Divergent patterns of telomere shortening in tropical compared to temperate stonechats

Abstract

Telomeres have emerged as important biomarkers of health and senescence as they predict chances of survival in various species. Tropical birds live in more benign environments with lower extrinsic mortality and higher juvenile and adult survival than temperate birds. Therefore, telomere biology may play a more important role in tropical compared to temperate birds. We measured mean telomere length of male stonechats (Saxicola spp.) at four age classes from tropical African and temperate European breeding regions. Tropical and temperate stonechats had similarly long telomeres as nestlings. However, while in tropical stonechats pre‐breeding first‐years had longer telomeres than nestlings, in temperate stonechats pre‐breeding first‐years had shorter telomeres than nestlings. During their first breeding season, telomere length was again similar between tropical and temperate stonechats. These patterns may indicate differential survival of high‐quality juveniles in tropical environments. Alternatively, more favorable environmental conditions, that is, extended parental care, may enable tropical juveniles to minimize telomere shortening. As suggested by previous studies, our results imply that variation in life history and life span may be reflected in different patterns of telomere shortening rather than telomere length. Our data provide first evidence that distinct selective pressures in tropical and temperate environments may be reflected in diverging patterns of telomere loss in birds.

Population differences in the length and early-life dynamics of telomeres among European pied flycatchers

“…Interestingly, chick growth affected more negatively telomere shortening in northern populations (Finland and Estonia) than in south-western ones (England and Spain). Similarly, telomeres of temperate juvenile stonechats ( Saxicola rubicola ) shortened during growth while those of tropical stonechats ( S. torquatus axillaris ) showed lengthening (Apfelbeck et al, 2019). However, to our knowledge, this sort of pattern has not been observed previously within one species.…”

Contrasting seasonal patterns of telomere dynamics in response to environmental conditions in the ectothermic sand lizard, Lacerta agilis

“…In Seychelle's warblers (Acrocephalus sechellensis) telomere length was positively associated with temporal variation in environmental conditions (island-wide insect abundance) 45 . Environmental effects also play out over larger scales; in stone chats (Saxicola spp), Aspfelbach et al 46 provide evidence that distinct selective pressures in tropical and temperate environments may be reflected in divergent patterns of telomere loss with more favorable environmental conditions potentially minimising telomere shortening. While there are emerging patterns in birds, studies in mammals are scarcer.…”

Telomeres in a spatial context: a tool for understanding ageing pattern variation in wild populations

“…The first study compares age‐related telomere length in two phylogenetically closed stonechat species inhabiting contrasting environments (i.e. tropical and temperate, Apfelbeck et al 2019). Tropical African populations of Saxicola torquatus axillaris live in a more benign environment with lower extrinsic mortality than temperate populations of Saxicola rubicola .…”