Turkish Journal of Zoology Turk J Zool (2015) 39: 630-642 © TÜBİTAK doi:10.3906/zoo-1405-75 http://journals.tubitak.gov.tr/zoology/ Research Article Determination of genetic variations between Apodemus mystacinus populations distributed in Turkey inferred from mtDNA PCR–RFLP 1, 1 2 2 Gül OLGUN KARACAN *, Reyhan ÇOLAK , Ercüment ÇOLAK Department of Biology, Faculty of Science and Letters, Aksaray University, Aksaray, Turkey 2 Department of Biology, Faculty of Science, Ankara University, Ankara, Turkey Received: 30.05.2014 Accepted/Published Online: 27.02.2015 Printed: 30.07.2015 Abstract: The rocky mouse, Apodemus mystacinus, is a rodent species distributed in Anatolia. A total of 108 specimens from 19 localities in Turkey were collected to study the molecular variation of A. mystacinus inferred from RFLP of mtDNA cytochrome b (cytb) and D-loop. MboI, HaeIII, and RsaI from cytb digestion and MboI, BfaI, and HinfI from D-loop digestion showed differentiation among the studied specimens. The UPGMA dendrogram of the combined data of cytb and D-loop indicated 3 main clades, A. m. euxinus, A. m. mystacinus, and A. m. smyrnensis, distributed in Turkey. The haplotype diversity observed in the present study was high. Furthermore, the fixation index values (FST) ranged from 0.75093 to 0.83384, which indicated high diversity among the clades. These 3 A. mystacinus clades of Turkey were also supported by analysis of molecular variance (AMOVA) results, by revealing that genetic diversity was higher among groups (79.55%) than within the groups. Key words: Apodemus mystacinus, mtDNA, RFLP, cytochrome b, D-loop, Turkey 1. Introduction The rocky mouse, Apodemus mystacinus, is a rodent species distributed in the eastern Mediterranean region. This species lives in varied vegetation, including rocky and stony surfaces covered with forests, small bushes, or cultivated areas up to an elevation of 2700 m (Vohralik et al., 2002; Çolak et al., 2004). A. mystacinus has four controversial subspecies: A. m. mystacinus Danford and Alston (1877) from Sebil, Turkey; A. m. smyrnensis Thomas (1903) from western Turkey; A. m. rhodius Festa (1914) from Rhodes, Crete, and southwestern Turkey; and A. m. euxinus Allen (1915) from northern or northeastern Turkey. A. epimelas Nehring (1902), formerly described as a subspecies of A. mystacinus, is distributed in the Balkan region (former Yugoslavia, Greece, and Bulgaria). This subspecies has been raised to the level of species on the basis of morphometric studies using body size and dental characters (Spitzenberger, 1973; Mezhzherin, 1997; Vohralik et al., 2002), a paleontological approach (Storch, 1977), allozyme research (Filippucci et al., 2002), and DNA level (Michaux et al., 2002, 2005; Bugarski-Stanojević et al., 2011). Apart from the fact that A. mystacinus and A. epimelas can be easily separated from each other, these species are differentiated from the other Sylvaemus species. This *Correspondence: [email protected] 630 theory is supported by using morphological characters such as body size (Rietschel and Storch, 1973; Storch, 1974) and cranial differentiations (Kuncová and Frynta, 2009), enzymatic polymorphism studies (Filippucci et al., 2002), and DNA polymorphisms (Martin et al., 2000; Michaux et al., 2002; Bellinvia, 2004). Thus, A. mystacinus and A. epimelas belong to Karstomys, which is a controversial subgenus of Apodemus. The validity of A. m. smyrnensis is controversial; some authors have claimed that this subspecies is synonymous with A. m. mystacinus (Ellerman, 1948; Ellerman and Morrison-Scott, 1951; Çolak et al., 2004), while others have revealed that A. m. smyrnensis lives in the Taurus Mountains (Neuhäuser, 1936) and western Turkey (Çolak et al., 2007; Olgun et al., 2009). Similarly, there is a disagreement about the taxonomic status of A. m. euxinus (Allen, 1915) at the level of distribution and validity. Neuhäuser (1936) claimed that northern Turkey is the distribution area of this subspecies, whereas Çolak et al. (2007) showed differences in the Artvin (northeastern Turkey) populations from the other northern populations. Furthermore, studies including morphological, biometrical, karyological, bacular, and phallic differentiations (Çolak et al., 2004) and RAPD variations (Olgun et al., 2009) have indicated the homogeneity of the eastern and southeastern populations. OLGUN KARACAN et al. / Turk J Zool However, multivariate procedures based on molar, skull, and body measurements did not confirm the validity of this subspecies (Vohralik et al., 2002). When all of these studies are evaluated, it is obvious that the results are still controversial regarding the validity of the subspecies of the rocky mouse. While morphological studies have been especially insufficient in determining the variations of subspecies, a molecular viewpoint has been more effective in determining the lineages of species. In particular, DNA phylogenies may adduce the lineages, subspecies, and species (Hewitt, 1996). In many different applications, Cytb is one the most preferred proteinencoding regions of mtDNA to detect intra- or interspecific genetic variability (Deffontaine et al., 2005; Michaux et al., 2005; Hürner et al., 2010; Kryštufek et al., 2012; Zhang et al., 2013). Another frequently used mtDNA marker is the control region known as D-loop, which might be useful in taxonomic studies, since it is affected by selective pressure because of its noncoding and more variable nature (Matson and Baker, 2001; Bellinvia, 2004; Michaux et al., 2005; Macholán et al., 2007; Zhang et al., 2013). Polymerase chain reaction–restriction fragment length polymorphism (PCR–RFLP) of specific mtDNA has been a useful tool to infer genetic structure and differentiation at the species and subspecies levels of different organisms (Marchesin et al., 2008; Gonzalez et al., 2009; Presti et al., 2010; Suzuki et al., 2010; Darvish et al., 2012; Gherman et al., 2012; Rahim et al., 2013; Sanra et al., 2013). Therefore, in this study, we used mtDNA cytb and D-loop regions to investigate the genetic diversity and population structure of A. mystacinus distributed in Turkey, inferred by the PCR–RFLP technique. These findings would be useful to determine the subspecies of A. mystacinus and also to discover a subspecies-specific RFLP marker. 2. Materials and methods 2.1. Sample collection To study the molecular variation of A. mystacinus, 108 specimens (Table 1) from 19 localities in Turkey (Figure 1) were collected. Moreover, 11 Sylvaemus samples (4 specimens belonging to Apodemus uralensis, 4 specimens belonging to Apodemus witherbyi, and 3 specimens belonging to Apodemus flavicollis) were used as the outgroup in this study. 2.2. DNA isolation and PCR amplification DNA was extracted from kidney tissue by using cetyltrimethylammonium bromide (CTAB), using Doyle and Doyle’s (1991) isolation protocol with modifications. The cytb gene was amplified using the universal primers L14724a (5’-CGAAGCTTGATATGAAAAACCATCGTTG-3’) and H15915a (5’-AACTGCAGTCATCTCCGGTTTACAA GAC-3’) (Irwin et al., 1991). Amplification reactions consisted of an initial denaturation at 94 °C for 5 min, 35 cycles of denaturation at 93 °C for 1 min, annealing at 46 °C for 1 min, extension at 65 °C for 1 min 30 s, and a 10-min final extension at 65 °C. D-loop sequence was amplified using L15926 (5’-TCAAAGCTTACACCAGTCTTGTAAACC-3’) and HN00651 (5’-TAACTGCAGAAGGCTAGGACCAAA CCT-3’) (Matson and Baker, 2001). Reactions for D-loop were carried out following this protocol: 40 cycles of denaturation at 95 °C for 30 s, annealing at 45 °C for 1 min, extension at 65 °C for 1 min, and a 5-min final extension at 65 °C. The reactions were performed in a THERMO PX2 thermal cycler (Thermo Scientific Hybaid). The PCR was prepared in 25 µL of a reaction mixture containing 80 ng of the DNA samples; 10X reaction buffer (750 mM Tris-HCl pH: 8.8, 200 mM (NH4)2SO4, 0.1%, Tween 20; Thermo); 1.5 u of Taq DNA polymerase (500 units, Thermo); 0.2 mM of each deoxynucleotide triphosphate (100 mM of dNTP set solutions, Thermo); 2 mM MgCl2; and 20 pmol of each primer (Thermo). 2.3. Restriction digestion Afterwards, only one PCR sequence from each mtDNA region was sequenced. NEBcutter Version 2.0 (Vincze et al., 2003) was utilized in order to determine which enzymes could be used for digestion. Therefore, we digested cytb with the HaeIII, MboI, RsaI, HinfI, BamHI, and TaqI restriction enzymes (RE), and D-loop with the MboI, HinfI, TaqI, BfaI, and NdeI enzymes (Table 2). As the next step, 0.1 µg of PCR products were digested with RE (Thermo Scientific) according to their incubation conditions. The restriction fragments were visualized on 2% agarose gel after staining with ethidium bromide. Fragment lengths were determined using a 100-bp ladder (Thermo). 2.4. Statistical analyses Restriction fragments were scored as the presence (1) and the absence (0) of bands. The UPGMA tree for RFLP fragments was constructed based on the binary data using PAST software (Hammer et al., 2001) by Jaccard similarity coefficient. The robustness of the tree was determined by bootstrap resampling (1000 replicates) (Felsenstein, 1985). Furthermore, Numerical Taxonomy and Multivariate Analysis System-pc (NTSYS) version 2.2 (Exeter Software, Setauket, NY, USA) and Statistical Package for the Social Sciences version 20 (SPSS) (IBM Corp., Armonk, NY, USA) software were used together for principal coordinate analyses (PCoA). NTSYS was run to calculate the eigenvalues, and the PCoA graphic was visualized with SPSS using these eigenvalues. Analysis of molecular variance (AMOVA) was performed to detect the genetic variation within and among the clades using the Arlequin version 3.5 (Excoffier and Lischer, 2010) software package with 10,100 permutations. 631 OLGUN KARACAN et al. / Turk J Zool Table 1. Number of specimens belonging to localities and their distribution by region. Species A. mystacinus Locality Number of specimens ARTVİN 9 RİZE 6 TRABZON 6 ORDU 2 KASTAMONU 1 ZONGULDAK 8 DÜZCE 1 BALIKESİR 12 İZMİR 3 AYDIN 2 MUĞLA 11 BURDUR 1 KONYA 3 ANTALYA 9 MERSİN 8 ADANA 7 KAHRAMANMARAŞ 8 ERZİNCAN 9 ADIYAMAN 2 Sylvaemus (outgroup) A. flavicollis A. uralensis A. witherbyi EASTERN BLACK SEA CENTRAL BLACK SEA WESTERN BLACK SEA WESTERN TURKEY SOUTHWESTERN TURKEY SOUTHERN TURKEY EASTERN TURKEY MUĞLA 1 ADANA 2 ARDAHAN 1 ARTVİN 1 TRABZON 2 İZMİR 1 ANKARA 2 KONYA 1 To determine the genetic differentiation among clades, the pairwise fixation index (FST) was evaluated with Arlequin. Slatkin’s linearized FST values (Slatkin, 1995) were also used to estimate the gene flow (Nm), with the formula Nm = (1 – FST)/4 FST. Tajima’s D (Tajima, 1989) and Fu’s Fs (Fu, 1997) values were calculated using Arlequin, as well as with the bootstrap method, to introduce the population demographic expansion, bottleneck, and neutrality, using 10,000 permutations. Haplotype diversities (h) and pairwise differences, which gave information about the structure of the clades, were also evaluated with Arlequin. 3. Results In total, the cytb and D-loop regions of the 108 specimens obtained from the 19 localities were analyzed both 632 Region separately and combined. Each mtDNA region has nearly 1100 base pairs. 3.1. Restriction patterns obtained from the cyt b and D-loop regions Three of six restriction enzymes produced different band profiles among the A. mystacinus populations inferred from cytb: MboI, HaeIII, and RsaI (Figure 2). Five restriction enzymes were used to digest the D-loop region, and while two (MboI and BfaI) exhibited intrapopulation variable patterns, one gained population-specific profiles (HinfI) (Figure 3). Each RE pattern is represented with a letter (A–J) and each individual is described through the specific combination of 6 RFLP patterns (6 letters). There were 24 haplotypes out of 108 individuals (Table 3). The UPGMA dendrogram was constructed using binary matrices (1/0) obtained from the haplotypes of the OLGUN KARACAN et al. / Turk J Zool Figure 1. Sampling localities of A. mystacinus specimens. Table 2. Restriction enzymes and their digestion sites with reaction procedures. Restriction enzyme BamHI BfaI HaeIII HinfI MboI NdeI RsaI TaqI Restriction site 5’...G↓G A T C C...3’ 3’...C C T A G↑G...5’ 5’...C↓T A G...3’ 3’...G A T↑C...5’ 5’...G G↓C C...3’ 3’...C C↑G G...5’ 5’...G↓A N T C...3’ 3’...C T N A↑G...5’ 5’...↓G A T C ...3’ 3’... C T A G↑...5’ 5’...C A↓T A T G...3’ 3’...G T A T↑A C...5’ 5’...G T↓A C...3’ 3’...C A↑T G...5’ 5’...T↓C G A...3’ 3’...A G C↑T...5’ Reaction degree Reaction time 37 °C 16 h 37 °C 15 min 37 °C 15 min 37 °C 15 min 37 °C 16 h 37 °C 15 min 37 °C 16 h 65 °C 16 h 633 OLGUN KARACAN et al. / Turk J Zool Figure 2. Restriction patterns of MboI, HaeIII, and RsaI inferred from cytb digestion (M: Marker–100bp DNA Ladder, 1. Ordu, 2. Trabzon, 3. Rize, 4. Artvin, 5. Erzincan, 6. Kahramanmaraş, 7. Adıyaman, 8. Adana, 9. Muğla, 10. Burdur, 11. Konya, 12. Antalya, 13. Mersin, 14. Kastamonu, 15. Zonguldak, 16. Düzce, 17. Balıkesir, 18. İzmir, 19. Aydın, 20. A. uralensis, 21. A. witherbyi, 22. Cytb PCR product). combined data, and this dendrogram indicated 3 main clades of A. mystacinus distributed in Turkey (Figure 4). Furthermore, PcoA exhibited the segregation of these 3 clades clearly (Figure 5). Clade 1 included specimens from the eastern Black Sea (Rize–Artvin–Trabzon), the central Black Sea (Ordu), and eastern (Erzincan–Adıyaman) and southern Anatolia (Kahramanmaraş–Adana). This clade had 2 subgroups, Clade 1a (Rize, Artvin, and the other specimens in this clade) and Clade 1b (only specimens from Rize and Artvin). The other main clade was Clade 2, which branched from the same node as Clade 1. Clade 2 included the specimens from the southwest (Muğla) and the rest of southern Anatolia (Burdur–Konya–Antalya–Mersin). The western 634 Anatolian specimens (Kastamonu–Zonguldak–Düzce– Balıkesir–İzmir–Aydın) constituted Clade 3, which was separate from the other clades (Figures 4–5). A total of 24 combined haplotypes were detected in the 3 clades, and are listed in Table 3. It seemed that there were no common haplotypes among the clades according to these results; Hap01–Hap10 were distinctive for Clade 1, while Clade 2 comprised Hap11–Hap18, and Hap19– Hap24 were representative for Clade 3. The haplotype diversity (h) in each A. mystacinus clade ranged between 0.8401 and 0.5988, and the highest haplotype diversity was calculated in Clade 1 (0.8401) while the lowest was in Clade 2 (0.5988) (Table 3). OLGUN KARACAN et al. / Turk J Zool Table 3. Distribution of composite haplotypes among 3 A. mystacinus clades. Haplotype compositions* Haplotypes Hap_01 Clade 1 Clade 2 Clade 3 (N = 49) (N = 32) (N = 27) Specimens Artvin–Trabzon AAAAAA 0.286 0 0 Ordu Kahramanmaraş Hap_02 AAAABA 0.0816 0 0 Kahramanmaraş Hap_03 AAABAA 0.0408 0 0 Rize–Adana Hap_04 AAACAA 0.245 0 0 Hap_05 AAACBA 0.0612 0 0 Hap_06 AAAEAA 0.0612 0 0 Hap_07 ABAAAA 0.0612 0 0 Artvin Hap_08 ABABAA 0.0204 0 0 Artvin Hap_09 ABACAA 0.122 0 0 Rize Hap_10 AEAAAA 0.0204 0 0 Artvin Hap_11 CAAGBA 0 0.625 0 Hap_12 CAAHBA 0 0.0312 0 Muğla Hap_13 CAAIBA 0 0.0312 0 Mersin Hap_14 CAAJBA 0 0.125 0 Mersin Hap_15 CACGBA 0 0.0312 0 Muğla Hap_16 CACGBB 0 0.0312 0 Muğla Hap_17 CACHBB 0 0.0312 0 Muğla Hap_18 CDAGBA 0 0.0938 0 Konya Hap_19 CCBDBA 0 0 0.037 Düzce Hap_20 CCBEBA 0 0 0.296 Zonguldak Hap_21 CCBEBB 0 0 0.519 Hap_22 CCBFBA 0 0 0.037 Balıkesir Hap_23 CCBGBA 0 0 0.037 Balıkesir Hap_24 DCBEBA 0 0 0.0741 Balıkesir Haplotype diversity 0.8401 0.5988 0.6581 Standard deviation ± 0.0302 ± 0.0951 ± 0.0721 Adana–Erzincan Adıyaman Erzincan Kahramanmaraş Erzincan–Adana Muğla–Burdur Antalya–Mersin Kastamonu–Balıkesir İzmir–Aydın *A single capital letter (A–J) was assigned to each of 6 PCR–RFLP profiles in cytb and D-loop. 635 OLGUN KARACAN et al. / Turk J Zool Figure 3. Restriction patterns of HinfI inferred from D-loop digestion (M: Marker–100bp DNA Ladder, 1. Ordu, 2. Trabzon, 3. Rize, 4. Artvin, 5–6. Erzincan, 7–8. Kahramanmaraş, 9. Adıyaman, 10–11. Adana, 12. Muğla, 13. Burdur, 14. Konya, 15. Antalya, 16. Mersin, 17. Kastamonu, 18. Zonguldak, 19. Düzce, 20. Balıkesir, 21. İzmir, 22. Aydın, 23. A. uralensis, 24. A. witherbyi, 25. D-loop PCR products). AMOVA was executed to determine the genetic variation rate; 79.55% (P < 0.01) of the total variation explained the correlation within groups, while 20.45% (P < 0.01) of the correlation was among groups (Table 4). Genetic differentiations among clades were obtained from the pairwise FST values: the highest was between Clades 2 and 3 (0.83384), the lowest was between Clades 1 and 2 (0.75093) (Table 5). The Nm inferred from the FST values was higher between Clades 1 and 2 (0.08292) than that from among other clades (Table 5). Tajima’s D and Fu’s Fs tests were performed to present the demographic structure as the expansion, bottleneck, or selective effects of the A. mystacinus clades. If the population began to expand generally after a bottleneck, the D and Fs values would be negative due to the loss of mutations, unlike the positive values (Tajima, 1989; Fu, 1997). Moreover, the negative values were not sufficient to remark about the demographics of the populations 636 separately and so P was a value to measure the significance of D and Fs; if P was below 0.05, the sums of D and Fs would be evaluated as significant. In our results, Clade 2 had the highest negative for Tajima’s D and Fu’s Fs values as –0.89106 and –1.98851, respectively. However, none of the results obtained from any of the clades were significant at P > 0.05 (Table 6). 4. Discussion In this study, mtDNA sequences from both cytb and D-loop regions were used to exhibit the genetic differentiation among A. mystacinus populations. A total of 24 composite haplotypes, obtained from restriction profiles of cytb and D-loop, were specified for each individual and clade (Table 3). Diversities among the clades were supported by various analyses, including haplotype diversity, molecular variance, and neutrality tests. OLGUN KARACAN et al. / Turk J Zool Figure 4. UPGMA dendrogram of the composite data by combining cytb and D-loop regions. 637 OLGUN KARACAN et al. / Turk J Zool Figure 5. PCoA analysis of A. mystacinus clades. The scatter plot is of the scores of three principal eigenvalues inferred from NTSYS software. Each scatter point represents a specimen of A. mystacinus. Table 4. AMOVA of mtDNA composite haplotypes inferred from cytb and D-loop among A. mystacinus groups. Source of variation DF* Sum of squares Variance components Percentage of variation (%) Among groups 2 364.348 5.20118Va 79.55 Within groups 105 140.355 1.33672Vb 20.45 Total 107 504.704 6.53790 0.79554 (P = 0.000) Fixation index FST *DF: Degrees of freedom. Table 5. Pairwise FST (below diagonal) and Nm (above diagonal) values among A. mystacinus clades. Population Clade 1 Clade 2 Clade 3 Clade 1 - 0.08292 0.0589 Clade 2 0.75093 (0.00000)* - 0.0498 Clade 3 0.80924 (0.00000)* 0.83384 (0.00000)* - * P values are given in parentheses. 638 OLGUN KARACAN et al. / Turk J Zool Table 6. Neutrality tests of A. mystacinus clades. Neutrality tests Tajima’s D Fu’s Fs No. of specimens CLADE 1 CLADE 2 CLADE 3 No. of specimens 49 32 27 D 1.33034 –0.89106 –0.3941 P 0.919 0.216 0.398 49 32 27 Fs 0.34907 –1.98851 0.628 P 0.595 0.126 0.649 The haplotype diversity observed in the three clades was high in the present study (Table 3). While Clade 1 had the highest haplotype diversity (0.8401), Clade 2 had the lowest (0.5988). The high haplotype diversity might indicate a bottleneck (Michaux et al., 2004; Liu et al., 2008; Xiao et al., 2008), where many species were affected by Pliocene and early Pleistocene events (Grant and Bowen, 1998). Similarly, Michaux et al. (2004) found that the high haplotype diversity of A. flavicollis in Turkey indicated the expansion of this population. This study supported both the recent expansion and the bottleneck of A. mystacinus clades in Turkey according to the haplotype diversities. While Clade 1 might indicate a bottleneck scenario, Clade 2 might tend to indicate a recent expansion after a bottleneck. The pairwise FST statistics (Table 5) and AMOVA (Table 4) were studied to examine the genetic differentiation among the A. mystacinus groups. The FST values ranged between 0.75093 and 0.83384, which indicated high diversity among the clades, i.e. values greater than 0.25 were evaluated as substantially different (Nei, 1987). This diversity was also supported by the Nm obtained from the FST values, which indicated genetic distance when the Nm was <1 (Wright, 1951). High diversities among subspecies could also lead to speciation by decreasing the gene flow over time. The highest genetic differentiation, between Clades 2 and 3 (FST = 0.83384), also indicated the lowest gene flow between these two clades (Nm = 0.0498) (Table 5). It could be said that there were more effective factors inhibiting the genetic breeding between these clades than that of the others. These diversities were supported by RAPD data (Olgun et al., 2009) and esterase variations (Çolak et al., 2007). Contrary to our findings, morphometric studies using the body and skull measurements showed that the western specimens (indicated as Clade 3 in our study) were closer to the southeastern specimens (Clade 1 in our study) (Çolak et al., 2004). These three A. mystacinus clades of Turkey were also supported by AMOVA results, which showed that the genetic diversity was higher among the groups (79.55%) than within the groups (20.45%). These genetic structures among the groups and within the groups were similar to those of the other Apodemus species, i.e. A. sylvaticus (Michaux et al., 2003) and A. flavicollis (Michaux et al., 2004). Despite the fact that Clade 2 was negative for Tajima’s D and Fu’s Fs, indicating recent expansion after a bottleneck, none of the results were significant at P < 0.05 in this study (Table 6). Moreover, although Clade 1 for D and Clade 1 and 3 for Fs had positive values that did not indicate a recent expansion, P was again not significant. Similarly, Gündüz et al. (2007) studied a small rodent species, Spermophilus taurensis, distributed in the Taurus Mountains and southwestern Anatolia. They concluded that the Taurus Mountains were a glacial refugium, based on positive values for both Tajima’s D and Fu’s Fs. The Taurus refugium was also supported by Çıplak (2003), who studied grasshoppers in that region. In our study, the specimens from the Taurus Mountains were collected from the Antalya region and were in Clade 2. Contrary to the results of Gündüz et al. (2007) and Çıplak (2003), this clade had the highest negative values in neutrality tests, and low haplotype diversity indicated that this region was not a refugium for A. mystacinus populations. All of these findings indicate that there are 3 subspecies of A. mystacinus. The specimens from the eastern Black Sea region and eastern and southeastern Anatolia that were grouped together as Clade 1 may refer to A. m. euxinus, which was also supported by Çolak et al. (2004) and Olgun et al. (2009). This group was also separated into 2 subgroups; the Artvin and Rize specimens were situated in both of these 2 subgroups (Clade 1a and Clade 1b). Doğramacı (1972) suggested, according to the morphological data, that Artvin was a hybrid zone between A. m. mystacinus and A. m. euxinus; this was supported by Çolak et al. (2007) using esterase variations. Similarly, the hierarchy in Clade 1 also may indicate that the region including the Artvin and Rize specimens is a hybrid zone for A. m. euxinus in our study. 639 OLGUN KARACAN et al. / Turk J Zool The southern Anatolia populations, including the type locality of A. mystacinus (Sebil–Mersin), constituted Clade 2. Differentiations between A. m. mystacinus and A. m euxinus were supported by the morphological data: the ears were longer in A. m. mystacinus than in A. m. euxinus (Çolak et al., 2004). Furthermore, a separate lineage that included the western Anatolia and western Black Sea specimens (Clade 3) corresponded to A. m. smyrnensis, which had been confirmed in previous studies (Çolak et al., 2007; Olgun et al., 2009). Neuhäuser (1936) reported that A. m. smyrnensis was distributed in western Anatolia and in the Taurus Mountains. Similarly, Ellerman (1948) claimed that A. m. smyrnensis was synonymous with A. m. mystacinus. We have presented here a different lineage that places A. m. smyrnensis in western Anatolia. Similarly, Çolak et al. (2004) proved the validity of A. m. smyrnensis using body and skull measurements (the condylobasal lengths, hind foot, and ear). However, Michaux et al. (2005) reported a different lineage in southwestern Turkey that was synonymous with A. m. rhodius, using DNA analysis. This has also been supported by RAPD markers (Olgun et al., 2009). However, our findings disagree, as we did not find this subspecies. The possible reasons for subspeciation of the A. mystacinus populations might be the geographic structure of Anatolia and the effects of climatic fluctuations during the Pleistocene. The Kızılırmak River and its valley may be a barrier between A. m. smyrnensis (distributed in northwestern and western Anatolia) and the northeastern specimens of A. m. euxinus. A similar case might be possible for A. m. mystacinus and A. m. euxinus populations, due to the influence of the rivers in the southeastern region (i.e. Seyhan River, Ceyhan River); the results showed that the Nm between these two clades was higher than the others, indicating the permanence of the gene flow. Furthermore, southwestern Anatolia seems to have been a barrier separating A. m. smyrnensis and A. m. mystacinus, perhaps due to the collapsing of this region below sea level during the Pleistocene (Görür et al., 1995). The lowest Nm value between A. m. smyrnensis and A. m. mystacinus in this study also supports the reduction of gene flow between these two clades. In conclusion, we confirm that RFLP markers could be a useful tool to determine the geographical differentiation of A. mystacinus. However, the RFLP data were not sufficient to discover the possible reasons for this differentiation, or to display the speciation tendency of A. mystacinus clades. Therefore, further analysis using more efficient markers such as sequence analyses or microsatellites should be used to clarify the speciation of A. mystacinus subspecies in Turkey. Acknowledgments We would like to thank Lisa Anne Meredith for the English editing, Dr Tamer Çırak for image editing, and the two anonymous referees and the editor, who provided valuable comments. References Bellinvia E (2004). A phylogenetic study of the genus Apodemus by sequencing the mitochondrial DNA control region. J Zool Syst Evol Res 42: 289–297. 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