. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Polyploidy in bisexual Lepidoptera 323. Fig. 9: Three diploid spermatids in a brundle together with normal haploid ones in male of Zygaena fillipendulae (Lepidoptera, Zygaenidae). Bar represents 10 urn. namely achiasmatic oogenesis and chiasmatic spermatogenesis. The absence of chiasmata in autotetraploid females leads to the formation of a normal number of common or doubled bivalents during meiosis and, as a consequence, to the regular disjunction of chromosomes. I
. Bonner zoologische Beiträge : Herausgeber: Zoologisches Forschungsinstitut und Museum Alexander Koenig, Bonn. Biology; Zoology. Polyploidy in bisexual Lepidoptera 323. Fig. 9: Three diploid spermatids in a brundle together with normal haploid ones in male of Zygaena fillipendulae (Lepidoptera, Zygaenidae). Bar represents 10 urn. namely achiasmatic oogenesis and chiasmatic spermatogenesis. The absence of chiasmata in autotetraploid females leads to the formation of a normal number of common or doubled bivalents during meiosis and, as a consequence, to the regular disjunction of chromosomes. In autotetraploid males the polyvalent conjugation of homologues is complicated by the formation of chiasmata. It leads to the disturbance of chromsome disjunction in the course of the reduction division. This leads to the conclusion that tetraploid bisexual species could only become allopolyploid by the way of hybridisation of species whose homologous chromo- somes lost the capacity to conjugate entirely or to a greater extent. Thus, polyploidy in bisexual Lepidoptera cannot be achieved without hybridisation. 2) Obstacles on the way to allopolyploidy in the Lepidoptera Theoretically, an allotetraploid organism may occur due to the fusion of a diploid spermatozoid of one species with a diploid ovule of another species. However, all the obstacles and barriers existing on this way have already been described in the preceding paragraph. Moreover, as frequently described in the literature, interspecific hybridisation in Lepidoptera is of low frequency in nature, A much more realistic way to obtain an allotetraploid line might be found in the hybridisation of triploid parthenogenetic females of one species with diploid males of another species. Triploid parthenogenetic races are not a rarity amongst polyploid animals (Astaurov 1977). Within triploid females the reduction division is absent in the meiosis, therefore these females can produce triploid gametes, the conjunction of which
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