scholarly journals Telomere length covaries with age across an elevational gradient in a Mediterranean lizard

2019 ◽  
Author(s):  
Pablo Burraco ◽  
Mar Comas ◽  
Senda Reguera ◽  
Francisco Javier Zamora-Camacho ◽  
Gregorio Moreno-Rueda

AbstractThe timing of organisms’ senescence is developmentally programmed but also shaped by the interaction between environmental inputs and life-history traits. In ectotherms, ageing dynamics are still poorly understood despite their particularities concerning thermoregulation, regeneration capacity, or growth trajectory. Here, we investigate the role of life-history traits such as age, sex, body size, body condition, and tail autotomy (i.e self-amputation) in shaping telomere length of six populations of the Algerian sand lizard (Psammodromus algirus) distributed across an elevational gradient from 300 to 2500 meters above the sea level. Additionally, we show in a review table the available information on reptiles’ telomere length. We found that telomeres elongated with lizards’ age. We also observed that body size and age class showed a positive relationship, suggesting that cell replication did not shorten lizards’ telomeres by itself. Elevation affected telomere length in a non-linear way, a pattern that mirrored the variation in age structure across elevation. Telomere length was unaffected by tail autotomy, and was sex-independent, but positively correlated with body condition. Our results show that telomeres elongate throughout the first four years of lizards’ lifetime, a process that stress the role of telomerase in maintaining ectothermic telomeres, and, likely, in extending lifespan in organisms with indeterminate growth. Regarding the non-linear impact that elevation had on telomere length of lizards, our results suggest that habitat (mainly temperature) and organisms’ condition might play a key role in regulation ageing rate. Our findings emphasize the relevance of understanding species’ life histories (e.g. age and body condition) and habitat characteristics for fully disentangling the causes and consequences of lifespan trajectory.

Author(s):  
François Criscuolo ◽  
F. Stephen Dobson ◽  
Quentin Schull

Longevity is highly variable among animal species, and has coevolved with other of life-history traits, like body size and rates of reproduction. Telomeres, through their erosion over time, are one of the cell mechanisms that produce senescence at the cell level, and might even have an influence on the rate of ageing in whole organisms. However, uneroded telomeres are also risk factors of cell immortalization. The associations of telomere lengths, their rate of change, and life-history traits independent of body size are largely underexplored for birds. To test associations of life-history traits and telomere dynamics, we conducted a phylogenetic meta-analysis using studies of 53 species of birds. We restricted analyses to studies that applied the telomere restriction fragment length (TRF) method, and examined relationships between mean telomere length at the chick (Chick TL) and adult (Adult TL) stages, the mean rate of change in telomere length during life (TROC), and life-history traits. We examined 3 principal components of 12 life-history variables that represented: body size (PC1), the slow-fast continuum of pace-of-life (PC2) and post-fledging parental care (PC3). Phylogeny had at best a small-to-medium influence on Adult and Chick TL (r² = 0.190 and 0.138, respectively), but a substantial influence on TROC (r² = 0.688). Phylogeny strongly influenced life histories: PC1 (r² = 0.828), PC2 (0.838), and PC3 (0.613). Adult TL and Chick TL were poorly associated with the life-history variables. TROC, however, was negatively and moderate-to-strongly associated with PC2 (unadjusted r = -0.340; with phylogenetic correction, r = -0.490). Independent of body size, long-lived species with smaller clutches and slower embryonic rate of growth may exhibited less change in telomere length over their lifetimes. We suggest that telomere lengths may have diverged even among closely avian related species, yet telomere dynamics are strongly linked to the pace of life.


Author(s):  
Maren N. Vitousek ◽  
Laura A. Schoenle

Hormones mediate the expression of life history traits—phenotypic traits that contribute to lifetime fitness (i.e., reproductive timing, growth rate, number and size of offspring). The endocrine system shapes phenotype by organizing tissues during developmental periods and by activating changes in behavior, physiology, and morphology in response to varying physical and social environments. Because hormones can simultaneously regulate many traits (hormonal pleiotropy), they are important mediators of life history trade-offs among growth, reproduction, and survival. This chapter reviews the role of hormones in shaping life histories with an emphasis on developmental plasticity and reversible flexibility in endocrine and life history traits. It also discusses the advantages of studying hormone–behavior interactions from an evolutionary perspective. Recent research in evolutionary endocrinology has provided insight into the heritability of endocrine traits, how selection on hormone systems may influence the evolution of life histories, and the role of hormonal pleiotropy in driving or constraining evolution.


2018 ◽  
Vol 93 ◽  
pp. 36-44 ◽  
Author(s):  
Manuel A. Otero ◽  
Favio E. Pollo ◽  
Pablo R. Grenat ◽  
Nancy E. Salas ◽  
Adolfo L. Martino

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9792
Author(s):  
Aluwani Nengovhela ◽  
Christiane Denys ◽  
Peter J. Taylor

Temporal changes in body size have been documented in a number of vertebrate species, with different contested drivers being suggested to explain these changes. Among these are climate warming, resource availability, competition, predation risk, human population density, island effects and others. Both life history traits (intrinsic factors such as lifespan and reproductive rate) and habitat (extrinsic factors such as vegetation type, latitude and elevation) are expected to mediate the existence of a significant temporal response of body size to climate warming but neither have been widely investigated. Using examples of rodents, we predicted that both life history traits and habitat might explain the probability of temporal response using two tests of this hypothesis. Firstly, taking advantage of new data from museum collections spanning the last 106 years, we investigated geographical and temporal variation in cranial size (a proxy for body size) in six African rodent species of two murid subfamilies (Murinae and Gerbillinae) of varying life history, degree of commensality, range size, and habitat. Two species, the commensal Mastomys natalensis, and the non-commensal Otomys unisulcatus showed significant temporal changes in body size, with the former increasing and the latter decreasing, in relation with climate warming. Commensalism could explain the increase in size with time due to steadily increasing food availability through increased agricultural production. Apart from this, we found no general life history or habitat predictors of a temporal response in African rodents. Secondly, in order to further test this hypothesis, we incorporated our data into a meta-analysis based on published literature on temporal responses in rodents, resulting in a combined dataset for 50 species from seven families worldwide; among these, 29 species showed no significant change, eight showed a significant increase in size, and 13 showed a decline in size. Using a binomial logistic regression model for these metadata, we found that none of our chosen life history or habitat predictors could significantly explain the probability of a temporal response to climate warming, reinforcing our conclusion based on the more detailed data from the six African species.


PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2640 ◽  
Author(s):  
Ramiro J.A. Ovejero Aguilar ◽  
Graciela A. Jahn ◽  
Mauricio Soto-Gamboa ◽  
Andrés J. Novaro ◽  
Pablo Carmanchahi

BackgroundProviding the context for the evolution of life-history traits, habitat features constrain successful ecological and physiological strategies. In vertebrates, a key response to life’s challenges is the activation of the Stress (HPA) and Gonadal (HPG) axes. Much of the interest in stress ecology is motivated by the desire to understand the physiological mechanisms in which the environment affects fitness. As reported in the literature, several intrinsic and extrinsic factors affect variability in hormone levels. In both social and non-social animals, the frequency and type of interaction with conspecifics, as well as the status in social species, can affect HPA axis activity, resulting in changes in the reproductive success of animals. We predicted that a social environment can affect both guanaco axes by increasing the secretion of testosterone (T) and Glucocorticoid (GCs) in response to individual social interactions and the energetic demands of breeding. Assuming that prolonged elevated levels of GCs over time can be harmful to individuals, it is predicted that the HPA axis suppresses the HPG axis and causes T levels to decrease, as GCs increase.MethodsAll of the data for individuals were collected by non-invasive methods (fecal samples) to address hormonal activities. This is a novel approach in physiological ecology because feces are easily obtained through non-invasive sampling in animal populations.ResultsAs expected, there was a marked adrenal (p-value = .3.4e−12) and gonadal (p-value = 0.002656) response due to seasonal variation inLama guanicoe. No significant differences were found in fecal GCs metabolites between males/females*season for the entire study period (p-value = 0.2839). Despite the seasonal activity variation in the hormonal profiles, our results show a positive correlation (p-value = 1.952e−11, COR = 0.50) between the adrenal and gonadal system. The marked endocrine (r2 = 0.806) and gonad (r2 = 0.7231) response due to seasonal variation in male guanaco individuals highlights the individual’s energetic demands according to life-history strategies. This is a remarkable result because no inhibition was found between the axes as theory suggests. Finally, the dataset was used to build a reactive scope model for guanacos.DiscussionGuanacos cope with the trade-off between sociability and reproductive benefits and costs, by regulating their GCs and T levels on a seasonal basis, suggesting an adaptive role of both axes to different habitat pressures. The results presented here highlight the functional role of stress and gonad axes on a critical phase of a male mammal’s life—the mating period—when all of the resources are at the disposal of the male and must be used to maximize the chances for reproductive success.


2015 ◽  
Vol 37 (3) ◽  
pp. 518-531 ◽  
Author(s):  
Paolo Ruggeri ◽  
Andrea Splendiani ◽  
Massimo Giovannotti ◽  
Tatiana Fioravanti ◽  
Giulia Occhipinti ◽  
...  

2004 ◽  
Vol 71 (sup2) ◽  
pp. 117-120 ◽  
Author(s):  
Elena Marzona ◽  
Daniele Seglie ◽  
Cristina Giacoma

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