Genomic selection signatures in farmed Colossoma macropomum from tropical and subtropical regions in South America

Tambaqui or cachama (Colossoma macropomum) is one of the most important neo-tropical freshwater fish used for aquaculture in South America, and its production is concentrated at low latitudes (close to the Equator, 0°), where the water tempera-ture is warm. Therefore, understanding how selection shapes genetic variations and structure in farmed populations is of paramount importance in evolutionary biology. High- throughput sequencing to generate genome-wide data for fish species allows for elucidating the genomic basis of adaptation to local or farmed conditions and un-covering genes that control the phenotypes of interest. The present study aimed to detect genomic selection signatures and analyze the genetic variability in farmed pop-ulations of tambaqui in South America using single- nucleotide polymorphism (SNP) markers obtained with double-digest restriction site-associated DNA sequencing. Initially, 199 samples of tambaqui farmed populations from different locations (lo-cated in Brazil, Colombia, and Peru), a wild population (Amazon River, Brazil), and the base population of a breeding program (Aquaculture Center, CAUNESP, Jaboticabal, SP, Brazil) were genotyped. Observed and expected heterozygosity was 0.231–0.350 and 0.288– 0.360, respectively. Significant genetic differentiation was observed using global FST analyses of SNP loci (FST = 0.064, p< 0.050). Farmed populations from Colombia and Peru that differentiated from the Brazilian populations formed distinct groups. Several regions, particularly those harboring the genes of significance to aq-uaculture, were identified to be under positive selection, suggesting local adapta-tion to stress under different farming conditions and management practices. Studies aimed at improving the knowledge of genomics of tambaqui farmed populations are essential for aquaculture to gain deeper insights into the evolutionary history of these fish and provide resources for the establishment of breeding programsConselho Nacional de Desenvolvimento Científico e Tecnológico, Grant/Award Number: 140740/2016–3, 311559/2018– 2 and 422670/2018-9; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior; Fundação de Amparo à Pesquisa do Estado de São Paulo, Grant/Award Number: 2016/18294–9, 2016/21011– 9, 2017/19717-3, 2017/26900–9, 2018/08416–5, 2019/08972-8 and 2019/10662-7; Comisión Nacional de Investigación Científica y Tecnológica.S

Vitelogênese pós-desova em lambaris, Astyanax altiparanae, mantidos em laboratório

The possibility of successive spawning in laboratory conditions permits a qualitative and quantitative increase in aquaculture. Recent studies indicate that the yellowtail tetra (Astyanax altiparanae) presents high reproductive plasticity which the reproductive cycle may be manipulated out of breeding season. In addition, the manipulation of enviromental condition, may induce the spawning during winter period. Therefore, given the breeding potential of this species and the increasing demand from fish farmers, the aim of this experiment was to investigate if the same female can prepare for a second induced spawning at laboratory conditions, what are the characteristics of the process and the time required to perform this second spawning. The results obtained were promising, as we observed that the same female maintained in a recirculating water system at a controlled temperature (29.24 ± 0.42°C) presentes vitellogenic oocytes 6 days after spawning. Obtaining complete reproductive cycles in the laboratory at short inter spawning period optimize the use of space and water, making the production of this species appropriate for a modern, sustainable and competitive aquacultureA possibilidade de desovas sucessivas em condições de laboratório permite um incremento qualitativo e quantitativo na produção aquícola. Estudos recentes indicam que o lambari do rabo amarelo (Astyanax altiparanae), apresenta alta plasticidade reprodutiva e que o ciclo reprodutivo pode ser manipulado fora da época de reprodução. Além disso, a manipulação da condição ambiental, pode induzir a desova durante o período de inverno. Por tanto, dado o potencial zootécnico desta espécie e sua crescente procura por parte de produtores, o objetivo deste trabalho foi investigar se a mesma fêmea maturaria novamente em condições laboratoriais, quais seriam as características do processo e o tempo necessário para a realização de uma segunda desova. Os resultados aqui obtidos foram promissores, pois observamos que uma mesma fêmea mantida num sistema de recirculação de água com temperatura controlada (29,24 ± 0,42°C) apresenta ovócitos vitelogênicos completos 6 dias após a desova. A obtenção de ciclos reprodutivos completos em laboratório em curtos períodos inter desovas otimiza o uso do espaço e de água, tornando a produção desta espécie ainda mais adequada aos preceitos de sustentabilidade atrelados à uma aquicultura moderna e competitivaConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq