Biogeography and origin of Lilium longiflorum and L. formosanum (Liliaceae) endemic to the Ryukyu Archipelago and Taiwan as determined by allozyme diversity

Abstract

Allozyme diversity on 13 isozyme loci was investigated for two bulbous species, Lilium longiflorum and L. formosanum, endemic to the subtropical archipelago of continental origin located in East Asia. Degrees of allozyme variability and divergence for L. longiflorum were very high for insular endemic species, indicating relatively longtime persistence of the present widespread distribution across many islands in this phenotypically little-changed species. Lilium formosanum exhibited rather lower variability and divergence than did L. longiflorum and was genetically close to the southern peripheral populations of L. longiflorum with 0.978 as its highest genetic identity value. Combined with other biological and insular geohistorical information, our results suggest that L. longiflorum was established around the end of the Pliocene when the current distribution area was still a continuous part of the ancient Asian continent, and L. formosanum was derived from southern populations of L. longiflorum around the late Pleistocene when the mainland of Taiwan was completely separated from the adjacent islands and the main continent. Depauperization of allozyme variability in some L. longiflorum populations was found on islands with lower altitudes. This reflects bottleneck effects after the complete or almost complete submergence of such low islands during the archipelago's development.

Variation of Dormancy and Early Flowering Ability in Lilium longiflorum and L. formosanum Populations in the Ryukyu Archipelago and Taiwan

“…Since L. formosanum is a derivative of L. longiflorum (Hiramatsu et al, 2001a), lack or reduction of bulb dormancy with early flowering ability is the result of adaptation to southern climate conditions from a heavy dormancy trait in L. longiflorum.…”

“…Based on genetic and morphological analyses, L. formosanum and L. longiflorum populations have a close relationship (Nishikawa et al, 2001), and it has been confirmed by allozyme analysis that L. formosanum is a derivative of L. longiflorum. L. formosanum shows early onset of flowering among Lilium species (Hiramatsu et al, 2001a). It is considered that this trait was obtained by shifting the anthesis time to late summer to ensure firstyear biomass accumulation (Saruwatari, 2009).…”

Phylogenetic Relationship between Degree of Self-compatibility and Floral Traits in Lilium longiflorum Thunb. (Liliaceae)

“…Although its cultivars have been used as a suitable plant material to study the SI reaction mechanism Peloquin, 1966, 1970;Li et al, 1996;Matsubara, 1973;Suzuki et al, 2001;Tezuka et al, 2007;van Tuyl et al, 1982), selfcompatible individuals and cultivars had never been discovered. Recently, Hiramatsu et al (2001a) revealed that genetic variability and divergence in L. longiflorum are very high, and that isozyme loci with a significant excess of homozygous genotypes frequently occur in some natural populations. Self-fertilization by selfcompatible individuals has been suggested as a potential cause of homozygous excesses.…”

“…It is possible to distinguish these species by leaf morphology, flowering time, and habitat (Hiramatsu et al, 2001b). Hiramatsu et al (2001a) suggested that L. formosanum is a derivative of L. longiflorum populations at the southern edge of the species distribution based on the data from allozyme diversity. Multiple transitions from SI dominance to SC dominance may have occurred in L. longiflorum populations.…”

Species Occurrence, Hybridization and Speciation in Postglacial East and South Asia

“…Sea-level changes during the Pleistocene glacials were also responsible for the composition of species around the coasts and the continental islands of East Asia and the genetic diversity of species, including, for example, gobioid fishes in the northeastern Pacific coasts (Fu et al, 2010), lilies in Taiwan and Ryukyus (Hiramatsu et al, 2001), the genus Kirengeshoma in East China and South Korea and Japan , and monkeys in China, Japan, and Taiwan (Wu et al, 2007). The varied diversification rate through the time period of Clade 3 (Figure 2) that primarily encompassed the East Asian continental islands (Taiwan and Japan) was probably a consequence of repeated fragmentation and secondary contacts of populations between the islands (Japan and Taiwan) and the continent (China) during the Pleistocene glacial oscillations.…”