Life Expectancy in Marine Mammals Is Unrelated to Telomere Length but Is Associated With Body Size.

Kittisak Buddhachat,Korakot Nganvongpanit,Kongkiat Kittiwattanawong,Janine L Brown,Anocha Poommouang,Patcharaporn Kaewmong,Manthanee Kaewkool

doi:10.3389/fgene.2021.737860

Abstract

Marine mammals vary greatly in size and lifespan across species. This study determined whether measures of adult body weight, length and relative telomere length were related to lifespan. Skin tissue samples (n = 338) were obtained from 23 marine mammal species, including four Mysticeti, 19 Odontoceti and one dugong species, and the DNA extracted to measure relative telomere length using real-time PCR. Life span, adult body weight, and adult body length of each species were retrieved from existing databases. The phylogenetic signal analysis revealed that body length might be a significant factor for shaping evolutionary processes of cetacean species through time, especially for genus Balaenoptera that have an enormous size. Further, our study found correlations between lifespan and adult body weight (R2 = 0.6465, p < 0.001) and adult body length (R2 = 0.6142, p ≤0.001), but no correlations with relative telomere length (R2 = −0.0476, p = 0.9826). While data support our hypothesis that larger marine mammals live longer, relative telomere length is not a good predictor of species longevity.

Highlights

Marine mammals consist of cetaceans, sirenians, pinnipeds, marine and sea otters, and the polar bear (Jefferson et al, 1994)
We found that lifespan and body length showed a significant phylogenetic signal for Blomberg’s K (K > 0, p < 0.05), whereas for Pagel’s λ, lifespan, body weight and body length indicated a high phylogenetic signal (λ > 0, p < 0.05)
Our results revealed two significant findings: (i) lifespan and body size appeared to be phylogenetically conserved, especially body length, based on Blomberg’s K and Pagel’s λ = 1; and (ii) lifespan is likely to be connected to body size, both weight and length, but not to median relative telomere length (rTL)

Summary

Introduction

Marine mammals consist of cetaceans (mysticetes and odontocetes), sirenians (manatees and dugong), pinnipeds (phocids, otarids, and walrus), marine and sea otters, and the polar bear (Jefferson et al, 1994). These species are not randomly distributed across the world’s oceans, but rather occupy species-specific geographical niches that vary by depth, temperature, and food resources (Jefferson et al, 1994). Indirect threats include degradation of habitats and food sources that increase disease susceptibility and reduce reproductive rates, all of which negatively

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