INVESTIGADORES
MIRANDA Leandro Andres
congresos y reuniones científicas
Título:
Otolith-based evaluation of the effects of water temperature on the sex determination of pejerrey in lake Chascomús. XX Jornadas de la Sociedad Argentina de Biología, Buenos Aires,
Autor/es:
OKAJIMA H; YOKOCHI H; KAKUTA N; YAMAMOTO Y; STRÜSSMANN CA; MIRANDA LA; COLAUTTI DC; BERASAIN GE
Lugar:
Buenos Aires
Reunión:
Jornada; XX Jornadas de la Sociedad Argentina de Biología; 2018
Institución organizadora:
SAB
Resumen:
The pejerrey Odontesthesbonariensis is known for its strong temperature-dependent sex determination(TSD) system. In laboratory experiments with environmentally relevanttemperatures, low temperatures favor the formation of females and hightemperatures that of males. However, the extent that TSD affects the sex ratiosof natural populations is still unknown. On the other hand, we have also shownthat this species has the XY system of sex determination and a major, if notmaster, testis determining gene, the Y-chromosome-linked anti-Müllerian hormone(amhy). This gene strongly directsgonadal development towards testicular differentiation at intermediatetemperatures between the low, feminizing and high, masculinizing extremes. The presence/absenceof amhy serves therefore as a markerof genotypic sex and makes possible to monitor the changes in genotypic andphenotypic sex ratios of wild pejerrey populations as well as to analyze theimpacts of anthropogenic and climatic factors on pejerrey resources. We havebeen monitoring the pejerrey population in Lake Chascomús since 2014 and have uncovered highly skewed sex ratios, severalsex-reversed XX males and XY females, and even YY (supermales) that are likelythe 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 theusefulness of otolith analysis to discriminate between fish from differentyear-classes and between fish born in different seasons (e.g. spring vsautumn). The samples were ascribed to the 2016 (3-12 cm SL) and the 2015 (12-19cm SL) year-classes based on otolith analysis. Sex-reversed XX males were foundin 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 autumnwhereas sex-reversed XX males were born in early autumn and in spring.Monitoring wild pejerrey populations with a combination of otolith analysis andmolecular tools may provide crucial insight on the reproductive ecology of thisspecies.