Austin R. Mast

Origin, adaptive radiation and diversification of the Hawaiian lobeliads (Asterales: Campanulaceae)

The endemic Hawaiian lobeliads are exceptionally species rich and exhibit striking diversity in habitat, growth form, pollination biology and seed dispersal, but their origins and pattern of diversification remain shrouded in mystery. Up to five independent colonizations have been proposed based on morphological differences among extant taxa. We present a molecular phylogeny showing that the Hawaiian lobeliads are the product of one immigration event; that they are the largest plant clade on any single oceanic island or archipelago; that their ancestor arrived roughly 13 Myr ago; and that this ancestor was most likely woody, wind-dispersed, bird-pollinated, and adapted to open habitats at mid-elevations. Invasion of closed tropical forests is associated with evolution of fleshy fruits. Limited dispersal of such fruits in wet-forest understoreys appears to have accelerated speciation and led to a series of parallel adaptive radiations in Cyanea, with most species restricted to single islands. Consistency of Cyanea diversity across all tall islands except Hawai i suggests that diversification of Cyanea saturates in less than 1.5 Myr. Lobeliad diversity appears to reflect a hierarchical adaptive radiation in habitat, then elevation and flower-tube length, and provides important insights into the pattern and tempo of diversification in a species-rich clade of tropical plants.

Finding Our Way through Phenotypes

Imagine if we could compute across phenotype data as easily as genomic data; this article calls for efforts to realize this vision and discusses the potential benefits.

Contrasted patterns of hyperdiversification in Mediterranean hotspots.

Dating the Tree of Life has now become central to relating patterns of biodiversity to key processes in Earth history such as plate tectonics and climate change. Regions with a Mediterranean climate have long been noted for their exceptional species richness and high endemism. How and when these biota assembled can only be answered with a good understanding of the sequence of divergence times for each of their components. A critical aspect of dating by using molecular sequence divergence is the incorporation of multiple suitable age constraints. Here, we show that only rigorous phylogenetic analysis of fossil taxa can lead to solid calibration and, in turn, stable age estimates, regardless of which of 3 relaxed clock-dating methods is used. We find that Proteaceae, a model plant group for the Mediterranean hotspots of the Southern Hemisphere with a very rich pollen fossil record, diversified under higher rates in the Cape Floristic Region and Southwest Australia than in any other area of their total distribution. Our results highlight key differences between Mediterranean hotspots and indicate that Southwest Australian biota are the most phylogenetically diverse but include numerous lineages with low diversification rates.

Phylogenetic Relationships in Primula L. and Related Genera (Primulaceae) Based on Noncoding Chloroplast DNA

We sequenced the trnL and rpl16 introns of the chloroplast DNA from 95 of the ca. 425 species (30 of 37 sections, seven of eight subgenera) of Primula L. in order to reconstruct the phylogenetic history of the group. Among the 24 additional taxa sampled are representatives of all genera that are likely to be embedded in Primula, as well as outgroups from the Maesaceae, Theophrastaceae, and Myrsinaceae. In the strict consensus of the most parsimonious trees, Primula and the genera embedded in it (Dionysia Fenzl., Sredinskya [Stein] Fedorov, Dodecatheon L., and Cortusa L.) are sister to a clade of several genera previously suspected to be embedded in Primula (Hottonia L., Omphalogramma [Franchet] Franch., and Soldanella L.). In recognition of this, two new rankless names are defined for these clades (/Primula and /Soldanella). Close relationships are inferred between Dionysia and Primula subgenus Sphondylia (Duby) Rupr., Sredinskya and Primula subgenus Primula, Dodecatheon and Primula subgenus Auriculastrum Schott, and Cortusa and Primula subgenus Auganthus (Link) Wendelbo. The largest subgenus, Aleuritia (Duby) Wendelbo, is dispersed among three clades that are not each others closest relatives. Primula sections Muscarioides Balf. f., Soldanelloides Pax, Denticulata Watt, Armerina Lindley, and Aleuritia Duby are resolved as para‐ or polyphyletic with moderate to strong support. Throughout, we consider the striking morphological and cytological variation seen in Primula within a phylogenetic context, particularly as it relates to the close relationship implied here between Dionysia and Primula subgenus Sphondylia. The homology of involute leaf vernation in Primula is reconsidered in light of its two independent origins, and we come to the conclusion that vernation in subgenus Sphondylia is better characterized as conduplicate.

Historical biogeography and the origin of stomatal distributions in Banksia and Dryandra (Proteaceae) based on their cpDNA phylogeny

Banksia and Dryandra have undergone extensive speciation and adaptive radiation, especially in Australias isolated Southwest Botanical Province. We derive a phylogeny for these groups based on cpDNA sequences and use it to reconstruct their historical biogeography and evolution of leaf traits thought to be adapted to drought and/or nutrient poverty. Slowly evolving regions (trnL intron, trnL/trnF spacer) are used to resolve large-scale relationships; faster evolving regions (rp116 intron, psbA/trnH and trnT/trnL spacers) are used to resolve relationships among closely related species. Banksia is paraphyletic with respect to Dryandra. The lineage underwent a basal split into two clades (here named /Cryptostomata and /Phanerostomata), and four infrageneric taxa supported by morphological cladistic analyses (series Spicigerae, Abietinae, Tetragonae, and Banksia) are not monophyletic. Dispersal-vicariance analysis resolves a southwestern Australian origin for the lineage, with two later expansions to the east followed by vicariance events. Stomatal crypts arose with the /Cryptostomata, which is characterized by tough, long-lived leaves and common in southwestern Australia. Sequestering of stomata also arose multiple times in /Phanerostomata, which is characterized by softer, short-lived leaves and common in moister coastal areas, via inrolling of the margins of narrow leaves and restricting stomata to shallow pits. The hypothesis that sclerophylly preadapted the plants to xeromorphy is supported in the case of shallow stomatal pits and deep stomatal crypts, but not narrow, needle-like leaves.

Phylogenetic relationships and biogeography of Fuchsia (Onagraceae) based on noncoding nuclear and chloroplast DNA data.

To examine relationships and test previous sectional delimitations within Fuchsia, this study used parsimony and maximum likelihood analyses with nuclear ITS and chloroplast trnL-F and rpl16 sequence data for 37 taxa representing all sections of Fuchsia and four outgroup taxa. Results support previous sectional delimitations, except for F. verrucosa, which is related to a Central American clade rather than to section Fuchsia and is described here as a new section Verrucosa. The basal relationships within Fuchsia are poorly resolved, suggesting an initial rapid diversification of the genus. Among the species sampled, there is strong support for a single South Pacific lineage, a southern South American/southern Brazilian lineage, a tropical Andean lineage, and one or two Central American and Mexican lineages. There is no clear support for an austral origin of the genus, as previously proposed, which is more consistent with Fuchsias sister group relationship with the boreal Circaea. An ultrametric molecular clock analysis (all minimal dates) places the split between Fuchsia and Circaea at 41 million years ago (mya), with the diversification of the modern-day lineages of Fuchsia beginning at 31 mya. The South Pacific Fuchsia lineage branches off around 30 mya, consistent with fossil records from Australia and New Zealand. The large Andean section Fuchsia began to diversify around 22 mya, preceded by the divergence of the Caribbean F. triphylla at 25 mya. The Brazilian members of section Quelusia separated from the southern Andean F. magellanica around 13 mya, and the ancestor of the Tahitian F. cyrtandroides split off from the New Zealand species of section Skinnera approximately 8 mya.

Using a Null Model to Recognize Significant Co-Occurrence Prior to Identifying Candidate Areas of Endemism

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The transfer of Dryandra R.Br. to Banksia L.f. (Proteaceae)

Phylogenies inferred from both chloroplast and nuclear DNA regions have placed the south-west Australian genus Dryandra R. Br. ( 93 spp.) among the descendents of the most recent common ancestor of the more widespread Australian genus Banksia L. f. ( 80 spp.). Here we consider the alternative solutions to maintaining monophyly at the generic rank and choose to make new combinations and replacement names for Dryandra in Banksia. We make the new combination Banksia ser. Dryandra in Banksia subgen. Banksia for 108 of the 109 new combinations at the ranks of species, subspecies, and variety and all 18 of the replacement names. We treat Banksia subgen. Banksia as the most inclusive clade that includes the type of Banksia ( B. serrata) but not B. integrifolia. We erect Banksia subgen. Spathulatae to accommodate the species in the most inclusive clade that includes B. integrifolia but not B. serrata. These two subgenera of Banksia are equivalent to the clades informally called /Cryptostomata and /Phanerostomata elsewhere. We treat one of the new combinations, Banksia subulata, as incertae sedis within Banksia subgen. Banksia.

An assessment of old and new DNA sequence evidence for the paraphyly of Banksia with respect to Dryandra (Proteaceae)

Banksia (80 spp.; Proteaceae) has undergone extensive speciation and adaptive radiation on the island continent of Australia. Its members range from prostrate shrubs in the dry, infertile sandplains to 25 m tall trees in the loams of river margins, and they display striking variation in their fire survival strategies and floral and foliar morphologies. We examine the weight of both previously published (most trnL intron, trnL/F spacer, and rpl16 intron data) and new (matK, atpB, and waxy data, as well as most ITS data) DNA sequence evidence for the paraphyly of Banksia with respect to a monophyletic Dryandra (93 spp.). The nuclear waxy gene appears to be at two loci in the Proteaceae, and sequences presumably from the same locus resolve Banksia as paraphyletic with respect to Dryandra. The waxy and combined chloroplast DNA (cpDNA) data reject the monophyly of Banksia at a threshold of P = 0.05 using the winning sites and Kishino–Hasegawa tests. We consider this result and the repeated placement of Dryandra in the same clade (/Cryptostomata) of Banksia with each separate analysis of the DNA datasets (cpDNA, ITS, and waxy), to be strong molecular support for the paraphyly of Banksia with respect to Dryandra. The morphological synapomorphy of beaked follicles for /Cryptostomata (including Dryandra) reinforces this conclusion. We argue that realignment of taxa to produce one or more monophyletic genera is best attained by moving the taxa of Dryandra to Banksia. This would produce an easily recognised genus Banksia with four morphological synapomorphies. It would also probably confer some of the research attention garnered by the adaptive radiation of Banksia to the under-studied taxa of Dryandra, for Dryandra makes the radiation of Banksia even more remarkable.

Time-calibrated phylogeny of the woody Australian genus Hakea (Proteaceae) supports multiple origins of insect-pollination among bird-pollinated ancestors

PREMISE OF THE STUDY A past study based on morphological data alone showed that the means by which plants of the Australian genus Hakea reduce florivory is related to the evolution of bird pollination. For example, bird pollination was shown to have arisen only in insect-pollinated lineages that already produced greater amounts of floral cyanide, a feature that reduces florivory. We examine a central conclusion of that study, and a common assumption in the literature, that bird pollination arose in insect-pollinated lineages, rather than the reverse. METHODS We combined morphological and DNA data to infer the phylogeny and age of the Australian genus Hakea, using 9.2 kilobases of plastid and nuclear DNA and 46 morphological characters from a taxonomically even sampling of 55 of the 149 species. KEY RESULTS Hakea is rooted confidently in a position that has not been suggested before. The phylogeny implies that bird pollination is primitive in Hakea and that multiple shifts to insect pollination have occurred. The unexpectedly young age of Hakea (a crown age of ca. 10 Ma) makes it coincident with its primary bird pollinators (honeyeaters) throughout its history. CONCLUSIONS Our study demonstrates that Hakea is an exception to the more commonly described shift from insect to bird pollination. However, we note that only one previous phylogenetic study involved Australian plants and their honeyeater pollinators and that our finding might prove to be more common on that continent.