INVESTIGADORES
COLAUTTI Dario Cesar
congresos y reuniones científicas
Título:
OTOLITH-BASED EVALUATION OF THE EFFECTS OF WATER TEMPERATURE ON THE SEX DETERMINATION OF PEJERREY IN LAKE CHASCOMUS
Autor/es:
OKAJIMA, H.; YOKOCHI, H.; KAKUTA, N.; YAMAMOTO, Y.; STRUSSMANN, C. A.; MIRANDA, L. A.; COLAUTTI, D. C.; BERASAIN, G. E.
Lugar:
CABA
Reunión:
Jornada; XX Jornadas Anuales de la Sociedad Argentina de Biología y XVII Jornadas de la Sociedad Uruguaya de Biociencias.; 2018
Institución organizadora:
Sociedad Argentina de Biología
Resumen:
The pejerrey Odontesthes bonariensis is known for its strong temperature-dependent sex determination (TSD) system. In laboratory experiments with environmentally relevant temperatures, low temperatures favor the formation of females and high temperatures that of males. However, the extent that TSD affects the sex ratios of natural populations is still unknown. On the other hand, we have also shown that this species has the XY system of sex determination and a major, if not master, testis determining gene, the Y-chromosome-linked anti-Müllerian hormone (amhy). This gene strongly directs gonadal development towards testicular differentiation at intermediate temperatures between the low, feminizing and high, masculinizing extremes. The presence/absence of amhy serves therefore as a marker of genotypic sex and makes possible to monitor the changes in genotypic and phenotypic sex ratios of wild pejerrey populations as well as to analyze the impacts of anthropogenic and climatic factors on pejerrey resources. We have been monitoring the pejerrey population in Lake Chascomús since 2014 and have uncovered highly skewed sex ratios, several sex-reversed XX males and XY females, and even YY (supermales) that are likely the offspring from crosses between normal XY males and sex-reversed XY females. In this study, we extended the analysis to 150 fish captured in Lake Chascomús in 2016 and conducted a preliminary investigation of the usefulness of otolith analysis to discriminate between fish from different year-classes and between fish born in different seasons (e.g. spring vs autumn). The samples were ascribed to the 2016 (3-12 cm SL) and the 2015 (12-19 cm SL) year-classes based on otolith analysis. Sex-reversed XX males were found in both year-classes whereas XY females were found only in the 2015 year-class. Sex-reversed XY females were born predominantly in the second half of autumn whereas sex-reversed XX males were born in early autumn and in spring. Monitoring wild pejerrey populations with a combination of otolith analysis and molecular tools may provide crucial insight on the reproductive ecology of this species.