High-latitude Tertiary Migrations of an Exclusively Tropical Clade: Evidence from Malpighiaceae

Explanations of tropical intercontinental disjunctions involving South America and Africa typically invoke vicariance of western Gondwanan biotas or long-distance dispersal. However, many plant groups originated and diversified well after the last direct connection between Africa and South America (ca. 105 million years before the present [mybp]), and it is unlikely that long-distance dispersal accounts for the distribution of all of these. A less commonly invoked explanation, the boreotropics hypothesis, indicates that some tropical disjunctions arose during the Tertiary via high-latitude land connections when northern forests supported tropical vegetation. Malpighiaceae are widely distributed across Africa and South America and have been explained as ancient "Gondwanian aborigines" (i.e., vicariants of western Gondwanan biotas) or more recent "American colonists" (i.e., long-distance dispersalists from South America into the Old World). Fossil and phylogenetic evidence from clock-independent estimates of molecular divergence times indicate that Malpighiaceae originated in South America during the latest Cretaceous (ca. 68 mybp), in isolation from Africa, and that six amphi-Atlantic disjunctions within the family occurred during three major episodes: late Paleocene (ca. 60 mybp), latest Eocene-earliest Oligocene (ca. 34-31 mybp), and early Miocene (ca. 21-17 mybp). These age estimates reject a Gondwanan origin for Malpighiaceae, and strict dispersal scenarios ignore paleoclimate, paleoland configurations, and fossil evidence that indicates that the family once inhabited northern latitudes. Instead, these data suggest that Paleocene-Oligocene amphi-Atlantic disjunct groups in Malpighiaceae moved into North America from South America via the Caribbean Basin, crossed the North Atlantic into Eurasia, and subsequently reached the Old World Tropics during warm intervals when land configurations would have facilitated this migration. Whether Miocene migrations of evergreen thermophilic Malpighiaceae proceeded via northern latitudes or long-distance dispersal is less clear.Organismic and Evolutionary Biolog

PHYLOGENY OF ACRIDOCARPUS-BRACHYLOPHON (MALPIGHIACEAE): IMPLICATIONS FOR TERTIARY TROPICAL FLORAS AND AFROASIAN BIOGEOGRAPHY

A major tenet of African Tertiary biogeography posits that lowland rainforest dominated much of Africa in the late Cretaceous and was replaced by xeric vegetation as a response to continental uplift and consequent widespread aridification beginning in the late Paleogene. The aridification of Africa is thought to have been a major factor in the extinction of many African humid-tropical lineages, and in the present-day disparity of species diversity between Africa and other tropical regions. This primarily geologically based model can be tested with independent phylogenetic evidence from widespread African plant groups containing both humid- and xeric-adapted species. We estimated the phylogeny and lineage divergence times within one such angiosperm group, the acridocarpoid clade (Malpighiaceae), with combined ITS, ndhF , and trnL-F data from 15 species that encompass the range of morphological and geographic variation within the group. Dispersal-vicariance analysis and divergence-time estimates suggest that the basal acridocarpoid divergence occurred between African and Southeast Asian lineages approximately 50 million years ago (mya), perhaps after a southward ancestral retreat from high-latitude tropical forests in response to intermittent Eocene cooling. Dispersion of Acridocarpus from Africa to Madagascar is inferred between approximately 50 and 35 mya, when lowland humid tropical forest was nearly continuous between these landmasses. A single dispersal event within Acridocarpus is inferred from western Africa to eastern Africa between approximately 23 and 17 mya, coincident with the widespread replacement of humid forests by savannas in eastern Africa. Although the spread of xeric environments resulted in the extinction of many African plant groups, our data suggest that for others it provided an opportunity for further diversification.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72798/1/j.0014-3820.2002.tb00165.x.pd

Novedades nomenclaturales para Gaultheria (Ericaceae) en Chile

After a revision of Gaultheria species for Flora de Chile project, we found new specimens and information that has prompted us to make two new combinations and a lectotype for this genus. Pernettya linifolia Phil. was described by R. A. Philippi and subsequently treated taxonomists as a variety of either Gaultheria (Pernettya) mucronata or Gaultheria(Pernettya) poeppigii. We treat Pernettya linifolia at the species level, and move it to Gaultheria as Gaultheria linifolia (Phil.) Teillier & R.A. Rodr., in line with the new classification of Ericaceae. The combination Gaultheria angustifolia (Lindl.) Teillier (Ericaceae) was recently made for a distinct species from Chile and Argentina, but this name is a later homonym of Gaultheria angustifolia Brandegee from Mexico. A new name, Gaultheria marticorenae Teillier & P.W. Fritsch, is therefore provided as a replacement for this species. A lectotype for the heterotypic synonym Pernettya leucocarpa var. linearis Reiche is also designated.Una actualización de Gaultheria en el marco del proyecto “Flora de Chile” nos ha llevado a proponer dos nuevas combinaciones y una lectotipificación para este género. Pernettya linifolia Phil. fue descrita por R.A. Philippi, y posteriormente incluida, ya sea en Gaultheria (Pernettya) mucronata o en Gaultheria (Pernettya) poeppigii; en este trabajo se propone que se trata de una buena especie, que de acuerdo con la nomenclatura actual de las ericáceas, debería denominarse Gaultheria linifolia (Phil.) Teillier & R.A. Rodr. La combinación Gaultheria angustifolia (Lindl.) Teillier fue recientemente publicada para otra especie de Chile y Argentina, pero se demostró que el nombre constituye un homónimo posterior a Gaultheria angustifolia Brandegee, una especie mexicana; en este trabajo se propone su reemplazo por Gaultheria marticorenae Teillier & P.W. Fritsch. Finalmente, se propone un lectotipo para el sinónimo heterotípico Pernettya leucocarpa var. linearis Reiche

Flora da Serra do Cipó, Minas Gerais: Styracaceae

The study of the family Styracaceae is part of the project "Flora of the Serra do Cipó, Minas Gerais, Brasil". In that area, the family is represented by the genus Styrax, with six species: S. camporum, S. ferrugineus, S. maninul, S. martii, S. pedicellatus and S. rotundatus. Keys to species, descriptions and illustrations as well as comments on the geographic distribution, phenology and morphological variation of the species are presented.O estudo da família Styracaceae é parte do levantamento da Flora da Serra do Cipó, Minas Gerais, Brasil. A família está representada naquela área pelo gênero Styrax, com seis espécies: S. camporum, S. ferrugineus, S. maninul, S. martii, S. pedicellatus e S. rotundatus. São apresentadas chaves para as espécies, descrições e ilustrações das mesmas, além de comentários sobre sua distribuição geográfica, fenologia e variabilidade

Vaccinium (Ericaceae) in Sulawesi: a new species and a list of known taxa

Vaccinium sulawesiense Mustaqim & P.W.Fritsch, a newly discovered endemic to Sulawesi, Indonesia, is described. This species is similar to V. simulans Sleumer but differs in having an acuminate leaf apex, larger floral organs, and an absence of trichomes in the upper half of the inner surface of corolla and disk. This species is known from the two specimens, one from a mid-montane rain forest in Mamasa Regency, Sulawesi Barat Province and the another from Poso Regency, Sulawesi Tengah Province. An updated list of the 17 known Vaccinium species in Sulawesi is also provided

Phylogeny and Classification of Paris (Melanthiaceae) Inferred from DNA Sequence Data

• Background and Aims Paris (Melanthiaceae) is a temperate genus of about 24 perennial herbaceous species distributed from Europe to eastern Asia. The delimitation of the genus and its subdivisions are unresolved questions in the taxonomy of Paris. The objective of this study is to test the generic and infrageneric circumscription of Paris with DNA sequence data

Evolutionary response of Caragana (Fabaceae) to Qinghai-Tibetan Plateau uplift and Asian interior aridification

Caragana is endemic to temperate Asia, with most species distributed on the Qinghai-Tibetan Plateau (QTP) and in Northwestern China. Consequently its biogeography should be hypothesized to have been affected by QTP uplift. To examine the biogeography of Caragana in relation to QTP uplift and consequent interior aridification, we conducted molecular dating analyses based on three genes (ITS, cpDNA trnS-trnG and rbcL). Results from relaxed Bayesian BEAST, relaxed Bayesian Multidivtime, and PL (penalized likelihood) indicate that QTP uplift, especially the onset of Himalayan motion at 21-17 Ma, triggered the origin of Caragana (with estimated ages 16-14 Ma). The subsequent QTP rapid uplift at 8 Ma is inferred to have driven the evolution and diversification of the three major clades of Caragana: section Caragana (northern China and the Junggar-Altai-Sayan region), section Frutescentes (Central Asia), and sections Bracteolatae and Jubatae, centered in the QTP. A rapid and active speciation process occurring in the QTP intense uplift at 3.4-1.8 Ma, is indicated by the chronogram

Nonequilibrium spectral diffusion due to laser heating in stimulated photon echo spectroscopy of low temperature glasses

A quantitative theory is developed, which accounts for heating artifacts in three-pulse photon echo (3PE) experiments. The heat diffusion equation is solved and the average value of the temperature in the focal volume of the laser is determined as a function of the 3PE waiting time. This temperature is used in the framework of nonequilibrium spectral diffusion theory to calculate the effective homogeneous linewidth of an ensemble of probe molecules embedded in an amorphous host. The theory fits recently observed plateaus and bumps without introducing a gap in the distribution function of flip rates of the two-level systems or any other major modification of the standard tunneling model.Comment: 10 pages, Revtex, 6 eps-figures, accepted for publication in Phys. Rev.

Side-chain influence on the mass density and refractive index of polyfluorenes and star-shaped oligofluorene truxenes

The density of organic semiconductor films is an important quantity because it is related to intermolecular spacing which in turn determines the electronic and photophysical properties. We report thin film density and refractive index measurements of polyfluorenes and star-shaped oligofluorene truxene molecules. An ellipsometer and a procedure using a spectrophotometer were used to determine film thickness and mass of spin-coated films, respectively. We present a study of the effect of alkyl side-chain length on the volumetric mass density and refractive index of the materials studied. The density measured for poly(9,9-di-n-octylfluorene) (PF8) was 0.88 ± 0.04 g/cm3 and decreased with longer alkyl side chains. For the truxene molecule with butyl side chains (T3 butyl), we measured a density of 0.90 ± 0.04 g/cm3, which also decreased with increasing side-chain length