Hymenoptera are haplodiploid and usually display very low genetic variation. Most data concern social or parasitic Apocrita, while the little information available for the primitive phytophagous species of the suborder Symphyta is contradictory. The present study is related tea seven species of the genus Cephalcia, living in coniferous forests of Northern Eurasia and sharing spruce (Picea sp. pi.) as host plant. individuals from 22 populations belonging to Cephalcia abietis, C. alashanica, C. arvensis, C. erythrogaster, C. fallenii, C. fulva, C. klugii from Europe and China were surveyed for genetic variation at 28 loci using enzyme electrophoresis. Pairs of sibling species were recognized within C. arvensis and C. fallenii, corresponding to different phenological and morphological forms. In the latter case, reproductive isolation in sympatry occurs despite low genetic distance (D = 0.059). Large genetic distances and fixed alternate alleles were observed between Chinese and European populations of C. abietis and C. arvensis. Expected heterozygosity of Cephalcia populations (0.197, SD 0.064) is significantly higher than that of other Symphyta (Tenthredinoidea) (average H-exp 0.059, SD 0.032) (two-tailed Mann-Whitney test, Z = 4.39, p <0.01). These data suggest that haplodiploidy per se does not reduce the genetic variation in most Cephalcia populations. Most of the factors that can lower the potential for genetic diversity in a haplodiploid genetic system are not so effective in Cephalcia populations, which seem to be comparable to diplodiploid insect populations in diversity. In a few isolated populations the large number of fixed loci and the large genetic distances may support the predicted faster rate of fixation, as a consequence of haplodiploidy.

High genetic variability despite haplodiploidy in primitive sawflies of the genus Cephalcia (Hymenoptera, Pamphiliidae)

BATTISTI, ANDREA
1996

Abstract

Hymenoptera are haplodiploid and usually display very low genetic variation. Most data concern social or parasitic Apocrita, while the little information available for the primitive phytophagous species of the suborder Symphyta is contradictory. The present study is related tea seven species of the genus Cephalcia, living in coniferous forests of Northern Eurasia and sharing spruce (Picea sp. pi.) as host plant. individuals from 22 populations belonging to Cephalcia abietis, C. alashanica, C. arvensis, C. erythrogaster, C. fallenii, C. fulva, C. klugii from Europe and China were surveyed for genetic variation at 28 loci using enzyme electrophoresis. Pairs of sibling species were recognized within C. arvensis and C. fallenii, corresponding to different phenological and morphological forms. In the latter case, reproductive isolation in sympatry occurs despite low genetic distance (D = 0.059). Large genetic distances and fixed alternate alleles were observed between Chinese and European populations of C. abietis and C. arvensis. Expected heterozygosity of Cephalcia populations (0.197, SD 0.064) is significantly higher than that of other Symphyta (Tenthredinoidea) (average H-exp 0.059, SD 0.032) (two-tailed Mann-Whitney test, Z = 4.39, p <0.01). These data suggest that haplodiploidy per se does not reduce the genetic variation in most Cephalcia populations. Most of the factors that can lower the potential for genetic diversity in a haplodiploid genetic system are not so effective in Cephalcia populations, which seem to be comparable to diplodiploid insect populations in diversity. In a few isolated populations the large number of fixed loci and the large genetic distances may support the predicted faster rate of fixation, as a consequence of haplodiploidy.
1996
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2515728
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