Utility of telomere length measurements for age determination of humpback whales

This study examines the applicability of telomere length measurements by quantitative PCR as a tool for minimally invasive age determination of free-ranging cetaceans. We analysed telomere length in skin samples from 28 North Atlantic humpback whales (Megaptera novaeangliae), ranging from 0 to 26 years of age. The results suggested a significant correlation between telomere length and age in humpback whales. However, telomere length was highly variable among individuals of similar age, suggesting that telomere length measured by quantitative PCR is an imprecise determinant of age in humpback whales. The observed variation in individual telomere length was found to be a function of both experimental and biological variability, with the latter perhaps reflecting patterns of inheritance, resource allocation trade-offs, and stochasticity of the marine environment

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

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

Biopsying Southern right whales: their reactions and effects on reproduction

Collecting skin biopsies from large whales for genetic analysis is often subject to national permit, and in the case of cow-calf pairs, it may be prohibited. We present results of 906 biopsy attempts on southern right whales (Eubalaenaustralis) in South African waters between 1995 and 1997, including 147 cow-calf pairs. Our sampling success was higher for biopsy darts with a bore of 4 mm compared to 4.6 mm. Contact periods averaged 17.7 min for cow-calf pairs and 25.4 min for whales unaccompanied by calves. There were no significant differences in the short-term reactions of males and females to biopsying, but the reaction of single animals of either sex was greater than for larger groups. Cows accompanied by calves had the strongest reactions, which were significantly greater than even single females. We found evidence of sensitization to repeat biopsying (over periods of hours to 65 days) for cows but not calves (n = 20). We compared the subsequent reproductive history of 117 biopsied cows with that of 163 unbiopsied cows from the same years, and we compared the distribution of calving intervals for biopsied animals with 829 intervals recorded from 1985 to 1995. We did not detect any adverse effects on the proportion of successful reproductive cycles, and hence calf survival, or the proportion of longer-than-normal cycles, although the power of all the statistical tests was low. We concluded that any prohibition on the biopsy sampling of cow-calf pairs should be carefully reconsidered in the light of the valuable genetic insights such sampling could achieve