ◽  
Genetic Covariance ◽  
Trade Offs ◽  
Immunological Factors ◽  
Immune Defences

Infections and parasite loads vary among hosts. Variation results from ecological, genetic, and immunological factors. Immune defences provide benefits as well as costs and are, therefore, a compromise. Costs result from trade-offs with other needs and can be genetically encoded or plastic (i.e. can change depending on circumstances). Costs are physiological (e.g. energy consumption) or based on evolved genetic covariance. Self-damage (immunopathology) is a further, important cost. Natural selection should optimize the costs and benefits of defences and thus leads to various outcomes in terms of specificity, response delay and strength, or the formation of memory. Moreover, hosts can either resist an infection by eventual clearance, or tolerate the consequences of parasitism.

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