Review: Genetic structure and local adaptation in natural forests of Cryptomeria japonica

Abstract

Cryptomeria japonica is a very important and useful forestry tree in Japan and there are vast areas of plantation area that occupy 44% of the total man-made forest in the country. Natural populations have declined as a result of logging and overexploitation for more than a thousand years. The natural distribution of C. japonica is from Aomori Prefecture to Kagoshima Prefecture and it has adapted to widely different environments in Japan. In China, the variety C. japonica var. sinensis is distributed. The genetic diversity is higher in Japanese Cryptomeria than in the Chinese variety, and within Japan, western populations have higher genetic diversity than northern populations. Genetic structure of C. japonica within Japan was clear, with isolation by distance (IBD), and the omote-sugi on the Pacific Ocean side and ura-sugi group on the Sea of Japan side were clearly separated by STRUCTURE analysis. Genetic structure was also clear in the Chinese population but there was no IBD, which suggested considerable human disturbance in the past. Local adaption is apparent in this species, in, for example, morphological traits among the three groups such as omote-sugi, ura-sugi, and Chinese population. The time of divergence among the three groups was at least before last glacial maximum. Global climate change largely affects species distributions and local adaptation, which play important roles in adaptation and speciation. A suitable conservation strategy for natural populations of C. japonica is ex situ conservation of large trees and applying a zoning method to the remaining natural forests.

Genotypic variations appear in fine root morphological traits of Cryptomeria japonica trees grown in a common garden

“…Some C. japonica ne roots can form arbuscular mycorrhizas (AM) primarily in the 1st root order (Hishi et As Yaku cedar has distinctly low aboveground productivity during the early growth stage in its native habitat (Takashima et al 2009;Itaka et al 2013) and in the common garden (Ohta et al 2019;Azuma et al 2023), ne root morphological traits of Yaku cedar were also differentiated from trees of other provenances, despite large differences in soil chemical properties between the present common garden and its unique native habitat on Yakushima Island where higher soil phosphorus contents are observed owing to volcanic ash (Mukai et al 2016). Furthermore, Yaku cedar has a relatively long genetic distance from Yanase and Yoshino cedars (Tsumura 2023), implying the limits of functional plasticity against growing environments and the consistency of inherent characteristics determined by the genetic background.…”

Preface: Functional biogeography in Japanese cedar

“…They showed that the Japanese cedar is now only locally distributed in restricted natural forests, but since at least 7000 years ago until modern times, it has been widely distributed in the Japanese archipelago except in Hokkaido, and was the dominant species in the temperate zone of Japan due to its large biomass. Tsumura (Tsumura, 2023) outlines the distributional transitions and local adaptations inferred from the genetic variation of the Japanese cedar in the Japanese archipelago and China, and proposes methods to prevent genetic disturbance of geographically differentiated populations. Genetic differentiation occurred as a result of restricted gene flow and local adaptation due to distributional area fragmentation or fluctuation with warming from the coldest glacial period and recolonization from the Hypsithermal period to the modern era.…”

“…Its amount of academic information is comparable to that of the European beech ( Fagus sylvatica ), the Scots pine ( Pinus sylvestris ), and the Norway spruce ( Picea abies ) in Europe (e.g., Benavides et al, 2021; Schulze, 2000; Vila‐Cabrera et al, 2015). In the case of the Japanese cedar, the genetic diversity remained after the presence of several refugia even in the Last Glacial Maximum (LGM; Takahara et al, 2023; Tsumura, 2022), and therefore, it is expected that the geographic, genetic, and functional variations are also large. Based on these characteristics, the Japanese cedar will provide a good material for investigating the response of each local forest ecosystem under climate change, based on the geographic functional differentiation and its cascading effects.…”

“…Genetic differentiation occurred as a result of restricted gene flow and local adaptation due to distributional area fragmentation or fluctuation with warming from the coldest glacial period and recolonization from the Hypsithermal period to the modern era. Genetic analysis suggests that the LGM refugia existed at least near the Izu Peninsula, southern Kii Peninsula, southern Shikoku, Wakasa Bay, and Yaku Island (Tsumura, 2023). Since pollen fossils during the LGM have been found at four of these sites from regions other than the southern Kii Peninsula, as well as from Sado Island, Oki Island, and western Chugoku (Takahara et al, 2023), it is considered that the LGM expanded its distribution from at least these eight regions to form its present distribution area with global warming (Figure 1).…”

Message from the new Editor‐in‐Chief

“…Our editorial team will continue to publish original papers covering a diverse range of topics in ecology. Last year, we published original papers on population ecology (e.g., Tsumura, 2023;Worth et al, 2023), community ecology (e.g., Chang et al, 2023;Ohkawara & Taijiri, 2023), ecosystem ecology (e.g., Matsumoto et al, 2023), conservation ecology (Hirano et al, 2023;Tsujimoto et al, 2023), plant-animal interactions (e.g., Kawata & Takimoto, 2023;S anchez-Collazo et al, 2023), behavioral ecology (Bibi et al, 2023), and physiological ecology (e.g., Rooney et al, 2023;Sugimoto & Ishida, 2023), among others. Our papers also cover topics that are of high societal interest, including the analysis of the ongoing invasion of the whitefooted ant (Technomyrmex brunneus Forel) in eastern Asia (Putri & Cronin, 2023), recent expansion of a Japanese land leech (Haemadipsa japonica Whitman) associated with the migration of sika deer (Morishima et al, 2023) and future persistence of high-mountain lizards worldwide under climate change (Moreira et al, 2023).…”