Spermatogenic and testosterone cycles in a desert-adapted amphibian Odontophrynus barrioi from Monte desert, Argentina.

QUIROGA L.; SANABRIA E.; JAHN, G.; FORNÉS M.

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Lugar: Salt Lake City; Año: 2018 vol. 52 p. 12 - 18

0022-1511

Few studies have characterized the reproductive cycles of desert anurans, particularly species from South America. This has hampered efforts to identify broad patterns in anuran reproduction, which are known to vary both phylogenetically and throughout climatic gradients. We studied the reproductive cycle of male Odontophrynus barrioi, a small (~20 g) terrestrial toad from the Monte Desert of San Juan, Argentina. The main goal of this work is to determine spermatogenic activity, plasma testosterone concentrations, and reproductive parameters during pre-reproductive (preR), reproductive (R), and post-reproductive (postR) periods. We determined the plasma testosterone concentrations in male toads by radioimmunoassay (RIA). We performed histological analyses of the testes of males using the hematoxylin and eosin method, and examined with a light microscope. During the preR and R periods, spermatogenesis in O. barrioi showed substantial development of the late stages (sperm bundles), which was coincident with high sperm percentage (spermiation) in the seminiferous tubules. Spermiation occurred when testosterone levels were high. This species exhibits a continuous spermatogenic cycle, with maximum levels of testosterone during the dry season. Therefore O. barrioi is a desert-adapted anuran exhibiting an "associated" reproductive strategy given its association between breeding season and high plasma testosterone concentrations. This reproductive strategy likely evolved to coordinate the reproductive cycle with brief rains in summer as an adaptation to the challenging climate imposed by the desert environment as well as Monte Desert.