Análise de parentesco em filhotes de pirarucu (Arapaima gigas Cuvier, 1817), utilizando marcadores microssatélites.

Abstract

Arapaima gigas, known in Brazil as pirarucu, is on of the most economically important species in the Amazon watershed. However there is scarce knowledge of some aspects of its biology, behavior and growing rates in any modality of intensive farming. Pirarucu presents a complex reproductive behavior, including formation of couples; nest building; and parental care by male, as observed by farmers and other authors. The present work aim to generate information about genetic kinship between nestling of pirarucu from captivity and semi-open areas (Santarém), by means of microsatellite markers. This technique is the most used molecular marker to reveal leveis or genetic relationships within and between group of brothers and dose relatives. Kinship analyses were carried out with nine (the most polymorphic) microsatellite developed for A. gigas. The genotypes were done in the automatic DNA sequencer MegaBace 1000 using the software Genetic Profiler v1.2. Allelic frequencies and expected and observed heterozigosity values were obtained in the software ARLEQUIN and GENETIX v. 4. Genotypes of all the nestling of two offspring were used to calculate the pairwise kinship relationships and kinship relationships using the software KINSHIP vl. 2, based on all loci. The reitionships categories were estimated in the sofiware ML-RELATE. Our results indicated that, on average, the captivity offspring presented a high estimative of relationship, varying from 0.48 in Itacoatiara 2 e Rio Preto da Eva, to 0.51 in Itacoatiara 1. In Santarém samples, the average values varied from 0,46 to 0,80 in STM G2 e STM G3, respectiveiy. The relationship categories matrixes show that the higher frequency observed in nestling is the category of non-related (U), both in captivity groups as semi-open areas groups. When we analyzed separately each sample, we find other level of kinship reiationships or kinship categories in the nestling. These results indicate that, despite the nestling are highly related, the hypotheses of an “extra maternity or paternity” of the pair of reiationship can not be ignored. These results demonstrate a reproductive strategy natural and effective to keep the genetie variability in the nestling of Arapaima gigas.