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25 September 2022, Volume 44 Issue 05
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  • Review article
    Pollinator diversity benefits natural and agricultural ecosystems, environmental health, and human welfare
    Daniel Mutavi Katumo, Huan Liang, Anne Christine Ochola, Min Lv, Qing-Feng Wang, Chun-Feng Yang
    2022, 44(05):  429-435.  doi:10.1016/j.pld.2022.01.005
    Abstract ( 145 )   HTML ( )   PDF (477KB) ( 128 )   Save
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    Biodiversity loss during the Anthropocene is a serious ecological challenge. Pollinators are important vectors that provide multiple essential ecosystem services but are declining rapidly in this changing world. However, several studies have argued that a high abundance of managed bee pollinators, such as honeybees (Apis mellifera), may be sufficient to provide pollination services for crop productivity, and sociological studies indicate that the majority of farmers worldwide do not recognize the contribution of wild pollinator diversity to agricultural yield. Here, we review the importance of pollinator diversity in natural and agricultural ecosystems that may be thwarted by the increase in abundance of managed pollinators such as honeybees. We also emphasize the additional roles diverse pollinator communities play in environmental safety, culture, and aesthetics. Research indicates that in natural ecosystems, pollinator diversity enhances pollination during environmental and climatic perturbations, thus alleviating pollen limitation. In agricultural ecosystems, pollinator diversity increases the quality and quantity of crop yield. Furthermore, studies indicate that many pollinator groups are useful in monitoring environmental pollution, aid in pest and disease control, and provide cultural and aesthetic value. During the uncertainties that may accompany rapid environmental changes in the Anthropocene, the conservation of pollinator diversity must expand beyond bee conservation. Similarly, the value of pollinator diversity maintenance extends beyond the provision of pollination services. Accordingly, conservation of pollinator diversity requires an interdisciplinary approach with contributions from environmentalists, taxonomists, and social scientists, including artists, who can shape opinions and behavior.
    Research paper
    Species richness patterns and the determinants of larch forests in China
    Wen-Jing Fang, Qiong Cai, Qing Zhao, Cheng-Jun Ji, Jiang-Ling Zhu, Zhi-Yao Tang, Jing-Yun Fang
    2022, 44(05):  436-444.  doi:10.1016/j.pld.2022.05.002
    Abstract ( 93 )   HTML ( )   PDF (9821KB) ( 111 )   Save
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    Larch forests are important for species diversity, as well as soil and water conservation in mountain regions. In this study, we determined large-scale patterns of species richness in larch forests and identified the factors that drive these patterns. We found that larch forest species richness was high in southern China and low in northern China, and that patterns of species richness along an elevational gradient depend on larch forest type. In addition, we found that patterns of species richness in larch forests are best explained by contemporary climatic factors. Specifically, mean annual temperature and annual potential evapotranspiration were the most important factors for species richness of tree and shrub layers, while mean temperature of the coldest quarter and anomaly of annual precipitation from the Last Glacial Maximum to the present were the most important for that of herb layer and the whole community. Community structural factors, especially stand density, are also associated with the species richness of larch forests. Our findings that species richness in China's larch forests is mainly affected by energy availability and cold conditions support the ambient energy hypothesis and the freezing tolerance hypothesis.
    Forest gaps regulate seed germination rate and radicle growth of an endangered plant species in a subtropical natural forest
    Jing Zhu, Lan Jiang, De-Huang Zhu, Cong Xing, Meng-Ran Jin, Jin-Fu Liu, Zhong-Sheng He
    2022, 44(05):  445-454.  doi:10.1016/j.pld.2021.10.003
    Abstract ( 79 )   HTML ( )   PDF (4846KB) ( 64 )   Save
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    The survival rate of Castanopsis kawakamii from seed to seedling is relatively low, leading to difficulties in the regeneration of its natural forests. Forest gaps play a vital role in plant regeneration and biodiversity maintenance in forest ecosystems. Unfortunately, our understanding of the effects of gap size and within-gap position on the seed germination and radicle growth of C.kawakamii is still limited. In particular, our knowledge on the relationship between gap size and environmental factors and their influence on seed germination and radicle growth is incomplete. In the present study, we studied the influences of forest gaps and within-gap position on seed regeneration on the germination and radicle growth of an endangered species C.kawakamii in a subtropical natural forest in China. We selected three large gaps (LG, gap size above 200m2), three medium gaps (MG, gap size 50–100m2), three small gaps (SG, gap size 30–50m2), and non-gap (NG), and planted the seeds of C.kawakamii in five positions within each gap. The results showed that (1) the influence of forest gaps on seed germination rate was, from highest to lowest, medium gaps (51%), non-gap (47%), small gaps (40%) and large gaps (17%), and the seed germination rate was the highest in all positions in medium gaps, with the exception of the east position. (2) Radicle length in forest gaps was, from highest to lowest, medium gaps, small gaps, large gaps and non-gap, and it was the highest in the east, south, west and north positions of medium gaps. (3) Canopy openness (gap size) and air temperature were the main factors influencing seed germination and radicle growth of C.kawakamii. We concluded that medium-sized gaps were the most suitable for seed germination and radicle growth of C.kawakamii, and they promote the regeneration of this endangered species in the investigated natural forest.
    Adaptive responses drive the success of polyploid yellowcresses (Rorippa, Brassicaceae) in the Hengduan Mountains, a temperate biodiversity hotspot
    Ting-Shen Han, Zheng-Yan Hu, Zhi-Qiang Du, Quan-Jing Zheng, Jia Liu, Thomas Mitchell-Olds, Yao-Wu Xing
    2022, 44(05):  455-467.  doi:10.1016/j.pld.2022.02.002
    Abstract ( 70 )   HTML ( )   PDF (7097KB) ( 45 )   Save
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    Polyploids contribute substantially to plant evolution and biodiversity; however, the mechanisms by which they succeed are still unclear. According to the polyploid adaptation hypothesis, successful polyploids spread by repeated adaptive responses to new environments. Here, we tested this hypothesis using two tetraploid yellowcresses (Rorippa), the endemic Rorippa elata and the widespread Rorippa palustris, in the temperate biodiversity hotspot of the Hengduan Mountains. Speciation modes were resolved by phylogenetic modeling using 12 low-copy nuclear loci. Phylogeographical patterns were then examined using haplotypes phased from four plastid and ITS markers, coupled with historical niche reconstruction by ecological niche modeling. We inferred the time of hybrid origins for both species as the mid-Pleistocene, with shared glacial refugia within the southern Hengduan Mountains. Phylogeographic and ecological niche reconstruction indicated recurrent northward colonization by both species after speciation, possibly tracking denuded habitats created by glacial retreat during interglacial periods. Common garden experiment involving perennial R.elata conducted over two years revealed significant changes in fitness-related traits across source latitudes or altitudes, including latitudinal increases in survival rate and compactness of plant architecture, suggesting gradual adaptation during range expansion. These findings support the polyploid adaptation hypothesis and suggest that the spread of polyploids was aided by adaptive responses to environmental changes during the Pleistocene. Our results thus provide insight into the evolutionary success of polyploids in high-altitude environments.
    Mapping the habitat suitability of Ottelia species in Africa
    Boniface K. Ngarega, John M. Nzei, Josphat K. Saina, Marwa Waseem A. Halmy, Jin-Ming Chen, Zhi-Zhong Li
    2022, 44(05):  468-480.  doi:10.1016/j.pld.2021.12.006
    Abstract ( 82 )   HTML ( )   PDF (35447KB) ( 70 )   Save
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    Understanding the influence of environmental covariates on plant distribution is critical, especially for aquatic plant species. Climate change is likely to alter the distribution of aquatic species. However, knowledge of this change on the burden of aquatic macroorganisms is often fraught with difficulty. Ottelia, a model genus for studying the evolution of the aquatic family Hydrocharitaceae, is mainly distributed in slow-flowing creeks, rivers, or lakes throughout pantropical regions in the world. Due to recent rapid climate changes, natural Ottelia populations have declined significantly. By modeling the effects of climate change on the distribution of Ottelia species and assessing the degree of niche similarity, we sought to identify high suitability regions and help formulate conservation strategies. The models use known background points to determine how environmental covariates vary spatially and produce continental maps of the distribution of the Ottelia species in Africa. Additionally, we estimated the possible influences of the optimistic and extreme pessimistic representative concentration pathways scenarios RCP 4.5 and RCP 8.5 for the 2050s. Our results show that the distinct distribution patterns of studied Ottelia species were influenced by topography (elevation) and climate (e.g., mean temperature of driest quarter, annual precipitation, and precipitation of the driest month). While there is a lack of accord in defining the limiting factors for the distribution of Ottelia species, it is clear that water-temperature conditions have promising effects when kept within optimal ranges. We also note that climate change will impact Ottelia by accelerating fragmentation and habitat loss. The assessment of niche overlap revealed that Ottelia cylindrica and O. verdickii had slightly more similar niches than the other Ottelia species. The present findings identify the need to enhance conservation efforts to safeguard natural Ottelia populations and provide a theoretical basis for the distribution of various Ottelia species in Africa.
    SSR markers development and their application in genetic diversity evaluation of garlic (Allium sativum) germplasm
    Xiaxia Li, Lijun Qiao, Birong Chen, Yujie Zheng, Chengchen Zhi, Siyu Zhang, Yupeng Pan, Zhihui Cheng
    2022, 44(05):  481-491.  doi:10.1016/j.pld.2021.08.001
    Abstract ( 109 )   HTML ( )   PDF (9341KB) ( 88 )   Save
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    Garlic (Allium sativum), an asexually propagated vegetable and medicinal crop, has abundant genetic variation. Genetic diversity evaluation based on molecular markers has apparent advantages since their genomic abundance, environment insensitivity, and non-tissue specific features. However, the limited number of available DNA markers, especially SSR markers, are insufficient to conduct related genetic diversity assessment studies in garlic. In this study, 4372 EST-SSR markers were newly developed, and 12 polymorphic markers together with other 17 garlic SSR markers were used to assess the genetic diversity and population structure of 127 garlic accessions. The averaged polymorphism information content (PIC) of these 29 SSR markers was 0.36, ranging from 0.22 to 0.49. Seventy-nine polymorphic loci were detected among these accessions, with an average of 3.48 polymorphic loci per SSR. Both the clustering analyses based on either the genotype data of SSR markers or the phenotypic data of morphological traits obtained genetic distance divided the 127 garlic accessions into three clusters. Moreover, the Mantel test showed that genetic distance had no significant correlations with geographic distance, and weak correlations were found between genetic distance and the phenotypic traits. AMOVA analysis showed that the main genetic variation of this garlic germplasm collection existed in the within-population or cluster. Results of this study will be of great value for the genetic/breeding studies in garlic and enhance the utilization of these garlic germplasms.
    Evolutionary importance of the relationship between cytogeography and climate: New insights on creosote bushes from North and South America
    Romina Vidal-Russell, Mariana Tadey, Romana Urfusová, Tomáš Urfus, Cintia Paola Souto
    2022, 44(05):  492-498.  doi:10.1016/j.pld.2021.11.006
    Abstract ( 55 )   HTML ( )   PDF (2081KB) ( 45 )   Save
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    Relationships between genome size and environmental variables suggest that DNA content might be adaptive and of evolutionary importance in plants. The genus Larrea provides an interesting system to test this hypothesis, since it shows both intra- and interspecific variation in genome size. Larrea has an amphitropical distribution in North and South American deserts, where it is most speciose. Larrea tridentata in North America shows a gradient of increasing autopolyploidy; while three of the four studied South American species are diploids, Larrea divaricata, Larrea nitida, Larrea ameghinoi, and the fourth is an allopolyploid, Larrea cuneifolia. We downloaded available focal species’ georeferenced records from seven data reservoirs. We used these records to extract biologically relevant environmental variables from WorldClim at 30 arcseconds scale, to have a broad characterization of the variable climatic conditions of both regions, and a climatic envelope for each species. We estimated relative DNA content index and relative monoploid genome values, by flow cytometry, of four most abundant Larrea species throughout their respective ranges. Then we winnow the bioclimatic dataset down to uncorrelated variables and sampled locales, to analyse the degree of association between both intra- and interspecific relative DNA content and climatic variables that are functionally relevant in arid environments using Pearson correlations, general linear and mixed effects models. Within the genus Larrea, relative DNA content increases with rising temperature and decreases with rising precipitation. At the intraspecific level, all four species show relative DNA content variation across climatic conditions. Larrea is a genus that shows genome size variation correlated with climate. Our results are also consistent with the hypothesis that extreme environmental pressures may have facilitated repeated whole genome duplication events in North America, while in South America, reticulate evolution, as allopolyploidization, and speciation might have been climate-dependent since the Oligocene.
    Plant invasions facilitated by suppression of root nutrient acquisition rather than by disruption of mycorrhizal association in the native plant
    Jing Chen, Hai-Yan Zhang, Ming-Chao Liu, Mei-Xu Han, De-Liang Kong
    2022, 44(05):  499-504.  doi:10.1016/j.pld.2021.12.004
    Abstract ( 70 )   HTML ( )   PDF (947KB) ( 69 )   Save
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    Invasive species have profound negative impacts on native ranges. Unraveling the mechanisms employed by invasive plant species is crucial to controlling invasions. One important approach that invasive plants use to outcompete native plants is to disrupt mutualistic interactions between native roots and mycorrhizal fungi. However, it remains unclear how differences in the competitive ability of invasive plants affect native plant associations with mycorrhizae. Here, we examined how a native plant, Xanthium strumarium, responds to invasive plants that differed in competitive abilities (i.e., as represented by aboveground plant biomass) by measuring changes in root nitrogen concentration (root nutrient acquisition) and mycorrhizal colonization rate. We found that both root nitrogen concentration and mycorrhizal colonization rate in the native plant were reduced by invasive plants. The change in mycorrhizal colonization rate of the native plant was negatively correlated with both aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant in monocultures relative to mixed plantings. In contrast, the change in root nitrogen concentration of the native plant was positively correlated with aboveground plant biomass of the invasive plants and the change in aboveground plant biomass of the native plant. When we compared the changes in mycorrhizal colonization rate and root nitrogen concentration in the native plant grown in monocultures with those of native plants grown with invasive plants, we observed a significant tradeoff. Our study shows that invasive plants can suppress native plants by reducing root nutrient acquisition rather than by disrupting symbiotic mycorrhizal associations, a novel finding likely attributable to a low dependence of the native plant on mycorrhizal fungi.
    Taxonomic synopsis of Berberis (Berberidaceae) from the northern Hengduan mountains region in China, with descriptions of seven new species
    Yao-Ke Li, Julian Harber, Chuan Peng, Zhi-Qiang Du, Yao-Wu Xing, Chih-Chieh Yu
    2022, 44(05):  505-517.  doi:10.1016/j.pld.2022.03.002
    Abstract ( 110 )   HTML ( )   PDF (19220KB) ( 105 )   Save
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    Though Berberis (Berberidaceae) is widely distributed across the Eurasian landmass it is most diverse in the Himalaya–Hengduan Mountain (HHM) region. There are more than 200 species in China where it is one of the most common mountain shrubs. The study on the taxonomy and evolution of Berberis in this region can thus provide an important insight into the origin and diversification of its flora. A prerequisite to this is mapping and describing the various species of Berberis in the region – a task that despite recent progress is by no means complete. It is clear that in China there may be a significant number of species still to be described and that even with published species much about their distribution remains to be discovered. As a contribution to the first of these tasks seven new species from the northern Hengduan Mountain of N. Sichuan and S. Qinghai: Berberis chinduensis, Berberis degexianensis, Berberis jiajinshanensis, Berberis jinwu, Berberis litangensis, Berberis longquensis and Berberis riparia, are described here. Differences in overall morphology and especially in floral structures with each other and with similar species of Berberis in the same region are presented. The report is the result of phylogenetic analyses based on plastome and partial nrDNA sequences of both the seven proposed new species and a significant number of similar species already published. Provisional conclusions as to the insights provides on the history of the genetic divergence are discussed.