DUGi

Size-independent age effects on reproductive effort in a small, short-lived fish

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@12418

1. Age-related changes in reproductive effort have been predicted by theoretical models and observed in a wide range of organisms. However, for indeterminate growers such as fish, an allometric relationship linking gonad weight to body size is commonly observed. There is often a positive linear relationship when these variables are log-transformed, which by implication reduces the influence of age on reproductive effort. 2. Contrasting with this usual pattern, we report a nonlinear relationship between gonad weight and fish size (after log-transformation) in mosquitofish (Gambusia holbrooki), clearly resulting from age changes. The declining rate of increase of gonad mass as a function of body size revealed a higher reproductive effort for younger individuals relative to size. 3. This size-independent age effect on reproductive effort was predicted based on previous studies of mosquitofish and is certainly related to their particular life-history strategy, combining an early maturation and short lifespan with the physiological costs of reproduction and over-wintering. Our findings probably apply to other small, short-lived species with similar life history

Financial support was provided by the Spanish Ministry of Education (REN200300477 and CGL2006-11652-C02-01 ⁄BOS) and the Government of Catalonia (Catalan Government Distinction Award for University research 2004 to E. García-Berthou)

Wiley