A clue to the evolutionary history of modern East Asian flora: Insights from phylogeography and diterpenoid alkaloid distribution pattern of the Spiraea japonica complex.

Each subkingdom of East Asian flora (EAF) has a unique evolutionary history, but which has rarely been described based on phylogeographic studies of EAF species. The Spiraea japonica L. complex, which is widespread in East Asia (EA), has received considerable attention because of the presence of diterpenoid alkaloids (DAs). It provides a proxy for understanding the genetic diversity and DA distribution patterns of species under various environmental conditions associated with the geological background in EA. In the present study, the plastome and chloroplast/nuclear DNA of 71 populations belonging to the S. japonica complex and its congeners were sequenced, combined with DA identification, environmental analyses, and ecological niche modelling, to investigate their phylogenetic relationships, genetic and DAs distribution patterns, biogeography, and demographic dynamics. An "ampliative" S. japonica complex was put forward, comprising all species of Sect. Calospira Ser. Japonicae, of which three evolutionary units carrying their respective unique types of DAs were identified and associated with the regionalization of EAF (referring to the Hengduan Mountains, central China, and east China). Moreover, a transition belt in central China with its biogeographic significance was revealed by genetic and DA distribution patterns from the perspective of ecological adaptation. The origin and onset differentiation of the "ampliative" S. japonica complex was estimated in the early Miocene (22.01/19.44 Ma). The formation of Japanese populations (6.75 Ma) was facilitated by the land bridge, which subsequently had a fairly stable demographic history. The populations in east China have undergone a founder effect after the Last Glacial Maximum, which may have been promoted by the expansion potential of polyploidization. Overall, the in-situ origin and diversification of the "ampliative" S. japonica complex since the early Miocene is a vertical section of the formation and development of modern EAF and was shaped by the geological history of each subkingdom.

Phylogeny and classification of the tribe Lepisoreae (Polypodiaceae; pteridophyta) with the description of a new genus, Ellipinema gen. nov., segregated from Lepisorus.

Lepisoroid ferns (tribe Lepisoreae, Polypodiaceae) are arguably one of the most confusing fern groups in Polypodiaceae in terms of delimitation of genera largely because of their simple morphology. Previous molecular studies either had very small taxon sampling of the non-Lepisorus genera and did not well resolve the relationships among these genera, or had a relatively large sampling at species level but the critical species were missing or their relationships were not well resolved. A recent study resolved the newly sampled Lepisorus jakonensis as sister to the remaining genera in Lepisoreae excluding Paragramma, and the authors lumped all the six well recognized genera into Lepisorus. In the present study, to infer a phylogeny we used DNA sequences of five plastid markers (matK, rbcL, rbcL-atpB, rps4 &rps4-trnS, trnL &trnL-F) of 172 accessions representing ca. 44 species of non-Lepisorus genera and 54 accessions representing ca. 50 species of Lepisorus as ingroup, and 10 non-Lepisoreae accessions from the most closely related four genera (Leptochilus, Microsorum, Phymatosorus, and Goniophlebium) in Microsoroideae and one genus (Pyrrosia) in Platycerioideae. Our major results include: (1) All seven currently defined genera except Lepisorus in Lepisoreae are confirmed to be monophyletic; (2) The Lepisorus jakonensis clade is confirmed to be the second earliest diverged lineage in Lepisoreae; (3) Neolepisorus is resolved as sister to the rest in a clade containing all non-Lepisorus genera except Paragramma; (4) Lemmaphyllum is sister to a clade containing Lepidomicrosorium, Neocheiropteris, and Tricholepidium; and (5) Ellipinema gen. nov. is segregated from Lepisorus based on the phylogeny and morphology in order to stabilize the current usage of the existing six non-Lepisorus genera and species names in these genera. A key to all eight genera of Lepisoreae is provided.

Oviposition by mutualistic seed-consuming pollinators reduces fruit abortion in a recently discovered pollination mutualism.

A prerequisite for the evolutionary stability of pollinating seed-consuming mutualisms is that each partner benefits from the association. However, few studies of such mutualism have considered the benefit gained by the pollinators. Here, we determined how the pollinating seed-predators ensure the provisioning of their offspring in the recently discovered mutualism between Rheum nobile and Bradysia flies. The correlation between flower fate and fly oviposition was examined. Floral traits and patterns of variation in fruit abortion and fly oviposition were investigated to determine whether female flies exhibit preferences for particular flowers when laying eggs. Indole-3-acetic acid (IAA) was quantified to determine whether female flies manipulate host physiology. Flowers that flies oviposited on had a significantly lower probability of fruit abortion compared with intact flowers. Females did not exhibit oviposition preference for any of the floral traits examined. There was no significant correlation between fruit abortion and fly oviposition in terms of either flower position or timing of flowering. IAA concentrations in oviposited flowers were significantly higher than in intact flowers. Our results suggest that oviposition by the mutualistic seed-consuming pollinator Bradysia sp., greatly reduces the probability of fruit abortion of its host, R. nobile; this may be attributed to the manipulation of host physiology through regulating IAA levels.