Chloroplast DNA Restriction Site Research Articles

Chloroplast DNA phylogeography and cytotype geography in autopolyploid Plantago media

In order to gain insight into the causes of parapatric diploid and tetraploid distributions in Plantago media chloroplast DNA (cpDNA) restriction site polymorphism was studied in 36 European populations. Parapatric distributions are often explained by adaptive differences between cytotypes to an underlying heterogeneity in environmental factors. Alternatively, such distribution patterns may be explained nonadaptively, through frequency‐dependant production of hybrids with low fitness. However, nonadaptive explanations have been neglected in polyploid literature. In this study nine chloroplast haplotypes were found. Their phylogeny suggests that tetraploids arose at least three times from diploids. In general, related haplotypes were also geographically clustered, although there were some marked geographical discontinuities. In the Pyrenees, diploids and tetraploids carried diverged haplotypes throughout their parapatric ranges. At the contact zone the level of cpDNA introgression in a mixed diploid‐tetraploid population was low. It is discussed that the cpDNA phylogeography supports the nonadaptive hypothesis that parapatric cytotype distributions may be explained by postPleistocene range expansions followed by mutual minority cytotype exclusion, due to hybrid unfitness.

Phylogenetic Relationships of Clerodendrum s.l. (Lamiaceae) Inferred from Chloroplast DNA

Seventy-nine accessions representing forty-seven taxa of Clerodendrumn s.l. (Lamiaceae) and seven putative outgroup genera are included in an analysis of chloroplast DNA restriction sites for ten enzymes. Parsimony analysis of 456 potentially informative characters identifies four large discrete clades (Clades I-IV) within Clerodenidruim s.l. and shows that Clerodendruim s.l. is polyphyletic. Clades I and II comprise Asian and African taxa respectively. Clade III comprises coastal species from Africa, Asia and central America and presents an hypothesis of relationship within Clerodendrutm that has not previously been explicit in classifications of the genus. Clade IV, comprising subg. Cyclonema and sect. Konocalyx (subg. Clerodendrrnm pro parte) emerges as a lineage distinct from the rest of Clerodendrtni. Traditional sections Squamnata, Odontocalyx (subg. Clerodendrutm), Cyclonenia and Stacheocymosa (subg. Cycloinema) are well-supported mono- phyletic groups. Subgenus Clerodenidrutm and sections Clerodendrutm and Axilliflora (subg. Clerodendrnm pro parte) are shown to be polyphyletic. The polyphyly of Clerodendruni s.l. is also supported by a separate analysis of chloroplast ndhF sequences, in which a smaller sampling of Clerodendruman is included in a broader sample of labiate genera. The ndhF sequence data suggest that Tetraclea belongs in Clade I of Clerodendruni and support the monophyly of the recently circumscribed subfamily Teucriodeae.

Astragalus molybdenus s.l. (Leguminosae): Higher Taxonomic Relationships and Identity of Constituent Species

The Rocky Mountain Astragalus molybdenuis s.l. comprises A. molybdenus from Colorado, A. shultziorum from Wyoming, and A. lackschewitzii sp. nov. endemic to Montana. These three species are determined to be closely related to the species of Astragalus sect. Polares. Section Minerales, formerly a monotypic taxon that accommodated A. molybdenus in the Phacoid Phalanx next to sect. Astragalus, is now synonymized with sect. Polares. Supporting evidence comes from morphometric and cladistic analysis of morphological and chloroplast DNA restriction site data, and is consistent with findings reported elsewhere on sequence variation of the internal transcribed spacers that flank 5.8S nuclear ribosomal DNA. A previously overlooked attribute of A. molybdenus s.l. (the mature pod, which is deciduous from a marescent, ventrally ruptured calyx) is used to pinpoint the relationships of this species group to the piptoloboid Homalobi subgroup of Neo-astragalus. Additionally, chloroplast DNA sequences are exceptionally divergent among populations, on the order of 1.5-2.0%, and this evidence is used in part to support the recognition of three constituent species within A. molybdenus s.l.

Chloroplast DNA variation and evolution in the genus Lens Mill

Chloroplast DNA (cpDNA) restriction site diversity was assessed by 21 enzyme/probe combinations in 30 accessions of six Lens species, including the recently recognized L. lamottei and L. tomentosus. A total of 118 fragments were scored and 26 restriction site mutations were identified. The cpDNA restriction pattern supports circumscribing L. lamottei and L. tomentosus as independent species. The value of the data for reconstructing phylogeny in the genus is discussed. The cpDNA of all 13 accessions of the lentil’s wild progenitor, L. culinaris subsp. orientalis, differed from that of the single lentil cultivars used in this study. This diversity indicates that other populations of this subspecies from Turkey and Syria examined by Mayer and Soltis (1994) are potentially the founder members of lentil. Examination of L. lamottei×L. nigricans hybrids between accessions having different restriction patterns showed paternal plastid inheritance in L. nigricans.

Polyphyly of the Tuberous Lomatiums (Apiaceae): cpDNA Evidence for Morphological Convergence

Overlapping patterns of morphological variation in Lomatium have obscured interspecific relationships and thwarted attempts at infrageneric classification. However, the tuberous lomatiums, a group of 13 species mostly from the Inland Pacific Northwest of the U.S.A. and allied primarily by their thickened roots, have long been considered an informal assemblage in Lomatium, although they have received formal taxonomic recognition at the infrageneric level only once. Variation in root morphology is coupled with interspecific differences in leaf and fruit morphology, flower color, and involucel structure. To test the monophyly of the tuberous group and to examine patterns of relationship and morphological divergence among these species, a phylogenetic analysis was conducted using chloroplast DNA (cpDNA) restriction site variation. Samples of all taxa of tuberous lomatiums except the narrowly endemic L. stebbinsii were analyzed. Also included were samples of 18 other species of Lomatium, representing all but one of the morphological groups in the genus, and the related genus, Angelica. Phylogenetic trees of Lomatium were well resolved but generally weakly supported. The tuberous group is apparently polyphyletic, comprising members of at least four distinct lineages: 1) L. watsonii, associated with the L. columbianum group from the Pacific Northwest; 2) L. ambiguum, an apparent relative of several nontuberous species from California; 3) L. hendersonii, one branch of a speciose trichotomy and apparently only distantly related to other tuberous species, and 4) the remaining nine tuberous species sampled. Thus, within Lomatium, tuberous roots may have evolved in parallel several times. Developmental studies are needed to determine the mode of root thickening and the organogenesis of these storage structures.

Phylogenetic Relationships of Wild Potatoes, Solanum Series Conicibaccata (Sect. Petota)

Solanum sect. Petota series Conicibaccata is a group of 40 wild potato species, composed of diploids, tetraploids, and hexaploids, distributed from central Mexico to central Bolivia. This study examined their species boundaries and interrelationships by phenetic analyses of morphological data and cladistic analyses of chloroplast DNA restriction site data. Mitotic chromosome counts were obtained for 114 accessions; species whose first counts are reported here are S. garcia-barrigae, S. orocense, and S. sucubunense. Most results were concordant in showing three main groups of species: 1) tetraploids and hexaploids from central Mexico to southern Ecuador; 2) diploids from northern Peru to Bolivia, included in a cpDNA clade of diploids and hexaploids assigned to ser. Demissa and ser. Tuberosa, and 3) diploids and tetraploids from southern Colombia to Peru, cladistically related to members of ser. Piurana. Some species boundaries, and even series boundaries of ser. Conicibaccata and ser. Piurana, are supported morphologically only by a combination of widely overlapping character states, none of which is constant for a species. Other species have no support, and it is likely that too many species are recognized in the group. The cladistic analysis of chloroplast DNA data suggested that some species represent a combination of apospecies and plesiospecies, and some populations are of possible hybrid origin. The genus Solanum L. contains about 1,000 to 1,100 species (D'Arcy 1991) and is one of the largest genera of angiosperms. Solanum sect. Petota Dumort., the potato and its wild relatives, includes 232 species as recognized by Hawkes (1990), or 223 species with the exclusion of nine nontuber-bearing species alternatively placed in sect. Etuberosum (Bukasov and Kameraz) A. Child, sect. Juglandifolium (Rydb.) A. Child, and sect. Lycopersicon (Mill.) Wettst. (Child 1990; Spooner et al. 1993). The tuber-bearing species are distributed from the southwestern United States to southern Chile, from sea level to over 4,500 m, with a concentration of diversity in the Andes. Section Petota contains diploids (2n = 2x = 24), tetraploids (2n = 4x = 48) and hexaploids (2n = 6x = 72), with occasional triploids and pentaploids. Section Petota is taxonomically difficult with much disagreement regarding species boundaries, affiliation of species to series, rank of infraspecific taxa, and hypotheses of hybridization (Spooner and van den Berg 1992a). Solanum ser. Conicibaccata Bitter presents many problems regarding species and series boundaries and is in need of revision. Bitter (1912) was the first to recognize series in sect. Petota. When Bitter (1912) first described the two series Conicibaccata and Maglia Bitter, the morphological distinction between the conical fruits of the former and rounded to ovoid fruits of the latter presented few taxonomic problems. As new species and series were described, these distinctions became imprecise and assignment of species to series varied widely among taxonomists, as summarized in Spooner and Sytsma (1992) and Spooner and van den Berg (1992a). The latest taxonomic treatment of sect. Petota (Hawkes 1990) recognized 19 tuber-bearing

A Synopsis of Arabidopsis (Brassicaceae)

New combinations in Arabidopsis are proposed. Species previously placed in Cardaminopsis are here transferred to Arabidopsis and taxa previously recognized in Arabidopsis, other than A. thaliana and A. suecica, are excluded from the Distributions and a key to the nine species and five subspecies are presented. Based on analyses of rDNA sequences, the genus Arabidopsis as understood prior to this study is not only highly paraphyletic but also includes taxa that are distant in the Brassicaceae (unpublished results). This situation is particularly alarming given the central place that A. thaliana (L.) Heynhold plays in a myriad of current studies of genome evolution, developmental genetics, morphological evolution and development, etc. (Meyerowitz & Pruitt, 1985; Endress, 1992; Maluszynska & Heslop-Harrison, 1993; Crone & Lord, 1994; Larkin et al., 1994; Price et al., 1994; Teutonico & Osborn, 1994; Zhang & Lechowica, 1994; Tsukaya, 1995). Without a well-documented phylogenetic reconstruction of the genus and a congruent taxonomy, studies that make assumptions about its relations are likely to be inconclusive and to arrive at irrelevant conclusions. A number of recent studies (e.g., Maluszynska & Heslop-Harrison, 1993; Kamm et al., 1995; Tsukaya et al., 1997) have assumed close relationships between A. thaliana and species currently included in the genus that molecular data do not support (Price et al., 1994; O'Kane et al., 1995). The genus has been variously placed close to several other genera (Arabis, Braya, Cardaminopsis, Cymatocarpus, Drabopsis, Halimolobos, Hylandra, Microsisymbrium, Nasturtiopsis, and Neotorularia) based on morphological similarity (Hedge, 1968; Jafri, 1973; Al-Shehbaz, 1988; Ball, 1993). Rather than showing a close relationship among these genera, our work indicates that the circumscription of some of these genera and Arabidopsis is needed to better represent phylogenetic relationships. Recently, for instance, A. erysimoides has been moved to Erysimum (Al-Shehbaz, 1994), A. parvula (Schrenk) O. E. Schulz has been transferred to Thellungiella (Al-Shehbaz & O'Kane, 1995), and both A. gamosepala Hedge and A. tuemurnica Kuan & An have been placed in Neotorularia (Al-Shehbaz & O'Kane, 1997). The nomenclatural changes proposed here aim to align the taxonomy of Arabidopsis with the results of recent analyses of rDNA sequences (O'Kane et al., 1997) and on-going phylogenetic analyses. The changes given here were anticipated by both Hylander (1957) and Ball (1993). Hylander (1957: 602-603) stated that should Cardaminopsis and Arabidopsis be combined, Cardaminopsis must be dropped into the latter genus [Arabidopsis], the limits of which would thereby be considerably widened-or, perhaps more correctly, drawn in quite another way than e.g. by Schulz. Ball (1993: 322) echoed this by stating, It seems probable that Cardaminopsis should be combined with Arabidopsis, and some species of Arabidopsis may have to be removed from the enlarged genus. Furthermore, Jones (1964) suggested that Arabis cebennensis and A. pedemontana might better be placed in the genus Cardaminopsis (here Arabidopsis). These earlier morphological predictions are now strongly supported by two independent molecular studies: Price et al. (1994) using chloroplast DNA restriction site variation and rbcL gene sequences, and O'Kane et al. (1997 and unpublished) using nuclear rDNA sequences. Essentially, the nomenclatural changes proposed herein deal with the transfer of species from Cardaminopsis to Arabidopsis. Except for the nine species and five subspecies treated in this paper, all of the remaining 49 binomials variously assigned to Arabidopsis are excluded from the Work is in progress to assign those to other genera. Arabidopsis (DC.) Heynhold, in Holl & Heynhold, F1. Sachsen 1: 538. 1842; nom. cons. TYPE: Arabidopsis thaliana (L.) Heynhold. Cardaminopsis (C. A. Meyer) Hayek, F1. Steiermark 1: 477. 1908. Syn. nov. Basionym: Arabis sect. CardaNovoN 7: 323-327. 1997. This content downloaded from 207.46.13.128 on Tue, 06 Sep 2016 06:08:56 UTC All use subject to http://about.jstor.org/terms

Evolution and homology of bird pollination syndromes in Erythrina (Leguminosae)

Erythrina L. (Leguminosae: Phaseoleae) is a pantropical genus of over 100 species, all of which are either hummingbird or passerine pollinated. Phylogenetic hypotheses based on morphological and chloroplast DNA restriction site characters suggest that shifts from passerine to hummingbird pollination have occurred a minimum of four times in the genus. In hummingbird‐pollinated species the inflorescences are held upright, the flowers are arranged radially along the axis, and the narrow standard petal is conduplicately folded to form a pseudotube. In most of the passerine‐pollinated species, the inflorescences are held horizontally, the flowers are secund, and the standard petal is open so that the nectar and androecium are easily visible and accessible. Nectar amino acid concentrations and sucrose to hexose ratios are closely associated with pollination mode. Despite the general resemblance in flower and inflorescence morphology among species with the same pollination type, homology assessment reveals that petal morphology and size, and calyx and pollen morphology differ. Morphological characters, even if comprising modifications associated with adaptive pollination systems, therefore provide useful phylogenetic information.

Chloroplast DNA Analysis of Solanum bulbocastanum and S. cardiophyllum, and Evidence for the Distinctiveness of S. cardiophyllum Subsp. ehrenbergii (Sect. Petota)

Chloroplast DNA restriction site analysis was used to test hypotheses of sister group relationships of the diploid Mexican wild potato species Solanum bulbocastanum (ser. Bulbocastana) and S. cardiophyllum (ser. Pinnatisecta). A prior chloroplast DNA study including two accessions each of these two species supported them as sister taxa, widely separated from their presumed closest Mexican diploid species relatives. The present study samples more widely by examining 28 accessions of all three subspecies of S. bulbocastanum, and 20 accessions of all three subspecies of S. cardiophyllum. The results support two main clades exclusive of the outgroup: 1. Solanum bulbocastanum (all subspecies) and S. cardiophyllum (all subspecies except subsp. ehrenbergii), and 2. S. cardiophyllum subsp. ehrenbergii and members of ser. Pinnatisecta other than subsp. ehrenbergii. In the first clade, there was little resolution and some chloroplast types were shared by three subspecies of S. bulbocastanum and two subspecies of S. cardiophyllum. These results, in combination with an earlier chloroplast DNA study of the Mexican and Central American species, suggest that subsp. ehrenbergii is related to other members of ser. Pinnatisecta, possibly S. brachistotrichum or S. stenophyllidium, or alternatively that subsp. ehrenbergii obtained the chloroplast genome of a species in ser. Pinnatisecta by introgression.

Implications for the Phylogeny, Classification, and Biogeography of Solanum from cpDNA Restriction Site Variation

A phylogenetic analysis of Solanum based on chloroplast DNA restriction site variation confirms previous findings that Lycopersicon and Cyphomandra are derived from within Solanum. Three out of four Solanum subgenera with more than one representative in this analysis (Minon, Potatoe, Solanum) are found to be polyphyletic, suggesting that the subgeneric classification of the genus needs revision. Subgenus Leptostemonum is monophyletic within the context of our sampling. Three primary clades can be distinguished within Solanum. Clade I includes representatives of sections Archaesolanum, Dulcamara, Holophylla, Jasminosola- num, and Solanum. Clade II includes members of subgenus Potatoe (sections Basarthrum, Lycopersicon, and Petota). Clade III includes all representatives sampled from subg. Leptostemonum, sects. Allophyllum, Brevan- therum, Gemninata, Pseduocapsicum, and Cyphomandropsis, and species formerly assigned to Cyphomandra. Solanum as a whole and each of the three primary clades apppear to be New World in origin. Within Leptostemonum, African and Australian members are derived from New World ancestors.

Molecular and Morphological Data Provide Phylogenetic Resolution at Different Hierarchical Levels in Andira

Cladistic analyses of molecular (chloroplast DNA restriction site) and morphological data matrices for species of Andira, a genus of Neotropical woody plants, were performed. The molecular data provided considerable phylogenetic resolution but failed to resolve relationships within species groups. The morphological data produced large numbers of equally most-parsi- monious trees that yielded an entirely unresolved strict consensus tree. This lack of resolution reflects the small number of macromorphological characters in Andira that display discontinuous variation and thus are suitable for cladistic analysis. A directly combined cladistic analysis re- sulted in four far more highly resolved equally most-parsimonious trees. In contrast, combining the data sets using consensus techniques yielded poor phylogenetic resolution. The increased resolution of the directly combined analysis is explained by the molecular and morphological characters providing phylogenetic resolution at different hierarchical levels. The utility of the phy- logenetic framework provided by this combined analysis is demonstrated by using the phylogeny to study the evolution of dispersal syndromes in Andira. Patterns of morphological variation in Andira are typical of many species-rich genera of woody tropical plants, which are an important component of diversity in tropical vegetation. This example demonstrates that cladistic analysis of combined molecular and morphological data may greatly improve phylogeny reconstruction of these organisms. (Andira; bat dispersal; data combination; Leguminosae; rodent dispersal; tropical trees.)

Chloroplast DNA restriction site variation and RAPD‐analyses in Cochlearia (Brassicaceae): Biosystematics and speciation

Chloroplast DNA (cpDNA) restriction site variation (RFLP), has been analysed in the genus Cochlearia L. sections Cochlearia O.E. Schulz and Glaucocochlearia O.E. Schulz. Members of section Glaucocochlearia are clearly separated from those of section Cochlearia by 28 site mutations, thus supporting taxonomic arrangements into the two sections mentioned. RAPD studies provide further strong evidence for closer relationships among tax a within each section than between sections. CpDNA sequence divergence values in section Cochlearia are extremely low. Although 91 accessions representing 11 species have been analysed by 25 restriction enzymes, only four restriction site mutations were detected characterising six different cp genome types. Low levels of chloroplast DNA divergence would suggest that taxa of section Cochlearia are closely related and most likely have diversified recently. Polyploid Cochlearia offcinalis (2n=24), C. anglica (2n=48) and C. danica (2n=42) displayed infraspecific variation for cp genomes, which could be partly explained by multiple origin and by reticulate evolution. RAPD analyses (22 primers, 140 informative characters, ten taxa from 17 accessions) do not only strongly support these arguments but also helped to clarify speciation processes and biogeographic aspects in more detail. It is argued that South West Europe was the primary center of origin of the polyploids, second centers may be the British Isles, Iceland and locally restricted parts of Middle Europe.

Testing for Phylogenetic Conflict Among Molecular Data Sets in the Tribe Triticeae (Gramineae)

Four molecular data sets are available for the diploid intersterile genera of the cereal grain tribe Triticeae, and there are numerous differences among the four published trees. All six pairwise combinations of data sets were examined using tree comparisons, the incongruence length difference test, the Wilcoxon signed ranks test, and a permutation test. We describe some advantages, disadvantages, and properties of the different comparison methods. Test results provide no evidence for significant differences in the phylogenetic signal among the three nuclear data sets, with the exception of the placement of a single taxon. The chloroplast DNA restriction site data, however, support a significantly different tree, and the differences probably reflect a separate evolutionary history of the chloroplast genome.

Evolution of the Eastern Asian and Eastern North American Disjunct Genus Symplocarpus (Araceae): Insights from Chloroplast DNA Restriction Site Data

Chloroplast DNA (cpDNA) variation was surveyed with 20 restriction endonucleases for the eastern Asian and eastern North American disjunct genus Symplocarpus (Araceae). The cpDNA phylogeny reveals a sister group relationship between S. foetidus from eastern North America and S. renifolius from eastern Asia. The cpDNA divergence between the two intercontinental sister species is 0.61%, which suggests an estimated divergence time of 6.1 million years ago during the late Miocene. The Bering land bridge hypothesis is compatible with the estimated time of divergence for the migration of Symplocarpus between eastern Asia and North America. Furthermore, a single origin of the exothermic spadices in Symplocarpus is suggested by the phylogeny. The cpDNA data also provide independent support for the recognition of three species within the genus.

Phylogenetic Relationships in Cornus Based on Chloroplast DNA Restriction Sites: Implications for Biogeography and Character Evolution

Chloroplast DNA (cpDNA) restriction site analysis was used to elucidate phylogenetic relationships within the taxonomically controversial genus, Cornus. Twenty-nine species representing all major morphological subgroups of the genus were analyzed with 21 restriction endonucleases. Major lineages within Cornus identified by the cpDNA restriction site data are highly concordant with those suggested by both rbcL sequences and morphology. Relationships among these lineages are well-resolved by the restriction site data. The genus diverged early into two major clades: the blue-fruited group bearing blue or white fruits and the red-fruited group bearing red fruits. The blue-fruited clade further comprises two lineages: the alternate-leaved group and the opposite-leaved group. The red-fruited clade is composed of three lineages: the cornelian cherries, the dwarf dogwoods, and the big-bracted dogwoods, with the latter two as sister- groups. The cpDNA restriction site data also correlate closely with the evolution of chromosome number, morphology, and phytochemistry. Most notably, the chromosome number of n = 10 evolved twice in Cornuis, and the small, non-petaloid bracts in C. disciflora apparently represent a reversal to the non-showy state. Furthermore, the presence of iridoids in the red-fruited dogwoods apparently is a retention of the plesiomor- phic condition.

The origin and relationships of the pepino,Solanum muricatum (solanaceae): DNA restriction fragment evidence

The pepino (or pepino dulce:Solanum muricatum) is a domesticate, of interest because of its close relationship to tomatoes and potatoes, because it is enjoying increasing exposure in the international market, and because it is a cultigen with no known wild ancestor. Morphologically this South American native is a member of the Solanum sect. Basarthrum, and as such, is allied to a number of Andean wild species. Data from other studies are combined with results from restriction site analysis of chloroplast and nuclear ribosomal DNA to assay relationships and the potential origin of the pepino. The pepino may have existed in the wild previously and may be represented today only by the cultigen. However, if its ancestors are extant, three wild species—Solanum basendopogon (Peru),S. caripense (Costa Rica through Peru), S. tabanoense (Colombia and Ecuador)—emerge as most likely progenitors. Phylogenetic analyses of 61 accessions, including 27 of the pepino, dependent on chloroplast DNA (cpDNA) and nuclear ribosomal (rDNA) restriction site data show the pepino to be polymorphic, suggest independent origins for some of the cultivars, and most strongly supportS. tabanoense as the progenitor of the cultigen.Solanum caripense also may have been a direct ancestor of the pepino, or may have hybridized subsequent to its origin with the pepino to yield some of the haplotype variation. Similarly, S.cochoae may have hybridized with the pepino. There are no DNA characters supporting the involvement ofS. basendopogon in the origin.

Evolution of the Eastern Asian and Eastern North American disjunct genus Symplocarpus (Araceae): insights from chloroplast DNA restriction site data

Chloroplast DNA (cpDNA) variation was surveyed with 20 restriction endonucleases for the eastern Asian and eastern North American disjunct genus Symplocarpus (Araceae). The cpDNA phylogeny reveals a sister group relationship between S. foetidus from eastern North America and S. renifolius from eastern Asia. The cpDNA divergence between the two intercontinental sister species is 0.61%, which suggests an estimated divergence time of 6.1 million years ago during the late Miocene. The Bering land bridge hypothesis is compatible with the estimated time of divergence for the migration of Symplocarpus between eastern Asia and North America. Furthermore, a single origin of the exothermic spadices in Symplocarpus is suggested by the phylogeny. The cpDNA data also provide independent support for the recognition of three species within the genus.

Chloroplast DNA evidence of colonization, adaptive radiation, and hybridization in the evolution of the Macaronesian flora.

Most evolutionary studies of oceanic islands have focused on the Pacific Ocean. There are very few examples from the Atlantic archipelagos, especially Macaronesia, despite their unusual combination of features, including a close proximity to the continent, a broad range of geological ages, and a biota linked to a source area that existed in the Mediterranean basin before the late Tertiary. A chloroplast DNA (cpDNA) restriction site analysis of Argyranthemum (Asteraceae: Anthemideae), the largest endemic genus of plants of any volcanic archipelago in the Atlantic Ocean, was performed to examine patterns of plant evolution in Macaronesia. cpDNA data indicated that Argyranthemum is a monophyletic group that has speciated recently. The cpDNA tree showed a weak correlation with the current sectional classification and insular distribution. Two major cpDNA lineages were identified. One was restricted to northern archipelagos--e.g., Madeira, Desertas, and Selvagens--and the second comprised taxa endemic to the southern archipelago--e.g., the Canary Islands. The two major radiations identified in the Canaries are correlated with distinct ecological habitats; one is restricted to ecological zones under the influence of the northeastern trade winds and the other to regions that are not affected by these winds. The patterns of phylogenetic relationships in Argyranthemum indicate that interisland colonization between similar ecological zones is the main mechanism for establishing founder populations. This phenomenon, combined with rapid radiation into distinct ecological zones and interspecific hybridization, is the primary explanation for species diversification.

Reclassification of North American Haplopappus (Compositae: Astereae) Completed: Rayjacksonia gen. nov.

Rayjacksonia R. L. Hartman & M. A. Lane, gen. nov. (Compositae: Astereae), is named to accommodate the “phyllocephalus complex,” formerly of Haplopappus Cass. sect. Blepharodon DC. The new combinations are R. phyllocephalus (DC.) R. L. Hartman & M. A. Lane, R. annua (Rydb.) R. L. Hartman & M. A. Lane, and R. aurea (A. Gray) R. L. Hartman & M. A. Lane. This transfer completes the reclassification of the North American species of Haplopappus sensu Hall, leaving that genus exclusively South American. Rayjacksonia has a base chromosome number of x = 6. Furthermore, it shares abruptly ampliate disk corollas, deltate disk style-branch appendages, and corolla epidermal cell type, among other features, with Grindelia, Isocoma, Olivaea, Prionopsis, Stephanodoria, and Xanthocephalum. Phylogenetic analyses of morphological and chloroplast DNA restriction site data, taken together, demonstrate that these genera are closely related but distinct.

Reclassification of North American Haplopappus (Compositae: Astereae) completed: Rayjacksonia gen. nov.

Rayjacksonia R. L. Hartman & M. A. Lane, gen. nov. (Compositae: Astereae), is named to accommodate the “phyllocephalus complex,” formerly of Haplopappus Cass. sect. Blepharodon DC. The new combinations are R. phyllocephalus (DC.) R. L. Hartman & M. A. Lane, R. annua (Rydb.) R. L. Hartman & M. A. Lane, and R. aurea (A. Gray) R. L. Hartman & M. A. Lane. This transfer completes the reclassification of the North American species of Haplopappus sensu Hall, leaving that genus exclusively South American. Rayjacksonia has a base chromosome number of x = 6. Furthermore, it shares abruptly ampliate disk corollas, deltate disk style‐branch appendages, and corolla epidermal cell type, among other features, with Grindelia, Isocoma, Olivaea, Prionopsis, Stephanodoria, and Xanthocephalum. Phylogenetic analyses of morphological and chloroplast DNA restriction site data, taken together, demonstrate that these genera are closely related but distinct.