Chromosomal and electric signal diversity in three sympatric electric knifefish species (Gymnotus, Gymnotidae) from the Central Amazon Floodplain |
| |
Authors: | Susana Suely Rodrigues Milhomem William Gareth Richard Crampton Julio Cesar Pieczarka Danillo dos Santos Silva Adauto Lima Cardoso Patricia Corrêa da Silva Jonas Alves de Oliveira Cleusa Yoshiko Nagamachi |
| |
Institution: | (1) Instituto de Ci?ncias Biol?gicas, Universidade Federal do Par?, Campus do Guam?, Av. Perimetral, sn. Guam?, Bel?m, Par?, 66075-900, Brazil;(2) CNPq, Bras?lia, Brazil;(3) CNPq—on Genetics and Molecular Biology, Bras?lia, Brazil;(4) Department of Biology, University of Central Florida, Orlando, FL 32816-2368, USA;(5) CAPES—on Genetics and Molecular Biology, Bras?lia, Brazil;(6) Instituto de Desenvolvimento Sustent?vel Mamirau?, IDSM, Amazonas, Brazil; |
| |
Abstract: | We describe chromosomal and electric signal diversity in three sympatric species of Gymnotus (Gymnotidae) fish from the Central Amazon Floodplain. Gymnotus arapaima presents a karyotype of 2n = 44 (24 m-sm + 20st-a), G. mamiraua 2n = 54 (42 m-sm + 12st-a), and G. jonasi 2n = 52 (12 m-sm + 40st-a). No evidence for a chromosomal sexual system was observed in two species for which both males
and females were analyzed (G. mamiraua and G. arapaima). In all three species the constitutive heterochromatin is located primarily in pericentromeric regions, but also at some
other sites. G. arapaima and G. mamiraua exhibit simple nucleolar organizing regions (NORs) on short arms of chromosome pairs 19 and 24, respectively. Gymnotus jonasi exhibits a multiple interstitial NOR on the long arm of pairs 9 and 10, and on the short arm of pair 11. G. arapaima and G. mamiraua exhibit several additional similarities in their karyotypic formulas—reflecting the phylogenetic proximity of these species
within a G. carapo group clade (based on molecular phylogenetic evidence). The chromosomal differences among these three sympatric species imply
complete post-zygotic reproductive isolation. A prominent pattern of partitioning of the peak power frequency of the electric
organ discharge of these three species indicates pre-zygotic reproductive isolation of mate attraction signals. We conclude
by discussing the evolutionary events that may have promoted signal divergence and reproductive isolation in Gymnotus of the Central Amazon, and the role that chromosomal rearrangements may place in diversification. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|