Dispersal Capacity and Genetic Structure of Arapaima gigas on Different Geographic Scales Using Microsatellite Markers

Abstract

Despite the ecological and economic importance of the Arapaima gigas (Cuvier 1817), few data about its dispersal capacity are available. The present study was based on the analysis of microsatellite markers in order to estimate the dispersal capacity of the species on fine, meso, and large geographic scales. For this, 561 specimens obtained from stocks separated by distances of up to 25 km (fine scale), 100 km (meso scale), and 1300–2300 km (large scale) were analyzed. The fine scale analysis indicated a marked genetic similarity between lakes, with low genetic differentiation, and significant differences between only a few pairs of sites. Low to moderate genetic differentiation was observed between pairs of sites on a meso scale (100 km), which could be explained by the distances between sites. By contrast, major genetic differentiation was recorded in the large scale analysis, that is, between stocks separated by distances of over 1300 km, with the analysis indicating that differentiation was not related solely to distance. The genetic structuring analysis indicated the presence of two stocks, one represented by the arapaimas of the Mamirauá Reserve, and the other by those of Santarém and Tucuruí. The dispersal of arapaimas over short distances indicates a process of lateral migration within the várzea floodplains, which may be the principal factor determining the considerable homogeneity observed among the várzea lakes. The populations separated by distances of approximately 100 km were characterized by reduced genetic differentiation, which was associated with the geographic distances between sites. Populations separated by distances of over 1300 km were characterized by a high degree of genetic differentiation, which may be related primarily to historical bottlenecks in population size and the sedentary behavior of the species. Evidence was found of asymmetric gene flow, resulting in increasing genetic variability in the population of the Mamirauá Reserve.

Genetic diversity of Arapaima gigas (Schinz, 1822) (Osteoglossiformes: Arapaimidae) in the Araguaia-Tocantins basin estimated by ISSR marker

“…For populations that are separated on a mesoscale (100 km), there is low to moderate genetic differentiation (Araripe et al, 2013). This relationship was not found in this study, because the localities of Novo Santo Antônio and São Félix do Araguaia are separated by 111 km and have a much higher genetic differentiation (F ST =0.424).…”

“…The floodplain inundation areas remain at very high rates for an extended period, allowing for the movement of "pirarucus" for a longer period (called the process lateral migration) (Castello, 2008a), since the lakes remain connected for a relatively long time. Thus, Hrbek et al (2005Hrbek et al ( , 2007 and Araripe et al (2013) results demonstrated that the levels of genetic diversity among stocks from different localities of the Amazon basin, although reflecting a consistent population structure, show that there is an effective gene flow. On the other hand, the results for the middle rio Araguaia region are interesting as they show little genetic variability and low gene flow, indicating that some of the stocks studied apparently represent consistent family groups.…”

“…Several studies about genetic diversity in A. gigas have been carried in the Amazon region, with the purpose of determining the risk of extinction of this species and helping to define appropriate strategies for their management (Farias et al, 2003;Hrbek et al, 2005;Hrbek & Farias, 2008;Hamoy et al, 2008;Araripe et al, 2013). Thus, while there are already several studies concerning the stocks of the Amazonian plain, there is only one study based on chromosomal/ genetic markers in the plain of the rio Araguaia, and this study was conducted at a single location in the middle rio Araguaia (Marques et al, 2006).…”

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

“…Even though it has been exploited commercially for many years, much basic life history data are still lacking. However, several recent publications have made significant advances of our understanding of growth and reproductive behavior (Arantes et al, 2010), population dynamics (Coutinho et al, 2010;Castello et al, 2011), spatial and temporal distribution and trophic ecology (Watson et al, 2013) as well as population structuring (Hrbek et al, 2005;Hrbek et al, 2007;Araripe et al, 2013).…”

RAPID-COMMUNICATION Genetic diversity and differentiation in natural populations of Arapaima gigas from lower Amazon revealed by microsatellites

“…In comparison, some studies using other microsatellite markers, such as the ones by Araripe et al (2013) and Farias et al (2003), found mean values of N A of approximately 6.5 in populations of the Lower Amazon and southeast of Pará.…”