科研之友
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摘要
the genus anastrepha schiner, endemic to tropical and subtropical am谷rica, includes the species anastrepha ludens, a. obliqua, a. striataanda. serpentina, which are polyphagous and parasite a wide range of plants. these species were studied because of their broad geographic distribution and because they parasite different fruit species. larvae in their third stage reared in the laboratory of the programa moscafrut in metapa de dom赤nguez, chiapas, m谷xico, were used. the cerebral ganglia were dissected in an aqueous solution of 1% (w/v) sodium citrate in which they were kept for 20 min, then transferred to methanol:acetic acid (3:1 (v/v) and macerated in 60% acetic acid. one drop of this tissue suspension was placed on a slide on a hot plate (45-50～c) and observed with a microscope (zeiss axioskop 40) with phase contrast, and the cells with disperse chromosomes were selected. these were photographed with an axiocam camera and axiovision 4.0 software, and measurements were taken with image tool 3.0. twenty cells/sex/species were analyzed. the centromere was observed without pretreatment. karyotypes were determined in each species: a. ludens , 2n=12, xg xg+vii telo, n. f. 12, , 2n=12, xg yp+vii telo n. f. 12; a. obliqua , 2n=12, xg xg+vii telo, n. f. 12, , 2n=12, xg yg+vii telo n. f. 12; a. striata , 2n=12, xg xg+iiii meta+iiiii telo n. f. 16, , 2n=12, xg yp+iiii meta+iiii telo n. f. 16; a. serpentina , 2n=12, x1 x1 x2 x2+ivii meta n. f. 20, , 2n=11 x1 x2, yg+ivii meta n. f.22. it is proposed that this group of species has robertsonian translocations as a speciation mechanism parting from a. serpentina.
