Papers by Florence Nyirenda
Morphological characters of herbarium samples
Combined pdf containing nine supplementary figures and three supplementary tables
Genetic exchanges between closely related groups of organisms with different adaptations have wel... more Genetic exchanges between closely related groups of organisms with different adaptations have well-documented beneficial and detrimental consequences. In plants, pollen-mediated exchanges affect the sorting of alleles across physical landscapes and influence rates of hybridization. How these dynamics affect the emergence and spread of novel phenotypes remains only partially understood. Here, we use phylogenomics and population genomics to retrace the origin and spread of two geographically overlapping ecotypes of the African grass <i>Alloteropsis angusta</i>. In addition to an ecotype inhabiting wetlands, we report the existence of a previously undescribed ecotype inhabiting Miombo woodlands and grasslands. The two ecotypes are consistently associated with different nuclear groups, which represent an advanced stage of divergence with secondary low-level gene flow. However, the seed-transported chloroplast genomes are consistently shared by distinct ecotypes inhabiting th...
Proceedings of the Royal Society B: Biological Sciences, 2022
Genetic exchanges between closely related groups of organisms with different adaptations have wel... more Genetic exchanges between closely related groups of organisms with different adaptations have well-documented beneficial and detrimental consequences. In plants, pollen-mediated exchanges affect the sorting of alleles across physical landscapes and influence rates of hybridization. How these dynamics affect the emergence and spread of novel phenotypes remains only partially understood. Here, we use phylogenomics and population genomics to retrace the origin and spread of two geographically overlapping ecotypes of the African grass Alloteropsis angusta. In addition to an ecotype inhabiting wetlands, we report the existence of a previously undescribed ecotype inhabiting Miombo woodlands and grasslands. The two ecotypes are consistently associated with different nuclear groups, which represent an advanced stage of divergence with secondary low-level gene flow. However, the seed-transported chloroplast genomes are consistently shared by distinct ecotypes inhabiting the same region. Thes...
Molecular Ecology, 2021
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This a preprint and has not been peer reviewed. Data may be preliminary.
Journal of Experimental Botany, 2019
C4 photosynthesis is a complex trait that boosts productivity in tropical conditions. Compared wi... more C4 photosynthesis is a complex trait that boosts productivity in tropical conditions. Compared with C3 species, the C4 state seems to require numerous novelties, but species comparisons can be confounded by long divergence times. Here, we exploit the photosynthetic diversity that exists within a single species, the grass Alloteropsis semialata, to detect changes in gene expression associated with different photosynthetic phenotypes. Phylogenetically informed comparative transcriptomics show that intermediates with a weak C4 cycle are separated from the C3 phenotype by increases in the expression of 58 genes (0.22% of genes expressed in the leaves), including those encoding just three core C4 enzymes: aspartate aminotransferase, phosphoenolpyruvate carboxykinase, and phosphoenolpyruvate carboxylase. The subsequent transition to full C4 physiology was accompanied by increases in another 15 genes (0.06%), including only the core C4 enzyme pyruvate orthophosphate dikinase. These changes...
Plant Systematics and Evolution, 2017
Variation has been known to be a result of various causes including plasticity, gene flow or the ... more Variation has been known to be a result of various causes including plasticity, gene flow or the lack of it. In this work morphological variation exhibited within five species of Barleria (B. bechuanensis C.B. Clarke, B. irritans Nees, B. jubata S. Moore, B. pungens L.f. and B. rigida Nees) was studied to establish whether it was discrete or continuous. Morphological characters were examined and recorded in the form of matrices and photographs. Variation was analysed from three aspects: macromorphology, micro-morphology and distribution of morphological characters. Cluster analysis imposed a hierarchical non-overlapping association among operational taxonomic units (OTUs) while ordination established whether the variation was discrete or continuous. Cluster analysis and ordination demonstrated that some of the species complexes exhibited discrete variation while others exhibited both continuous and discrete variation. Distribution maps which illustrated the distribution of clusters and some of the morphological characters in geographic space suggested that allopatric, parapatric and / or sympatric speciation could have occurred bringing about the differentiation. Pubescence revealed that trichome morphology and distribution can to some extent be used to define intra-specific variation. On the basis of phenetics analysis, B. jubata is maintained as a single species while the B. bechuanensis and B. irritans complexes are separated into two species each (differentiated by leaf size, shape and margins; and by bracteole size and number of veins in the bracteole respectively). Within the B. rigida complex, two species are recognised where one has lobed bracteoles and calyx lobes and the other has nonlobed bracteoles and calyx lobes. Included within the latter are plants formerly known as B. ilicina (E. Mey. ex T. Anders.). Barleria pungens is separated into two species, one with flat green leaf margins and the other with wavy green or white leaf margins.
SummaryIn the absence of strong reproductive barriers, genetic exchanges between closely related ... more SummaryIn the absence of strong reproductive barriers, genetic exchanges between closely related groups of organisms with different adaptations have well-documented beneficial and detrimental consequences. In plants, pollen-mediated exchanges affect the sorting of alleles across physical landscapes, and influence rates of hybridisation. How these dynamics affect the emergence and spread of novel ecological strategies remains only partially understood.We use phylogenomics and population genomics to retrace the origin of two geographically overlapping ecotypes of the African grass Alloteropsis angusta.We report the existence of a previously undescribed ecotype inhabiting miombo woodlands and grasslands. The two ecotypes have divergent nuclear genomes. However, the seed-transported chloroplast genomes are consistently shared by distinct ecotypes inhabiting the same region. These patterns suggest that the nuclear genome of one ecotype can reach the seeds of the other via pollen movement...
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Papers by Florence Nyirenda