Karyotype Patterns ofHypsolebias antenori(Cyprinodontiformes: Rivulidae): An Endangered Killifish of the Semiarid Region of Brazil

Wallace Silva Do Nascimento,Maria Emília Yamamoto,Juliana Galvão Bezerra,Sathyabama Chellappa,Paulo Augusto Lima-Filho,Wagner Franco Molina

doi:10.1155/2014/862434

Abstract

Annual fish which belong to the order Cyprinodontiformes constitute an excellent model for evolutionary studies. their short life cycle, distribution in ecologically dynamic environments, and low agility make them favorable for genetic analyses. The species Hypsolebias antenori (Rivulidae), encountered in seasonal pools located in the semiarid region of Northeastern Brazil, has been the object of surveys with a view to study its ecological and behavioral aspects. This study reports on the karyotype patterns of this species, which represents the first contribution to the cytogenetics of this genus. The karyotype of this species is composed of 2n = 48 chromosomes (6m + 4sm + 36st; NF = 96); the heterochromatic regions are located in centromeric or pericentromeric position and are more pronounced in the nucleolar organizer regions. Two sites Ag-NORs/CMA+/DAPI were identified in the short arms of pairs 2 (metacentric) and 21 (subtelocentric). Unlike the other species of this family which show an evolution modulated by events of centric fusions, H. antenori shows the maintenance of a basal diploid number and the large number of bibrachial elements indicates karyotypic diversification derived by pericentric inversions. Cytogenetic analyzes in this species will provide new taxonomic markers capable of being utilized in conservation issues and systematics.

Highlights

IntroductionThe family Rivulidae, pertaining to the order Cyprinodontiformes, is one of the largest families of freshwater fish of the Neotropical region
The family Rivulidae, pertaining to the order Cyprinodontiformes, is one of the largest families of freshwater fish of the Neotropical region. It is a diverse group of annual fish, most popularly known as “killifish,” which occur in seasonal freshwater pools of tropical and subtropical areas of South America
Cytogenetic analyses were performed on 16 specimens of males and females of H. antenori, captured from temporary pools, located in the municipality of Russas, Ceara (04∘57󸀠39.8󸀠󸀠 S and 37∘54󸀠26.2󸀠󸀠 W), Northeastern Brazil (Figure 1)

Summary

Introduction

The family Rivulidae, pertaining to the order Cyprinodontiformes, is one of the largest families of freshwater fish of the Neotropical region It is a diverse group of annual fish, most popularly known as “killifish,” which occur in seasonal freshwater pools of tropical and subtropical areas of South America. This group of fish exhibit short life cycles, limiting the process of sexual maturation and completion of reproductive cycle between specific seasons of a year. To survive under these extreme conditions, the fish eggs are deposited in the sediment of the pools, which go through diapause stages, during which the embryonic development becomes temporarily arrested. It demonstrates to be more plastic than it was thought previously [5]

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