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Skeletal Growth Marks and Testis Lobulation as Criteria for Age in Triturus spp. (Amphibia) in Central Norway
Author(s) -
Dolmen Dag
Publication year - 1982
Publication title -
acta zoologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.414
H-Index - 37
eISSN - 1463-6395
pISSN - 0001-7272
DOI - 10.1111/j.1463-6395.1982.tb00761.x
Subject(s) - biology , triturus , anatomy , juvenile , life span , population , humerus , femur , zoology , ecology , evolutionary biology , paleontology , demography , sociology
Two methods of age determination in newts. Triturus vulgaris and T. cristatus , have been examined and compared: (1) Counting growth rings in the bone tissue of humerus or femur is an accurate method, but possible supplementary rings may make the reading difficult. The innermost periosteal zone corresponds to the first year of life. Later, new zones are added each year. (2) Every second year after maturing a new lobe is developed on the testes. Knowing the juvenile life span in a population, it is possible to determine the age of male newts with a possible error of one year. The correlation between growth marks and testis lobes in T. vulgaris and T. cristatus is highly significant. The testis lobing method, however, is less applicable in older newts, since no more than three or four lobes can be developed on a testis.