Genetic Evidence of a Progenitor–Derivative Species Pair in East Asian Lilium
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Ann. Bot. Fennici 52: 211–218 ISSN 0003-3847 (print) ISSN 1797-2442 (online) Helsinki 9 April 2015 © Finnish Zoological and Botanical Publishing Board 2015 Genetic evidence of a progenitor–derivative species pair in East Asian Lilium Mi Yoon Chung1,3, Jordi López-Pujol2 & Myong Gi Chung3,* 1) Department of Biology Education, Seowon University, Cheongju 361-742, Republic of Korea 2) BioC, GReB, Botanic Institute of Barcelona (IBB-CSIC-ICUB), Passeig del Migdia s/n, ES-08038 Barcelona, Spain 3) Department of Biology and the Research Institute of Natural Science, Gyeongsang National University, Jinju 660-701, Republic of Korea (*corresponding author’s e-mail: mgchung@gnu. ac.kr) Received 31 Jan. 2014, inal version received 27 Jan. 2015, accepted 12 Feb. 2015 Chung M.Y., López-Pujol J. & Chung M.G. 2015: Genetic evidence of a progenitor–derivative spe- cies pair in East Asian Lilium. — Ann. Bot. Fennici 52: 211–218. Boreal Lilium distichum and temperate L. tsingtauense are morphologically very similar, thus they have been placed in the section Martagon. Recent molecular phy- logenetic analyses revealed that L. distichum and L. tsingtauense are indeed the most closely related species within that section. Lilium distichum has a wider geographic range and a broader niche than L. tsingtauense. We hypothesized that L. distichum– L. tsingtauense might be a classical “progenitor–derivative” (P–D) species pair and examined the levels of allozyme diversity in the two species in South Korea. Whereas the allelic composition of L. tsingtauense represented a subset of L. distichum, the former had signiicantly lower allozyme variability at both the population and the species levels than the latter. Except for the locus Fe (luorescent esterase), allele fre- quencies of L. distichum were very similar to those of L. tsingtauense. Accordingly, pairwise genetic identities between populations of L. distichum and L. tsingtauense were very high, with a mean of 0.919. Our allozyme results support the hypothesis that L. tsingtauense is a derivative species of the progenitor L. distichum. Introduction Fig. 1). In Korea, L. distichum occurs in grass- lands or gaps of Quercus mongolica-dominated Lilium consists of approximately 100 species temperate deciduous forests, at altitudes of 900– that are widely distributed throughout boreal and 1600 m a.s.l. along the Baekdudaegan (the main temperate regions of the northern hemisphere mountain system of Korea, which runs through (MacRae 1998). Among them, L. distichum most of the length of the Korean Peninsula) and is a boreal species usually occurring on for- in one of its main branches, the Nakdongjeong- ested slopes, forest margins, and hillsides along maek (Fig. 1). The species is relatively common streams (200–1800 m), distributed in Russian where it occurs, with the number of individu- Far East (Primorsky Krai), northeastern China als per population on the order of hundreds. Its (Heilongjiang, Jilin, and Liaoning provinces) and congener L. tsingtauense is a temperate species the Korean Peninsula (Liang & Tamura 2000; with a narrower range, distributed in eastern 212 Chung et al. • ANN. BOT. FENNICI Vol. 52 Fig. 1. Locations of sam- pled populations of Lilium distichum (LD-1 to LD-7) and L. tsingtauense (LT-1 to LT-11) in South Korea. Sample sizes: LD-1 = 47, LD-2 = 24, LD-3 = 44, LD-4 = 21, LD-5 = 27, LD-6 = 45, LD-7 = 37; LT-1 = 18, LT-2 = 48, LT-3 = 41, LT-4 = 29, LT-5 = 37, LT-6 = 22, LT-7 = 36, LT-8 = 38, LT-9 = 42, LT-10 = 58, LT-11= 74. The solid line indicates the location and shape of the main mountain range of the country, the Baekdu- daegan, which runs from north to south along the Korean Peninsula (span- ning over 1600 km). The dotted line represents the Nakdongjeongmaek, one of the 13 mountainous branches of the Baekdu- daegan. The approximate geographic ranges of both Lilium species are shown in the inset map (dotted line, L. distichum; dashed line, L. tsingtauense). China (Shandong and Anhui provinces) and in L. distichum, L. tsingtauense is locally common, the Korean Peninsula (Liang & Tamura 2000; with populations of hundreds of individuals. Fig. 1). In China, it occurs on sunny forested Because of their similar morphology, L. disti- slopes or in bushy or grassy places, at a wide chum and L. tsingtauense were placed in the same range of elevations (100–1000 m a.s.l.; Liang section Martagon, one of the seven sections in & Tamura 2000, Guo et al. 2011). In Korea, L. Lilium proposed by Comber (1949). A close rela- tsingtauense is mainly found in relatively open tionship has been further corroborated by molecu- habitats in low-altitude mountains (0–500 m; lar phylogenetic analyses, which clearly point hereafter we deine low elevation as < 500 outm, that L. distichum and L. tsingtauense are the mid elevation as 500–1000 m, and high elevation most closely related species within this section as > 1000 m) across the Peninsula, including (Sultana et al. 2010, 2011, Lee et al. 2011). They peripheral regions of the Baekdudaegan and the are sympatric in some locations in mid-elevation islands. Isolated individuals, however, can be mountains in Korea (e.g. LD-2, 902 m, and LT-1, found at mid to high elevations in montane habi- 889 m, at Mt. Deokhang; Fig. 1). However, L. dis- tats on the main ridge of the Baekdudaegan. Like tichum has a much wider geographic range, with ANN. BOT. FENNICI Vol. 52 • Progenitor-derivative species pair in East Asian Lilium 213 a broader niche (as estimated from ecological papillose stem and leaves in a whorl of 7–9 near niche modelling analyses in Chung et al. 2014a) the middle of stem. Two to seven orange to pale than L. tsingtauense. Lilium distichum thrives in vermilion lowers with purple-red spots (tepals places with temperatures ranging from –21.5 °C are ca. 5.0 cm long) are arranged in racemes, to 24.8 °C (mean temperatures in winter and nodding to horizontal, and open from July to summer, respectively) and precipitation ranging August. Fruits (capsules) are obovoid, 1.5 cm from 550 mm to 1500 mm, whereas L. tsingtau- long. Lilium tsingtauense is a somewhat shorter ense has narrower temperature and precipitation plant (40–85 cm tall), with leaves in one or two ranges (from –7 °C to 24.6 °C, and from 700 mm whorls of 5–14. Orange to vermilion lowers to 1500 mm, respectively). Based on phylogenetic with purple-red spots are solitary or in racemes information, ecological traits, and distribution of up to seven, of similar size to those of L. data, we hypothesize that L. distichum–L. tsing- distichum, and open from June to July. Capsules tauense might constitute a “progenitor–deriva- are also ca. 1.5 cm long. The breeding systems tive” (hereafter P–D) species pair; that is, instead and pollinators for the two Lilium species are of true sister species pair, a D or “derived” species unknown, although many lilies are known to be budded off and acquired new traits while the P or insect-pollinated and self-compatible (Yang & “parental” species remained largely unchanged Sun 2005, Arzate-Fernández et al. 2007, Rodger (Gottlieb 1984, 2003, Crawford 1985, 1990, et al. 2010) with few exceptions (e.g. L. longilo- 2010). Under this scenario, we can expect three rum is generally regarded as self-incompatible; genetic outcomes. First, the spectrum of alleles Miller 1993). observed in L. tsingtauense should be a subset of those found in L. distichum, with few, if any, unique alleles. Second, levels of within-popula- Population sampling tion genetic variation observed in L. tsingtauense should be lower than in L. distichum. Third, For L. distichum, we collected 245 individuals interspeciic genetic identities would be similarfrom seven populations (Table 1 and Fig. 1), to or slightly lower than intraspeciic identities, iveas from the main ridge of the Baekdudaegan a result of the recent divergence of the D species (LD-1 to LD-3, LD-6, and LD-7) and two from (Gottlieb 1973, 2003, Crawford 1983, 2010). the Nakdongjeongmaek (LD-4 and LD-5). For L. tsingtauense, we sampled a total of 443 individu- als from 11 populations (Table 1 and Fig. 1), Material and methods mostly located on the low- to mid-elevation peripheral areas of the Baekdudaegan, although Study plants three populations (LT-9, LT-10, and LT-11) were located on Oenaro Island, on the southern coast Lilium distichum is a herb 60–120 cm tall, with a of the Korean Peninsula (Fig. 1). As populations Table 1. Levels of genetic diversity of Lilium distichum and L. tsingtauense in South Korea estimated from 7 and 11 populations, respectively. Statistics for levels of within-population genetic variation are provided in Chung et al. (2014a: table 1). Abbreviations: n = number of individuals sampled, %P = percentage of polymorphic loci, AR = mean allelic richness, A = mean number of alleles per locus, Ho = observed heterozygosity, He = H-W expected heterozygosity or genetic diversity, SE = standard error. Species n %P AR A Ho (SE) He (SE) Lilium distichum population average 35 65.3 1.90 1.94 0.151 (0.012) 0.190 (0.012) pooled samples 245 85.7 2.57 0.204 (0.046) Lilium tsingtauense population average 40 56.5 1.68 1.81 0.090 (0.009) 0.113 (0.007) pooled samples 443 78.6 2.57 0.114 (0.037) 214 Chung et al. • ANN. BOT. FENNICI Vol. 52 of both species are of large size, we collected observed, regardless of their frequencies. We samples (one leaf per individual) as random as estimated the following genetic diversity param- possible, from well-separated individuals.