Mountains as Evolutionary Arenas: Patterns, Emerging Approaches, Paradigm Shifts, and Their Implications for Plant Phylogeographic Research in the Tibeto-Himalayan Region

Recently, the “mountain-geobiodiversity hypothesis” (MGH) was proposed as a key concept for explaining the high levels of biodiversity found in mountain systems of the Tibeto-Himalayan region (THR), which comprises the Qinghai–Tibetan Plateau, the Himalayas, and the biodiversity hotspot known as the “Mountains of Southwest China” (Hengduan Mountains region). In addition to the MGH, which covers the entire life span of a mountain system, a complementary concept, the so-called “flickering connectivity system” (FCS), was recently proposed for the period of the Quaternary. The FCS focuses on connectivity dynamics in alpine ecosystems caused by the drastic climatic changes during the past ca. 2.6 million years, emphasizing that range fragmentation and allopatric speciation are not the sole factors for accelerated evolution of species richness and endemism in mountains. I here provide a review of the current state of knowledge concerning geological uplift, Quaternary glaciation, and the main phylogeographic patterns (“contraction/recolonization,” “platform refugia/local expansion,” and “microrefugia”) of seed plant species in the THR. In addition, I make specific suggestions as to which factors future avenues of phylogeographic research should take into account based on the fundamentals presented by the MGH and FCS, and associated complementary paradigm shifts

Analysis of Unusual Sulfated Constituents and Anti-infective Properties of Two Indonesian Mangroves, Lumnitzera littorea and Lumnitzera racemosa (Combretaceae)

Lumnitzera littorea and Lumnitzera racemosa are mangrove species distributed widely along the Indonesian coasts. Besides their ecological importance, both are of interest owing to their wealth of natural products, some of which constitute potential sources for medicinal applications. We aimed to discover and characterize new anti-infective compounds, based on population-level sampling of both species from across the Indonesian Archipelago. Root metabolites were investigated by TLC, hyphenated LC-MS/MS and isolation, the internal transcribed spacer (ITS) region of rDNA was used for genetic characterization. Phytochemical characterization of both species revealed an unusual diversity in sulfated constituents with 3,3’,4’-tri-O-methyl-ellagic acid 4-sulfate representing the major compound in most samples. None of these compounds was previously reported for mangroves. Chemophenetic comparison of L. racemosa populations from different localities provided evolutionary information, as supported by molecular phylogenetic evidence. Samples of both species from particular locations exhibited anti-bacterial potential (Southern Nias Island and East Java against Gram-negative bacteria, Halmahera and Ternate Island against Gram-positive bacteria). In conclusion, Lumnitzera roots from natural mangrove stands represent a promising source for sulfated ellagic acid derivatives and further sulfur containing plant metabolites with potential human health benefits

<I>Cyrtandra argentii</I>, a new species of <I>Cyrtandra</I> (Gesneriaceae) from the Philippines, and a review of the <I>C. villosissima</I> group

Cyrtandra argentii Olivar, H.J.Atkins & Muellner sp. nov., endemic to the Philippines and named after George Argent, is herein described and illustrated. Collections associated with this new species are often confused with three other species, namely C. ferruginea Merr., C. villosissima Merr., and C. hirtigera H.J.Atkins & Cronk. Distinguishing characters including keys, updated descriptions, distribution maps, and photos of live specimens are provided to aid identification of the four species. Following the International Union for the Conservation of Nature (IUCN) criteria, C. argentii sp. nov. is considered to be Near Threatened (NT) due to its distribution in a zone susceptible to anthropogenic pressure and the lack of any formal protection

Cyrtandra argentii, a new species of Cyrtandra (Gesneriaceae) from the Philippines, and a review of the C. villosissima group

Cyrtandra argentii Olivar, H.J.Atkins & Muellner sp. nov., endemic to the Philippines and named after George Argent, is herein described and illustrated. Collections associated with this new species are often confused with three other species, namely C. ferruginea Merr., C. villosissima Merr., and C. hirtigera H.J.Atkins & Cronk. Distinguishing characters including keys, updated descriptions, distribution maps, and photos of live specimens are provided to aid identification of the four species. Following the International Union for the Conservation of Nature (IUCN) criteria, C. argentii sp. nov. is considered to be Near Threatened (NT) due to its distribution in a zone susceptible to anthropogenic pressure and the lack of any formal protection

Testing the forest refuge hypothesis in sub-Saharan Africa using species distribution modeling for a key savannah tree species, Senegalia senegal (L.) Britton

Quaternary geographic range dynamics of savannah tree species are still not fully understood. The forest refuge hypothesis postulates that climatic and vegetational upheavals during the Pleistocene fragmented the previously continuous ranges of many species into isolated refuges that would have acted as shelters for rainforest taxa and allowed their survival through the Pleistocene cold stages. This hypothesis has recently been applied to studies of taxa in the African savannahs. We here test this hypothesis using the savannah tree species Senegalia senegal (L.) Britton., which is widely distributed across sub-Saharan Africa. Specifically, we ask the following questions: (i) Do we find evidence for savannah refugia during the last 130,000 before-present in sub-Saharan Africa? (ii) Would the climate in West Africa already have been suitable for S. senegal prior to the Last Glacial Maximum (LGM)? Using 1,132 occurrence records,we modeled the geographic distribution of S. senegal and projected the model into the past using climatic conditions from four time slices spanning the last 130,000 years bp. Our analyses show that the projected geographic extent of S. senegal was broader during the Last Interglacial, with a dramatic decline during the LGM and the subsequent recovery through the mid-Holocene to the present day. Our results indicate a range expansion at least from the mid-Holocene to the present and further show that S. senegal had similarly continuous distribution during the LGM as found today in sub-Saharan Africa. We also assessed the regional variation of environmental niche occupancy using a principal components analysis (PCA). The PCA reveals variation in the occupancy of environmental space across sub-Saharan Africa, a key indication of a wide ecological amplitude exhibited by the species. This study provides insights into the ancestral distribution and the temporal dynamics of a key savannah species that have shaped its current areas of occupancy

Spatio-temporal evolution of Allium L. in the Qinghai–Tibet-Plateau region: Immigration and in situ radiation

A plethora of studies investigating the origin and evolution of diverse mountain taxa has assumed a causal link between geological processes (orogenesis) and a biological response (diversification). Yet, a substantial delay (up to 30 Myr) between the start of orogenesis and diversification is often observed. Evolutionary biologists should therefore identify alternative drivers of diversification and maintenance of biodiversity in mountain systems. Using phylogenetic, biogeographic, and diversification rate analyses, we could identify two independent processes that most likely explain the diversity of the widespread genus Allium in the Qinghai–Tibet Plateau (QTP) region: (1) While the QTP-related taxa of the subgenus Melanocrommyum diversified in situ, (2) QTP-related taxa of other subgenera migrated into the QTP from multiple source areas. Furthermore, shifts in diversification rates within Allium could not be attributed spatially and temporally to the uplift history of the QTP region. Instead, global cooling and climate oscillations in the Quaternary were major contributors to increased speciation rates in three clades of Allium. Our study therefore adds to the growing evidence supporting the “mountain-geo-biodiversity hypothesis”, which highlights the role of climate oscillations for the diversification of mountain organisms

A synopsis of Philippine Cyrtandra (Gesneriaceae)

A taxonomic synopsis of Philippine Cyrtandra (Gesneriaceae) is presented. Following a study of 138 published names and their types, we accept 98 Cyrtandra species for the Philippine flora. Except for C. angularis, C. elatostemoides, and C. yaeyamae, all are endemic to the country. Lectotypes or neotypes are designated for all names for which this is necessary, except for six names for which we were unable to locate original material. We also validate a species name that was previously described without a Latin diagnosis (C. peninsula), synonymize three names, and provide taxonomic notes for each species. In addition, we propose two replacement names for taxa for which a legitimate name in Cyrtandra does not currently exist: C. edanoi for a Philippine species and C. siporensis for a Sumatran species. A look-up table is provided to facilitate referencing of currently accepted names in Philippine Cyrtandra

Analysis of Unusual Sulfated Constituents and Anti-infective Properties of Two Indonesian Mangroves, Lumnitzera littorea and Lumnitzera racemosa (Combretaceae)

Lumnitzera littorea and Lumnitzera racemosa are mangrove species distributed widely along the Indonesian coasts. Besides their ecological importance, both are of interest owing to their wealth of natural products, some of which constitute potential sources for medicinal applications. We aimed to discover and characterize new anti-infective compounds, based on population-level sampling of both species from across the Indonesian Archipelago. Root metabolites were investigated by TLC, hyphenated LC-MS/MS and isolation, the internal transcribed spacer (ITS) region of rDNA was used for genetic characterization. Phytochemical characterization of both species revealed an unusual diversity in sulfated constituents with 3,3’,4’-tri-O-methyl-ellagic acid 4-sulfate representing the major compound in most samples. None of these compounds was previously reported for mangroves. Chemophenetic comparison of L. racemosa populations from different localities provided evolutionary information, as supported by molecular phylogenetic evidence. Samples of both species from particular locations exhibited anti-bacterial potential (Southern Nias Island and East Java against Gram-negative bacteria, Halmahera and Ternate Island against Gram-positive bacteria). In conclusion, Lumnitzera roots from natural mangrove stands represent a promising source for sulfated ellagic acid derivatives and further sulfur containing plant metabolites with potential human health benefits