Caroline M. Pannell

Bio: Caroline M. Pannell is an academic researcher from University of Oxford. The author has contributed to research in topics: Aglaia & Biological dispersal. The author has an hindex of 12, co-authored 26 publications receiving 545 citations. Previous affiliations of Caroline M. Pannell include Royal Botanic Gardens & Queen's University Belfast.

New Guinea has the world’s richest island flora

Abstract: New Guinea is the world’s largest tropical island and has fascinated naturalists for centuries1,2. Home to some of the best-preserved ecosystems on the planet3 and to intact ecological gradients—from mangroves to tropical alpine grasslands—that are unmatched in the Asia-Pacific region4,5, it is a globally recognized centre of biological and cultural diversity6,7. So far, however, there has been no attempt to critically catalogue the entire vascular plant diversity of New Guinea. Here we present the first, to our knowledge, expert-verified checklist of the vascular plants of mainland New Guinea and surrounding islands. Our publicly available checklist includes 13,634 species (68% endemic), 1,742 genera and 264 families—suggesting that New Guinea is the most floristically diverse island in the world. Expert knowledge is essential for building checklists in the digital era: reliance on online taxonomic resources alone would have inflated species counts by 22%. Species discovery shows no sign of levelling off, and we discuss steps to accelerate botanical research in the ‘Last Unknown’8. A catalogue of the vascular flora of New Guinea indicates that this island is the most floristically diverse in the world, and that 68% of the species identified are endemic to New Guinea.

The origin and evolution of Indomalesian, Australasian and Pacific island biotas: insights from Aglaieae (Meliaceae, Sapindales)

Abstract: Aim The role of long-distance dispersal in the Indomalesian, Australasian and Pacific flora is currently hotly debated. The lack of well-resolved phylogenetic trees for Pacific plants has been a major limitation for biogeographical analysis. Here, we present a well-resolved phylogenetic tree for the tribe Aglaieae in the mahogany family, Meliaceae, and use it to investigate the origin, evolution and dispersal history of biotas in this area. The subfamily Melioideae, including the tribe Aglaieae (Meliaceae, Sapindales), is a plant group with good representation in the region in terms of biomass and species numbers, wide ecological attributes and known animal vectors. The family has a good fossil record (especially from North America and Europe). Genera and species in the tribe Aglaieae therefore provide an excellent model group for addressing this debate. Location Indomalesia, Australasia, Pacific islands. Methods Results from nuclear internal transcribed spacer ribosomal DNA analyses of 82 taxa, based on sequence alignment guided by secondary structure models, were combined with evidence from fossils and distribution data. We used strict and relaxed molecular clock approaches to estimate divergence times within Aglaieae. Putative ancestral areas were investigated through area-based and event-based biogeographical approaches. Information on dispersal routes and their direction was inferred from the investigation of dispersal asymmetries between areas. Results Our study indicates that the crown group of Aglaieae dates back at least to the Late Eocene, with major divergence events occurring during the Oligocene and Miocene. It also suggests that dispersal routes existed during Miocene–Pliocene times from the area including Peninsular Malaysia, Sumatra and Borneo to Wallacea, India and Indochina, and from the area including New Guinea, New Ireland and New Britain further east to the Pacific islands at the peripheries of the distribution range. The origin of the Fijian species dates back to the Pliocene. Main conclusions Dispersal over oceanic water barriers has occurred during geological time and seems to have been a major driving force for divergence events in Aglaieae, with some old Gondwanan land masses (e.g. Australia) colonized only during recent times. Movement from the ancestral area was predominantly towards the east. Extant Fijian species of Aglaia are monophyletic and share morphological features rarely found in species of other areas, suggesting speciation within an endemic clade. Divergence of living taxa from their closest living relatives took place during both the Miocene and the Pliocene, and peaked in the Pliocene. The present-day distribution of many species in the tribe must therefore have arisen as a result of dispersal rather than vicariance events. Furthermore, colonization from Indomalesia to Australasia and the Pacific has frequently been followed by speciation.

Bioactive Flavaglines and Other Constituents Isolated from Aglaia perviridis

Abstract: Eight new compounds, including two cyclopenta[b]benzopyran derivatives (1, 2), two cyclopenta[b]benzofuran derivatives (3, 4), three cycloartane triterpenoids (5-7), and an apocarotenoid (8), together with 16 known compounds, were isolated from the chloroform-soluble partitions of separate methanol extracts of a combination of the fruits, leaves, and twigs and of the roots of Aglaia perviridis collected in Vietnam. Isolation work was monitored using human colon cancer cells (HT-29) and facilitated with an LC/MS dereplication procedure. The structures of the new compounds (1-8) were determined on the basis of spectroscopic data interpretation. The Mosher ester method was employed to determine the absolute configurations of 5-7, and the absolute configuration of the 9,10-diol unit of compound 8 was established by a dimolybdenum tetraacetate [Mo2(AcO)4] induced circular dichroism procedure. Seven known rocaglate derivatives (9-15) exhibited significant cytotoxicity against the HT-29 cell line, with rocaglaol (9) being the most potent (ED50 0.0007 μM). The new compounds 2-4 were also active against this cell line, with ED50 values ranging from 0.46 to 4.7 μM. The cytotoxic compounds were evaluated against a normal colon cell line, CCD-112CoN. In addition, the new compound perviridicin B (2), three known rocaglate derivatives (9, 11, 12), and a known sesquiterpene, 2-oxaisodauc-5-en-12-al (17), showed significant NF-κB (p65) inhibitory activity in an ELISA assay.

Aglaia (Meliaceae): an evaluation of taxonomic concepts based on DNA data and secondary metabolites.

Abstract: We performed maximum parsimony and Bayesian analyses (nuclear ITS rDNA, plastid rps16 intron) to estimate phylogenetic relationships within Aglaia (over 100 species in Southeast Asia, the Pacific, and Australia) and its relations among Aglaieae (Meliaceae). Based on 67 accessions of Aglaieae, three taxa of Guareae, and two taxa of Melieae (outgroup), this study provides the first assessment of the current circumscription of Aglaieae, Aglaia, and its sections and to a more limited extent of species concepts in Aglaia. DNA data are compared to recently collected data on chemical profiles. Our analyses indicate (1) the monophyly of Aglaieae; (2) the polyphyly of Aphanamixis; (3) the paraphyly of Aglaia; (4) the existence of at least three entities with respect to Aglaia: (a) the core group of Aglaia section Amoora (dehiscent fruits) with close relationships to Lansium and Reinwardtiodendron, (b) a group comprising morphological intermediates between the two sections, and (c) the core group of Aglaia section Aglaia (indehiscent fruits). Macro- and micromolecular data indicate that complex species are more heterogeneous, i.e., probably containing more than one taxon each, than taxonomically isolated species. A third section in Aglaia is recognized to accommodate A. lawii, A. teysmanniana, and A. beccarii.

The ecology of seeds

Abstract: What determines the number and size of the seeds produced by a plant? How often should it reproduce them? How often should a plant produce them? Why and how are seeds dispersed, and what are the implications for the diversity and composition of vegetation? These are just some of the questions tackled in this wide-ranging review of the role of seeds in the ecology of plants. The authors bring together information on the ecological aspects of seed biology, starting with a consideration of reproductive strategies in seed plants and progressing through the life cycle, covering seed maturation, dispersal, storage in the soil, dormancy, germination, seedling establishment, and regeneration in the field. The text encompasses a wide range of concepts of general relevance to plant ecology, reflecting the central role that the study of seed ecology has played in elucidating many fundamental aspects of plant community function.

Biogeography of the Indo-Australian Archipelago

Abstract: The extraordinary species richness and endemism of the Indo-Australian Archipelago (IAA) exists in one of the most geologically dynamic regions of the planet. The provenance of its biota has been debated, particularly in the area known as Wallacea. Application of molecular genetic approaches and a better understanding of the region’s complex geology have stimulated much recent biogeographic work in the IAA. We review molecular phylogenetic and phylogeographic studies in light of current geological evidence. Present distribution patterns of species have been shaped largely by pre-Pleistocene dispersal and vicariance events, whereas more recent changes in the connectivity of islands within the Archipelago have influenced the partitioning of intraspecific variation. Many genetic studies have uncovered cryptic species with restricted distributions. We discuss the conservation significance of the region and highlight the need for cross-taxon comparative studies using newly developed analytical approaches well suited to the challenges of historical inference in this region.

Secondary Metabolites Of Fleshy Vertebrate‐Dispersed Fruits: Adaptive Hypotheses And Implications For Seed Dispersal

Abstract: We discuss seven hypotheses to explain the adaptive significance of secondary me- tabolites in ripe fleshy fruits and their implications for seed dispersal. These hypotheses are the attraction/association, seed germination inhibition, attraction/repulsion, protein assimilation, gut retention time, directed toxicity, and defense trade-off hypotheses. We examine evidence that supports or refutes these hypotheses and suggest further tests of each. In addition, we summarize recent work with Solanum fruit pulp glycoalkaloids that bears directly on three of these hypothe- ses (directed toxicity, gut retention time, and defense trade-off ). We conclude that evidence ad- dressing many of these hypotheses is either observational or indirect, but most hypotheses find at least some level of support. Because many of the hypotheses are not mutually exclusive, we also conclude that synergistic interactions and multifunctionality in secondary metabolites may provide economical evolutionary solutions for plants facing disparate and temporally variable se- lective pressures that impinge on fruits and seeds.