Age Estimation and Longevity in Reptiles

Abstract

After a brief recall of the classical meaning of the concept of longevity, the first part of this chapter describes and summarises the main current technique for the estimation of age in reptiles. Among them, sclerochronology is primarily taken into account. The cautious analysis of seasonal growth cycles recorded in hard tissues, although not as rigorous as the mark-release-recapture method of animals in their natural conditions, now appears as a rapid and reliable chronological tool already successfully used in individuals of many reptile species. Sclerochronology is especially efficient for the comparison of several populations, and it is the only method for fossils. The second part presents a synthetic review of known longevities and records in the different groups of reptiles. A short discussion about the significance of longevity shows that for reptiles, because of their thermic metabolism (ectothermy), the physiological longevity must be strongly distinguished from the chronological longevity, especially for a comparison with that known for birds and most mammals.

The African turquoise killifish: A research organism to study vertebrate aging and diapause

“…While virtually all species experience aging, organismal lifespan is an amazingly diverse trait in nature. For example, the documented maximal lifespans range from days in the medfly to over 500 years in clams, comprising all intermediaries including ~4 months in fruit flies, ~4 years in mice, ~120 years in humans, ~150 years in giant tortoises, and ~400 years in Greenland sharks (Butler, Wanamaker, Scourse, Richardson & Reynolds, 2013; Castanet, 1994; Karney et al., 2011; Luckinbill & Clare, 1985; Miller, Harper, Dysko, Durkee & Austad, 2002; Nielsen et al., 2016). The extraordinary diversity of lifespan and life history of various organisms raises many exciting possibilities for modeling and understanding the aging process.…”

Impact of exceptional growth rates on estimations of life-stage duration in Hawaiian green sea turtles

“…It has been used successfully to estimate age and growth in numerous species of reptiles and amphibians (Castanet 1994, Smirina 1994, in cluding sea turtles (see Avens & Snover 2013 for re view). The annual deposition of growth marks, as well as the timing of growth mark deposition, has been validated for Hawaiian green sea turtles , Goshe et al 2016.…”

Age estimation through skeletochronology and mark-recapture of free-living Liolaemus leopardinus (Squamata: Liolaemidae) from Chile

“…This is achieved by marking and recapturing the animals systematically, measuring them, and building growth curves or displaying the data in charts showing the lifetime relationship between age and growth (Halliday and Verrell 1988, Forester and Lykens 1991, Arakelyan et al 2013. However, following individuals of a cohort over time can be a challenge if the species of interest is long-lived or elusive (Castanet 1994, Lemos-Espinal et al 2005, Mills 2006). Therefore, researchers have relied on the size-frequency method and used body size as a proxy for age of free-ranging animals as both traits are positively correlated (Castanet 1994, Chen et al 2011, Comas et al 2016.…”

“…However, following individuals of a cohort over time can be a challenge if the species of interest is long-lived or elusive (Castanet 1994, Lemos-Espinal et al 2005, Mills 2006). Therefore, researchers have relied on the size-frequency method and used body size as a proxy for age of free-ranging animals as both traits are positively correlated (Castanet 1994, Chen et al 2011, Comas et al 2016. To utilize the size-frequency method, a large number of animals are captured and measured during a short period of time, the data are displayed in a histogram, and age-classes are assigned based on the size-frequency distribution (Halliday and Verrell 1998).…”

“…To utilize the size-frequency method, a large number of animals are captured and measured during a short period of time, the data are displayed in a histogram, and age-classes are assigned based on the size-frequency distribution (Halliday and Verrell 1998). The size-frequency method requires a clear-cut knowledge of agespecific variation in body size of the species studied to avoid overlapping age-classes (Gibbons 1976, Halliday and Verrell 1988, Castanet 1994. But, in order to minimize overlaps, researchers tend to group subjects into only two, three, or sometimes four age-classes (Halliday and Verrell 1988, Castanet 1994, Borczyk and Paśko 2011.…”