Age structure and growth pattern of a high‐altitude lizard population based on age determination by skeletochronology

Abstract

Age determination provides crucial data regarding the life history of a species.Skeletochronology is considered to be a reliable method for age determination but is seldom applied to the genus Phrynocephalus (Agamidae) as it requires careful bone histological analysis to determine the formation of the lines of arrested growth (LAGs). We analyzed LAGs in different bones of Phrynocephalus vlangalii, a small, high-altitude lizard, and demonstrated that the phalanges are the best materials for skeletochronology in this species. We also found that the proximal half of the phalangeal diaphysis exhibits the most complete LAGs because of the unidirectional longitudinal growth of the phalange. Histologically, as the embryo bone that developed during the embryonic period was preserved even in very old individuals, no LAGs were eroded by endosteal resorption in the phalanges. The maximum age was 4 years for males and 5 years for females. It was determined that the age at maturity was 3 years for males and 2 or 3 years for females. On the basis of age determination, the age structures of both sexes were compared, and age-specific growth differences between the sexes were also analyzed. No differences in the snout-vent length were observed between sexes in any age group. However, the tail length of males aged 3 and above was significantly longer than that of females. Thus, the use of phalanges in the age determination of P. vlangalii is effective and can be widely applied to the ecological studies of this species as well as other small lizards.

Variations in age structure and growth in congeners Lacerta viridis and Lacerta media

“…Numerous research on reptile species found a favorable link between age and SVL (Altunıs ¸ık et al, 2022b;Ma et al, 2022;Piantoni et al, 2006;Yıldırım et al, 2019). But not all species exhibit this positive link (Odabas ¸et al, 2019), and in some, the correlation may differ based on sex (Cabezas-Cartes et al, 2015).…”

“…Extrinsic and intrinsic variables can influence life history features as growth rate, fertility, age at maturity, and lifespan, with natural selection acting on phenotypes (Zamudio et al, 2016). For instance, habitat quality and ecological circumstances have a direct impact on a number of demographic factors, including longevity, fertility, and age structure (Altunıs ¸ık, 2018;Altunıs ¸ık et al, 2022aAltunıs ¸ık et al, , 2022bAtkins et al, 2020;Ma et al, 2022). For many species, determining an animal's age is challenging.…”

“…The individual's physiology, life expectancy, and sexual maturity are all revealed by this alteration and histomorphological structure. Lizards are one of the vertebrate groups whose growth is unstable and in this respect, they are used as model organisms for the study of parameters related to demography and body size (Altunıs ¸ık & Eksilmez, 2021;Curtin, 2006;Ma et al, 2022).…”

Age structure of the population of Anguis colchica orientalis (Reptilia, Anguidae) in the Talysh Mountains

“…В этом случае альтернативой трубчатым костям конечностей для изучения возраста могут являться поперечные срезы позвонков. У большинства изученных видов в этих костях образуются линии задержанного роста, соответствующие диапаузам Ma et al, 2022), что было доказано экспериментально в неволе на нескольких видах подвязочных змей (Thamnophis sp.) .…”

“…Стоит, однако, отметить, что использование позвонков, как регистрирующих структур, имеет свои недостатки: подготовка препаратов из них более трудоемка, первые линии задержанного роста могут быть резорбированы из-за ремоделирований костной ткани. Также не у всех особей удается однозначно отличить зимовочные линии от дополнительных, что может приводить к недооценке или переоценке возраста Ma et al, 2022). В связи с этим подобные исследования не получили широкого распространения или применяются на очень небольших выборках.…”