RÉSUMÉ
Abstract Colossoma macropomum is the second largest scaled fish of the Amazon. It is economically important for commercial fisheries and for aquaculture, but few studies have examined the diversity and genetic structure of natural populations of this species. The aim of this study was to investigate the levels of genetic variability and connectivity that exist between three natural populations of C. macropomum from the Amazon basin. In total, 247 samples were collected from the municipalities of Tefé, Manaus, and Santarém. The populations were genotyped using a panel of 12 multiplex microsatellite markers. The genetic diversity found in these populations was high and similar to other populations described in the literature. These populations showed a pattern of high gene flow associated with the lack of a genetic structure pattern, indicating that the number of migrants per generation and recent migration rates are high. The values of the FST, RST, and exact test of differentiation were not significant for pairwise comparisons between populations. The Bayesian population clustering analysis indicated a single population. Thus, the data provide evidence for high genetic diversity and high gene flow among C. macropomum populations in the investigated region of the Amazon basin. This information is important for programs aiming at the conservation of natural populations.
RÉSUMÉ
The family Bathylagidae contains eight genera and 22 species, of which only five occur in the Southwest Atlantic. Until recently, only adult specimens of the bathylaginin Melanolagus bericoides had been recorded off southern Brazil, between the Santa Marta Cape and Rio Grande (31º S and 49º W). The present work reports the first occurrence of Dolicholagus longirostris larvae on the northern Brazilian coast, expanding its distribution in the Southwest Atlantic. The two specimens found were collected near the mouth of the Amazon River (02º 00' 19" N, 47º 03' 30" W, and 00º 49' 06" N, 46º 25' 09" W).
A família Bathylagidae apresenta oito gêneros e 22 espécies, sendo que apenas cinco destas espécies ocorrem no Atlântico Sudoeste. No sul do Brasil já havia sido registrada a ocorrência de exemplares adultos de Melanolagus bericoides entre o Cabo de Santa Marta e Rio Grande (31º S e 49º W). Este trabalho registra a primeira ocorrência de larvas de Dolicholagus longirostris na costa norte brasileira, ampliando sua distribuição no Atlântico Sudoeste. Os dois exemplares encontrados foram coletados na foz do Rio Amazonas (02º 00' 19" N, 47º 03' 30" W, e 00º 49' 06" N, 46º 25' 09" W).