Evidence of multiple paternity and cooperative parental care in the so called monogamous silver arowana Osteoglossum bicirrhosum (Osteoglossiformes: Osteoglossidae)

Monogamy is rare in fishes and is usually associated with elaborate parental care. When parental care is present in fishes, it is usually the male that is responsible, and it is believed that there is a relationship between the high energetic investment and the certainty of paternity (except in the case of sneaker males). Osteoglossum bicirrhosum is considered a monogamous fish, and has particular behavioral traits that permit the study of mating systems and parental care, such as male mouthbrooding. We investigated the genetic relationships of males with the broods found in their oral cavities in Osteoglossum samples collected in a natural environment in the lower Purus river basin, Amazonas, Brazil. Fourteen broods were analyzed for parentage (268 young and 14 adult males) using eight microsatellite loci. The results indicate that eleven broods show a monogamous system. In one brood, however, approximately 50% of the young were genetically compatible with being offspring of another male, and in another two broods, none of the subsampled young were compatible with the genotypes of the brooding male. The result of this first brood may be explained by the extra-parental contribution of a sneaker male, whereas cooperative parental care may explain the result in the other two broods. © 2014 Sociedade Brasileira de Ictiologia

Evidence of multiple paternity and cooperative parental care in the so called monogamous silver arowana Osteoglossum bicirrhosum (Osteoglossiformes: Osteoglossidae)

Monogamy is rare in fishes and is usually associated with elaborate parental care. When parental care is present in fishes, it is usually the male that is responsible, and it is believed that there is a relationship between the high energetic investment and the certainty of paternity (except in the case of sneaker males). Osteoglossum bicirrhosum is considered a monogamous fish, and has particular behavioral traits that permit the study of mating systems and parental care, such as male mouthbrooding. We investigated the genetic relationships of males with the broods found in their oral cavities in Osteoglossum samples collected in a natural environment in the lower Purus river basin, Amazonas, Brazil. Fourteen broods were analyzed for parentage (268 young and 14 adult males) using eight microsatellite loci. The results indicate that eleven broods show a monogamous system. In one brood, however, approximately 50% of the young were genetically compatible with being offspring of another male, and in another two broods, none of the subsampled young were compatible with the genotypes of the brooding male. The result of this first brood may be explained by the extra-parental contribution of a sneaker male, whereas cooperative parental care may explain the result in the other two broods

Ocorrência de paternidade múltipla em ninhadas de aruanã branco Osteoglossum bicirrhosum Cuvier, 1829 (Osteoglossiformes: Osteoglossidae)

Monogamy is rare in fish and is usually associated with elaborate and prolonged parental care. Among fish, the male is usually responsible for parental care, and it is believed that there is a relationship between this high energetic investment and the certainty of paternity, but not when sneaker males occur. The silver arowana, Osteoglossum bicirrhosum, is considered monogamous and has special behavioral traits that allow the study of mating systems and parental care, such as mouthbrooding performed by males and formation of aggregations of males during parental care. Using microsatellite markers, we investigated the genetic relationships between males and the brood found in their oral cavity. Samples were collected on Sustainable Development Reserve Piagaçu-Purus, lower Purus River, Amazonas, Brazil. Fourteen broods were analyzed (268 young and 14 adult males) using eight microsatellite loci. The results indicate that most broods (11) show monogamous mating. Three broods had revealed the occurrence of multiple paternity. In one brood, about 50% of the young were genetically compatible with the male who was performing the parental care, and in the other two the genotypes of parents were not compatible with any of the young. The result of the first clutch may be explained by the interference of a sneaker male, whereas cooperative parental care may explain the lack of relationship between males and pups in the other two broods. We suggest that cooperative care may occur as brood mixing.A monogamia é rara em peixes e está usualmente relacionada a cuidado parental elaborado e prolongado. Entre peixes, o macho é normalmente responsável pelo cuidado parental, e acredita-se que exista uma relação entre esse investimento energético e a certeza da paternidade, mas não quando ocorrem machos oportunistas. O aruanã branco Osteoglossum bicirrhosum é considerado monogâmico e possui características especiais para o estudo de sistemas de acasalamento e cuidado parental, como o comportamento de incubação bucal realizado pelo macho e formação de agregações de machos durante a fase de cuidado paternal. Utilizando análises de microssatélites, investigamos relações genéticas entre machos e os filhotes encontrados na respectiva cavidade bucal. As amostras foram coletadas na Reserva de Desenvolvimento Sustentável Piagaçu-Purus, no baixo rio Purus, Amazonas, Brasil. Foram analisados oito loci microssatélites, genotipados a partir de amostras de 14 ninhadas (268 filhotes e 14 machos adultos). Na maioria das ninhadas (11), os resultados sugerem acasalamento monogâmico. Em três ninhadas houve indicações de ocorrência de múltipla paternidade. Em uma delas, os resultados sugeriram que cerca de 50% dos filhotes eram filhos do macho que estava realizando o cuidado, e nas outras duas os resultados indicaram que nenhum dos filhotes analisados eram filhos dos machos que estavam realizando cuidado. O resultado da primeira ninhada pode ser explicado pela ocorrência de machos oportunistas (sneakers). Cuidado cooperativo pode explicar a falta de relação entre machos e filhotes nas outras duas ninhadas. Sugerimos que esse cuidado cooperativo pode ocorrer na forma de mistura de ninhadas

Evidence of multiple paternity and cooperative parental care in the so called monogamous silver arowana Osteoglossum bicirrhosum (Osteoglossiformes: Osteoglossidae)

Monogamy is rare in fishes and is usually associated with elaborate parental care. When parental care is present in fishes, it is usually the male that is responsible, and it is believed that there is a relationship between the high energetic investment and the certainty of paternity (except in the case of sneaker males). Osteoglossum bicirrhosum is considered a monogamous fish, and has particular behavioral traits that permit the study of mating systems and parental care, such as male mouthbrooding. We investigated the genetic relationships of males with the broods found in their oral cavities in Osteoglossum samples collected in a natural environment in the lower Purus river basin, Amazonas, Brazil. Fourteen broods were analyzed for parentage (268 young and 14 adult males) using eight microsatellite loci. The results indicate that eleven broods show a monogamous system. In one brood, however, approximately 50% of the young were genetically compatible with being offspring of another male, and in another two broods, none of the subsampled young were compatible with the genotypes of the brooding male. The result of this first brood may be explained by the extra-parental contribution of a sneaker male, whereas cooperative parental care may explain the result in the other two broods

Evidence of polygamy in the socially monogamous Amazonian fish Arapaima gigas (Schinz, 1822) (Osteoglossiformes, Arapaimidae)

Arapaima gigas is one of the largest freshwater fishes of the world. It is socially monogamous, forming pairs, constructing a nest and providing parental care. We performed a paternity analysis under three scenarios in captive, semi-natural and natural areas using 10 microsatellite markers. As a positive control, we analyzed three pairs and their offspring isolated individually in artificial breeding ponds (a priori very high probability of monogamy). We then analyzed two samples of offspring from large artificial ponds with multiple adults but only one reproductive pair (a priori high probability of monogamy), two samples from semi-natural breeding station with multiple adults but only one reproductive pair (a priori high probability of monogamy), and a sample from a natural lake with multiple adults, some potentially breeding (a priori medium probability of monogamy). Analysis of patterns of Mendelian heredity suggested an extra-pair contribution for all broods except the positive controls. Similarly, results based on multilocus analysis estimated at least two sib-groups per nest. These results reject monogamy as a system of breeding in Arapaima gigas. From a management perspective, this behavior may be exploited to maintain genetic diversity in captive and as well in wild populations of Arapaima gigas

The largest fish in the world's biggest river: Genetic connectivity and conservation of Arapaima gigas in the Amazon and Araguaia-Tocantins drainages.

Arapaima, pirarucu or paiche (Arapaima gigas) is one of the largest freshwater fish in the world, and has a long history of commercial exploitation in the Amazon region. To estimate levels of genetic variability and historical and recent connectivity in Arapaima, we examined variation in eleven microsatellite DNA markers in individuals from 22 localities in Brazil, Colombia, and Peru. The results of analysis of molecular variance, Bayesian clustering and discriminant analysis of principal components showed that Arapaima in our samples represents two major populations, one in the Amazonas and one in the Araguaia-Tocantins River basins. The Amazonas population is further structured by isolation-by-distance with the hydrologically largely unconnected Amapá locality representing the eastern-most extreme of this continuum; gene flow predominates at distances of less than 1500 km with localities separated by over 2000 km dominated by genetic drift and effectively forming different populations. We saw no evidence of multiple species of Arapaima in the Amazonas basin, and analysis of pairwise genetic divergence (FST) with Mantel tests and correlograms indicated that this largest population exhibits a large-scale pattern of isolation-by-distance, with which results from MIGRATE-N agreed. The degree and significance of genetic divergence indicates that most sampled localities represent demographically independent sub-populations, although we did identify several recent migration events between both proximal and more distant localities. The levels of genetic diversity were heterogeneous across sites, including low genetic diversity, effective population sizes, and evidence of genetic bottlenecks in several places. On average the levels of gene diversity and rarefied allelic richness were higher for localities along the Amazonas mainstem than in the tributaries, despite these being the areas of highest fishing pressure, while the lowest values were found in tributary headwaters, where landscape modification is a significant threat. We recommend that managers consider the regional and local threats to these populations and tailor strategies accordingly, strategies which should ensure the ability of young A. gigas to disperse through floodplain corridors to maintain genetic diversity among otherwise sedentary adult sub-populations