Molecular adaptation of telomere associated genes in mammals

Abstract

BackgroundPlacental mammals display a huge range of life history traits, including size, longevity, metabolic rate and germ line generation time. Although a number of general trends have been proposed between these traits, there are exceptions that warrant further investigation. Species such as naked mole rat, human and certain bat species all exhibit extreme longevity with respect to body size. It has long been established that telomeres and telomere maintenance have a clear role in ageing but it has not yet been established whether there is evidence for adaptation in telomere maintenance proteins that could account for increased longevity in these species.ResultsHere we carry out a molecular investigation of selective pressure variation, specifically focusing on telomere associated genes across placental mammals. In general we observe a large number of instances of positive selection acting on telomere genes. Although these signatures of selection overall are not significantly correlated with either longevity or body size we do identify positive selection in the microbat species Myotis lucifugus in functionally important regions of the telomere maintenance genes DKC1 and TERT, and in naked mole rat in the DNA repair gene BRCA1.ConclusionThese results demonstrate the multifarious selective pressures acting across the mammal phylogeny driving lineage-specific adaptations of telomere associated genes. Our results show that regardless of the longevity of a species, these proteins have evolved under positive selection thereby removing increased longevity as the single selective force driving this rapid rate of evolution. However, evidence of molecular adaptations specific to naked mole rat and Myotis lucifugus highlight functionally significant regions in genes that may alter the way in which telomeres are regulated and maintained in these longer-lived species.

Sorting duplicated loci disentangles complexities of polyploid genomes masked by genotyping by sequencing

“…Numerous telomere‐associated genes in mammals have also been shown to be adaptively important (Morgan et al . ). Clearly, studies that filter duplicated loci may be missing genomic regions of adaptive importance.…”

“…Subtelomeric regions are known to harbour genes of adaptive importance (Mefford & Trask ; Morgan et al . ). Interestingly, a recent study performing whole‐genome resequencing in two flycatcher species ( Ficedula spp.)…”

Selective pressures on human cancer genes along the evolution of mammals

“…Episodes of positive selection of some FA/BRCA components have been identified in long-lived, and cancer-resistant species. Adaptive evolution of BRCA2 has been identified in the bats Myotis lucifugus and Myotis davidii [47,48], whereas some FANC members, such as FANCA, FANCE and FANCL, were inferred to be under positive selection in the naked mole rat [47]. On the other hand, germline variants in the FA/BRCA repair pathway have been associated with hereditary breast-ovarian cancer and Fanconi Anemia (FA) in humans [33].…”

Molecular evolution of growth hormone and insulin-like growth factor 1 receptors in long-lived, small-bodied mammals

“…A high quality genome is available for H. glaber (Kim et al, 2011), and through this and related resources, several possible underlying molecular mechanisms underpinning its exceptional lifespan have begun to be documented (Kim et al, 2011;Yu et al, 2011;Edrey et al, 2012;Morgan et al, 2013). However, to date little is known about the molecular evolution of the GH and IGF1 receptors in the naked mole-rat and closely related rodent species.…”