Phylogeography of two closely related species of Allium endemic to East Asia: Population evolution in response to climate oscillations

The influence of climate change on the suitable habitats of Allium species endemic to Iran

Identifying the consequences of global warming on the potential distribution of plant taxa with high species diversity or a high proportion of endemic species is one of the critical steps in conservation biology. Here, present and future spatial distribution patterns of 20 Allium endemic species were predicted in Iran. In this regard, the maximum entropy model (MaxEnt) and seven environmental factors were applied. In addition, optimistic (RCP2.6) and pessimistic (RCP8.5) scenarios of 2050 and 2080 were also considered to predict the future spatial distributions. The results showed that annual mean temperature (BIO1), temperature annual range (P5-P6) (BIO7), soil organic carbon content, annual precipitation (BIO12), and depth of soil were the most important environmental variables affecting the distributions of the studied taxa. In total, the model predictions under the future scenarios represented that the suitable habitats for all Allium species endemic to Zagros except for A. saralicum and A. esfahanicum are most probably increased. In contrast, the suitable habitats for all species in Azerbaijan Plateau, Kopet Dagh-Khorassan region, and Alborz except for A. derderianum are most likely decreased under the future climate conditions. The present study indicates that the habitats of Alborz, Azarbaijan, and Kopet Dagh-Khorassan will be probably very fragile and vulnerable to climate change and most species will respond strongly negatively under applied scenarios, while Zagros species occupy new habitats by expanding their distributions. Therefore, determining conservation strategies for the species in these regions seems to be very important and high priority for decision makers.

Population genetic structures of two ecologically distinct species Betula platyphylla and B. ermanii inferred based on nuclear and chloroplast DNA markers

Climatic oscillations during the last glacial maximum (LGM) significantly affected the distribution patterns and genetic structure of extant plants. Northeast China (NEC) is a major biodiversity center in East Asia, and the influence of historical climate change on NEC populations is critical for understanding species responses to future climate change. However, only a few phylogeographic studies of cool temperate deciduous tree species have been conducted in the area, and results are inconsistent for species with different niches or distribution areas. We employed multiple chloroplast and nuclear markers to investigate the genetic structure of two ecologically contrasting species, Betula platyphylla and B. ermanii, in NEC. Rare haplotypes were identified in the chloroplast genome of these species, and both exhibited high levels of nucleotide diversity based on a fragment of the nuclear gene G3PDH and microsatellites. Moreover, significant phylogeographic structure was detected for B. platyphylla, suggesting that these populations had recolonized from independent glacial refuges, whereas no genetic structure was found for B. ermanii.

OPEN RESEARCH BADGES

The nSSR datasets used in the current study and the table of pairwise FST (below diagonal) and its standardized F'ST (above diagonal) among 25 populations based on seven SSRs are available from the Dryad (DOI: https://doi.org/10.5061/dryad.230d176). Sequences generated from this study were deposited in GenBank under Accession nos. KY199568-KY200162 and MK819541-MK819970.