scholarly journals Androgen Elevation Accelerates Reproductive Senescence in Three-Spined Stickleback

2021 ◽  
Vol 9 ◽  
Author(s):  
Mirre J. P. Simons ◽  
Marion Sebire ◽  
Simon Verhulst ◽  
Ton G. G. Groothuis
Keyword(s):  
Vitamin E ◽  
Reproductive Effort ◽  
Negative Relationship ◽  
Life History Evolution ◽  
Reproductive Capacity ◽  
Costs Of Reproduction ◽  
Iris Color ◽  
Future Reproduction ◽  
Reproductive Activities ◽  
Breeding Coloration

Costs of reproduction shape the life-history evolution of investment in current and future reproduction and thereby aging. Androgens have been proposed to regulate the physiology governing these investments. Furthermore, androgens are hypothesized to play a central role in carotenoid-dependent sexual signaling, regulating how much carotenoids are diverted to ornamentation and away from somatic maintenance, increasing oxidative stress, and accelerating aging. We investigated these relationships in male three-spined stickleback in which we elevated 11-ketotestosterone and supplied vitamin E, an antioxidant, in a 2 × 2 design. Androgen elevation shortened the time stickleback maintained reproductive activities. We suspect that this effect is caused by 11-ketotestosterone stimulating investment in current reproduction, but we detected no evidence for this in our measurements of reproductive effort: nest building, body composition, and breeding coloration. Carotenoid-dependent coloration was even slightly decreased by 11-ketotestosterone elevation and was left unaffected by vitamin E. Red coloration correlated with life expectancy and reproductive capacity in a quadratic manner, suggesting overinvestment of the individuals exhibiting the reddest bellies. In contrast, blue iris color showed a negative relationship with survival, suggesting physiological costs of producing this aspect of nuptial coloration. In conclusion, our results support the hypothesis that androgens regulate investment in current versus future reproduction, yet the precise mechanisms remain elusive. The quadratic relationships between sexual signal expression and aspects of quality have wider consequences for how we view sexual selection on ornamentation and its relationship with aging.

scholarly journals The physiological costs of reproduction in small mammals

2007 ◽  
Vol 363 (1490) ◽  
pp. 375-398 ◽  
Author(s):  
John R Speakman
Keyword(s):  
Life History ◽  
Small Mammals ◽  
Morphological Changes ◽  
Life History Evolution ◽  
Indirect Costs ◽  
Direct Costs ◽  
Costs Of Reproduction ◽  
Dominant Component ◽  
Trade Offs ◽  
Almost All

Life-history trade-offs between components of fitness arise because reproduction entails both gains and costs. Costs of reproduction can be divided into ecological and physiological costs. The latter have been rarely studied yet are probably a dominant component of the effect. A deeper understanding of life-history evolution will only come about once these physiological costs are better understood. Physiological costs may be direct or indirect. Direct costs include the energy and nutrient demands of the reproductive event, and the morphological changes that are necessary to facilitate achieving these demands. Indirect costs may be optional ‘compensatory costs’ whereby the animal chooses to reduce investment in some other aspect of its physiology to maximize the input of resource to reproduction. Such costs may be distinguished from consequential costs that are an inescapable consequence of the reproductive event. In small mammals, the direct costs of reproduction involve increased energy, protein and calcium demands during pregnancy, but most particularly during lactation. Organ remodelling is necessary to achieve the high demands of lactation and involves growth of the alimentary tract and associated organs such as the liver and pancreas. Compensatory indirect costs include reductions in thermogenesis, immune function and physical activity. Obligatory consequential costs include hyperthermia, bone loss, disruption of sleep patterns and oxidative stress. This is unlikely to be a complete list. Our knowledge of these physiological costs is currently at best described as rudimentary. For some, we do not even know whether they are compensatory or obligatory. For almost all of them, we have no idea of exact mechanisms or how these costs translate into fitness trade-offs.

Reproductive effort and costs of reproduction in female European ground squirrels

Oecologia ◽  
1999 ◽  
Vol 121 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Susanne Huber ◽  
Eva Millesi ◽  
Manfred Walzl ◽  
John Dittami ◽  
Walter Arnold
Keyword(s):  
Reproductive Effort ◽  
Ground Squirrels ◽  
Costs Of Reproduction

Meristem allocation and life-history evolution in herbaceous plants

2006 ◽  
Vol 84 (1) ◽  
pp. 143-150 ◽  
Author(s):  
Stephen P. Bonser ◽  
Lonnie W. Aarssen
Keyword(s):  
Life History ◽  
Apical Dominance ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Meristem Development ◽  
Vegetative Traits ◽  
History Evolution ◽  
Meristem Allocation ◽  
Branching Intensity ◽  
Iteroparous Species

Generalisations of life histories in plants are often framed in terms of allocation to reproduction. For example, relative allocation to reproduction is commonly found to be higher in semelparous than in iteroparous plant species. However, the association between vegetative traits and life history has been largely unexplored. In higher plants, reproductive and vegetative function can be measured in terms of meristem allocation. Under this approach, two vegetative traits (apical dominance (the suppression of axillary meristem development) and branching intensity (the commitment of axillary meristems to branches)) can be measured as well as one reproductive trait (reproductive effort). We used phylogenetically independent contrasts to compare reproductive and vegetative function in annual semelparous and perennial iteroparous species. Twenty congeneric species pairs (each species pair represented by one semelparous and one iteroparous species) across nine families were selected based on availability of herbarium specimens. Semelparous life-history evolution was associated with higher reproductive effort. Conversely, iteroparous life-history evolution was associated with higher apical dominance. Branching intensity was not associated with life history. An evolutionary association between life history and apical dominance but not branching intensity suggests a complex relationship between allocation to vegetative traits and the evolution of plant strategies across environments.

Intraspecific variation in reproductive effort by female Parapediasia teterrella (Lepidoptera: Pyralidae) and its relation to body size

1990 ◽  
Vol 68 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Larry D. Marshall
Keyword(s):  
Life History ◽  
Body Size ◽  
Egg Production ◽  
Egg Size ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Parameters ◽  
Trade Offs ◽  
Egg Number ◽  
Lepidoptera Pyralidae

Daily egg production of the moth Parapediasia teterrella declined over the life-span of the female but egg size remained constant. The absence of water resulted in lower fecundity and early mortality. Egg size and lifetime fecundity showed considerable inter-individual variation and large females produced more and larger eggs than their smaller counterparts. Large females expended greater reproductive effort than small females. Hatching success was negatively related to egg size. In spite of this, large females laying large eggs had higher fitness than small females. I postulate that multiple reproductive strategies within a species, resulting from differences in reproductive effort expended, may explain why expected trade-offs in reproductive parameters (e.g., egg size versus egg number) were not found in this species. Furthermore, I argue that the prevalent interpretation of life-history evolution (that body size is the important determining parameter of life-history parameters) may reflect correlation of body size with reproductive effort, and reproductive effort may be more important in determining the nature of trade-offs between reproductive parameters.

Reproductive Effort and Costs

2021 ◽  
pp. 59-74
Author(s):  
Jeffrey A. Hutchings
Keyword(s):  
Life History ◽  
Reproductive Success ◽  
Total Energy ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Costs ◽  
Positive Outcomes ◽  
Differential Allocation ◽  
Trade Offs ◽  
Potential Benefits

Predictions about life-history evolution are intellectually bereft without a consideration of trade-offs. Benefits derived from making one life-history ‘decision’ are made at a cost of not realizing potential benefits associated with alternative decisions. These trade-offs are the inevitable product of constraints, often driven by an individual’s differential allocation of fixed resources to reproduction versus survival or growth. These allocations prevent multiple positive outcomes from being simultaneously realized. Reproductive effort is the proportion of total energy or resources allocated to all elements of reproduction. Reproductive effort generates reproductive costs. Increases in current reproductive effort reduce future reproductive success by affecting survival, growth, and/or fecundity. The causal mechanisms of these costs can be energetic, ecological, behavioural, or genetic. Evidence for reproductive costs is widespread. Instances where the evidence of costs is equivocal are usually caused by using among-individual correlations to study what is a within-individual phenomenon.

Older conservatives: reproduction in female Alpine chamois (Rupicapra rupicapra) is increasingly risk-averse with age

2016 ◽  
Vol 94 (5) ◽  
pp. 311-321 ◽  
Author(s):  
A. Morin ◽  
M. Rughetti ◽  
S. Rioux-Paquette ◽  
M. Festa-Bianchet
Keyword(s):  
Reproductive Success ◽  
Reproductive Effort ◽  
Risk Averse ◽  
Costs Of Reproduction ◽  
Rupicapra Rupicapra ◽  
Terminal Investment ◽  
Age Dependent ◽  
Alpine Chamois ◽  
Old Females ◽  
Investment Hypothesis

In long-lived mammals, costs of reproduction may vary with age. The terminal investment hypothesis predicts greater reproductive effort as females approach the end of their life expectancy. We monitored 97 individually marked female Alpine chamois (Rupicapra rupicapra (L., 1758)) between 2007 and 2013 to determine how age-specific reproduction affected body mass and subsequent reproductive success. We captured and weighed females between April and August and monitored reproductive success from April to October through mother–kid associations. Reproductive success was strongly age-dependent and peaked at 70% for prime-aged females (4–7 years). Reproductive senescence began at 8 years, earlier than reported by other studies of ungulates. There was no clear evidence of reproductive costs in any age class. Reproductive success was very heterogeneous for old females, suggesting variability in the onset of senescence. Old females were less likely to reproduce in poor years despite being heavier than prime-aged females, suggesting reproductive restraint in late life rather than terminal investment. Female mass remained stable from May to August with no effect of lactation. Our results suggest that chamois reproductive strategy becomes increasingly conservative with age, resulting in no detectable costs of reproduction.

Evaluation of the Efficiency of Combined and Separated Antioxidant Supplementation of Vitamin C and E on Semen Parameters in Streptozotocin-Induced Diabetic Male Wistar Rats

2018 ◽  
Vol 7 (4) ◽  
pp. 166-172
Author(s):  
Amina Benabbou ◽  
Meghit Boumediene Khaled ◽  
Ali Saeed Alchalabi
Keyword(s):  
Diabetes Mellitus ◽  
Vitamin E ◽  
Vitamin C ◽  
Wistar Rats ◽  
Sperm Count ◽  
Reproductive Capacity ◽  
Semen Parameters ◽  
Testis Weight ◽  
Male Wistar Rats ◽  
Hormonal Levels

Male reproductive functions could be affected at multiple levels due to dia-betes mellitus. Antioxidants vitamins have direct impact on improving male reproductive capacity. Our objective was to assess the efficiency of treat-ment with vitamin C and E in the case of whether diabetes mellitus is the cause of infertility or if infertile men suffer from diabetes by inducing diabe-tes on male Wistar rats. Adult male Wistar rats were divided into 5 groups of 6 animals each: a normoglycemic control. Other four groups were given a single dose of streptozotocin, and divided into: diabetic control, diabetic + 250 mg/kg/day of vitamin C, diabetic + 250 mg/kg/day of vitamin E, diabetic + 250 mg/kg/day of vitamin C + 250 mg/kg/day of vitamin E by gavage during 30 consecutive days. Animals were anesthetized, sacrificed to evaluate body and reproductive organ weights, plasma hormone levels, and semen quality. Compared to normoglycemic animals, diabetic rats showed reduced body weight (211.33 ± 8.70gr) and epididymis (1.35 ± 0.10 gr). The testis weight (3.10 ± 0.14 gr) and sperm count (2.72 ± 4.61 x 106) were maintained. A reduction of LH and testosterone levels (0.10 ± 0.00, and 0.25 ± 0.12) respec-tively. There was a significant increase (p<0.05) in the final body and epididy-mis weights, hormonal levels, and sperm count among diabetes vitamins treated groups as compared to the normoglycemic and hyperglycemic groups. Diabetes mellitus induces adverse effects on reproductive capacity. Antioxidant vitamins C and E improves sperm quality and increases hormonal levels.

scholarly journals Unrestricted migration favours virulent pathogens in experimental metapopulations: evolutionary genetics of a rapacious life history

2010 ◽  
Vol 365 (1552) ◽  
pp. 2503-2513 ◽  
Author(s):  
Christal M. Eshelman ◽  
Roxanne Vouk ◽  
Jodi L. Stewart ◽  
Elizabeth Halsne ◽  
Haley A. Lindsey ◽  
...  
Keyword(s):  
Population Structure ◽  
Life History ◽  
Negative Relationship ◽  
Life History Evolution ◽  
Tragedy Of The Commons ◽  
Viral Pathogen ◽  
Lower Productivity ◽  
The Commons ◽  
History Evolution ◽  
The Impact

Understanding pathogen infectivity and virulence requires combining insights from epidemiology, ecology, evolution and genetics. Although theoretical work in these fields has identified population structure as important for pathogen life-history evolution, experimental tests are scarce. Here, we explore the impact of population structure on life-history evolution in phage T4, a viral pathogen of Escherichia coli . The host–pathogen system is propagated as a metapopulation in which migration between subpopulations is either spatially restricted or unrestricted. Restricted migration favours pathogens with low infectivity and low virulence. Unrestricted migration favours pathogens that enter and exit their hosts quickly, although they are less productive owing to rapid extirpation of the host population. The rise of such ‘rapacious’ phage produces a ‘tragedy of the commons’, in which better competitors lower productivity. We have now identified a genetic basis for a rapacious life history. Mutations at a single locus ( rI ) cause increased virulence and are sufficient to account for a negative relationship between phage competitive ability and productivity. A higher frequency of rI mutants under unrestricted migration signifies the evolution of rapaciousness in this treatment. Conversely, spatially restricted migration favours a more ‘prudent’ pathogen strategy, in which the tragedy of the commons is averted. As our results illustrate, profound epidemiological and ecological consequences of life-history evolution in a pathogen can have a simple genetic cause.

Life History Adaptation in Prey

2018 ◽  
pp. 323-346
Author(s):  
Gary A. Wellborn
Keyword(s):  
Life History ◽  
Life History Theory ◽  
Reproductive Effort ◽  
Life History Evolution ◽  
Reproductive Value ◽  
Offspring Size ◽  
Selective Predation ◽  
Antipredator Defense ◽  
Trade Offs ◽  
History Evolution

Predation is a powerful agent of life history evolution in prey species, as demonstrated in diverse examples in crustaceans. Ubiquitous size- and age-selective predation mediates trade-offs among reproductive effort, survival, and growth, which cause evolution of constitutive and phenotypically plastic shifts in age and size at maturity. In accord with predictions of life history theory, comparative studies demonstrate that contrasting forms of selective predation generate divergent evolutionary changes in age- and size-specific allocation of reproductive effort within populations and species. Predation risk also influences egg and offspring size, and some crustaceans exhibit phenotypic plasticity in offspring size in response to chemical cues of predators. Because age-selective predation impacts the relative benefits of earlier versus later reproductive investment, predation may also shape senescence and life span of crustaceans. Additionally, individual differences in risk-taking behavior, sometimes termed “personalities,” have been examined in several crustaceans, and these may arise through among-individual variation in reproductive value. Finally, in some crustacean groups limb autotomy is a common, but costly, antipredator defense, and life history perspectives on autotomy suggest individuals may balance costs and benefits during predator encounters. Much of our understanding of predation’s role in life history evolution of prey derives from studies of crustaceans, and these organisms continue to be promising avenues to elucidate mechanisms of life history evolution.

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