Efeito da privação de ninho sobre a agressividade e o sucesso de acasalamento em machos de tilápia do Nilo
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Data
2006-03-02
Autores
Mendonça, Francine Zocoler de [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Machos dominantes de Oreochromis niloticus defendem território no substrato, onde escavam ninhos para a reprodução. Alguns sistemas de criação de tilápia do Nilo utilizam tanques sem substrato, assim, testamos se a privação da construção de ninho aumenta a agressividade e interfere no sucesso de acasalamento dos machos dominantes. Foram utilizados dois grupos formados por 2 machos e 3 fêmeas: um com substrato (COM: n = 9), onde o aquário (~140L) continha uma camada de 3 cm de substrato de pedrisco, e um grupo sem substrato (SEM: n = 11) onde os animais foram privados da construção de ninho. Os animais permaneceram agrupados por 10 dias e o comportamento agonístico do macho dominante foi registrado através de quatro sessões de filmagens (20 min cada), sendo a primeira, 24 horas após o agrupamento e as outras três, a cada 72 horas. A agressividade foi inferida pela freqüência total de unidades de alta intensidade (frontal, lateral, paralelo e ondulação) emitidas pelo macho dominante para o submisso e para as fêmeas. A agressividade foi maior no grupo SEM (97.73 l 31.77. 80 min-1) do que no COM (61.75 l 13.24. 80 min-1; Mann-Withney, p = 0.008). Foram analisados a Taxa de Crescimento Específico (TCE) e o Índice Hepatossomático (IHS) dos dominantes como indicador de gasto energético. A TCE e o IHS foram menores para os dominantes que construíram ninhos (TCE: COM 0.86 l 0.44%.10 dia-1; SEM 1.48 l 0.52% .10 dia-1; teste t, p = 0.10; IHS: COM 1.39 l 0.42% .10 dia-1; SEM 2.16 l 0.82% .10 dia-1; teste t, p = 0.10), o que é indicativo de que os machos dominantes gastam energia escavando ninho, diminuindo a energia disponível para os ataques de alta intensidade. Além disso, foram registrados a latência e a porcentagem de desova, sendo esses similares nos grupos COM e SEM. O índice gonadossomático foi também analisado e maior nos dominantes...
Dominant males of Nile tilapia, Oreochromis niloticus, defend territory on substrates where they dig mating nests. Because some kinds of rearing systems of Nile tilapia use tanks with no substrate inside, our aim was to test whether nest digging privation increases aggressiveness in that species. As we have observed spawning in such conditions, we also tested the effect of nesting privation on dominant s mating success. Two groups formed by 2 males and 3 females each were used: a substrate inside-group (INS; n = 9), whose glass aquaria (~140L) had a 3 cm-layer of gravel, and a non substrate-group (NOS; n = 11) where animals were unable to dig nests. Groups were kept by 10 days and the agonistic behavior of dominant male was video-recorded in 4 sessions (20 min each), the first after 24 hours from grouping and the other 3, every 72 hours. Aggressiveness was inferred by the total frequency of high aggression intensity units (nip, mouthfight, lateral fight and undulation) given by the dominant male in contests with females and subordinate males. The aggressiveness was higher in the NOS (97.73 l 31.77. 80 min-1) than in the INS group (61.75 l 13.24. 80 min-1; Mann-Withney, p = 0.008). We analyzed the Specific Growth Rate and Hepatosomatic Index of dominants as indicators of energy expenditure, whose were higher for dominants that dig nests (SGR: INS 0.86 l 0.44% .10 day-1; NOS 1.48 l 0.52% .10 day- 1; t test, p = 0.10; HIS: INS 1.39 l 0.42% .10 day-1; NOS 2.16 l 0.82% .10 day-1; t test, p = 0.10). Dominant males seem to spend much energy digging nests and deviate energy from high aggressive contests. Moreover, we registered the latency to spawn and the percentage of spawning, whose was similar among INS and NOS groups. Gonadosomatic Index was also analyzed and it was higher in dominant... (Complete abstract click electronic access below)
Dominant males of Nile tilapia, Oreochromis niloticus, defend territory on substrates where they dig mating nests. Because some kinds of rearing systems of Nile tilapia use tanks with no substrate inside, our aim was to test whether nest digging privation increases aggressiveness in that species. As we have observed spawning in such conditions, we also tested the effect of nesting privation on dominant s mating success. Two groups formed by 2 males and 3 females each were used: a substrate inside-group (INS; n = 9), whose glass aquaria (~140L) had a 3 cm-layer of gravel, and a non substrate-group (NOS; n = 11) where animals were unable to dig nests. Groups were kept by 10 days and the agonistic behavior of dominant male was video-recorded in 4 sessions (20 min each), the first after 24 hours from grouping and the other 3, every 72 hours. Aggressiveness was inferred by the total frequency of high aggression intensity units (nip, mouthfight, lateral fight and undulation) given by the dominant male in contests with females and subordinate males. The aggressiveness was higher in the NOS (97.73 l 31.77. 80 min-1) than in the INS group (61.75 l 13.24. 80 min-1; Mann-Withney, p = 0.008). We analyzed the Specific Growth Rate and Hepatosomatic Index of dominants as indicators of energy expenditure, whose were higher for dominants that dig nests (SGR: INS 0.86 l 0.44% .10 day-1; NOS 1.48 l 0.52% .10 day- 1; t test, p = 0.10; HIS: INS 1.39 l 0.42% .10 day-1; NOS 2.16 l 0.82% .10 day-1; t test, p = 0.10). Dominant males seem to spend much energy digging nests and deviate energy from high aggressive contests. Moreover, we registered the latency to spawn and the percentage of spawning, whose was similar among INS and NOS groups. Gonadosomatic Index was also analyzed and it was higher in dominant... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Tilapia (Peixe) - Comportamento agressivo, Peixe - Reprodução, Comportamento social dos animais, Comportamento animal, Oreochromis niloticus, Tilápia do Nilo - Acasalamento, Nile tilapia - Aggressiveness, Territorial behavior
Como citar
MENDONÇA, Francine Zocoler de. Efeito da privação de ninho sobre a agressividade e o sucesso de acasalamento em machos de tilápia do Nilo. 2006. 43 f. Dissertação (Mestrado) - Universidade Estadual Paulista, Instituto de Biociências, Letras e Ciências Exatas, 2006.