The rise of baobab trees in Madagascar.

The baobab trees (genus Adansonia) have attracted tremendous attention because of their striking shape and distinctive relationships with fauna1. These spectacular trees have also influenced human culture, inspiring innumerable arts, folklore and traditions. Here we sequenced genomes of all eight extant baobab species and argue that Madagascar should be considered the centre of origin for the extant lineages, a key issue in their evolutionary history2,3. Integrated genomic and ecological analyses revealed the reticulate evolution of baobabs, which eventually led to the species diversity seen today. Past population dynamics of Malagasy baobabs may have been influenced by both interspecific competition and the geological history of the island, especially changes in local sea levels. We propose that further attention should be paid to the conservation status of Malagasy baobabs, especially of Adansonia suarezensis and Adansonia grandidieri, and that intensive monitoring of populations of Adansonia za is required, given its propensity for negatively impacting the critically endangered Adansonia perrieri.

Comparative and phylogenetic analyses of six Kenya Polystachya (Orchidaceae) species based on the complete chloroplast genome sequences.

BACKGROUND: Polystachya Hook. is a large pantropical orchid genus (c. 240 species) distributed in Africa, southern Asia and the Americas, with the center of diversity in Africa. Previous studies on species of this genus have not obtained the complete chloroplast genomes, structures and variations. Additionally, the phylogenetic position of the genus in the Orchidaceae is still controversial and uncertain. Therefore, in this study, we sequenced the complete plastomes of six Kenya Polystachya species based on genome skimming, subjected them to comparative genomic analysis, and reconstructed the phylogenetic relationships with other Orchidaceae species. RESULTS: The results exhibited that the chloroplast genomes had a typical quadripartite structure with conserved genome arrangement and moderate divergence. The plastomes of the six Polystachya species ranged from 145,484 bp to 149,274 bp in length and had an almost similar GC content of 36.9-37.0%. Gene annotation revealed 106-109 single-copy genes. In addition, 19 genes are duplicated in the inverted regions, and 16 genes each possessd one or more introns. Although no large structural variations were observed among the Polystachya plastomes, about 1 kb inversion was found in Polystachya modesta and all 11 ndh genes in the Polystachya plastomes were lost or pseudogenized. Comparative analysis of the overall sequence identity among six complete chloroplast genomes confirmed that for both coding and non-coding regions in Polystachya, SC regions exhibit higher sequence variation than IRs. Furthermore, there were various amplifications in the IR regions among the six Polystachya species. Most of the protein-coding genes of these species had a high degree of codon preference. We screened out SSRs and found seven relatively highly variable loci. Moreover, 13 genes were discovered with significant positive selection. Phylogenetic analysis showed that the six Polystachya species formed a monophyletic clade and were more closely related to the tribe Vandeae. Phylogenetic relationships of the family Orchidaceae inferred from the 85 chloroplast genome sequences were generally consistent with previous studies and robust. CONCLUSIONS: Our study is the initial report of the complete chloroplast genomes of the six Polystachya species, elucidates the structural characteristics of the chloroplast genome of Polystachya, and filters out highly variable sequences that can contribute to the development of DNA markers for use in the study of genetic variability and evolutionary studies in Polystachya. In addition, the phylogenetic results strongly support that the genus of Polystachya is a part of the tribe Vandeae.

Contributions to the Flora of Tropical East Africa.

Tropical East Africa (TEA) is one of the most important biodiversity hotspots on the planet. Its rich flora diversity and inventory have been clearly recognized after the publication of the last volume of the Flora of Tropical East Africa (FTEA) in 2012. However, many new and newly recorded taxa have been named and documented since the publication of the first volume of FTEA in 1952. In this study, we comprehensively compiled new taxa and new records by reviewing the literature on the taxonomic contributions of vascular plants in TEA from 1952 to 2022. Our list includes 444 new and newly recorded species belonging to 81 families and 218 genera. Among these taxa, 94.59% of the plants are endemic to TEA and 48.42% are herbs. Additionally, members of Rubiaceae and Aloe are the most numerous family and genus respectively. These new taxa are unevenly distributed in TEA, but are found mainly in areas of high species richness, such as coastal, central and western areas of Kenya, central and southeastern Tanzania. This study offers summative assessment of the newly recorded flora inventory in TEA and provides recommendations for future research on plant diversity survey and conservation.

Phylogenetic and comparative analyses of Hydnora abyssinica plastomes provide evidence for hidden diversity within Hydnoraceae.

BACKGROUND: To date, plastid genomes have been published for all but two holoparasitic angiosperm families. However, only a single or a few plastomes represent most of these families. Of the approximately 40 genera of holoparasitic angiosperms, a complete plastid genome sequence is available for only about half. In addition, less than 15 species are currently represented with more than one published plastid genome, most of which belong to the Orobanchaceae. Therefore, a significant portion of the holoparasitic plant plastome diversity remains unexplored. This limited information could hinder potential evolutionary pattern recognition as well as the exploration of inter- and intra-species plastid genome diversity in the most extreme holoparasitic angiosperms. RESULTS: Here, we report the first plastomes of Kenyan Hydnora abyssinica accessions. The plastomes have a typical quadripartite structure and encode 24 unique genes. Phylogenetic tree reconstruction recovers the Kenyan accessions as monophyletic and together in a clade with the Namibian H. abyssinica accession and the recently published H. arabica from Oman. Hydnora abyssinica as a whole however is recovered as non-monophyletic, with H. arabica nested within. This result is supported by distinct structural plastome synapomorphies as well as pairwise distance estimates that reveal hidden diversity within the Hydnora species in Africa. CONCLUSION: We propose to increase efforts to sample widespread holoparasitic species for their plastid genomes, as is the case with H. abyssinica, which is widely distributed in Africa. Morphological reinvestigation and further molecular data are needed to fully investigate the diversity of H. abyssinica along the entire range of distribution, as well as the diversity of currently synonymized taxa.

Predicting the potential impacts of climate change on the endangered endemic annonaceae species in east africa.

Globally, endemic species and natural habitats have been significantly impacted by climate change, and further considerable impacts are predicted. Therefore, understanding how endemic species are impacted by climate change can aid in advancing the necessary conservation initiatives. The use of niche modeling is becoming a popular topic in biological conservation to forecast changes in species distributions under various climate change scenarios. This study used the Australian Community Climate and Earth System Simulator version 1 (ACCESS-CM2) general circulation model of coupled model intercomparison project phase 6 (CMIP6) to model the current distribution of suitable habitat for the four threatened Annonaceae species endemic to East Africa (EA), to determine the impact of climate change on their suitable habitat in the years 2050 (average for 2041-2060) and 2070 (average for 2061-2080). Two shared socio-economic pathways (SSPs) SSP370 and SSP585 were used to project the contraction and expansion of suitable habitats for Uvariodendron kirkii, Uvaria kirkii, Uvariodendron dzomboense and Asteranthe asterias endemic to Kenya and Tanzania in EA. The current distribution for all four species is highly influenced by precipitation, temperature, and environmental factors (population, potential evapotranspiration, and aridity index). Although the loss of the original suitable habitat is anticipated to be significant, appropriate habitat expansion and contraction are projections for all species. More than 70% and 40% of the original habitats of Uvariodendron dzombense and Uvariodendron kirkii are predicted to be destroyed by climate change, respectively. Based on our research, we suggest that areas that are expected to shrink owing to climate change be classified as important protection zones for the preservation of Annonaceae species.

The colonial legacy of herbaria.

Herbarium collections shape our understanding of Earth's flora and are crucial for addressing global change issues. Their formation, however, is not free from sociopolitical issues of immediate relevance. Despite increasing efforts addressing issues of representation and colonialism in natural history collections, herbaria have received comparatively less attention. While it has been noted that the majority of plant specimens are housed in the Global North, the extent and magnitude of this disparity have not been quantified. Here we examine the colonial legacy of botanical collections, analysing 85,621,930 specimen records and assessing survey responses from 92 herbarium collections across 39 countries. We find an inverse relationship between where plant diversity exists in nature and where it is housed in herbaria. Such disparities persist across physical and digital realms despite overt colonialism ending over half a century ago. We emphasize the need for acknowledging the colonial history of herbarium collections and implementing a more equitable global paradigm for their collection, curation and use.

An annotated checklist of the vascular plants of Taita Hills, Eastern Arc Mountain.

Taita Hills forests are an ecological island within the Tsavo plains and are the northern-most part of the Eastern Arc Mountains in southeast Kenya. They are highly fragmented forests embedded in a mosaic of human settlements and farms on the slopes and hilltops. Despite their intensive degradation, they exhibit a high degree of plant diversity and endemism, and therefore are regarded as a biodiversity hotspot. In spite of their distinct importance to the biodiversity of the region as well as supporting the livelihoods of the surrounding communities, floristic studies in these hills have been finite. Through repetitive floral expeditions, herbarium records from the East African Herbarium (EA), Global Biodiversity Information (GBIF), and the Integrated Digitized Biocollections (iDigbio) databases, as well as plant lists from literature and monographs, we provide a comprehensive checklist of 1594 taxa representing 159 families, 709 genera, 1530 species, 39 subspecies, 27 varieties, and 2 hybrids. Out of these, 75 are endemic or near-endemic, 59 are exotic, and 83 are listed as either endangered or near endangered as evaluated in the IUCN Redlist. Zehneriatuberifera G.W.Hu & Q.F.Wang, a new species to science, which has previously been described, was also discovered from the Ngangao forest fragment. Information on the habit(s), habitat(s), and altitudinal range of each taxon is provided in this study. This checklist is an updated inventory of the vascular plants of the Taita Hills. It confirms the high plant diversity of the hills and provides a clear baseline for strategic conservation and sustainable management of plant resources and diversity under the Convention on Biological Diversity (CBD).

Complex Interaction Networks Among Cyanolichens of a Tropical Biodiversity Hotspot.

Interactions within lichen communities include, in addition to close mutualistic associations between the main partners of specific lichen symbioses, also more elusive relationships between members of a wider symbiotic community. Here, we analyze association patterns of cyanolichen symbionts in the tropical montane forests of Taita Hills, southern Kenya, which is part of the Eastern Afromontane biodiversity hotspot. The cyanolichen specimens analyzed represent 74 mycobiont taxa within the order Peltigerales (Ascomycota), associating with 115 different variants of the photobionts genus Nostoc (Cyanobacteria). Our analysis demonstrates wide sharing of photobionts and reveals the presence of several photobiont-mediated lichen guilds. Over half of all mycobionts share photobionts with other fungal species, often from different genera or even families, while some others are strict specialists and exclusively associate with a single photobiont variant. The most extensive symbiont network involves 24 different fungal species from five genera associating with 38 Nostoc photobionts. The Nostoc photobionts belong to two main groups, the Nephroma-type Nostoc and the Collema/Peltigera-type Nostoc, and nearly all mycobionts associate only with variants of one group. Among the mycobionts, species that produce cephalodia and those without symbiotic propagules tend to be most promiscuous in photobiont choice. The extent of photobiont sharing and the structure of interaction networks differ dramatically between the two major photobiont-mediated guilds, being both more prevalent and nested among Nephroma guild fungi and more compartmentalized among Peltigera guild fungi. This presumably reflects differences in the ecological characteristics and/or requirements of the two main groups of photobionts. The same two groups of Nostoc have previously been identified from many lichens in various lichen-rich ecosystems in different parts of the world, indicating that photobiont sharing between fungal species is an integral part of lichen ecology globally. In many cases, symbiotically dispersing lichens can facilitate the dispersal of sexually reproducing species, promoting establishment and adaptation into new and marginal habitats and thus driving evolutionary diversification.

Euphorbiambuinzauensis, a new succulent species in Kenya from the Synadenium group in Euphorbiasect.Monadenium (Euphorbiaceae).

Euphorbiambuinzauensis, a succulent new species of the Synadenium group in Euphorbiaceae from Makueni County, Kenya, is described and illustrated. Morphologically, it is most similar to E.pseudomollis, but differs mainly by its shrubby habit (up to 4 m), abaxial leaves surfaces with densely stellate hairs, 2-4-forked cymes, smaller bracts (ca. 2.5 × 3.0 mm), smaller cyathia (6 mm wide), crimson glands without narrow smooth margin, smaller fruits (ca. 8 × 7 mm) and ovoid seeds (ca. 1.8 × 2.2 mm). Furthermore, we performed a molecular phylogenetic analysis of the Synadenium group in Euphorbiasect.Monadenium, based on complete nuclear ribosomal DNA (nrDNA) datasets. This phylogenetic inference also supports it to be a distinct species. The new species is assessed as Endangered using the IUCN criteria.

Understanding the Ethnobotany, Chemistry, Pharmacology, and Distribution of Genus Hydnora (Aristolochiaceae).

The genus Hydnora (Hydnoraceae) is one of the basal angiosperms in the order Piperales, found in the semi-arid regions of Africa, and the Southern Arabian Peninsula. Plants in this genus play essential roles in communities around the world as revealed by various studies. Currently, there are eight species of the genus Hydnora; seven in Africa and one in the Arabian Peninsula. Notably, Hydnora abyssinica A.Br. and Hydnora africana Thunb. are widely distributed compared to other species. They are widely used for their medicinal and nutritional values. The information on ethnobotany, chemistry, pharmacology, and distribution of genus Hydnora was gathered using phytochemical and ethnobotanical books, electronic sources, and published articles. Preliminary phytochemical screening shows that flavonoids, phenolics, proanthocyanidins, and tannins are the main compounds in H. abyssinica and H. africana. Furthermore, 11 compounds have been isolated from H. abyssinica. The biological activities of H. abyssinica and H. africana have been reported. They include antibacterial, antiproliferative, antioxidant, antidiarrhea, and antifungal potentials. Despite the Hydnora species being practiced in ancient folkloric medicine, their traditional uses and pharmacological value are poorly documented. Based on the available information on ethnobotany, phytochemistry, pharmacology, and distribution, we aim to provide research gaps and challenges for a better understanding of this genus. This may be resourceful in the development of effective phytomedicines, and aid in conservation. The available studies on this genus on some aspects such as phytochemistry, pharmacological activities, and distribution are under-reported hence the need for further research.