scholarly journals Artificial size selection experiment reveals telomere length dynamics and fitness consequences in a wild passerine

2021 ◽  
Author(s):  
Michael Pepke ◽  
Thomas Kvalnes ◽  
Bernt Rønning ◽  
Henrik Jensen ◽  
Winnie Boner ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Early Life ◽  
Bird Species ◽  
Disruptive Selection ◽  
Size Selection ◽  
Trade Offs ◽  
Fitness Consequences ◽  
Selection For

Changes in telomere dynamics could underlie life-history trade-offs among growth, size and longevity, but our ability to quantify such mechanistic processes in natural, unmanipulated populations is limited. We investigated how 4 years of artificial selection for either larger or smaller body size affected early-life telomere length in two insular populations of wild house sparrows. A negative correlation between telomere length and structural size was evident under both selection regimes. The study also revealed that male sparrows had longer telomeres than females, after controlling for size, and there was a significant negative effect of harsh weather conditions on telomere length. The long-term fitness consequences of these changes in early-life telomere length induced by the artificial size selection were explored over a period of 11 years. These analyses indicated disruptive selection on telomere length because both short and long early-life telomere length tended to be associated with the lowest mortality rates and highest life expectancy. There was also weak evidence for a negative association between telomere length and annual reproductive success, but only in the population where body size was increased experimentally. Our results suggest that natural selection for optimal body size in wild animals will affect early-life telomere length during growth, which is known to be linked to longevity in birds, but also that the importance of telomeres for long-term somatic maintenance and fitness is complex in a wild bird species.

scholarly journals Early-life telomere length covaries with life-history traits and scales with chromosome length in birds

2021 ◽  
Author(s):  
Michael Le Pepke ◽  
Thor Harald Ringsby ◽  
Dan T. A. Eisenberg
Keyword(s):  
Life History ◽  
Telomere Length ◽  
Dna Sequences ◽  
Early Life ◽  
Life History Traits ◽  
Bird Species ◽  
Chromosome Length ◽  
Life History Variation ◽  
Trade Offs ◽  
Phylogenetic Framework

Telomeres, the short DNA sequences that protect chromosome ends, are an ancient molecular structure, which is highly conserved across most eukaryotes. Species differ in their telomere lengths, but the causes of this variation are not well understood. Here, we demonstrate that mean early-life telomere length is an evolutionary labile trait across 58 bird species (representing 35 families in 12 orders) with the greatest trait diversity found among passerines. Among these species, telomere length is significantly negatively associated with the fast-slow axis of life-history variation, suggesting that telomere length may have evolved to mediate trade-offs between physiological requirements underlying the diversity of pace-of-life strategies in birds. Curiously, within some species, larger individual chromosome size predicts longer telomere lengths on that chromosome, leading to the suggestion that telomere length also covaries with chromosome length across species. We show that longer mean chromosome length or genome size tends to be associated with longer mean early-life telomere length (measured across all chromosomes) within a phylogenetic framework constituting up to 32 bird species. Combined, our analyses generalize patterns previously found within a few species and provide potential adaptive explanations for the 10-fold variation in telomere lengths observed among birds.

scholarly journals Nestling telomere shortening, but not telomere length, reflects developmental stress and predicts survival in wild birds

2014 ◽  
Vol 281 (1785) ◽  
pp. 20133287 ◽  
Author(s):  
Jelle J. Boonekamp ◽  
G. A. Mulder ◽  
H. Martijn Salomons ◽  
Cor Dijkstra ◽  
Simon Verhulst
Keyword(s):  
Telomere Length ◽  
Brood Size ◽  
Developmental Stress ◽  
Free Living ◽  
Telomere Shortening ◽  
Developmental Effects ◽  
Fitness Consequences ◽  
Developmental Conditions ◽  
Fledgling Mass

Developmental stressors often have long-term fitness consequences, but linking offspring traits to fitness prospects has remained a challenge. Telomere length predicts mortality in adult birds, and may provide a link between developmental conditions and fitness prospects. Here, we examine the effects of manipulated brood size on growth, telomere dynamics and post-fledging survival in free-living jackdaws. Nestlings in enlarged broods achieved lower mass and lost 21% more telomere repeats relative to nestlings in reduced broods, showing that developmental stress accelerates telomere shortening. Adult telomere length was positively correlated with their telomere length as nestling ( r = 0.83). Thus, an advantage of long telomeres in nestlings is carried through to adulthood. Nestling telomere shortening predicted post-fledging survival and recruitment independent of manipulation and fledgling mass. This effect was strong, with a threefold difference in recruitment probability over the telomere shortening range. By contrast, absolute telomere length was neither affected by brood size manipulation nor related to survival. We conclude that telomere loss, but not absolute telomere length, links developmental conditions to subsequent survival and suggest that telomere shortening may provide a key to unravelling the physiological causes of developmental effects on fitness.

scholarly journals Genetic architecture and heritability of early-life telomere length in a wild passerine

2021 ◽  
Author(s):  
Michael Pepke ◽  
Thomas Kvalnes ◽  
Sarah Lundregan ◽  
Winnie Boner ◽  
Pat Monaghan ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Early Life ◽  
Genetic Basis ◽  
Skeletal Development ◽  
Cellular Growth ◽  
Phenotypic Correlation ◽  
Animal Populations ◽  
Genome Wide ◽  
Genomic Regions

Early-life telomere length (TL) is associated with fitness in a range of organisms. Little is known about the genetic basis of variation in TL in wild animal populations, but to understand the evolutionary and ecological significance of TL it is important to quantify the relative importance of genetic and environmental variation in TL. In this study, we measured TL in 2746 house sparrow nestlings sampled across 20 years and used an animal model to show that there is a small heritable component of early-life TL (h2=0.04), but with a strong component of maternal inheritance. Variation in TL among individuals was mainly driven by environmental (year) variance, but also brood and parental effects. We did not find evidence for a negative genetic correlation underlying the observed negative phenotypic correlation between TL and structural body size. Thus, TL may evolve independently of body size and the negative phenotypic correlation is likely to be caused by non-genetic environmental effects. We further used genome‐wide association analysis to identify genomic regions associated with TL variation. We identified several putative genes underlying TL variation; these have been inferred to be involved in oxidative stress, cellular growth, skeletal development, cell differentiation and tumorigenesis in other species. Together, our results show that TL is a lowly heritable, polygenic trait which is strongly affected by environmental conditions in a free-living bird.

scholarly journals Sexual Size Dimorphism and Morphological Evidence Supporting the Recognition of two Subspecies in the Galápagos Dove

The Condor ◽  
2007 ◽  
Vol 109 (1) ◽  
pp. 132-141
Author(s):  
Diego Santiago-Alarcon ◽  
Patricia G. Parker
Keyword(s):  
Body Size ◽  
Sexual Size Dimorphism ◽  
Bird Species ◽  
Morphological Data ◽  
Morphological Evidence ◽  
Life History Variation ◽  
Size Dimorphism ◽  
Selective Pressures ◽  
Trade Offs ◽  
Discriminant Analyses

Abstract Abstract Sexual size dimorphism is a conspicuous trait of many wild bird species. Differences in body size between the sexes might reflect selective pressures and trade-offs to optimize performance. Here, we analyze the size dimorphism of the Galápagos Dove (Zenaida galapagoensis) using principal component and discriminant analyses with samples obtained from six islands: Santiago, Santa Fe, Santa Cruz, Española, Genovesa, and Wolf. We also reanalyze published morphological data but also including additional samples from Wolf Island to account for morphological differences among islands. Males were significantly larger than females. Discriminant analyses correctly classified 98% of males and 100% of females, and cross-validation of the model correctly classified 97% of males and 98% of females. We created two sexual size dimorphism indices using wing chord and tarsus as body-size surrogates. Significant differences were found in the sexual size dimorphism index for both measurements among islands. Significant differences in sexual size dimorphism among islands might indicate the role of different selective pressures acting on individual islands (e.g., competition, predation, resources, sexual selection), which might result in life history variation of the species among islands. For the first time, we provide significant morphological evidence supporting the classification of the Galápagos Dove into two subspecies: Z. g. galapagoensis and Z. g. exsul.

Maternal fitness consequences of interactions among agents of mortality in early life of salmonids

2012 ◽  
Vol 69 (9) ◽  
pp. 1539-1555 ◽  
Author(s):  
Stephanie Mogensen ◽  
Jeffrey A. Hutchings
Keyword(s):  
Body Size ◽  
Early Life ◽  
Spatial Scales ◽  
Salmonid Fishes ◽  
Allee Effects ◽  
Functional Relationships ◽  
Fitness Consequences ◽  
Dependent Sources ◽  
The Relationship ◽  
Offspring Mortality

Maternal effects can be key determinants of female fitness through their influence on survival in early life. In salmonid fishes, three density-dependent sources of offspring mortality are redd superimposition, predation, and starvation. An individual-based model was developed to explore how these sources of mortality can affect functional relationships among maternal fitness, maternal phenotype (body size), spawner density, and spawning timing. We found that the strength of the relationship between maternal size and fitness was highly context-dependent, differing with the source of offspring mortality and with interactions among the mortality agents. Component Allee effects at low spawner densities were also detected in some simulations. The results reveal unanticipated interactions among offspring mortality sources, maternal body size, and fitness. Given the high probability that these mortality sources differ considerably across variable temporal and spatial scales, there would be considerable value in obtaining field-based empirical data to test the predictions proffered here to better understand the correlates of maternal fitness in salmonid fishes.

scholarly journals Do Early-Life Conditions Drive Variation in Senescence of Female Bighorn Sheep?

2021 ◽  
Vol 9 ◽  
Author(s):  
Gabriel Pigeon ◽  
Julie Landes ◽  
Marco Festa-Bianchet ◽  
Fanie Pelletier
Keyword(s):  
Reproductive Success ◽  
Environmental Conditions ◽  
Early Life ◽  
Life Histories ◽  
Bighorn Sheep ◽  
Long Term Effects ◽  
Trade Offs ◽  
Early Life Conditions ◽  
Specific Variation

The rate of senescence may vary among individuals of a species according to individual life histories and environmental conditions. According to the principle of allocation, changes in mortality driven by environmental conditions influence how organisms allocate resources among costly functions. In several vertebrates, environmental conditions during early life impose trade-offs in allocation between early reproduction and maintenance. The effects of conditions experienced during early life on senescence, however, remain poorly documented in wild populations. We examined how several early-life environmental conditions affected reproductive and survival senescence in wild bighorn sheep. We found long-term effects of high population density at birth, precipitations during the winter before birth, and temperature during the winter following birth that decreased survival after 7 years of age. High temperature during the first summer and autumn of life and high Pacific decadal oscillation decreased reproductive success at old ages. However, harsh early-life environment did not influence the rate of senescence in either survival or reproduction. Contrary to our expectation, we found no trade-off between reproductive allocation prior to senescence and senescence. Our results do show that early-life environmental conditions are important drivers of later survival and reproductive success and contribute to intra-specific variation in late-life fitness, but not aging patterns. These conditions should therefore be considered when studying the mechanisms of senescence and the determinants of variation in both survival and reproductive senescence at older ages.

scholarly journals On being the right size: increased body size is associated with reduced telomere length under natural conditions

2015 ◽  
Vol 282 (1820) ◽  
pp. 20152331 ◽  
Author(s):  
Thor Harald Ringsby ◽  
Henrik Jensen ◽  
Henrik Pärn ◽  
Thomas Kvalnes ◽  
Winnie Boner ◽  
...  
Keyword(s):  
Body Size ◽  
Telomere Length ◽  
Natural Populations ◽  
Negative Relationship ◽  
House Sparrows ◽  
Selection Regime ◽  
Trade Offs ◽  
Length Changes ◽  
The Relationship ◽  
Telomere Dynamics

Evolution of body size is likely to involve trade-offs between body size, growth rate and longevity. Within species, larger body size is associated with faster growth and ageing, and reduced longevity, but the cellular processes driving these relationships are poorly understood. One mechanism that might play a key role in determining optimal body size is the relationship between body size and telomere dynamics. However, we know little about how telomere length is affected when selection for larger size is imposed in natural populations. We report here on the relationship between structural body size and telomere length in wild house sparrows at the beginning and end of a selection regime for larger parent size that was imposed for 4 years in an isolated population of house sparrows. A negative relationship between fledgling size and telomere length was present at the start of the selection; this was extended when fledgling size increased under the selection regime, demonstrating a persistent covariance between structural size and telomere length. Changes in telomere dynamics, either as a correlated trait or a consequence of larger size, could reduce potential longevity and the consequent trade-offs could thereby play an important role in the evolution of optimal body size.

scholarly journals The influence of phylogeny and life history on telomere lengths and telomere rate of change among bird species: a meta-analysis

2021 ◽  
Author(s):  
François Criscuolo ◽  
F. Stephen Dobson ◽  
Quentin Schull
Keyword(s):  
Life History ◽  
Body Size ◽  
Telomere Length ◽  
Life History Traits ◽  
Meta Analysis ◽  
Bird Species ◽  
Rate Of Change ◽  
Pace Of Life ◽  
Life History Variables ◽  
Telomere Dynamics

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.

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