01_Mezhzherin-1.indd UDC 57.017.55:595.142.39 THE ALTERNATIVE DISTRIBUTION OF RELATED EARTHWORMS APORRECTODEA CALIGINOSA AND A. TRAPEZOIDES (OLIGOCHAETA, LUMBRICIDAE) IN UKRAINE AS A CASE OF GEOGRAPHICAL PARTHENOGENESIS S. V. Mezhzherin1, Yu. Yu. Chayka2, R. P. Vlasenko2, E. I. Zhalay1, O. V. Rostovskaya1, O. V. Harbar2 1Schmalhausen Institute of Zoology NAS of Ukraine, vul. B. Khmelnytskogo, 15, Kyiv, 01030 Ukraine E-mail: smezhzherin@gmail.com 2Zhytomyr Ivan Franko State University Velyka Berdychivska st., 40, Zhytomyr, 10008 Ukraine E-mail: o.v.harbar@gmail.com S. V. Mezhzherin (https://orcid.org/0000-0003-2905-5235) Yu. Yu. Chayka (https://orcid.org/0000-0002-3965-6088) R. P. Vlasenko (https://orcid.org/0000-0002-3743-4406) E. I. Zhalay (https://orcid.org/0000-0003-3637-1156) O. V. Rostovskaya (https://orcid.org/0000 0002 0712 6365) O. V. Harbar (https://orcid.org/0000-0003-4357-4525) Th e Alternative Distribution of Related Earthworms Aporrectodea caliginosa and A. trapezoides (Oligochaeta, Lumbricidae) in Ukraine as a Case of Geographical Parthenogenesis. Mezhzherin, S. V., Chayka, Yu. Yu., Vlasenko, R. P., Zhalay, E. I., Rostovskaya, O. V., Garbar, O. V. — Geographical parthenogenesis describes phenomenon when parthenogenetic hybrid forms or species have larger distribution areas or higher abundance than their amphimictic parental species, especially in climatically unfavorable conditions. Th is phenomenon was studied in Ukraine for the pair species of earthworms Aporrectodea сaliginosa (Savigny, 1826) s. l. We found that the hermaphroditic amphimictic A. caliginosa clearly predominates in the northern and western regions, and the apomictic parthenogenetic A. trapezoides (Duges, 1828) in the southern and eastern regions with a continental arid climate. In the sample sets of A. сaliginosa–A. trapezoides group, usually one of the species sharply predominated, and the equality of their abundance was very rare. Th e reason for this fact is both the alternative geographical distribution and the ability of A. trapezoides to form populations in habitats unfavorable for A. caliginosa. In general, the situation in this group agrees with the classical model of geographic parthenogenesis and confi rms the high adaptive potential of apomictic organisms. Th is fact once again raises the question of non-adaptive reasons for the exclusion of the apomictic reproduction in highly organized animals. K e y w o r d s : geographic parthenogenesis, earthworms, Aporrectodea, amphimixis, apomixis. Zoodiversity, 55(3): 185–194, 2021 DOI 10.15407/zoo2021.03.185 Ecology 186 S. V. Mezhzherin, Yu. Yu. Chayka, R. P. Vlasenko, E. I. Zhalay, O. V. Rostovskaya, O. V. Harbar Introduction A special case in the world of wildlife is geographical parthenogenesis, which is a phenomenon of wide but peripheral distribution of apomictic hybrid polyploid forms (species) comparing with the parental amphimictic diploid species. At the same time, the range of the parthenogenetic species falls on the places with unfavorable environmental conditions for amphimictic parental species (Vandel, 1928; Cuellar, 1977; Glesener, Tilman, 1978; Suomalainen et al., 1987; Bierzychudek 1985; Kearney, 2005; Vrijenhoek, Parker, 2009; Hörandl, 2009). Usually parthenogenetic species occur in the regions with extreme continental or cold climate (Grant, 1982; Suomalainen et al., 1987), expanding their range to the north, penetrating into the highlands or arid zones. Th is phenomenon is typical for plants and animals in terrestrial and freshwater ecosystems that, as a rule, belonged to extratropical zones (Grant, 1982; Cuellar, 1994), fi rst of all, Holarctic (Grant, 1982; Suomalainen et al., 1987; Cuellar, 1994) and desert regions of Australia (Moritz, 1983; Kearney et al., 2003, Kearney, Moussalli, 2003). Among animals, geographic parthenogenesis has been studied in detail in weevils (Suomalainen et al., 1987; Stenberg et al., 2003), stick insects (Morgan-Richards, Trewick, 2010), freshwater snail Melanoides tuberculata (Ben-Ami, Heller, 2007),  ostracodes (Schmit et al. 2013), lizards of the families Teiidae (Wright et al., 1978) and Gekkonidae (Moritz, 1983; Kearney et al., 2003). Th e concept of geographical parthenogenesis was introduced as early as the 1920s (Vandel, 1928), never- theless, the nature of this phenomenon remains not completely clear. Generally, the huge ranges of partheno- genetic forms and species that cover the territories with unsuitable conditions for parental species are explained by the ability of asexual forms to occupy the small areas that are relatively favourable for this species by single specimens, which makes rapid invasions possible (Peck et al., 1998; Suomalainen et al., 1987; Haag, Ebert, 2004; Kearney, 2005; Hörandl, 2009). As a result, in suitable microstations, small populations are formed in one gen- eration, and their members are not aff ected by inbreeding due to clonal reproduction. Parthenogenesis is widespread in earthworms and the number of unisexual species of the family Lumbric- idae in the Holarctic is not much less than of hermaphroditic ones (Jaenike, Selander, 1979; Viktorov, 1993). Th ey are thriving species with extensive ranges and populations oft en even more numerous than amphimictic species. (Muldal, 1952; Mezhzherin et al., 2018). Parthenogenetic earthworms are allopolyploids and originated from hybridization of diploid amphimictic species (Viktorov, 1993; Mezhzherin et al., 2018). Genetic studies of populations of parthenogenetic earthworms most oft en analyze the clonal diversity (Jaenike et al., 1980, 1985; Terhivuo, Saura, 1996, 1997; Terhivuo et al., 2002), and in some works, also the ecological aspects of its maintenance. Th ere is a known tendency for higher concentration of parthenogenetic earthworm species in the Palaearctic regions with environmental conditions that are extreme for earthworms (Perel’, 1982). Earthworms of two species, Aporrectodea сaliginosa (Savigny, 1826) and A. trapezoides (Duges, 1828) that were previously considered as subspecies of A. сaliginosa auct. (Vsevolodova-Perel, 1997), are a suitable object for studies of geographic parthenogenesis in the family Lumbricidae. Th e fi rst species is diploid, has amphimic- Fig. 1. A. caliginosa–A. trapezoides sample locations from the territory of Ukraine. 187Th e Alternative Distribution of Related Earthworms Aporrectodea caliginosa and A. trapezoides in Ukraine… tic reproduction, and is a parental species for the second one. A. trapezoides is a unisex hybrid, which is triploid, less oft en tetraploid, and reproduces by parthenogenesis (Mezhzherin et al., 2018). Material and methods Th e study is based on the sample sets of grey worms A. caliginosa and A.trapеzoides, collected by generally accepted methods of earthworm collecting in agro- and urban landscapes of Ukraine (fi g. 1). Totally 120 sam- ples were analyzed, which included 1903 specimens (2–71 specimens in the sample). Preliminary identifi cation of worms was carried out by morphological criteria. We used the coloration of the anterior part of the body: in most cases in A. trapezoides it is noticeably darker than in A. caliginosa (Vsevolodova-Perel, 1997; Mezhzherin et al., 2018). In order to increase the reliability of species identifi ca- tion, we carried out allozyme analysis using polyacrylamide gel electrophoresis and a Tris-EDTA-borate buff er system (Peacock et al., 1965). For the analysis, the following enzymes were taken: aspartate aminotransferase (locus Aat-1), malate dehydrogenase (locus Mdh-1) and the spectrum of nonspecifi c esterases encoded by a series of loci (Es-1, -2, -3, -4), and superoxide dismutase (Sod-1). Th e electrophoretic variability of the listed enzymes was described earlier (Mezhzherin et al., 2008). Results C o m p a r a t i v e a n a l y s i s o f t h e p o p u l a t i o n g e n e t i c s t r u c t u r e o f d i f f e r e n t s p e c i e s . A. caliginosa is a diploid amphimictic species. Genetic marking shows its homogeneity at loci Aat-1, Es-4, Mdh-1, Sod-1. Th ere is an ambiguous variability in the loci of nonspecifi c esterases (Es-1, Es-2), encoding products with high electrophoretic mobility. Th is variability defi es traditional genetic interpretation and is probably caused by peculiarities of gene regulation or null alleles. Maybe, this is an intraspecifi c variability or the result of microevolutionary diff erentiation. Th e latter is indirectly confi rmed by the fact that populations tend to fi x diff erent types of electromorphs. Nevertheless, the expected and observed genotype distributions of polyallelic system in Es-4 locus do not diff er for individuals with alternative electromorphs of Es-1 and Es-2 loci. Th is fact can be an evidence that evolutionarily signifi cant genetic diff erentiation are absent within this species. Among the individuals, primarily identifi ed as A. caliginosa, there were also specimens evading by electrophoretic spectra, in particular, with trigheterozygous spectra that are unusual for diploid organisms (fi g. 2). Ultimately, at the modern level of knowledge, the studied specimens identifi ed by morphological characteristics as A. caliginosa can be considered the representatives of a single biological species; possible exceptions, if any, are less than 1 %. Th e analysis of genotype distribution in the Es-4 locus, carried out in the largest sample sets, confi rmed the panmicticity of the species populations. Th e only exception is the population from Fedorivka village vicinity (Kyiv Region), with a shortage of heterozygotes in the samples (table 1). Th is case is most likely associated with the possibility of optional self-fertilization, caused by the peculiarities of the habitat. A. trapezoides is a triploid parthenogenetic species with a clonal population structure. By three enzyme systems, within Ukraine there were identifi ed Fig. 2. Electrophoretic spectrum variability of nonspecifi c esterases in A. caliginosa population (Sloboda-Selets village, Zhytomyr Re- gion). N o t e : “aa” is homozygote, “ab” and “ac” are standard het- erozygotes, “abc” is threeheterozygote. 188 S. V. Mezhzherin, Yu. Yu. Chayka, R. P. Vlasenko, E. I. Zhalay, O. V. Rostovskaya, O. V. Harbar at least 20 clones (Mezhzherin et al., 2008) with a certain geographic localization. In the sample sets, up to 5 clones were found, usually 1–2. D i s t r i b u t i o n o n t h e t e r r i t o r y o f U k r a i n e . Th e range of A. caliginosa covers the forest and forest-steppe Palaearctic zones, while A. trapezoides inhabit farther south territories (Vsevolodova-Perel, 1997), it occurs in forest-steppe, steppe and Mediterranean climatic regions. Th e ranges of these species intergrade in south forest, forest-steppe and north steppe zones. Th e ratio of A. caliginosa and A. trapezoides specimens within the sample sets at the territory of Ukraine is the following (fi g. 3). From 120 sample sets, in 62 only A. caliginosa specimens were found, in 10 only A. trapezoides specimens, and in 47 both A. caliginosa and A. trapezoides were present. Homogeneous sample sets were noted both in the southern and northern parts of Ukraine, but with a clear predominance of A. caliginosa in the northern and western regions, and A. trapezoides in the southern. Th e frequency of A. caliginosa in the samples from the southern regions was low, and on the contrary, of A. trapezoides it was the largest. In the northern and western regions of Ukraine, the situation was the opposite. Correlation analysis confi rmed the increased frequency of parthenogenetic species in the samples from the southern and eastern areas. Th us, there was a highly reliable negative correlation (r = – 0.46; р < 0.001; d.f. = 119) between the latitude of the sample location and A. trapezoides frequency in it (fi g. 4). A highly reliable, but in this case, positive correlation (r = 0.39; р < 0.001; d.f. = 119) was also registered between longitude and A. trapezoides T a b l e 1 . A sharp defi cit of heterozygotes in A. caliginosa population from Fedorivka village (Kyiv Region) Genotypes Es-4 χ2 d. f. aa ab ac bb bc cc 8 (4,5) 1 (3,8) 2 (6,2) 3 (0,8) 1 (2,6) 5(2,1) 15,9 1 N o t e . In parentheses, the expected values based on the Hardy-Weinberg formula. Fig. 3. A. caliginosa–A. trapezoides specimens ratio in A. caliginosa s. l. sample sets. Black fi lling — A. caliginosa, cross-hatching — A. trapezoids. 189Th e Alternative Distribution of Related Earthworms Aporrectodea caliginosa and A. trapezoides in Ukraine… frequency in the sample (fi g. 5). Th is means that the highest A. trapezoides frequency is in the southern and eastern areas of Ukraine, while A. caliginosa prevails in the northern and western regions. Based on the tendencies obtained, we may conclude that the increase of A. trapezoides abundance takes place in areas with a dry and continental climate. Th e alternative geographical distribution of A. caliginosa and A. trapezoides, revealed by correlation analysis, was also confi rmed for the samples combined according to the ad- ministrative zoning of Ukraine and natural climatic zones (table 2). Th us, the average fre- quency of A. trapezoides in the forest zone was only 0.11 ± 0.01, in the forest-steppe, it was 0.30 ± 0.02, and in the steppe zone, A. trapezoides completely prevailed over A. caliginosa; its frequency in the samples was 0.93 ± 0.02. Fig. 4. Changes in the proportion of A. trapezoides in A. caliginosa s. l. sample sets depending on geographical latitude. Fig. 5. Changes in the proportion of A. trapezoides in A. caliginosa s. l. sample sets depending on geographical longitude. 190 S. V. Mezhzherin, Yu. Yu. Chayka, R. P. Vlasenko, E. I. Zhalay, O. V. Rostovskaya, O. V. Harbar Th e excluding type of A. caliginosa and A. trapezoides geographical distribution from north-west to south and east was evident within the forest and forest-steppe zones (table 2). In the northwestern part of Polissia in the Volyn and Rivne Region, the share of A. trapezoides in the samples accounted for only 0.03 ± 0.03. In the central part of the forest zone (Zhytomyr Region), the frequency of this species was almost four times higher (0.11 ± 0.01). Th e same was the frequency in the left -bank part of the forest zone (0.125 ± 0.03). A similar trend takes place in the forest-steppe zone. In the west, the share of A. trapezoides was only 0.02 ± 0.02, in the Central forest-steppe zone (Kyiv and Cherkassy Regions) it increased 20 times (0.41 ± 0.02). In the east of the forest-steppe zone in the Poltava, Kharkiv and Dnipropetrovsk Regions, the parthenogenetic species outnumbered the amphimictic one with a frequency of 0.61 ± 0.11. C o m m u n i t y s t r u c t u r e . A. caliginosa and A. trapezoides, as befi ts the parent species and hybrid, do not have signifi cant diff erences in environmental preferences. Th ey are vi- carious species with a similar biotopic distribution, and habitat in open landscapes and dry soils. Th e distribution of these species in the samples has clearly alternative nature, which is manifested in two poles of concentration values (fi g. 6). In one of them there are samples with a predominance of A. caliginosa, in the other, with a predominance of A. trapezoides. A. caliginosa frequency of more than 80 % occurred in 65 % of the samples, and the sharp A. trapezoides predominance in 13 % of the samples. Samples with equal frequency of the species were extremely rare. Only 7 samples fall within the range of 40–60 %, which is only 6 % of the total number of samples. At fi rst glance, the reason for the mutually exclusive species distribution in the samples is a vicarious geographic distribution of these species. Th e amphimictic species is concen- trated in the northern and western regions of Ukraine, and the parthenogenetic species in the southern and eastern regions. In the central regions, both species are oft en found in equal proportions. Th erefore, the bipolar form of distribution can be explained by the lack of samples from the Northern Steppe and Southern Forest-Steppe. However, this is not entirely true, since homogeneous settlements are also observed in regions with pessimal conditions for each of the species: in the northwestern regions of Ukraine for A. trapezoi- des, and in the southern and eastern regions for A. caliginosa. Obviously, “antagonism” T a b l e 2 . A. caliginosa–A. trapezoides specimens ratio in the earthworm sample sets divided by natural- climatic zones and administrative units of Ukraine Zo ne s Region Species frequencies N n A. сaliginosa A. trapezoides Fo re st Volyn 0.96 0.04 2 25 Rivne 1 0 1 12 Zhytomyr 0.89 0.11 49 889 Chernihiv 0.87 0.14 5 76 Sumy 0.90 0.10 4 48 Generally 0.89 0.11 60 1028 Fo re st -S te pp e Khemlnitsky 0.96 0.04 5 50 Vinnytsia 1 0 3 30 Kyiv 0.63 0.37 36 559 Cherkasy 0.49 0.51 1 41 Poltava, Kharkiv, Dnipro 0.39 0.61 4 18 Generally 0.70 0.30 49 698 St ep pe Zaporizhzhia 0 1 1 9 Kherson 0.14 0.86 1 25 Odesa 0.11 0.89 4 56 AR of Crimea 0.05 0.95 2 40 Generally 0.07 0.93 8 130 191Th e Alternative Distribution of Related Earthworms Aporrectodea caliginosa and A. trapezoides in Ukraine… of the two species may be due to their ecological preferences, or the founder eff ect is very important for them. In Zhytomyr Region, the distribution of A. trapezoides is also of alternative type (fi g. 7), despite the fact that in most samples there were only few or no specimens of this species. Only in a few cases, A. trapezoides prevailed over A. caliginosa or formed the homo- geneous settlements. Th e dominance of A. trapezoides over A. caliginosa that is extremely rare for Ukrainian northern regions may be an accident, but the standard deviation of A. trapezoides distribution exceeded the mean by almost two times (M = 0.1; SD = 0.17), suggesting that empirical distribution did not correspond to the theoretical one described as a set of random rare events. Th is is confi rmed by the statistical reliability of the diff erence between the empirical and the theoretical distribution according to the Poisson formula (χ2 = 5.03; df = 1; p < 0.05). Th us the presence of few samples with A. trapezoides predominance in the Zhytomyr Region, where this species is quite rare, is natural. An analysis of abiotic characteristics of A. trapezoides habitats in northern Ukraine (Zhytomyr and Kyiv Regions) shows that, as a rule, this species inhabits poor sandy soils. Earthworm density in these places was very low and other earthworm species were not found there. Th us, at the northern limits of A. trapezoides range, homogeneous settlements are formed only when environmental conditions are pessimal for earthworms. It remains 0 10 20 30 40 50 60 70 0--10 10--20 20--30 30--40 40--50 50--60 60--70 70--80 80--90 90--100 S am pl e nu m be r % Fig. 6. Distribution of A. trapezoides proportion in the sample sets of A. caliginosa s. l. earthworms within the Ukraine. 0 5 10 15 20 25 30 35 0--10 10--20 20--30 30--40 40--50 50--60 60--70 70--80 80--90 90--100 S am pl e nu m be rs % Fig. 7. Distribution of A. trapezoides proportion in the sample sets of A. caliginosa s. l. earthworms in the north- ern part of the range (Zhytomyr Region). 192 S. V. Mezhzherin, Yu. Yu. Chayka, R. P. Vlasenko, E. I. Zhalay, O. V. Rostovskaya, O. V. Harbar unclear whether the colonization of these places is passive or A. trapezoides actively choose such habitats. Th e fi rst assumption is supported by the fact that in the poor soils, A. trap- ezoides abundance was insignifi cant and not higher than in the optimum soils for A. ca- liginosa s. l. Obviously, the parthenogenetic species evenly but with a low density inhabits the northern areas of Ukraine, and sandy soils are a neutral factor for it. Th e latter may be explained by the fact that, owing to parthenogenesis, this species can reproduce by single specimens and do not require dense reproductive groups, as for amphimixis. Discussion Th us, within Ukraine, two genetically close species of A. caliginosa s. l. replace each other in latitudinal and longitudinal directions and have a wide intergradation zone. Th e amphimictic parental species A. caliginosa dominates by abundance over the hybrid apomictic species A. trapezoides in the northern and western regions, sharply yielding to it in the southern and eastern regions with dry and continental climate. In general, the situation corresponds to geographic parthenogenesis, which key feature is a marginal distribution of the alloploid species, which range should fall on the territory with pessimal environmental conditions for the parental species. Th e obvious mechanism that ensures the stable existence of a parthenogenetic species under extreme conditions and low population density is ameiotic gametogenesis, which allows single individuals to fi nd microstations that are suitable for their existence, and eventually establish populations. Th is gives the ability to exist sustainably in unfavorable conditions, to increase an abundance rapidly, avoiding inbreeding, and then expand into new habitats. All of the above is true for the apomictic species A. trapezoides, which mainly inhabit dry and continental areas of Ukraine. Geographical parthenogenesis is the reason for the shift of parthenogenetic species range to the Palaearctic arid steppe regions, but we cannot so clearly explain A. trapezoides lack in northern latitudes with favorable conditions for earthworms. Genetic marking of gray worms carried out in the European part of Russia (Shekhovtsov et al., 2017) shows that within the Western Palaearctic, A. trapezoides was not found north than the forest-steppe, although A. caliginosa is quite common in the forest zone (Vsevolodova-Perel, 1997). We may assume that A. trapezoides distribution to the north is limited because this hybrid form either has antagonistic interactions with the parental species, or originated in the southern borders of A. caliginosa range, since it is quite possible that the second parental species had a southern range. Th e reason for ploidy level increase of A. trapezoides in the southernmost range limits is another problem related to geographic parthenogenesis in A. caliginosa s. l. group. While in the northern part of the range A. trapezoides specimens are triploid only, in the Crimea (Mezhzherin et al., 2018) and in the south of France (Casellato, 1987), tetraploids are common. In such a situation, the cause of tetraploidy should be the hybridization of the triploid form with a genetically similar amphimictic species. Ploidy level increase symptomatically occurs in another parthenogenetic species, Octolasion tyrtaeum, for which only diploids are found at the northern range limits, and in the south, they are replaced by triploids (Mezhzherin et al., 2018). Ploidy level increase in regions with the most unfavorable conditions has an analogy in the world of plants, where in the northern polar latitudes only polyploid forms grow (Grant, 1982). Carried out on earthworms research confi rms that avoiding amphimixis and recombinations gives clonal organisms a number of advantages. In A. trapezoides case, it gives a possibility not only to expand the range, but also to inhabit unsuitable places within the zone of A. caliginosa dominance, creating low-density settlements. In addition, parthenogenetic organisms are not “wasted” on males. Th is raises the question of the reasons why the most highly organized animal groups transit to an exclusively amphimictic reproduction. A selective advantage over apomixis as the reason for the evolutionary 193Th e Alternative Distribution of Related Earthworms Aporrectodea caliginosa and A. trapezoides in Ukraine… predominance of amphimixis has been repeatedly discussed (Maynard Smith, 1978; Lewis, 1987; West et al., 1999; Mogie et al., 2007), but a consensus has not yet been formed. Moreover, an explanation based on selective evolutionary concepts, which postulates that amphimixis and recombination have important adaptive signifi cance, is not confi rmed in the case of geographic parthenogenesis. It is obvious that amphimixis and bisexuality are a consequence of evolutionary specialization, which has no direct adaptive function. References Ben-Ami, F., Heller, J. 2007. Temporal patterns of geographic parthenogenesis in a freshwater snail. Biol. J. Lin. Soc., 91, 711–718. Bierzychudek, P. 1985. Patterns in plant parthenogenesis. Experientia, 41, 1255–1264. Casellato, S. 1987. On polyploidy in oligochaetes with particular reference to lumbricides. In: Bonvichi Pagia, A. M., Omodeo, P., eds. On earthworms. Selected symposia and monographs, 2. Modena, Italy, 75–87. Cuellar, O. 1977. Animal parthenogenesis. Science, 197 (4306), 837–843. Cuellar, O. 1994. Biogeography of parthenogenetic animals. Biogeographica, 70 (1), 1–13. Glesener, R. R., Tilman, D. 1978. Sexuality and the components of environmental uncertainty: clues from geographic parthenogenesis in terrestrial animals. Am. Nat., 112 (986), 659–673.  Grant, V. 1982. Plant speciation. Univ. Presses California, Columbia & Princeton, 1–432. Haag, C. R., Ebert, D. 2004. A new hypothesis to explain geographic parthenogenesis. Ann. Zool. Fennici, 41, 539–544. Hörandl, E. 2009. Geographical parthenogenesis: opportunities for asexuality. In: Schön, I, Martens, K., Van Dijk, P, eds. Lost Sex: the Evolutionary Biology of Parthenogenesis. Springer, Dordrecht, 161–186. Jaenike, J., Parker, E. D., Selander, R. K. 1985. On the coexistence of ecologically similar clones of parthenoge- netic earthworms. Oikos, 44, 512–514. Jaenike, J., Parker, E. D., Selander, R. K. 1980. Clonal niche structure in parthenogenetic earthworm Octolasion tirtaeum. Amer. Natur., 116, 196–205. Jaenike, J., Selander, R. K. 1979. Evolution and ecology of parthenogenesis in earthworms. Am. Zoologist., 19 (3), 729–737.  Kearney, M. 2005. Hybridization, glaciation and geographical parthenogenesis. Trends Ecol Evol.,  20, 495–502. Kearney, M., Moussalli, A., Strasburg, J., Lindenmayer, D., Moritz, C. 2003. Geographic parthenogenesis in the Australian arid zone: I. A climatic analysis of the Heteronotia binoei complex (Gekkonidae). Evol. Ecol. Res., 5 (7), 953–976. Kearney, M., Moussalli, A. 2003. Geographic parthenogenesis in the Australian arid zone: II. Climatic analyses of orthopteroid insects of the genera Warramaba and Sipyloidea. Evol. Ecol. Res., 5 (7), 977–997. Lewis, W. 1987. Th e evolution of sex and its consequences. In: Stearns, S, C., ed. Th e Cost of Sex. Birkhäuser, Basel, 33–57. Mezhzherin, S. V., Vlasenko, R. P., Garbar, A. V. 2008. Features of the genetic structure  of the earthworms Aporrectodea (superspecies) сaliginosa (Oligochaeta: Lumbricidae) complex in Ukraine. Cytology and Ge- netics, 42 (4), 50–57 [In Russian]. Mezhzherin, S. V., Garbar, A. V., Vlasenko, R. P., Оnishchuk, I. P., Коtsyuba, I. Y., Zhalay, E. I. 2018. Evolutionary paradox of parthenogenetic earthworms. Naukova Dumka, Kiev, 1–232 [In Russian]. Maynard Smith, J. 1978. Th e evolution of sex. Cambridge Univ. Press, Cambridge, U.K., 1–242. Mogie, M., Britton, N. F., Stewart-Cox, J. A. 2007. Asexuality, polyploidy and the male function. In: Hörandl, E., Grossniklaus, U., Van Dijk, P. J., Sharbel, T., eds.  Apomixis: Evolution, Mechanisms and Perspectives. Gantner, Ruggell, 169–194. Morgan-Richards, M., Trewick, S. A. 2010. Geographic parthenogensis and the common tea-tree stick insect of New Zealand. Mol. Ecol., 19 (6), 1227–1238. Moritz, C. 1983. Parthenogenesis in the endemic Australian lizard Heteronotia binoei (Gekkonidae). Science, 220 (4598), 735–737. Muldal, S. 1952. Th e chromosomes of the earthworms: I. Th e evolution of polyploidy. Heredity, 6 (1), 56–76. Peacock, F. C., Bunting, S. L., Queen, K. G. 1965. Serum protein electrophoresis in acrilamide gel patterns from normal human subjects. Science, 147, 1451–1455. Peck, J. R., Yearsley, J. M., Waxman, D. 1998. Explaining the geographic distributions of sexual and asexual populations. Nature, 391, 889–892. Perel’, T. S. 1982. Geographic features of reproduction of earthworms of the family Lumbricidae. Zh. Obshch. Biologii, 43 (5), 649–658 [In Russian]. Shekhovtsov, S. V., Golovanova, E. V., Bazarova, N. E., Belova, Yu. N., Berman, D. I., Derzhinsky, E. A., Shashkov, M. P., Peltek, S. E. 2017. Genetic diversity of the Aporrectodea caliginosa complex in Russia. Vavilov Journal of genetics and breeding, 21 (3), 374–379 [In Russian]. 194 S. V. Mezhzherin, Yu. Yu. Chayka, R. P. Vlasenko, E. I. Zhalay, O. V. Rostovskaya, O. V. Harbar Schmit, O., Saskia, N. S., Bode, A., Camacho, D., Horne, J. 2013. Linking present environment and the segregation of reproductive modes (geographical parthenogenesis) in Eucypris virens (Crustacea: Ostracoda). Journal of Biogeography, 40 (12), 2396-2408. Stenberg, P.,  Lundmark, M.,  Knutelski, S.,  Saura, A. 2003.  Evolution of clonality and polyploidy in a weevil system. Molecular Biology and Evolution, 20, 1626– 1632. Suomalainen, E., Saura, A., Lokki, J. 1987. Cytology and evolution in parthenogenesis. CRC Press, Boca Raton, Florida, 1–206. Terhivuo, J., Lundqvist, E., Saura, A. 2002. Clone diversity of Eiseniella tetraedra (Lumbricidae: Oligochaeta) along regulated and free-fl owing boreal rivers. Ecography, 25, 714–720. Terhivuo, J., Saura, A. 1996. Clone pool structure and morphological variation in endogeic and epigeic North- European parthenogenetic earthworm (Oligochaeta: Lumbricidae). Pedobiologia, 40 (3), 226–239. Terhivuo, J., Saura, A. 1997. Island biogeography of North European Parthenogenetic Lumbricidae: I. Clone pool affi nities and morphometric diff erentiation of Åland populations. Ecography, 20, 185–196. Vandel, A. 1928. La parthenogenese geographique. Contribution a l’etude biologique et cytologique de la par- thenogenese natural. Bull. Biol. France Belg., 62, 164–181. Viktorov, A. G. 1993. Diversity of polyploid races in the Earthworms Family Lumbricidae. Usp. Sovrem. Biol., 113 (3), 304–312 [In Russian]. Vrijenhoek, R. C., Parker, J. E. D. 2009. Geographical parthenogenesis: General purpose genotypes and frozen niche variation. In: Schön, I, Martens, K., Van Dijk, PJ, eds. Lost Sex: the Evolutionary Biology of Parthe- nogenesis. Springer, Dordrecht, 99–131. Vsevolodova-Perel, T. S. 1997. Earthworms in the Fauna of Russia: A Checklist with an Identifi cation Key. Nau- ka, Moscow, 1–104 [In Russian]. West, S. A., Lively, C. M., Read, A. F. 1999. A pluralist approach to sex and recombination. J. Evol. Biol., 12, 1003–1012. Wright, J. W., Cole, C. J., Cuellar, O. 1978. Parthenogenetic lizards. Science, 201 (4361), 1152–1155. 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