Features of the genetic structure of the earthworms Aporrectodea (Superspecies) Caliginosa (Oligochaeta: Lumbricidae) complex in Ukraine

Abstract

Abstract-An investigation of the genetic structure of the Aporrectodea caliginosa -A. trapezoids diploidpolyploid complex of earthworms found in the Ukraine is performed by means of biochemical genetic marking with respect to six loci (Aat, Es-1, -2, -3, and -4, and Mdh) and karyotyping. All 646 individuals from 21 samples are analyzed at the biochemical gene level and karyotype samples are obtained from 70 specimens. As a result, diploid amphimictic A. caliginosa individuals (2n = 36), which form panmictic populations, and triploid (2n = 54) A. trapezoides individuals, represented by 19 hypothetical clones discovered in the course of an analysis of 157 specimens, are clearly differentiated. A clear trend towards dominance of the triploid forms in the steppe zone of Ukraine is discovered. Here they represent roughly 70% as against 12% of all A. (superspecies) caliginosa individuals in the northern forest regions. Based on the stated nature of the heterozygosity of the loci studied and the behavior of the chromosomes in meiosis, it may be claimed that the cloned forms are allotriploids, formed as a result of hybridization of a series of related forms, which, judging from the allelic pools, does not include amphimictic species that now inhabit the territory of Ukraine. That is, either the apomictic clones of A. trapezoides lack a local origin and their appearance among the fauna of Ukraine is a consequence of settlement in arid steppe regions that are unfavorable for earthworms or, on the other hand, amphimictic A. caliginosa is an invasive species.

Variability of sexual organ possession rates and phylogenetic analyses of a parthenogenetic Japanese earthworm, Amynthas vittatus (Oligochaeta: Megascolecidae)

“…However, parthenogenesis with degradation of reproductive organs is not uncommon. Many studies examined the ecology and genetics of parthenogenetic earthworms, including two families of Lumbricidae and Megascolecidae (Lumbricidae: Jaenike and Selander, 1979;Terhivuo, 1988;Terhivuo and Saura, 1990, 1993a, 1993b, 2003Mezhzherin et al, 2008;Megascolecidae: Gates, 1956). Parthenogenetic earthworms evolutionarily trend towards reduction of reproductive organs, especially male organs (e.g.…”

Polyploid races, genetic structure and morphological features of the earthworm Octodrіlus transpadanus (Rosa, 1884) (Oligohaeta: Lumbricidae) in the Ukraine

“…As a result, the genetic variability in a population greatly increases and every specimen becomes as unique as if it were a separate clone. A similar case was registered in the parthenogenetic species Aporrectodea rosea (Savigny, 1826) with different levels of ploidy, populations of which have either a strict clonal structure or are an aggregate of specimens where each individual has its unique spectrum (Vlasenko, 2008).…”

“…At present the genetic structure of populations of many Lumbricid species is rather well investigated (Terhіvuo, Saura, 2006;Vlasenko et al, 2007;Mezhzherin et al, 2008). However, researchers have been interested basically in study of polyploid complexes, which are characterized by the clonal structure of populations.…”

Polyploid races, genetic structure and morphological features of earthworm Aporrectodea rosea (Savigny, 1826) (Oligohaeta, Lumbricidae) in Ukraine

“…Karyological studies (Muldal 1952, Omodeo 1952, Vedovini 1973, Mezhzherin et al 2007, etc.) have showed the apomictic (parthenogenetic) species represented by series of heteroploid forms.…”

“…They have never carried on this earthworm over the territory of the Eastern Europe up to nowadays. Preliminary data from Aporrectodea rosea Ukrainian populations (Garbar and Vlasenko 2007, Mezhzherin et al 2007, Vlasenko et al 2007) have showed that this species is represented by several chromosome races with different ploidy and its high clone variability let it consider one of the most variable taxa of earthworms. Thus further studying of this species genetic structure on the territory of Ukraine by means of biochemical gene marking and cytogenetic methods appears to be actual.…”