scholarly journals Local variation in endoparasite intensities of bank voles (Clethrionomys glareolus) from ecologically similar sites: morphometric and endocrine correlates

2002 ◽  
Vol 76 (2) ◽  
pp. 103-112 ◽  
Author(s):  
C.J. Barnard ◽  
J.M. Behnke ◽  
A. Bajer ◽  
D. Bray ◽  
T. Race ◽  
...  
Keyword(s):  
Life History ◽  
Adrenal Gland ◽  
Local Variation ◽  
Clethrionomys Glareolus ◽  
Endocrine Function ◽  
Life History Variation ◽  
Gland Weight ◽  
Bank Voles ◽  
Adrenal Gland Weight ◽  
Trade Offs

AbstractMuch interest has centred recently on the role of adaptive trade-offs between the immune system and other components of life history in determining resistance and parasite intensities among hosts. Steroid hormones, particularly glucocorticoids and sex steroids, provide a plausible mechanism for mediating such trade-offs. A basic assumption behind the hypothesis, however, is that steroid activity will generally correlate with reduced resistance and thus greater parasite intensities. Here, we present some findings from a field study of bank voles (Clethrionomys glareolus) in which we have looked at associations between parasite intensities, anatomical and morphometric measures relating to endocrine function and life history variation in three local populations inhabiting similar but mutually isolated woodland habitats. In general, sites with greater parasite intensities were those in which male C. glareolus had significantly larger adrenal glands, testes and seminal vesicles for their age and body size. Females also showed a site difference in adrenal gland weight. Some aspects of site-related parasite intensity were associated with asymmetry in adrenal gland weight and hind foot length, which may have reflected developmental effects on glucocorticoid activity.

Local variation in helminth burdens of bank voles (Clethrionomys glareolus) from ecologically similar sites: temporal stability and relationships with hormone concentrations and social behaviour

2003 ◽  
Vol 77 (3) ◽  
pp. 185-195 ◽  
Author(s):  
C.J. Barnard ◽  
K. Kulis ◽  
J.M. Behnke ◽  
A. Bajer ◽  
J. Gromadzka-Ostrowska ◽  
...  
Keyword(s):  
Helminth Infection ◽  
Temporal Stability ◽  
Negative Relationship ◽  
Infection Intensity ◽  
Local Variation ◽  
Clethrionomys Glareolus ◽  
Fragmented Forest ◽  
North East ◽  
Gland Weight ◽  
Bank Voles

AbstractPopulations of bank voles (Clethrionomys glareolus) in a fragmented forest habitat in north-east Poland showed local differences in helminth infection intensity, morphometric measures and organ weights that were consistent with differences at the same locations two years previously. Although overall intensities of infection were lower than previously, and there were some differences in the relative intensities of individual helminth species, site differences remained significant and were consistent across replicated subsites. In keeping with site differences in helminth infection and adrenal gland weight and asymmetry, voles at site 1 (high intensity infection) had higher circulating concentrations of corticosterone than those at site 2 (low intensity infection). Since males were sampled outside the breeding season, and thus non-scrotal, testosterone levels were low and did not differ between sites. As previously, voles at site 1 also showed greater hind foot asymmetry. Dyadic interactions between males from the same and different sites in the laboratory showed that males from site 1 were significantly less aggressive, especially when confronted with intruder males from site 2. There was no relationship between aggressiveness and intensity of infection overall or at site 1, but a significant negative relationship emerged at site 2. Aggression thus appeared to be downregulated at the higher intensity site independently of individual levels of infection. Terminal corticosterone concentrations were greater at site 1 and lower among residents that initiated more aggression. While corticosterone concentrations rose over the period of testing, they did not correlate with the amount of aggression initiated or received.

scholarly journals Dietary sodium manipulation during critical periods in development sensitize adult offspring to amphetamines

2008 ◽  
Vol 295 (3) ◽  
pp. R899-R905 ◽  
Author(s):  
Shawna M. McBride ◽  
Bruce Culver ◽  
Francis W. Flynn
Keyword(s):  
Adrenal Gland ◽  
Open Field ◽  
Postnatal Period ◽  
Early Postnatal Period ◽  
Dietary Sodium ◽  
Critical Periods ◽  
Open Field Behavior ◽  
High Sodium ◽  
Gland Weight ◽  
Adrenal Gland Weight

This study examined critical periods in development to determine when offspring were most susceptible to dietary sodium manipulation leading to amphetamine sensitization. Wistar dams ( n = 6–8/group) were fed chow containing low (0.12% NaCl; LN), normal (1% NaCl; NN), or high sodium (4% NaCl; HN) during the prenatal or early postnatal period (birth to 5 wk). Offspring were fed normal chow thereafter until testing at 6 mo. Body weight (BW), blood pressure (BP), fluid intake, salt preference, response to amphetamine, open field behavior, plasma adrenocorticotropin hormone (ACTH), plasma corticosterone (Cort), and adrenal gland weight were measured. BW was similar for all offspring. Offspring from the prenatal and postnatal HN group had increased BP, NaCl intake, and salt preference and decreased water intake relative to NN offspring. Prenatal HN offspring had greater BP than postnatal HN offspring. In response to amphetamine, both prenatal and postnatal LN and HN offspring had increased locomotor behavior compared with NN offspring. In a novel open field environment, locomotion was also increased in prenatal and postnatal LN and HN offspring compared with NN offspring. ACTH and Cort levels 30 min after restraint stress and adrenal gland weight measurement were greater in LN and HN offspring compared with NN offspring. These results indicate that early life experience with low- and high-sodium diets, during the prenatal or early postnatal period, is a stress that produces long-term changes in responsiveness to amphetamines and to subsequent stressors.

Effect of in Vivo Treatment with Delta9-THC on Mice Adrenal Gland

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
E. Moura ◽  
C. Esteves-Pinto ◽  
M.P. Serrão ◽  
I. Azevedo ◽  
M. Vieira-Coelho
Keyword(s):  
Adrenal Gland ◽  
Hpa Axis ◽  
Chronic Administration ◽  
Test Results ◽  
Gland Weight ◽  
Adrenal Gland Weight ◽  
Reduce Activity ◽  
Student’S T ◽  
Student’S T Test

Introduction:The efficacy of antidepressants has been linked in part to their ability to reduce activity of the hypothalamic-pituitary-adrenal (HPA) axis; however, the mechanism by which antidepressants regulate the HPA axis is largely unknown. Recent research has demonstrated that endocannabinoids can regulate the HPA axis and exhibit antidepressant potential.Aim:The purpose of this study was therefore to evaluate the effect of chronic administration of delta-9-tetrahydrocannabinol (delta9-THC) on the adrenal gland of mice.Methods:Delta9-THC (10 mg/kg, 1 THC:1 chremophor:18 saline) or vehicle (CT, 1 chremophor:18 saline) was administered i.p. for 10 days to C57Bl6 mice aged 15 weeks. At the end of the study rats were placed in metabolic cages. Noradrenaline (NA) and adrenaline (AD) levels in samples and tissues were evaluated by HPLC-ED. Statistical analysis was done by ANOVA followed by Student's t test. Results are presented as mean±SEM.Results:Treatment with delta9-THC did not produce changes in mice weight (CT: 25±1; delta9-THC: 24±1 g, n=5-6) but produced a significant reduction in adrenal gland weight (CT: 1.4±0.2; delta9-THC: 0.6±0.1* mg, n=5-6, *P˂0.01). However, treatment with delta9-THC did not produce significant changes in NA and AD adrenal content (NA: 7.5±2.1, 5.3±0.6; AD: 14.1±1.1, 11.1±2.1 nmol, CT and delta9-THC respectively, n=5-6) or in NA and AD urine levels (NA: 0.88±0.06, 1.18±0.17; AD: 0.64±0.07, 0.81±0.09 nmol/24h, CT and delta9-THC respectively, n=5-6).Conclusion:Chronic treatment with delta9-THC reduces adrenal gland weight in mice. These results suggest that endocannabinoids may act directly at the adrenal gland to regulate the HPA axis.

scholarly journals The influence of juvenile and adult environments on life-history trajectories

2005 ◽  
Vol 273 (1587) ◽  
pp. 741-750 ◽  
Author(s):  
Barbara Taborsky
Keyword(s):  
Life History ◽  
Life Histories ◽  
Adult Life ◽  
Growth Conditions ◽  
Offspring Size ◽  
Juvenile Growth ◽  
Life History Variation ◽  
Major Life ◽  
Adult Growth ◽  
Trade Offs

There is increasing evidence that the environment experienced early in life can strongly influence adult life histories. It is largely unknown, however, how past and present conditions influence suites of life-history traits regarding major life-history trade-offs. Especially in animals with indeterminate growth, we may expect that environmental conditions of juveniles and adults independently or interactively influence the life-history trade-off between growth and reproduction after maturation. Juvenile growth conditions may initiate a feedback loop determining adult allocation patterns, triggered by size-dependent mortality risk. I tested this possibility in a long-term growth experiment with mouthbrooding cichlids. Females were raised either on a high-food or low-food diet. After maturation half of them were switched to the opposite treatment, while the other half remained unchanged. Adult growth was determined by current resource availability, but key reproductive traits like reproductive rate and offspring size were only influenced by juvenile growth conditions, irrespective of the ration received as adults. Moreover, the allocation of resources to growth versus reproduction and to offspring number versus size were shaped by juvenile rather than adult ecology. These results indicate that early individual history must be considered when analysing causes of life-history variation in natural populations.

scholarly journals An ontogenetic perspective on individual differences

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151050 ◽  
Author(s):  
Nathan R. Senner ◽  
Jesse R. Conklin ◽  
Theunis Piersma
Keyword(s):  
Life History ◽  
Individual Differences ◽  
Functional Trait ◽  
Life History Variation ◽  
Phenotypic Differences ◽  
Developmental Context ◽  
Critical Gap ◽  
Trade Offs ◽  
Fitness Consequences ◽  
Timing Of Onset

Phenotypic differences among individuals can arise during any stage of life. Although several distinct processes underlying individual differences have been defined and studied (e.g. parental effects, senescence), we lack an explicit, unified perspective for understanding how these processes contribute separately and synergistically to observed variation in functional traits. We propose a conceptual framework based on a developmental view of life-history variation, linking each ontogenetic stage with the types of individual differences originating during that period. In our view, the salient differences among these types are encapsulated by three key criteria: timing of onset, when fitness consequences are realized, and potential for reversibility. To fill a critical gap in this framework, we formulate a new term to refer to individual differences generated during adulthood—reversible state effects. We define these as ‘reversible changes in a functional trait resulting from life-history trade-offs during adulthood that affect fitness’, highlighting how the adult phenotype can be repeatedly altered in response to environmental variation. Defining individual differences in terms of trade-offs allows explicit predictions regarding when and where fitness consequences should be expected. Moreover, viewing individual differences in a developmental context highlights how different processes can work in concert to shape phenotype and fitness, and lays a foundation for research linking individual differences to ecological and evolutionary theory.

scholarly journals Causes and consequences of life-history variation in North American stocks of Pacific cod

2008 ◽  
Vol 66 (2) ◽  
pp. 349-357 ◽  
Author(s):  
Olav A. Ormseth ◽  
Brenda L. Norcross
Keyword(s):  
Life History ◽  
North American ◽  
Egg Production ◽  
Atlantic Cod ◽  
North Pacific Ocean ◽  
Life History Strategies ◽  
Lifetime Reproductive Success ◽  
Life History Variation ◽  
Pacific Cod ◽  
Trade Offs

Abstract Ormseth, O. A., and Norcross, B. L. 2009. Causes and consequences of life-history variation in North American stocks of Pacific cod. – ICES Journal of Marine Science, 66: 349–357. Life-history strategies of four Pacific cod (Gadus macrocephalus) stocks in the eastern North Pacific Ocean are outlined. Southern stocks grew and matured quicker, but reached smaller maximum size and had shorter lifespans than northern stocks. The trade-offs resulted in similar lifetime reproductive success among all stocks. Growth was highly dependent on latitude, but not on temperature, possibly because of differences in the duration of the growing season. Comparisons with Atlantic cod (Gadus morhua) revealed similar latitude/growth relationships among Atlantic cod stocks grouped by geographic region. In Pacific cod, greater size and longevity in the north appeared to be adaptations to overcome environmental constraints on growth and to maintain fitness. An egg production-per-recruit model suggested that the life-history strategy of northern Pacific cod stocks made them less resilient to fishing activity and age truncation than southern stocks.

scholarly journals Life history variation is maintained by fitness trade-offs and negative frequency-dependent selection

2018 ◽  
Vol 115 (17) ◽  
pp. 4441-4446 ◽  
Author(s):  
Mark R. Christie ◽  
Gordon G. McNickle ◽  
Rod A. French ◽  
Michael S. Blouin
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Life History Strategies ◽  
Lifetime Reproductive Success ◽  
Life History Variation ◽  
Additional Energy ◽  
Frequency Dependent ◽  
Frequency Dependent Selection ◽  
Trade Offs ◽  
Negative Frequency Dependent Selection

The maintenance of diverse life history strategies within and among species remains a fundamental question in ecology and evolutionary biology. By using a near-complete 16-year pedigree of 12,579 winter-run steelhead (Oncorhynchus mykiss) from the Hood River, Oregon, we examined the continued maintenance of two life history traits: the number of lifetime spawning events (semelparous vs. iteroparous) and age at first spawning (2–5 years). We found that repeat-spawning fish had more than 2.5 times the lifetime reproductive success of single-spawning fish. However, first-time repeat-spawning fish had significantly lower reproductive success than single-spawning fish of the same age, suggesting that repeat-spawning fish forego early reproduction to devote additional energy to continued survival. For single-spawning fish, we also found evidence for a fitness trade-off for age at spawning: older, larger males had higher reproductive success than younger, smaller males. For females, in contrast, we found that 3-year-old fish had the highest mean lifetime reproductive success despite the observation that 4- and 5-year-old fish were both longer and heavier. This phenomenon was explained by negative frequency-dependent selection: as 4- and 5-year-old fish decreased in frequency on the spawning grounds, their lifetime reproductive success became greater than that of the 3-year-old fish. Using a combination of mathematical and individual-based models parameterized with our empirical estimates, we demonstrate that both fitness trade-offs and negative frequency-dependent selection observed in the empirical data can theoretically maintain the diverse life history strategies found in this population.

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