Sex group composition, social interaction, and metabolism in the fish Nile tilapia
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Data
2008-11-01
Autores
Carvalho, TB. [UNESP]
Gonçalves-de-Freitas, E. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Instituto Internacional de Ecologia
Resumo
O objetivo deste trabalho foi testar se grupos monossexuais de machos gastam mais energia e exibem perfil agonístico diferente de grupos formados por um macho e uma fêmea na tilápia-do-Nilo (Oreochromis niloticus). Tais diferenças são esperadas, pois machos e fêmeas competem por diferentes recursos reprodutivos. Foram utilizadas duplas de machos (MM) e duplas de macho-fêmea (MF) que permaneceram pareadas por 40 minutos. Durante esse período foi feito o registro da interação agonística (10 minutos iniciais e 10 minutos finais do pareamento) e determinado o gasto energético (consumo de O2) pelo Método de Winckler. A latência para o início dos confrontos (média ± DP, MM = 27,40 ± 25,15 s; MF = 14,22 ± 21,19 s; Mann-Whitney, U = 33,50, P = 0,21) e a freqüência de todas as unidades comportamentais (média ± DP, MM < 72,30 ± 25,29; MF < 73,50 ± 21,65.10/min; Mann-Whitney, P > 0,10) foram semelhantes entre os grupos MM e MF nos 10 minutos iniciais. Isso indica que cada intruso foi considerado um potencial competidor no início da interação. No entanto, a freqüência de ondulação (interação também exibida durante a corte) foi maior para o residente do grupo MF nos 10 minutos finais (média ± DP, MM = 3,56 ± 5,89; MF = 8,56 ± 4,00.10/min; Mann-Whitney, U = 15,50, P = 0,01). A freqüência de fuga, entretanto, foi menor para o intruso do mesmo grupo (média ± DP, MM = 3,90 ± 4,33; MF = 0,44 ± 0,96.10/min; Mann-Whitney, U = 23,50, P = 0,04). Além disso, o perfil agonístico no grupo MM foi composto por um maior número de itens comportamentais do que o MF (para residentes e intrusos). Apesar das diferenças comportamentais, o consumo de O2 não foi afetado pela composição sexual do grupo (média ± DP, MM = 1,93 ± 0,54; MF = 1,77 ± 0,46 mgO2.g peso seco-1.40/min; t-teste de Student, t = 0,71, P = 0,49).
We tested whether the fish Nile tilapia (Oreochromis niloticus) in a monosex male group spends more energy and displays an agonistic profile, differently from males in male-female groups. Such differences are expected because males and females should compete for different reproductive resources. An intruder male (MM) or female (MF) was paired with a resident male and agonistic interaction was quantified during 20 minutes, 10 minutes after pairing and another 10 minutes period 30 minutes later. Energetic cost was evaluated from O2 consumption, determined by Winckler's Method after 40 minutes pairing. Latency for fighting (mean ± SD, MM = 27.40 ± 25.15 s; MF = 14.22 ± 21.19 s; Mann-Whitney test, U = 33.50, P = 0.21) and frequency of the all agonistic acts in the first 10 minutes session (mean ± SD, MM < 72.30 ± 25.29; MF < 73.50 ± 21.65.10/min; Mann-Whitney test, P > 0.10) were not affected by group composition, thus suggesting that each intruder was a potential competitor at the beginning of the agonistic interaction. However, frequency of undulation (a behavior displayed also during courtship) was higher in the MF than in the MM resident fish (mean ± SD, MM = 3.56 ± 5.89; MF = 8.56 ± 4.00.10/min; Mann-Whitney test, U = 15.50, P = 0.01) at the end of the 10 min session. Frequency of flight, however, was lower in MF than in MM intruder (mean ± SD, MM = 3.90 ± 4.33; MF = 0.44 ± 0.96.10/min; Mann-Whitney test, U = 23.50, P = 0.04). Moreover, the agonistic profile in MM groups was composed of more types than in MF groups (less fighting types were exhibited by both resident and intruder fish). Despite the behavioral differences, energy cost in terms of O2 consumption was not affected by group composition (mean ± SD, MM = 1.93 ± 0.54; MF = 1.77 ± 0.46 mgO2. gDW-1.40/min; Student's t independent test, t = 0.71, P = 0.49).
We tested whether the fish Nile tilapia (Oreochromis niloticus) in a monosex male group spends more energy and displays an agonistic profile, differently from males in male-female groups. Such differences are expected because males and females should compete for different reproductive resources. An intruder male (MM) or female (MF) was paired with a resident male and agonistic interaction was quantified during 20 minutes, 10 minutes after pairing and another 10 minutes period 30 minutes later. Energetic cost was evaluated from O2 consumption, determined by Winckler's Method after 40 minutes pairing. Latency for fighting (mean ± SD, MM = 27.40 ± 25.15 s; MF = 14.22 ± 21.19 s; Mann-Whitney test, U = 33.50, P = 0.21) and frequency of the all agonistic acts in the first 10 minutes session (mean ± SD, MM < 72.30 ± 25.29; MF < 73.50 ± 21.65.10/min; Mann-Whitney test, P > 0.10) were not affected by group composition, thus suggesting that each intruder was a potential competitor at the beginning of the agonistic interaction. However, frequency of undulation (a behavior displayed also during courtship) was higher in the MF than in the MM resident fish (mean ± SD, MM = 3.56 ± 5.89; MF = 8.56 ± 4.00.10/min; Mann-Whitney test, U = 15.50, P = 0.01) at the end of the 10 min session. Frequency of flight, however, was lower in MF than in MM intruder (mean ± SD, MM = 3.90 ± 4.33; MF = 0.44 ± 0.96.10/min; Mann-Whitney test, U = 23.50, P = 0.04). Moreover, the agonistic profile in MM groups was composed of more types than in MF groups (less fighting types were exhibited by both resident and intruder fish). Despite the behavioral differences, energy cost in terms of O2 consumption was not affected by group composition (mean ± SD, MM = 1.93 ± 0.54; MF = 1.77 ± 0.46 mgO2. gDW-1.40/min; Student's t independent test, t = 0.71, P = 0.49).
Descrição
Palavras-chave
Cichlidae, consumo de O2, corte, interação agressiva, reconhecimento de sexo, aggressive interaction, cichlid, courtship, O2 consumption, sex recognition
Como citar
Brazilian Journal of Biology. Instituto Internacional de Ecologia, v. 68, n. 4, p. 807-812, 2008.