Genetic constitution of parthenogenetic form of Polydrusus inustus (Coleoptera: Curculionidae)--hints of hybrid origin and recombinations.
Asexual reproduction among insects may arise spontaneously, as a result of infectious agents or hybridization between phylogenetically distinct organisms. Polyploidy, which may be the result of auto- or allopoliploidization (also associated with hybridization), is often connected with parthenogenesis. However, all studied parthenogens of weevils were apomictic, rare meiotic stages have been observed in a few of them what could suggests in their genomes besides the mutational changeability also recombination may occurs. We studied the level of heterozygosity in Internal Transcribed Spacer 2 sequences, and congruence ofmitochondrial (cytochrome B) and nuclear genealogies among individuals of parthenogenetic form of Polydrusus inustus. High frequency (87.0%) of heterozygotes in ITS2 sequences may indicate a hybrid origin of the parthenogen. It is possible that this parthenogenetic form arose via a hybridization event between phylogenetically distinct lineages of bisexual P. inustus, known only from Georgia and Turkey, or between this species and one of the closely relatives from the subgenus Scythodrusus. Although result of partition- homogeneity test did not show significant incongruence of mitochondrial and nuclear genealogies, in the network was detected one loop. Most probable explanations for existence of that loop in parthenogenetic form and for origin of rare homozygotes, which were detected in ITS2 sequences, is gene conversion. It is supported by recently cytogenetic studies indicating rare meiotic stages during the oogenesis of triploids of P. inustus.
Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17, 31-016 Kraków, Poland. kajtoch@isez.pan.krakow.pl
Łukasz
Ł
Kajtoch
Dorota
D
Lachowska-Cierlik
D000818:Animals; D001483:Base Sequence; D001517:Coleoptera / Q000235:genetics*; D045303:Cytochromes b / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005260:Female; D008969:Molecular Sequence Data; D010312:Parthenogenesis / Q000235:genetics*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D004272:DNA, Mitochondrial; D021903:DNA, Ribosomal Spacer; D045303:Cytochromes b