Experimental crosses between Mepraia gajardoi and M. spinolai and hybrid chromosome analyses reveal the occurrence of several isolation mechanisms.
Hematophagous insects of the subfamily Triatominae include several species with a large variety of shapes, behavior and distribution. They have great epidemiological importance since most of them transmit the flagellated protozoan Trypanosoma cruzi, the etiologic agent of Chagas disease. In this subfamily several cases of species hybridization have been reported under experimental and natural conditions. Mepraia is a genus of Triatominae endemic in Chile, responsible for transmitting T. cruzi in the sylvatic cycle. This genus includes three species, M. gajardoi, M. spinolai and M. parapatrica; however, the differentiation of M. parapatrica as a separate species remains controversial considering the possible occurrence of introgression/hybridization processes in some populations of this putative species. Mepraia species show conspicuous wing polymorphism, and it has been proposed that the genes related to wings are linked to the Y chromosome, thus wingless males could not engender winged progeny. In order to determine the degree of reproductive isolation and to assess the wing phenotype in the offspring, we performed experimental crosses between the two most divergent Mepraia species (M. gajardoi and M. spinolai) together with chromosome analyses of hybrid progenies. Although fertile F1hybrids were obtained in only one direction of crossing, we verified the existence of different isolation mechanisms between parental species, including hybrid breakdown. The occurrence of winged males in the offspring of wingless parental males suggests that the wing character is not linked to the Y chromosome.
Instituto de Biología, Facultad de Ciencias, Pontificia Universidad Católica de Valparaíso, Valparaíso 2373223, Chile. Electronic address: ricardo.campos.s@pucv.cl.
Ricardo
R
Campos-Soto
Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Francisco
F
Panzera
Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Sebastian
S
Pita
Sección Genética Evolutiva, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Carol
C
Lages
Programa de Biología Celular y Molecular, ICBM, Facultad de Medicina, Universidad de Chile, Santiago 8380453, Chile.
Aldo
A
Solari
Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
Carezza
C
Botto-Mahan
D000818:Animals; D001947:Breeding; D059006:Chromosomes, Insect / Q000737:chemistry / Q000235:genetics*; D005260:Female; D059785:Karyotype; D008297:Male; D009693:Nucleic Acid Hybridization / Q000235:genetics* / Q000379:methods*; D014225:Triatominae / Q000145:classification / Q000235:genetics*
Chromosome hybrid studies; Experimental hybridization; Fertile hybrids; Hybrid breakdown; Mepraia