10 results on '"Nzei, John M."'
Search Results
2. Population genetics of Nelumbo lutea (American lotus) near its northwestern range limit
- Author
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Lu, Bei, Nzei, John M., Li, Zhizhong, Chen, Jinming, Yang, Xingyu, and Perleberg, Donna J.
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- 2023
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3. The complete chloroplast genomes of two species in threatened monocot genus Caldesia in China
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Mwanzia, Virginia M., Nzei, John M., Yan, Dong-Ying, Kamau, Peris W., Chen, Jin-Ming, and Li, Zhi-Zhong
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- 2019
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4. Assessment of Climate Change and Land Use Effects on Water Lily (Nymphaea L.) Habitat Suitability in South America.
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Nzei, John M., Ngarega, Boniface K., Mwanzia, Virginia M., Kurauka, Joseph K., Wang, Qing-Feng, Chen, Jin-Ming, Li, Zhi-Zhong, and Pan, Cheng
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LAND use , *WATER lilies , *GENERAL circulation model , *WATER use , *SEASONAL temperature variations - Abstract
Many aquatic species have restricted dispersal capabilities, making them the most vulnerable organisms to climate change and land use change patterns. These factors deplete Nymphaea species' suitable habitats, threatening their populations and survival. In addition, the species are poorly documented, which may indicate how scarce they are or will become. Members of Nymphaea are ecologically important as well as having cultural and economic value, making them of conservation interest. Therefore, using the maximum entropy (MaxEnt) approach, climatic variables, land use, and presence points were modeled for seven Nymphaea species in South America, using three general circulation models (CCSM4, HADGEM2-AO, and MIROC5) and in two representative concentration pathways (RCPs 4.5 and 8.5) and two scenarios (2050 and 2070). Our results indicated that mean diurnal range (bio2), precipitation of the wettest month (bio13), temperature seasonality (bio15), and land use (dom_lu) were the main influencing factors. For all species, suitable areas were concentrated east of Brazil, and they were variable in northern parts of the continent. Besides, inconsistent expansion and contraction of suitable habitats were noticed among the species. For example, N. amazonum, N. rudgeana, and N. lasiophylla future habitat expansions declined and habitat contraction increased, while for N. ampla and N. jamesoniana, both future habitat expansion and contraction increased, and for N. pulchella and N. rudgeana it varied in the RCPs. Moreover, the largest projected suitable habitats were projected outside protected areas, characterized by high human impacts, despite our analysis indicating no significant change between protected and unprotected areas in suitable habitat change. Finally, understanding how climate change and land use affect species distribution is critical to developing conservation measures for aquatic species. [ABSTRACT FROM AUTHOR]
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- 2022
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5. Ecological Niche Modeling of Water Lily (Nymphaea L.) Species in Australia under Climate Change to Ascertain Habitat Suitability for Conservation Measures.
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Nzei, John M., Mwanzia, Virginia M., Ngarega, Boniface K., Musili, Paul M., Wang, Qing-Feng, Chen, Jin-Ming, and Li, Zhi-Zhong
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HABITATS ,HABITAT conservation ,ECOLOGICAL niche ,ECOLOGICAL models ,WATER lilies ,GENERAL circulation model ,CLIMATE change - Abstract
The International Panel on Climate Change (IPCC) projects a global temperature rise of 4.3 ± 0.7 °C by 2100 and an extinction of 8.5% in one out of every six species. Australia's aquatic ecosystem is no exception; habitat loss, fragmentation, and loss of biodiversity are being experienced. As the center for Nymphaea species distribution, it presents the culturally, ecologically, and scientifically important genus as the best candidate for habitat suitability assessment in climate change, whose habitat suitability is presumed to decline. The models were run according to the maximum entropy (MaxEnt) method, using one general circulation model (GCM). Projections were made for the current, past, and future in medium (4.5) and high (8.5) representative concentration pathways. Significantly, bio2 and bio15 were highly preferred among the species. Less distribution was noted in West Australia compared to the north, east, and south of the continent, while north of the continent in Western Australia, Northern Territory, and Queensland indicate more habitat contractions compared to the east and southeast of Queensland and New South Wales, although it receives high precipitation. Generally, the species respond variably to both temperature and precipitation variables which is a key species response factor for planners and decision makers in species habitat and biodiversity conservation. [ABSTRACT FROM AUTHOR]
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- 2022
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6. The complete chloroplast genome of Protea kilimandscharica Engl. (Proteaceae).
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Nzei, John M., Saina, Josphat K., Mwanzia, Virginia M., Avoga, Sheila, and Pan, Cheng
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MACADAMIA ,PROTEACEAE ,CHLOROPLAST DNA ,NUCLEOTIDE sequencing ,TRANSFER RNA - Abstract
Protea kilimandscharica is endemic to the heath zone of Mt Kenya, restricted to the rocky slopes of the mountain. The complete chloroplast genome of P. kilimandscharica was determined by next-generation sequencing technology, with a total length of 158,657 bp. The cp genome encodes 115 unique genes, with four rRNA genes, 81 protein-coding genes (PCGs), and 30 tRNA genes. A 3.1 kb inversion was noted in the LSC. Phylogenetic analysis, based on 75 common protein-coding genes revealed P. kilimandscharica as sister to Macadamia integrifolia and Macadamia ternifolia. [ABSTRACT FROM AUTHOR]
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- 2020
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7. The past, current, and future distribution modeling of four water lilies (Nymphaea) in Africa indicates varying suitable habitats and distribution in climate change.
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Nzei, John M., K. Ngarega, Boniface, Mwanzia, Virginia M., Musili, Paul M., Wang, Qing-Feng, and Chen, Jin-Ming
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WATER lilies , *HABITATS , *CLIMATE change , *LAST Glacial Maximum , *WATER distribution , *CURRENT distribution - Abstract
[Display omitted] • Four water lily species were modeled in Maximum entropy. • Past and future projection scenarios were Last Glacial Maxima (LGM), Mid Holocene (MH) and Pathways (RCPs). • Low (2.6), Medium (4.5) and High (8.5) carbon emissions Representative Concentration. • The model indicated good and reliable performance with mean AUC > 0.8. • Greater change is projected in the past compared to future projections. Mapping and modeling suitable habitat and distribution of aquatic species is important to help assess the impact of factors such as climate change in affecting the shift, decline, or expansion of species habitat ranges. In Africa, the distribution of water lily (Nymphaea) species is geographically varied and the habitats suitable for individual species are prone to effects of global warming, though only limited conservation measures have been taken to date in aquatic environments. In this study, four widely distributed water lily species (N. nouchali , N. micrantha , N. lotus , and N. heudelotii) were modeled using MaxEnt which highlighted the individual species' suitable climatic distribution. The current distribution indicates a partial distribution of N. nouchali in West Africa unlike N. micrantha, N. lotus, and, N. heudelotii. Nymphaea lotus displays wider distribution in West, East, and parts of South African countries including their coastlines compared to all other species. Nymphaea nouchali indicates dense distribution in countries South of Africa while N. micrantha and N. heudelotii in West African countries. Greater habitat changes were noticed between the future and the past projection due to limited range expansion in 2.6, 4.5, and 8.5 (2050) Representative Concentration Pathways (RCPs) in almost all species. The species' suitable habitat distribution was mainly influenced by nine variables, mostly the temperature and precipitation variables. This study provides projections of future climatic scenarios potentially influencing the distribution of Nymphaea species in Africa, which may be useful for the ongoing conservation and management of these plants especially in areas loosing suitable climatic conditions. [ABSTRACT FROM AUTHOR]
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- 2021
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8. Intergeneric Relationships within the Early-Diverging Angiosperm Family Nymphaeaceae Based on Chloroplast Phylogenomics.
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He, Dingxuan, Gichira, Andrew W., Li, Zhizhong, Nzei, John M., Guo, Youhao, Wang, Qingfeng, and Chen, Jinming
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NYMPHAEACEAE ,WATER lilies ,CHLOROPLAST DNA ,PLANT phylogeny ,COMPARATIVE genomics - Abstract
The order Nymphaeales, consisting of three families with a record of eight genera, has gained significant interest from botanists, probably due to its position as a basal angiosperm. The phylogenetic relationships within the order have been well studied; however, a few controversial nodes still remain in the Nymphaeaceae. The position of the Nuphar genus and the monophyly of the Nymphaeaceae family remain uncertain. This study adds to the increasing number of the completely sequenced plastid genomes of the Nymphaeales and applies a large chloroplast gene data set in reconstructing the intergeneric relationships within the Nymphaeaceae. Five complete chloroplast genomes were newly generated, including a first for the monotypic Euryale genus. Using a set of 66 protein-coding genes from the chloroplast genomes of 17 taxa, the phylogenetic position of Nuphar was determined and a monophyletic Nymphaeaceae family was obtained with convincing statistical support from both partitioned and unpartitioned data schemes. Although genomic comparative analyses revealed a high degree of synteny among the chloroplast genomes of the ancient angiosperms, key minor variations were evident, particularly in the contraction/expansion of the inverted-repeat regions and in RNA-editing events. Genome structure, and gene content and arrangement were highly conserved among the chloroplast genomes. The intergeneric relationships defined in this study are congruent with those inferred using morphological data. [ABSTRACT FROM AUTHOR]
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- 2018
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9. Mapping the habitat suitability of Ottelia species in Africa.
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Ngarega BK, Nzei JM, Saina JK, Halmy MWA, Chen JM, and Li ZZ
- Abstract
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., Competing Interests: The authors declare no competing conflicts of interest., (© 2022 Kunming Institute of Botany, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd.)
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- 2022
- Full Text
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10. The complete chloroplast genome of Protea kilimandscharica Engl. (Proteaceae).
- Author
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Nzei JM, Saina JK, Mwanzia VM, Avoga S, and Pan C
- Abstract
Protea kilimandscharica is endemic to the heath zone of Mt Kenya, restricted to the rocky slopes of the mountain. The complete chloroplast genome of P . kilimandscharica was determined by next-generation sequencing technology, with a total length of 158,657 bp. The cp genome encodes 115 unique genes, with four rRNA genes, 81 protein-coding genes (PCGs), and 30 tRNA genes. A 3.1 kb inversion was noted in the LSC. Phylogenetic analysis, based on 75 common protein-coding genes revealed P . kilimandscharica as sister to Macadamia integrifolia and Macadamia ternifolia ., Competing Interests: No potential conflict of interest was reported by the authors., (© 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.)
- Published
- 2020
- Full Text
- View/download PDF
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