Age Structure and Growth Rate of the Triploid Batura Toad, Bufotes baturae (Anura: Bufonidae), Inhabitant of a High Altitude Hot Spring in the Eastern Pamirs (Tajikistan)

Abstract

The paper reports the results of the first skeletochronological study of age structure and distinguishing characteristics of growth in the triploid toad Bufotes baturae, inhabitant of Sasyk-Bulak hot spring in the Pamir Mountains (3797 m a.s.l.). Minimal and maximum ages of males of the species were three and seven years, respectively. The age of females ranged from three to six years. Mean age for both sexes was 4.0 years. The majority of males (46.2%) were three years old, most females (58.8%) were four years old. The age of sexual maturity was reached after three hibernations (46% in males and 24% in females). The majority of toads breed once at the age of three or four years. Only few (18% in females and 23% in males) individuals in this population were older. Harsh high-altitude cold desert conditions and limited food resources may cause high mortality of the toads. The correlation between the minimal age at sexual maturity and the degree of dryness of climate was demonstrated among species of the genus Bufotes. As a rule, toads which live in more humid climatic conditions mature earlier. Perhaps, this explains that substantial part of semi-aquatic individuals of B. baturae in the hot spring mature at earlier age (3 years) than other polyploid species (4 – 5 years) that inhabit arid environments. In both sexes of B. baturae, growth rate was similar to that of other closely related high-mountain species, diploid B. latastii and triploid B. pseudoraddei.