Reproduction

Résumé 0

The reproductive cycle of a species implies a set of physiological and behavioural processes influenced by various factors in the abiotic and biotic environment. Traditionally a distinction is made between gametogenesis and spawning. Gametogenesis is the physiological process involved in gonad development that leads to the formation of gametes (oocytes and spermatozoa). In tropical regions, gametogenesis is controlled by tiny changes in environmental factors, and its duration varies according to species (Munro, 1990). Spawning is the critical moment of the reproductive cycle, which includes the sequence of events that leads to laying of the gametes (maturation of oocytes, ovulation, spermiogenesis), under the influence of specific stimuli (Billard & Breton, 1978).Gametogenesis is the longest of these processes. It generally lasts several months, but reproductive success depends to a large extent on the success of a set of behavioural activities. These include the search for partners, parental care before and after spawning, whether or not migration is required to find suitable sites for eggs and larvae, synchronization of spawning with changes in environmental factors, synchronization of the genital products laying, etc. These activities may be accompanied by a set of phenological adaptations, such as the development of secondary sexual characters with regard to morphology or colouring.The study of the fish reproductive cycle thus requires a multidisciplinary approach that involves ecologists, physiologists, ethologists, and geneticists. Coordinating all these disciplines is not always a straightforward affair, and explains why data is often fragmentary. Yet we need studies that include them if we want to understand the cause-and-effect relationships between environmental factors, physiological processes, and reproductive behaviour of species.