Telomere length and age in humpback whales (Megaptera novaeangliae)

Telomeres are DNA sequences situated at the end of chromosomes that play
a key role in maintaining chromosome integrity and are crucial for normal
cell function. In vertebrates, telomeres tend to shorten with age, ultimately
reaching a threshold believed to trigger cellular and organismal senescence.
The average shortening of telomeres with age and the apparent variability
among individuals within a species suggest the potential use of telomeres as
an indicator for individual age, fitness and species life-history characteristics.
A fast and reliable method to obtain such information from free-ranging
animals will have wide applications within marine mammal science and
management. Here we report on the relationship between telomere length and
age in free-ranging humpback whales (Megaptera novaeangliae). We used
quantitative PCR to estimate the rate of telomere shortening in vivo from
multiple samples collected from 30 individual humpback whales. We also
estimated telomere lengths in additional 18 individuals of known ages. The
correlation between telomere length and age was very weak, and highly
variable among individuals of similar age. These results are consistent with
the life history strategy of this species and suggest that humpback whales
may have evolved mechanisms to maintain telomere length, but with varying
efficiency among individuals. Moreover, the results indicate that telomere
length measured by quantitative PCR is an imprecise determinant of age in
humpback whales. We discuss the potential factors responsible for the
observed patterns and provide perspectives for applying telomere length
estimates in studies of baleen whales.