02_Gural_05_21.indd UDC 594.38 (4-015) POLYMORPHISM OF THE INTRODUCED SNAIL CEPAEA NEMORALIS (GASTROPODA, HELICIDAE) FROM TWO DISTANT PARTS OF EASTERN EUROPE: ACCIDENTAL SIMILARITY OR REGULARITY? N. V. Gural-Sverlova*, R. I. Gural State Museum of Natural History, NAS of Ukraine Teatralna st., 18, Lviv, 79008 Ukraine *Corresponding author E-mail: sverlova@pip-mollusca.org N. V. Gural-Sverlova (https://orcid.org/0000-0002-3892-5338) R. I. Gural (https://orcid.org/0000-0002-1546-1956) Polymorphism of the Introduced Snail Cepaea nemoralis (Gastropoda, Helicidae) from two Distant Parts of Eastern Europe: Accidental Similarity or Regularity? Gural-Sverlova, N. V., Gural, R. I. — Th e shell coloration of Cepaea nemoralis (Linnaeus, 1758) from Western Ukraine (Ivano-Frankivsk, Lviv, and Ternopil Regions) and from the Moscow Region of Russia was analyzed, in total, almost 6 thousand specimens from 32 sites. In the samples from the Moscow Region, on average, there were half as many yellow shells and four times as many pink mid-banded shells. Th ere were no other statistically signifi cant diff erences. As in other areas of Eastern Europe, yellow unbanded and brown shells were oft en absent or represented by few individuals in both compared areas, and brown banded shells were completely (Western Ukraine) or almost completely (Moscow Region) absent, which may be related to the founder eff ect. Analysis of the literature data showed that in the introduced populations of C. nemoralis from Europe and USA, a distinct predominance of one or two of the 4 light phenotypes (yellow unbanded, yellow mid-banded, pink unbanded, and pink mid-banded) is oft en observed. Th e total frequency of these phenotypes in introduced populations is oft en higher than its average values calculated for diff erent parts of the natural range. A possible relationship between the observed pattern and climatic selection is discussed. K e y w o r d s : land mollusks, grove snail, phenotypic composition, climatic selection, Western Ukraine, Moscow Region, European Russia. Introduction Cepaea nemoralis (Linnaeus, 1758) is one of the best-known species of European land mollusks; many publications are devoted to the color and banding polymorphism of its shells . Long-term studies in England, France, Germany and other European countries already in the second half of the 20th century proved that the phenotypic composition of populations of this species is the result of a complex interaction of selective and non-selective (stochastic) factors (Jones et al., 1977). Th e infl uence of both mentioned groups of factors can theoretically be enhanced in the introduced populations of C. nemoralis (Sverlova, 2007) and related species Cepaea hortensis (O. F. Müller, 1774) (Gural-Sverlova & Gural, 2018) that live at a considerable distance from the main part of their present ranges. On one hand, the initial restriction of genetic and phenotypic diversity, caused by a limited number of founding individuals and the possibility of accidental disappearance of some traits in the initial stages of introduction, cannot be compensated for by immigration, but only by repeated Zoodiversity, 55(5):369–380, 2021 DOI 10.15407/zoo2021.05.369 370 N. V. Gural-Sverlova, R. I. Gural introduction of the snails by people from the main part of the range or from other introduced populations. On the other hand, introduced populations are oft en forced to adapt to climatic conditions not typical for the species, which may enhance the infl uence of climate selection on their peculiar phenotypic structure, initially determined by the founder eff ect. Th erefore, the phenotypic composition of each introduced popula- tion C. nemoralis can b e considered a result of a microevolutionary experiment, beginning with the intentional introduction (Egorov, 2018; Howe, 1898) or unintentional transfer of snails , for example, with ornamental plants (Alexander, 1952; Bąkowski, 1880). Recently, more and more reports have appeared not only about the fi nds of C. nemoralis, but also about the shell color and banding polymorphism of this species in Ukraine (Gural-Sverlova et al., 2020), Belarus (Kolesnik & Kruglova, 2016; Ostrovsky & Prokofi eva, 2017) and in the European part of Russia (Gural-Sverlova & Egorov, 2021; Mukhanov & Lisitsyn, 2018; Sverlova, 2007). A lot of data regarding this issue has been ac- cu mulated in the laboratory of malacology of the State Museum of Natural History of the National Academy of Sciences of Ukraine in Lviv (hereinaft er referre d as SMNH NANU). Th is al lows a preliminary comparison of quantitative data from diff erent parts of Eastern Europe both with each other and with similar data for other parts of the present range of C. nemoralis, signifi cantly expanded due to anthropochory, which became the main purpose of this publication. Material and methods Th e article uses da ta on shell coloration in almost 6 thousand individuals of C. nemoralis collected in Moscow Region of Russia (from 2006 to 2020) and in three administrative regions in Weastern Ukraine (2019– 2020). All samples from Moscow Region and part of materials from Western Ukraine are stored in the malaco- logical collection of SMNH NANU. Th e collecting sites are described below, and they are arranged in alphabeti- cal and numerical sequence of their codes. IF-1: Ukraine, Ivano-Fran kivsk Region, Ivano-Frankivsk City, Halytska street, 48°56´49.6˝ N 24°41´48.2˝ E, 2019. IF-2: Ivano-Frankivsk Region, Tysmenytsia District, Uhryniv village, Pol´ova street, between 48°57´25.3˝ N 24°41´2 6.1˝ E and 48°57´28.3˝ N 24°41´25. 4˝ E, 2019. IF-3: Ivano-Frankivsk Reg ion, Bohorodchany District, Bohorodchany urban-type settlement, Shevchen- ko street, between 48°48´39.6˝ N 24°32´29.1˝ E and 48°48´46.3˝ N 24°32´35.2˝ E, 2019. IF-4: ibidem, opposite side o f Shevchenko street, 48°48´46.9˝N 24°32´34.3˝E, 2019. L-1: Ukraine, Lviv Region, Lviv City , Horodotska street near the exit to the ring road, between 49°49´14.7˝ N 23°54´56.6˝ E and 49°49´17.0˝ N 23°55´09.6˝ E, 2020. L-2: ibidem, Liubinska street , near the old airport terminal, 49°48´59.5˝ N 23°57´19.6˝ E, 2020. L-3: ibidem, Liubinska street, on the former territory of a military unit, 49°49´08.5˝ N 23°57´36.0˝ E, 2020. L-4: ibidem, Syhnivka street, 49°49´ 31 .4˝ N 23°57´27.9˝ E, 2020. L-5: ibidem, Liutneva street, 49°49´33.0˝ N 23°57´43.1˝ E, 2020. L-6: ibidem, near the intersection of Hor od otska street with Bahrianyi street and Rivna street, between 49°49´48.4˝ N 23°58´35.2˝ E and 49°49´54.9˝ N 23°58´33.8˝ E, 2020. L-7: ibidem, near the intersection of General C huprynka street with Makovei street and Tsehelskyi street, between 49°49´21. 5˝ N 24°00´00.1˝ E and 49°49´18.5˝ N 24°00´02.8˝ E, 2020. L-8: ibidem, Chervona street, between 49°49´2 5.3˝ N 24°00´24.6˝ E and 49°49´30.9˝ N 24°00´25.0˝ E, 2020. L-9: ibidem, Vitovskyi street, between 49°49´47.1˝ N 24°01´35.8˝ E and 49°49´48.8˝ N 24°01´32.5˝ E, 2020. L-10: ibidem, Kalicha Hora street, between 49°50´05.4˝ N 24 °01´37.6˝ E and 49°50´07.7˝ N 24°01´33.6˝ E, 2019–2020. L-11: ibidem, Hnatiuk street, 49°50´29.8˝ N 24°01´21.0˝ E, 2020. L-12: ibidem, between Zelena street and Krymska street, between 4 9°49´28.6˝ N 24°02´41.0˝ E and 49°49´27.8˝ N 24°02´56.9˝ E, 2019–2020. L-13: ibidem, Chmola street, near the former garden center, between 49°48´52.1˝ N 24°01´30.2˝ E and 49°48´52.6˝ N 24°01´12.6˝ E, 2019–2020. L-14: ibidem, Khutorivka street, wasteland next to the garden center, bet ween 49°47´58.8˝ N 24°02´07.4˝ E and 49°47´58.9˝ N 24°02´02.6˝ E, 2020. L-15: Lviv Region, Pustomyty District, Zubra village, wasteland between 49°46´42.7˝ N 24°03´08.4˝ E and 49°46´43.4˝ N 24°03´01.4˝ E, 2019–2020. M-1: Russia, Moscow Region, Moscow City, Severnyi administrative District, Lianoz ovski forest-park, coordinates of the main sampling place 55°54´06.0˝ N 37°34´22.2˝ E, 2015–2018. M-2: ibidem, Yugo-Zapadnyi administrative District, Kotlovka municipal District, 55 °39´57.6˝ N 37°35´48.6˝ E and between 55°40´03.0˝ N 37°35´58.2˝ E and 55°40´05.4˝ N 37°36´03.0˝ E, 2016. M-3: Moscow Region, Dmitrov District, Dmitrov town, Pochtovaya street (56°20´26.4˝ N 37°3 0´58.2˝ E) and Professional´naya street (56°20´49.8˝ N 37°31´05.4˝ E), 2014-2017. M-4: Moscow Region, Dolgoprudnyi town, near the garden center “Medra”, 55°56´30.6˝ N 37°32´06 .6˝ E, 2017. 371Polymorphism of Cepaea nemoralis (Gastropoda, Helicidae) from two Distant Parts of Eastern Europe… M-5: ibidem, Sheremetievski microdistrict, corner of Pervomaiskaya street and Komarova street, 55°59´33.6˝ N 37°29´35.4˝ E, 2017 and 2019. M-6: Moscow Region, near the town of Lobnya, a sawmill in the forest, 55°59´37.8˝ N 37°25´50.4˝ E, 2018–2020; M-7: Moscow Region, Lyubertsy District, Malakhovka urban-type settlement, Kirov street (55°38´33.6˝ N 37°59´52.8˝ E) and Fevral´skaya street (55°38´34 .2˝ N 37°59´39.6˝ E), 2015–2017. M-8: Moscow Region, Mytishchi District, Mytishchi town, Zapadnaya street, between 55°53´37.2˝ N 37°42´12.6˝ E and 55°53´38.4˝ N 37°42´18.0˝ E, 2017–2018. M-9: Moscow Region, Krasnogorsk District, Nakhabino urban-type settlement, Panfi lov street, 5 sites be- tween 55°50´16.2˝ N 37°10´46.2˝ E, 55°50´10.2˝ N 37°10´53 .4˝ E, 55°50´05.4˝ N 37 °10´40.8˝ E and 5 5°50.22´ N, 37°10.57´  E designated as Nos. 1–4 and 7 in a previous publication (Gural-Sverlova & Egorov, 2021: fi g. 2), 2006, 2017–2018. M- 10: ibidem, opposite side of Panfi lov street, 2 sites between 55°50´13.2˝ N 37°10´34.2˝ E and 55°50´13.2˝ N 37°10 ́ 34.2˝ E designated as Nos. 5 and 6 in a previous publication (Gural-Sverlova & Egorov, 2021: fi g. 2), 2017. M-11: Moscow Region, Pushchino town, Park Pobedy (Victory Park), 54°50´16.2˝ N 37°36´49.8˝ E, 2016. M-12: Moscow Region, Schelkovo District, Zagoryanski urban-type settlement, Zelenaya street (55°55´28.2˝ N 37°55´14.4˝ E), Kooperativnaya street (55°55´32.4˝ N 37°55´00.0˝ E) and Lenin street (55°55´28.8˝ N 37°54´56.4˝ E), 2016, 2018. T-1: Ukraine, Ternopil Region, Chortkiv District, Chortkiv town, Zaliznychna street, 49°01´32.1˝ N 25°47´34.9˝ E, 2020. More detailed descriptions and images of some of the above-mentioned sites were given in previous publications (Egorov, 2018; Gural-Sverlova & Egorov, 2021; Gural-Sverlova et al., 2020). Most of the samples from Western Ukraine were collected personally by the authors of the article. Other collectors are listed in Acknowledgments. In Lviv and Ivano-Frankivsk Regions, where C. nemoralis usually lives together with another introduced species of the same genus, C. hortensis, only live adult snails were counted, less oft en their empty shells with well-preserved coloration. In other cases, to obtain more representative samples, immature individuals with a shell diameter of at least 1 cm were also collected. For each shell, the ground color designated as “Y”(yellow, relatively few white shells were also included in this group), “P” (p ink) or “B” (brown) as well as the banding type were determined: 1) unbanded shells — completely without bands, occasionally with 1–2 indistinct bands (modifi cations); 2) mid-banded — similarly for shells with one central band; 3) three-banded — the phenotypes with three lower bands, occasionally with traces of one or both upper bands; 4) fi ve-banded — a group of phenotypes with 5 discrete or fused bands, occasionally with the absence of one band. For samples containing at least 40 specimens, the frequencies of the following inherited traits (Murray, 1975) were calculated: 1) diff erent ground color of the shell (yellow, pink or brown); 2) complete absence of bands on the shell; 3) absence of all bands, except for the central one, on banded shells; 4) absence of two upper bands on multi-banded shells. We also calculated the frequencies of phenotype groups distinguished by the combination of the shell ground color and the banding type. Results Th e polymorphism in the shell banding type was registered at all studied sites, and such in the shell ground color at a lmost all sites, except for M-5 (table 1). However, brown shells were more oft en absent, and in other cases they were almost exclusively unbanded. Among the main types of shell banding (unbanded, mid-banded, three-banded, and fi ve- banded), the samples most oft en lacked shells with three lower bands: at 42 % of studied sites in the Moscow Region and at 45 % of sites in Western Ukraine. At almost all sites, all banded shells had dark, evenly pigmented bands. In Lviv, single individuals with depigmented (hyalozonate) or light colored bands were found. Adult snails of this coloration also had light edges of the aperture, not typical for C. nemoralis — from pinkish to white. Th e most original in this respect was the only sample from the Ternopil Region, in which about 26 % of the banded shells had unevenly pigmented bands, with al- ternating lighter and darker fragments, which in some cases gave the impression of spotty bands. Among the yellow banded shells, there were even more such specimens, about 41 %. 372 N. V. Gural-Sverlova, R. I. Gural A shell with similar “punctate” bands is shown in Richards et al. (2013). In Moscow Region, the higher mean frequencies in the samples (table 2) had, in de- scending order, pink mid-banded, pink unbanded, pink fi ve-banded, brown unbanded, and yellow fi ve-banded shells (table 2). In Western Ukraine, this order was slightly diff erent (pink unbanded, yellow fi ve-banded, yellow mid-banded, pink fi ve-banded), mainly due to the greater number of yellow and fewer pink mid-banded shells (see below). In both compared parts of Eastern Europe, the frequencies of phenotype groups and separately considered phenotypic traits (table 2) vary greatly between sites. Statistically sig- nifi cant diff erences between Western Ukraine and Moscow Region were found only for the mean frequencies of yellow as well as pink mid-banded shells. In the samples of C. nemora- T a b l e 1 . Th e phenotypic composition of the studied samples Site codes Localities Phenotype groups TotalY-0 Y-1 Y-3 Y-5 P-0 P-1 P-3 P-5 B-0 Western Ukraine, Ivano-Frankivsk Region IF-1 Ivano-Frankivsk – + – – 9 3 – – – 12 IF-2 Uhryniv – – 1 1 2 + – 3 – 7 IF-3 Bohorodchany – – – 29 66 – – – – 95 IF-4 Ibidem – 3 – 58 97 5 – 196 – 359 Total for this region – 3 1 88 174 8 – 199 – 473 Western Ukraine, Lviv Region L-1 Lviv 4 282 66 – 590 186 39 – – 1167 L-2 Ibidem – 4 – 19 294 19 – 52 – 388 L-3 Ibidem 1 28 – 17 37 5 – 7 – 95 L-4 Ibidem – + – 4 – 1 1 1 – 7 L-5 Ibidem – 9 – 1 – 9 – 1 – 20 L-6 Ibidem – 48 – 28 – 8 – 6 – 90 L-7 Ibidem 17 – 10 12 1 – 3 7 – 50 L-8 Ibidem – 1 7 12 19 1 4 7 – 51 L-9 Ibidem 12 4 1 13 2 1 1 – 17 51 L-10 Ibidem – 4 13 24 33 5 7 14 3 103 L-11 Ibidem – – – 10 48 – – 7 – 65 L-12 Ibidem 13 7 4 6 6 9 7 8 – 60 L-13 Ibidem 5 120 23 291 73 66 27 127 – 732 L-14 Ibidem – 63 5 – – 18 8 – 13 107 L-15 Zubra 23 9 – 18 1 – – 2 – 53 Total for this region 75 579 129 455 1104 328 97 239 33 3039 Western Ukraine, Ternopil Region T-1 Chortkiv 3 6 34 28 2 5 77 69 – 224 Total for Western Ukraine 78 588 164 571 1280 341 174 507 33 3736 Russia, Moscow Region M-1 Moscow 1 94 – 96 66 87 1 102 – 447 M-2 Ibidem 11 1 – 1 14 1 – 10 13 51 M-3 Dmitrov – 3 – – 26 114 – 17 – 160 M-4 Dolgoprudnyi 3 10 6 100 21 16 18 72 – 246 M-5 Ibidem – – – – – 31 9 4 – 44 M-6 Lobnya 1 1 9 1 15 1 – – – 28 M-7 Malakhovka – 2 – 3 – 14 – 25 22 66 M-8 Mytishchi – 37 8 39 94 21 2 26 1 228 M-9 Nakhabino – 7 99 144 318 – – – – 568 M-10 Ibidem – 8 2 18 28 4 9 9 34 112 M-11 Pushchino – 3 – 2 1 2 – 2 – 10 M-12 Zagoryanski 1 1 – 1 3 22 – 35 88 152* Total for this region 17 167 124 405 586 313 39 302 158 2112* Grand total 95 755 288 976 1866 654 213 809 191 5848* N o t e . B-0 — brown unbanded; P-0 — pink unbanded; P-1 — pink mid-banded; P-3 — pink three- banded; P-5 — pink fi ve-banded; Y-0, Y-1, Y-3 and Y-5 — the same for yellow shells; *taking into account one brown mid-banded shell from Zagoryanski; + recorded only in juveniles. Th e most common coloration variant in each sample is shown in bold. 373Polymorphism of Cepaea nemoralis (Gastropoda, Helicidae) from two Distant Parts of Eastern Europe… lis from the Moscow Region, on average, yellow shells were found twice less oft en, but the mean frequency of pink mid-banded shells was four times higher (table 2). Discussion As we mentioned in previous publications (Gural-Sverlova & Egorov, 2021; Gural- Sverlova et al., 2020), in the regions we compare, as in other parts of Eastern Europe (Kole- snik & Kruglova, 2016; Mukhanov & Lisitsyn, 2018; Ostrovsky & Prokofi eva, 2017), the phenotypic composition of C. nemoralis demonstrates a number of common features that can be interpreted as an accidental result of the transfer of a relatively small number of individuals (snails and/or their eggs) and the initial reduction of genetic and phenotypic diversity. Th is leads to the most frequent absence in the introduced populations of those tra its, phenotypes or phenotype groups that are relatively rare or locally found even within the natural range, for example, a light lip, colorless (hyalozonate), light colored or “punctu- ate˝ bands, banded shells with brown ground color. Among the phenotypes more common for C. nemoralis, which can reach rather high frequencies in certain parts of the natural range or in certain types of habitats, in the introduced Eastern European populations, brown unbanded and yellow unbanded shells are oft en absent or very rare, although in some cases they can even prevail. Among the main types of shell banding, in Eastern Europe, as in the natural range of C. nemoralis (Schilder & Schilder, 1957: table 13; Sverlova, 2002: table 3), shells with three lower bands are the least common. However, not all features of the East European populations of C. nemoralis studied by various researchers can be explained by such stochastic population genetic factors as the founder eff ect or gene drift . Earlier, we suggested that the adaptation of introduced popula- tions of this species to living in the more continental climate of Eastern Europe can lead, fi rstly, to an increase in the proportion of light-colored phenotypes, and secondly, to act against both the darkest (stronger) and the lightest (weaker) variants of shell coloration Ta b l e 2 . Frequencies of inherited coloration traits and phenotype groups in the compared areas Traits / Phenotype groups Western Ukraine Moscow Region, Russia Diff erences (Mann-Whitney test)min–max mean min–max mean Phenotype groups distinguished by the combination of shell grund color and banding* Y-0 0–43.4 7.9 0–21.6 2.4 58 Y-1 0–58.9 14.3 0–21.0 5.7 96.5 Y-3 0–20.0 5.2 0–17.4 2.5 57 Y-5 0–39.8 19.3 0–40.7 12.8 56 P-0 0–75.8 27.1 0–56.0 19.1 90 P-1 0–16.8 5.5 0–71.3 21.8 45**** P-3 0–34.4 5.2 0–20.5 3.7 67.5 P-5 0–54.6 12.5 0–37.9 17.2 59.5 Inherited traits (shell grund color) Yellow 5.9–94.5 46.7 0–48.4 23.4 37**** Pink 5.7–94.1 50.3 39.5–100 61.8 68 Brown 0–33.3 3.0 0–58.6 14.8 73 Inherited traits (absence of all or part of the bands) Unbanded 0–75.8 38.0 0–74.5 36.2 82.5 Mid-banded ** 0–86.2 29.0 2.8–87.3 37.9 60 Th ree-banded*** 0–100 27.1 0–69.2 16.5 92 Light colored phenotypes together Y-0, Y-1, P-0, P-1 7.1–91.0 54.8 17.8–89.4 49.0 72 *Th e frequencies of brown unbanded shells (B-0) are not indicated, as they coincide with those of brown shells; **calculated from the number of banded shells; ***calculated from the number of multi-banded shells (i. e. shells with 3–5 bands); ****signifi cant at p = 0.05. Other designations are similar to table 1. Th e small sam- ples (IF-1, IF-2, L-4 and L-5 from Western Ukraine, M-6 and M-11 from the Moscow Region) were excluded from the calculations, see Material and methods. 374 N. V. Gural-Sverlova, R. I. Gural (Sverlova, 2007). Both of these features were also observed in the introduced populations of the related species C. hortensis in Western Ukraine, which demonstrate not only an abnormally high proportion of unbanded shells increased even more recently, but also a clearly pronounced predominance among them of not the lightest (white), but yellow shells (Gural-Sverlova & Gural, 2018). For C. nemoralis, both of these tendencies can be illustrated by comparing the ratio of diff erent banding types among shells with diff erent ground colors collected in Eastern Europe (our data) and in England (fi g. 1), which is part of the natural range and has a relatively cool but mild maritime climate with smoothed temperature fl uctuations. With a relatively similar ratio of yellow, pink, and brown shells in the considered sets, both in Western Ukraine and in Moscow R egion, multi-banded shells are less common among pink ones, and in Western Ukraine — also among yellow shells. However, in both cases, a decrease in the overall intensity of shell coloration does occur not due to an increase in the proportion of the lightest phenotype (yellow unban ded, whose rare occurrence may be due to random factors, see above), and in the climatic condition of Moscow Region, more se- vere for C. nemoralis, also not due to yellow shells with one band (fi g. 1). Th e predominant 0 20 40 60 80 100 Yellow (39.2%) Pink (51.6%) Brown (9.2%) England, according to Cain & Sheppard (1954) unbanded mid-banded other 0 20 40 60 80 100 Yellow (37.5%) Pink (61.6%) Brown (0.9%) Western Ukraine unbanded mid-banded other 0 20 40 60 80 100 Yellow (33.8%) Pink (58.7%) Brown (7.5%) Moscow region unbanded mid-banded other % % % Fig. 1. Dependence between the ground color of the shell and the banding pattern in C. nemoralis from diff erent parts of the range. 375Polymorphism of Cepaea nemoralis (Gastropoda, Helicidae) from two Distant Parts of Eastern Europe… type of coloration in the introduced Eastern European populations of C. nemoralis oft en becomes an unbanded pink shell (tables 1, 3). A number of facts have been described in the literature that indicate that lighter phe- notypes in Cepaea are more resistant to not only extremely high, but also low temperatures, as well as to sharp fl uctuations in ambient temperature (Arnason & Grant, 1976; Arnold, 1968; Lamotte, 1951, 1959). In particular, in most northern marginal populations of C. hor- tensis, snails with banded shells predominate (Alexandrov, Sergievsky, 1980; Arnason & Grant, 1976; Bengtson et al., 1979; Valovirta & Halkka, 1 976 etc.). However, in Iceland, the relatively low (in general ) frequency of unbanded individuals increases in the coldest habitats (Arnason & Grant, 1976). And in the north of Norway, where snails are forced to adapt to the most adverse climatic conditions, unbanded individuals predominate (Rost, 1952). A similar pattern was observed for C. nemoralis in the Pyrenees, when the frequen- cies of lighter — yellow and unbanded (Arnold, 1968), unbanded (Lamotte, 1951) — shells decreased at medium altitudes and increased again at high altitudes. Th is is in good agreement with the physical properties of dark-colored shells, which should not only heat up faster, but also cool faster when the ambient temperature drops sharply (Arnason & Grant, 1976; Sverlova, 2004 a). Th erefore, it has been suggested that lighter morphs may receive a selective advantage in a more continental climate, to which in troduced populations of C. nemoralis are oft en forced to adapt (Sverlova, 2007). Th e for- mation of darker shells in Cepaea can occur in two ways: due to a darker ground color or the presence of the dark spiral bands. However, the pink unbanded or mid-banded shells remain lighter overall than yellow shells with 3–5 broad and almost black bands. An analysis of the data published for introduced populations of C. nemoralis from diff erent countries (table 3) shows that many of them, indeed, have a relatively high fre- quency of one or two of the light phenotypes, what will be described in more detail below. Although the set of predominant morphs in introduced populations can be very diff erent (which is a completely natural consequence of the founder eff ect and subsequent stochastic population genetic processes), the total frequency of the 4 lightere variats of shell coloration in many cases exceeds 50 % (table 3). Th e average values of this indicator, calculated on the basis of a number of literature data for areas within the natural range o f C. nemoralis, oft en turn out to be lower, although there are some exceptions, which are shown in table 3. Particularly indicative in this respect is the high proportion of yellow unbanded shells in the cities of New York (Landman, 1956) and Marion (Clench, 1930; Johnson, 1927), eastern United States (table 3). In the city of Marion, the predominance of this phenotype was accompanied by a high proportion of yellow mid-banded shells. Compared to the re- lated species C. hortensis, yellow unbanded shells are relatively rare in many populations of C. nemoralis with in its natural range (Sverlova, 2007), although they reach higher fre- quencies in certain areas or in certain (open, with high insolation) habitats (table 3). In the American city of Burlington (New Jersey), whe re C. nemoralis was specially introduced from England in 1857 and multiplied in large numbers already by 1869, the prevailing coloration variant, as in many Eastern European populations of this species (see above), became a pink unbanded shell (Alexander, 1952). Among the populations of C. nemoralis from the eastern United States presented in table 3, the general trend is violated by those from Lexington and Lynchburg, with a dis- tinct predominance of fi ve-banded phenotypes. Th is may be due to the founder eff ect: it is considered that mollusks were brought to Lynchburg by people from nearby Lexington (Richards, Murray, 1975), and to Lexington they were accidentally introduced from Italy or the British Isles already in 1883 (Howe, 1898). According to the monograph of Schilder & Schilder (1957: 180, map 72), snails with fi ve-banded shells, on average, are more com- mon on the northern and southern borders of the natural range of C. nemoralis than in its central part, which theoretically should increase the likelihood of their presence among the founding individuals. 376 N. V. Gural-Sverlova, R. I. Gural Ta b l e 3 . P eculiarities of the phenotypic composition of C. nemoralis from diff erent parts of i ts range Territory, source N Frequencies, % grund color light phenotypes ye llo w pi nk br ow n Y -0 Y -1 P- 0 P- 1 T ot al Territories that are or may be part of the natural range Great Britain England, Warwickshire, Feldon area (Cameron & Pannet, 1985) 2746 42.9 55.6 1.4 3.7 6.8 9.3 11.4 31.2 England, Somerset, Berrow, dunes (Clarke & Murray, 1962; Murray & Clarke, 1978) 18 273 75.6 18.4 6.0 0.1 9.6 0.1 1.7 11.5 Eng land, Berkshire Downs (Carter, 1968) 17 800 58.4 34.7 6.9 5.6 19.3 7.3 8.3 40.5 England, Berkshire, Lambourn Downs (Cain & Currey, 1963) 2795 63.6 32.3 4.1 12.0 43.1 7.9 19.8 82.8 England, Wiltshire, Marlborough Downs (Cain & Currey, 1963; Cowie & Jones, 1998) 7542 48.5 22.8 28.7 14.7 20.6 11.2 6.8 53.3 England, Wiltshire, Salisbury Plain (Cameron & Dillon, 1984) 1161 31.3 57.5 11.1 2.0 7.9 15.0 23.2 48.1 England, East Sussex, eastern South Downs (Arnold, 1971) 4725 71.6 28.2 0.2 4.5 12.8 0.9 3.6 21.8 England, Dorset, Purbeck Hills (Carter, 1968) 1538 67.8 17.0 15.1 4.8 15.3 1.0 5.8 26.9 England, Dorset, South Haven Peninsula (Cam- eron, 2001) 3954 1.6 98.1 0.3 0.1 1.3 0.8 37.6 39.8 England, Cornwall, Isles of Scilly (Murray, 1966) 4894 19.9 80.1 – 5.6 6.9 22.0 30.6 65.2 Great Britain, by habitat character (Cain & Sheppard, 1954) Beechwoods 2271 10.9 76.2 12.9 2.5 5.6 28.1 25.4 61.7 Other deciduous woods 5639 24.8 64.7 10.5 4.1 4.3 15.8 11.7 35.2 Hedgerows 3454 57.8 38.3 4.0 7.2 7.1 4.5 4.7 23.6 Rough herbage 3378 66.8 30.2 3.0 10.1 9.4 4.5 4.0 27.9 Short turf 1977 33.3 46.1 20.6 12.4 7.5 12.4 11.2 43.6 Great Britain and Ireland British and Irish coasts, dunes (Cain, 1968) 19 338 57.8 36.0 6.2 3.9 9.7 2.2 4.5 20.3 Ireland Donegal, dunes (Clarke et al., 1968) 23 857 33.0 ? ? 8.9 0.4 5.2 ≤1.0 ≤ 15.5 Netherlands Groningen (Wolda, 1969 a) 4666 52.3 46.0 1.7 0.1 12.6 10.1 6.0 28.8 Gelderland (Wolda, 1969 b) 26 230 83.4 16.6 – 55.0 0.2 13.2 0.01 68.4 Germany *Northward from Th uringia and Saxony 8438 45.6 ? ? ? ? ? ? < 48.7 *Th uringia and Saxony 14 255 59.6 ? ? ? ? ? ? < 49.4 France Loir-et-Cher (Arnold, 1970) 1056 49.9 48.0 2.1 9.4 16.6 4.7 18.9 49.6 For the whole country (Lamotte, 1959) 152 305 ? ? ? ? ? ? ? < 49.1 France, Spain and Andorra Pyrenees (Arnold, 1968) 8806 81.9 18.1 – 33.6 2.3 4.7 0.9 41.5 Spain Pyrenees (Ramos, 1984) 6900 68.7 28.4 2.9 41.6 4.2 8.4 2.4 56.7 **Iberian Mountains (Mazon et al., 1989) 5066 30.5 69.5 ? 3.7 2.7 6.2 11.2 23.8 Central Spain (Ramos, 1985) 2048 51.7 47.6 0.6 5.6 1.7 3.7 1.9 13.0 Italy North part of the Adriatic coast (Sacchi, 1984) 1427 73.4 26.6 – 11.1 8.2 3.4 3.6 26.3 Territories for which the species was introduced from the second half of the 19th century and later USA Massachusetts, Marion town (Clench, 1930; Johnson, 1927) 2779 52.2 47.6 0.2 21.5 20.9 9.5 24.4 76.4 Ibidem (Brussard, 1975) 22 81.8 18.2 – 45.4 31.8 – 9.1 86.4 New York, New York City (Landman, 1956) 1402 90.9 9.1 – 51.6 3.7 7.9 0.9 64.1 New Jersey, Burlington town, data from 1893 to 2014 (Örstan & Cameron, 2015) 591 ? ? ? ? ? ? ? 91.0 Ibidem, collected in 1908 (Örstan & Cameron, 2015) 89 41.6 58.4 – 2.2 29.2 58.4 – 89.9 377Polymorphism of Cepaea nemoralis (Gastropoda, Helicidae) from two Distant Parts of Eastern Europe… Th e proportion of unbanded shells in Lexington was about 4 % at the end of the 19th century, 14–15 years aft er the introduction (Howe, 1898). By 1930 (McConnell, 1936) it increased more than 7 times, which was caused by the increa se in the proportion of the lightest phenotype (yellow unbanded). Th e total frequency of the 4 light phenotypes over the same period of time increased approximately 4 times (table 3). Th is may be an indica- tion of strong climatic selection favoring snails with light-colored shells. It should also be noted that in Lexington, already at the very early stages of research, shells with weak, rudi- mentary, or split bands were oft en found (Howe, 1898), which could somewhat reduce the intensity of pigmentation of fi ve-banded shells. More than half of C. nemoralis individuals collected in the Subcarpathian Voivodeship of Poland in 1998–2000 (Ożgo, 2005), were represented by only one phenotype (yellow mid-banded). Th e malacological collection of the State Museum of Natural History in Lviv demonstrates that a high proportion of this morph was also characteristic during the initial stages of the introduction of C. nemoralis to southeastern Poland, when this species was fi rst recorded in Łańcut (Bąkowski, 1880) and Rzeszów (Łomnicki, 1899). In the samples collected both at the end of the 19th century and the end of the 20th century, the proportion of the unbanded shells (not only yellow, but also pink) was very low (table 3). Th is may be attributed to the founder eff ect or random genetic drift in the initial stages of colony forma- tion. Unfortunately, the samples from the end of the 19th century are too small to be able to analyze possible changes in the phenotype frequencies that could have occurred during the 20th century. Ibidem, collected in 2013 and 2014 (Örstan & Cameron, 2015) 12 58.3 41.7 – – 50.0 33.3 8.3 91.7 Virginia, Lexington town (Howe, 1898) 3543 90.8 ? ? ? ? ? ? about 10 Ibidem (McConnell, 1936) 1553 96,9 3.1 – 29.7 10.0 1.4 1.1 42.2 Ibidem (Brussard, 1975) 315 96.8 3.2 – 36.8 2.8 0.6 0.3 40.6 Virginia, Lynchburg town (Brussard, 1975; Richards & Murray, 1975) 2761 100.0 – – 15.5 2.9 – – 18.5 ***6 other localities (Brussard, 1975) 416 51.7 40.1 8.2 19.9 7.0 15.1 11.8 53.8 Czech Republic Bohemia (Honěk, 1995) 14 249 49.9 50.1 – 0.7 21.3 10.5 17.3 49.9 Poland Lower Silesian Voivodeship, around Wrocław City (Pokryszko et al., 2012) 9340 55.7 44.1 0.2 17.7 7.8 12.0 9.5 47.0 Subcarpathian Voivodeship, end of 19-th cen- tury (SMNH NANU) 46 58.7 41.3 – 2.2 30.4 – 17.4 50.0 Ibidem (Ożgo, 2005) 7307 72.6 27.4 <0.1 2.0 51.2 4.4 17.2 74.8 Ukraine Ivano-Frankivsk, Lviv and Ternopil Regions, 2019–2020 ( this publication) 3736 37.5 61.6 0.9 2.1 15.7 34.3 9.1 61.2 Belarus Mogilyov Region, Bobruisk town (Ostrovsky & Prokofi eva, 2017) 280 17.1 77.5 5.4 – 5.0 30.4 28.2 63.6 European part of Russia Moscow Region, 2006–2020 (this publication) 2112 33.7 58.7 7.5 0.8 7.9 27.7 14.8 51.3 Nizhny Novgorod Region, Nizhny Novgorod City, 3 colonies with unspecifi ed size of each sample (Mukhanov & Lisitsyn, 2018) 218 47 53 – – 47 13 40 100 27 73 – – – 67 6 73 100 – – – 100 – – 100 *Calculated using modifi ed data from the Schilder´s archive used in the article (Sverlova, 2004 b); **excluding rare brown shells not concretely mentioned in the article; ***total for 6 settlements in Virginia (Staunton, Warm Springs, Harrisonburg), Massachusetts (Brewster, Eastham) and New York (Brighton); ≤ — the real fre quency may be slightly less than the specifi ed value due to the lack of data on the full composition of the phenotypes; < in the last column — the indicated amount also includes the frequencies of dark pheno- types B00000 and B00300; ? — it is impossible to calculate according to the data available in the publication; SMNH NANU — collection of the State Museum of Natural History in Lviv. Locations within one country are mentioned from north to south (England, Netherlands, Germany, Spain, USA) or from west to east (Poland, Russia). Frequencies in the last column exceeding 50 % are shown in bold. 378 N. V. Gural-Sverlova, R. I. Gural Such a pronounced predominance of one (or two) of the lightere phenotypes was not observed either in the Czech Republic (Honěk, 1995) or in southwestern Poland (Pokrysz- ko et al., 2012), i. e. in regions less distant from the eastern and south-eastern boundaries of the natural range of C. nemoralis (Gural-Sverlova & Egorov, 2021). Although in the Czech Republic, the total frequence of yellow and pink mid-banded shells was also close to 40 %. In southwestern Poland, snails with unbanded shells were relatively more common. Th e total proportion of those with yellow and pink ground colors there was 30 %, with a slight prevailing of the lighter (yellow) phen otype. Th e total frequency of the 4 lightest pheno- types both in the Czech Republic and in the south-west of Polan d also practically does not diff er from the average values of this indicator in neighboring Germany (table 3). Th ere- fore, it is possible that climatic selection in the territories adjacent to the natural range of the species is not so strong. At the same time, the chance of repeated introductions of snails and replenishment of the initial gene pool of the introduced populations here is higher. An interesting experiment was conducted at the end of the 20th century in Prague (Honěk, Martinkova, 2003). In 1995, mature and large immature individuals of C. nemora- lis from a single sample (N = 391) collected in the north-east of the Czech Republic were released at 9 sites. Th e most common in the sample were pink fi ve-banded shells (25.8 %). Th en, in decreasing order of frequencies, there were pink mid-banded (19.4 %), pink un- banded (16.9 %) and yellow mid-banded shells (16.4 %). Yellow unbanded shells were ab- sent. Before release to the new sites, the snails were sorted by shell color and banding pat- tern. Observations in 1997–2003 showed that snails did not survive at 5 sites, including two sites where mollusks with pink or yellow fi ve-banded shells were released. Th e initially released phenotype (pink or yellow mid-banded) was predominan t at two sites. At another two sites, where pink individuals without bands or with three upp er bands were released, the phenotype yellow mid-banded became predominant. Th e same phenotype also pre- vailed in a single colony, apparently formed due to the migration of snails from the site where individuals with pink unbanded shells were released. A s a result, yellow mid-banded shells became predominant in the formed colonies of C. nemoralis, their share was 65.8 % of all individuals found. Сonclusions In diff erent parts of Easte rn Europe, a number of similar features of the phenotypic composition of C. nemoralis are observed, which can only partly be explained by the greater likelihood of the founding individuals having traits that are more common in the natural range of this species. Both in Eastern Europe and in other introduced populations of C. ne- moralis, there is oft en a well pron ounced predominance of one or two of the 4 lightere variants of shell coloration (yellow unbanded, yellow mid-banded, pink unbanded or pink mid-banded), which, probably, can be interpreted as the result of the adaptation to the more continental climate conditions compared to the natural part of the present range of this species. 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