Patterns of investment of the reproductive strategy of two stream-dwelling Characidae

Brazilian Journal of Biology

R. Mazzoni²  R. Iglesias-rios¹ 

[1] ,Universidade do Estado do Rio de Janeiro - UERJ Instituto de Biologia Roberto Alcantara Gomes Departamento de EcologiaRio de Janeiro RJ ,Brazil

关键词: egg size;    fecundity;    breeding season;    migration;    rain forest stream;    trade-off;    tamanho dos ovos;    fecundidade;    estação reprodutiva;    migração;    riacho de floresta pluvial;    trade-off;   

DOI  :  10.1590/S1519-69842007000400015

来源: SciELO

【 摘 要 】

The reproductive strategy of two congeneric species (Astyanax janeiroensis - AJ and Astyanax hastatus - AH) was assessed, in order to address the costs imposed by different investment patterns, on four major life history characters: migratory behaviour, breeding time, fecundity and egg size. Altitudinal segregation of young and adult individuals plus data from the literature indicated that AJ is a migratory species, whereas AH is non migratory. Breeding season (BS) analysis revealed that AH was reproductively active year-round (12 months), whereas AJ breeds during 9 months. Brood costs (Ovarian Investment) were almost the same for both species (AJ - 364 oocytes / g and egg volume = 0.52 mm³; AH -702 oocytes / g and egg volume = 0.27 mm³). Reproductive costs (RC), considered as product of gamete production (OI) and gamete output (BS), were 1,703.7 for AJ and 2,274.0 for AH; thus RC is 25% higher in AH. It is concluded that the costs with OI (egg size and egg numbers) are equal for both species but as breeding season is larger for AH the overall strategy is 25% more expensive in AH. Thus, it is hypothesized that this 25% should be considered as the extra costs that AJ uses during migration and is compensated by its shorter breeding time (9 months versus 12 months of AH).

【 授权许可】

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