Showing papers by "Michael F. Fay published in 2001"

Rapid and recent origin of species richness in the Cape flora of South Africa

Abstract: The Cape flora of South Africa grows in a continental area with many diverse and endemic species. We need to understand the evolutionary origins and ages of such 'hotspots' to conserve them effectively. In volcanic islands the timing of diversification can be precisely measured with potassium-argon dating. In contrast, the history of these continental species is based upon an incomplete fossil record and relatively imprecise isotopic palaeotemperature signatures. Here we use molecular phylogenetics and precise dating of two island species within the same clade as the continental taxa to show recent speciation in a species-rich genus characteristic of the Cape flora. The results indicate that diversification began approximately 7-8 Myr ago, coincident with extensive aridification caused by changes in ocean currents. The recent origin of endemic species diversity in the Cape flora shows that large continental bursts of speciation can occur rapidly over timescales comparable to those previously associated with oceanic island radiations.

Molecular systematics of Iridaceae: evidence from four plastid DNA regions

Abstract: Iridaceae are one of the largest families of Lilianae and probably also among the best studied of monocotyledons. To further evaluate generic, tribal, and subfamilial relationships we have produced four plastid DNA data sets for 57 genera of Iridaceae plus outgroups: rps4, rbcL (both protein-coding genes), the trnL intron, and the trnL-F intergenic spacer. All four matrices produce similar although not identical trees, and we thus analyzed them in a combined analysis, which produced a highly resolved and well-supported topology, in spite of the fact that the partition homogeneity test indicated strong incongruence. In each of the individual trees, some genera or groups of genera are misplaced relative to morphological cladistic studies, but the combined analysis produced a pattern much more similar to these previous ideas of relationships. In the combined tree, all subfamilies were resolved as monophyletic, except Nivenioideae that formed a grade in which Ixioideae were embedded. Achlorophyllous Geosiris (sometimes referred to Geosiridaceae or Burmanniaceae) fell within the nivenioid grade. Most of the tribes were monophyletic, and Isophysis (Tasmanian) was sister to the rest of the family; Diplarrhena (Australian) fell in a well-supported position as sister to Irideae/Sisyrinchieae/Tigridieae/Mariceae (i.e., Iridoideae); Bobartia of Sisyrinchieae is supported as a member of Irideae. The paraphyly of Nivenioideae is suspicious due to extremely high levels of sequence divergence, and when they were constrained to be monophyletic the resulting trees were only slightly less parsimonious (<1.0%). However, this subfamily also lacks clear morphological synapomorphies and is highly heterogeneous, so it is difficult to develop a strong case on nonmolecular grounds for their monophyly.

Amplified fragment length polymorphisms (AFLP) reveal details of polyploid evolution in Dactylorhiza (Orchidaceae)

Abstract: The utility of the PCR-based AFLP technique (polymerase chain reaction; amplified fragment length polymorphisms) was explored in elucidating details of polyploid evolution in the Eurasian orchid genus Dactylorhiza. We emphasized Swedish taxa but also included some material from the British Isles and elsewhere in Europe. Three different sets of primers, amplifying different subsets of restriction fragments, independently revealed similar patterns for relationships among the Dactylorhiza samples investigated. The AFLP data support the general picture of polyploid evolution in Dactylorhiza, i.e., that allotetraploid derivatives have arisen repeatedly as a result of hybridization beween the two parental groups D. incarnata s.l. (sensu lato; diploid marsh orchids) and the D. maculata group (spotted orchids). Within the incarnata s.l. group, morphologically defined varieties were interdigitated. The D. maculata group consisted of two distinct subgroups, one containing autotetraploid D. maculata subsp. maculata and the other containing diploid D. maculata subsp. fuchsii. Allotetraploids showed a high degree of additivity for the putative parental genomes, and relationships among them were partly correlated to morphologically based entities, but also to geographic distribution. Thus, allotetraploid taxa from the British Isles clustered together, rather than with morphologically similar plants from other areas.

Molecular phylogeny of Helleborus (Ranunculaceae), with an emphasis on the East Asian-Mediterranean disjunction

Abstract: Phylogenetic relationships within the genus Helleborus (Ranunculaceae) were evaluated with analyses of plastid trnL-F and partial matK and nuclear ITS DNA sequences for all 16 currently recognised species in addition to several subspecies and geographical variants. The molecular study provides strong support for the monophyly of Helleborus. However, both traditional divisions of the genus, into two groups (Caulescentes and Scapigeri) or two subgenera (Helleborastrum and Helleborus), are refuted. All six currently recognised sections (Dicarpon, Chenopus, Griphopus, Helleborus, Helleborastrum, and Syncarpus) are monophyletic, four by default because they are monospecific. Section Dicarpon (H. thibetanus) is strongly supported as sister group to section Helleborastrum and could therefore be sunk into that section. Relationships between this pair of sections and the other sections are, however, not clear. At the specific level, all species which are clearly distinct morphologically are also distinct in terms of molecular divergence, but relationships between the poorly differentiated species in section Helleborastrum are not resolved with any degree of support. Using a molecular clock based on matK sequence divergence, the disjunction of H. thibetanus and section Helleborastrum between East Asia and the Mediterranean is tentatively dated at approximately 23 million years (middle Miocene), which corresponds well with the geological history of the area where H. thibetanus occurs.

Phylogenetic analysis of Phylica L. (Rhamnaceae) with an emphasis on island species: evidence from plastid trnL‐F and nuclear internal transcribed spacer (ribosomal) DNA sequences

Abstract: Las relaciones de las especies insulares de Phylica y otros generos en Phyliceae ( Rhamnaceae ) se evaluaron utilizando secuencias para el intron trnL del plastidio , el espaciador intergenico trnL-F y los espaciadores transcritos internos del ADN ribosomico nuclear. Ambas regiones proporcionaron patrones filogeneticos casi identicos, por lo que se analizaron como una matriz combinada. Se encontro que los generos Nesiota y Noltea eran especies paleoendemicas dentro del contexto de la tribu. La especie islena de Phylica formo un grupo monofiletico junto con la especie extensa del continente, P. paniculata.La morfologia plesiomorfica y generalista de este grupo contrasta con las caracteristicas morfologicas derivadas de la mayoria de las especies continentales. Sin embargo, el grupo ocupa una posicion derivada en los arboles filogeneticos, lo que indica una inversion o, mas probablemente, la retencion de estos rasgos primitivos.

The genetic status and conservation management of two cultivated bulb species extinct in the wild: Tecophilaea cyanocrocus (Chile) and Tulipa sprengeri (Turkey)

Abstract: Tecophilaea cyanocrocus and Tulipasprengeri are both extinct in the wild as aresult of overharvesting by commercialcollectors. Stocks of both species survive incultivation in amateur collections, commercialnurseries and botanic garden collections.Whilst both species share a similarconservation history, the distribution ofgenetic diversity within cultivated materialwas unknown. To support the long-termconservation of both species the geneticdiversity of the surviving stocks was assessedusing amplified fragment length polymorphisms(AFLPs). This study revealed different geneticstructures for the two bulb species. The Kewcollections of T. cyanocrocus, originallyobtained from a commercial nursery, VanTubergen, are genetically highly uniform andthe addition of samples from other collectionshas dramatically increased the level ofvariation. In contrast, the collections ofT. sprengeri held at Kew since the early20th century include representativegenotypes covering the whole range of geneticvariation found in this species and areprobably the source of all other cultivatedmaterial. The results are discussed in relationto the management of these species to ensuretheir continued survival in cultivation.

Phylogenetic position and taxonomic status of the genus Aegialitis and subfamilies Staticoideae and Plumbaginoideae (Plumbaginaceae): evidence from plastid DNA sequences and morphology

Abstract: Circumscription of Plumbaginaceae is evaluated using sequence data from three plastid regions (rbcL, the intron of trnL and the intergenic spacer of trnL-trnF) and a morphological dataset of 51 characters. Thirteen species representing the major genera of Staticoideae and Plumbaginoideae, as well as one species of Aegialitis, have been analysed using three species of Polygonaceae as an outgroup. Analyses of the molecular, morphological and combined datasets yield similar results. Plumbaginaceae are divided in two well-supported groups corresponding to subfamilies Staticoideae and Plumbaginoideae. Aegialitis is sister to the rest of Staticoideae. In the light of these data, we can conclude that the classification of Plumbaginaceae in two subfamilies is well supported. Moreover, Aegialitis should be regarded as a tribe in Staticoideae.

Phylogenetic analysis of Phylica L. (Rhamnaceae) with an emphasis on island species: evidence from plastid trnL-F and nuclear internal transcribed spacer

Abstract: Summary Richardson, J. E., Weitz, F. M., Fay, M. F., Cronk, Q. C. B., Linder, H. P., Reeves, G. & Chase, M. W.: Phylogenetic analysis of Phylica L. (Rhamnaceae) with an emphasis on island species: evidence from plastid trnL-F DNA and nuclear internal transcribed spacer (ribosomal DNA) sequences. - Taxon 50: 405-427. 2001. - ISSN 0040-0262. The relationships of the island species of Phylica and other genera in Phyliceae (Rhamnaceae) were evaluated using sequences for the plastid trnL intron, the trnL-F intergenic spacer and the internal transcribed spacers of nuclear ribosomal DNA. Both regions provided nearly identical phylogenetic patterns, so they were analysed as a combined matrix. The genera Nesiota and Noltea were found to be palaeoendemic species within the context of the tribe. The island species of Phylica formed a monophyletic group together with the widespread mainland species, P. paniculata. The plesiomorphic, generalist morphology of this group contrasts with the derived morphological characteristics of the majority of mainland species. However, the group occupies a derived position in the phylogenetic trees, thus indicating either a reversal or more likely the retention of these primitive traits.

Molecular data confirm the affinities of the south-west Australian endemic Granitites with Alphitonia (Rhamnaceae)

Abstract: Sobre la base de los datos de la secuencia de ADN, se confirma que las afinidades del genero Granitites (Rhamnaceae) recientemente descrito del sudoeste de Australia estan con Alphitonia, como sugirio Rye (1996), en lugar de miembros de Pomaderreae, como pensaron autores anteriores. . Los hallazgos de este estudio proporcionan una confirmacion molecular de que algunos componentes de la flora del suroeste de Australia pueden ser reliquias de antiguos linajes de la selva tropical

Ancient flowering plants: DNA sequences and angiosperm classification.

Abstract: Phylogenetic analyses of gene sequences provide a clear pattern of which extant flowering plant genera diversified earliest. Combined with complete genomic sequences, these data will vastly improve understanding of the genetic basis of plant diversity.