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.
The Chronic Effects of Copper and Cadmium on Life History Traits Across Cladocera Species: A Meta-analysis
